I have a few questions about this. I have been reading around and I am finding that there are a few of these out there, but most went out to a 3.1 before they turbocharged it. I was wondering if I could turbocharge the 2.8l without any internal work (for now) and get some decent power out of it. If you know of any archived threads out there with some good info on this let me know. or if you have any info yourself let me know.
also, what are my options for tuning? what are options for injectors?
Turbo Tech 101 ( Basic ) How a Turbo System Works Engine power is proportional to the amount of air and fuel that can get into the cylinders. All things being equal, larger engines flow more air and as such will produce more power. If we want our small engine to perform like a big engine, or simply make our bigger engine produce more power, our ultimate objective is to draw more air into the cylinder. By installing a Garrett turbocharger, the power and performance of an engine can be dramatically increased.
So how does a turbocharger get more air into the engine? Let us first look at the schematic below:
The components that make up a typical turbocharger system are:
The air filter (not shown) through which ambient air passes before entering the compressor (1) The air is then compressed which raises the air¡¯s density (mass / unit volume) (2) Many turbocharged engines have a charge air cooler (aka intercooler) (3) that cools the compressed air to further increase its density and to increase resistance to detonation After passing through the intake manifold (4), the air enters the engine¡¯s cylinders, which contain a fixed volume. Since the air is at elevated density, each cylinder can draw in an increased mass flow rate of air. Higher air mass flow rate allows a higher fuel flow rate (with similar air/fuel ratio). Combusting more fuel results in more power being produced for a given size or displacement After the fuel is burned in the cylinder it is exhausted during the cylinder¡¯s exhaust stroke in to the exhaust manifold (5) The high temperature gas then continues on to the turbine (6). The turbine creates backpressure on the engine which means engine exhaust pressure is higher than atmospheric pressure A pressure and temperature drop occurs (expansion) across the turbine (7), which harnesses the exhaust gas¡¯ energy to provide the power necessary to drive the compressor What are the components of a turbocharger?
The layout of the turbocharger in a given application is critical to a properly performing system. Intake and exhaust plumbing is often driven primarily by packaging constraints. We will explore exhaust manifolds in more detail in subsequent tutorials; however, it is important to understand the need for a compressor bypass valve (commonly referred to as a Blow-Off valve) on the intake tract and a Wastegates for the exhaust flow.
Other Components
Blow-Off (Bypass) Valves The Blow-Off valve (BOV) is a pressure relief device on the intake tract to prevent the turbo¡¯s compressor from going into surge. The BOV should be installed between the compressor discharge and the throttle body, preferably downstream of the charge air cooler (if equipped). When the throttle is closed rapidly, the airflow is quickly reduced, causing flow instability and pressure fluctuations. These rapidly cycling pressure fluctuations are the audible evidence of surge. Surge can eventually lead to thrust bearing failure due to the high loads associated with it. Blow-Off valves use a combination of manifold pressure signal and spring force to detect when the throttle is closed. When the throttle is closed rapidly, the BOV vents boost in the intake tract to atmosphere to relieve the pressure; helping to eliminate the phenomenon of surge.
Wastegates On the exhaust side, a Wastegates provides us a means to control the boost pressure of the engine. Some commercial diesel applications do not use a Wastegates at all. This type of system is called a free-floating turbocharger.
However, the vast majority of gasoline performance applications require a Wastegates. There are two (2) configurations of Wastegates, internal or external. Both internal and external Wastegates provide a means to bypass exhaust flow from the turbine wheel. Bypassing this energy (e.g. exhaust flow) reduces the power driving the turbine wheel to match the power required for a given boost level. Similar to the BOV, the Wastegates uses boost pressure and spring force to regulate the flow bypassing the turbine.
Internal Wastegates are built into the turbine housing and consist of a ¡°flapper¡± valve, crank arm, rod end, and pneumatic actuator. It is important to connect this actuator only to boost pressure; i.e. it is not designed to handle vacuum and as such should not be referenced to an intake manifold.
External Wastegates are added to the exhaust plumbing on the exhaust manifold or header. The advantage of external Wastegates is that the bypassed flow can be reintroduced into the exhaust stream further downstream of the turbine. This tends to improve the turbine¡¯s performance. On racing applications, this Wastegated exhaust flow can be vented directly to atmosphere.
Oil & Water Plumbing
The intake and exhaust plumbing often receives the focus leaving the oil and water plumbing neglected. Garrett ball bearing turbochargers require less oil than journal bearing turbos. Therefore an oil inlet restrictor is recommended if you have oil pressure over about 60 psig. The oil outlet should be plumbed to the oil pan above the oil level (for wet sump systems). Since the oil drain is gravity fed, it is important that the oil outlet points downward, and that the drain tube does not become horizontal or go ¡°uphill¡± at any point.
Following a hot shutdown of a turbocharger, heat soak begins. This means that the heat in the head, exhaust manifold, and turbine housing finds it way to the turbo¡¯s center housing, raising its temperature. These extreme temperatures in the center housing can result in oil coking.
To minimize the effects of heat soak-back, water-cooled center housings were introduced. These use coolant from the engine to act as a heat sink after engine shutdown, preventing the oil from coking. The water lines utilize a thermal siphon effect to reduce the peak heat soak-back temperature after key-off. The layout of the pipes should minimize peaks and troughs with the (cool) water inlet on the low side. To help this along, it is advantageous to tilt the turbocharger about 25¡ã about the axis of shaft rotation.
Many Garrett turbos are water-cooled for enhanced durability.
Which Turbocharger is Right for Me or more affectionately known as My Turbo & Me Selecting the proper turbocharger for your specific application requires many inputs. With decades of collective turbocharging experience, the Garrett Performance Distributors can assist in selecting the right turbocharger for your application.
The primary input in determining which turbocharger is appropriate is to have a target horsepower in mind. This should be as realistic as possible for the application. Remember that engine power is generally proportional to air and fuel flow. Thus, once you have a target power level identified, you begin to hone in on the turbocharger size, which is highly dependent on airflow requirements.
Other important factors include the type of application. An autocross car, for example, requires rapid boost response. A smaller turbocharger or smaller turbine housing would be most suitable for this application. While this will trade off ultimate power due to increased exhaust backpressure at higher engine speeds, boost response of the small turbo will be excellent.
Alternatively, on a car dedicated to track days, peak horsepower is a higher priority than low-end torque. Plus, engine speeds tend to be consistently higher. Here, a larger turbocharger or turbine housing will provide reduced backpressure but less-immediate low-end response. This is a welcome tradeoff given the intended operating conditions.
Selecting the turbocharger for your application goes beyond ¡°how much boost¡± you want to run. Defining your target power level and the primary use for the application are the first steps in enabling your Garrett Performance Distributor to select the right turbocharger for you. Journal Bearings vs. Ball Bearings The journal bearing has long been the brawn of the turbocharger, however a ball-bearing cartridge is now an affordable technology advancement that provides significant performance improvements to the turbocharger.
Ball bearing innovation began as a result of work with the Garrett Motorsports group for several racing series where it received the term the ¡®cartridge ball bearing¡¯. The cartridge is a single sleeve system that contains a set of angular contact ball bearings on either end, whereas the traditional bearing system contains a set of journal bearings and a thrust bearing
Journal Bearings Ball Bearings
Turbo Response ¨C When driving a vehicle with the cartridge ball bearing turbocharger, you will find exceptionally crisp and strong throttle response. Garrett Ball Bearing turbochargers spool up 15% faster than traditional journal bearings. This produces an improved response that can be converted to quicker 0-60 mph speed. In fact, some professional drivers of Garrett ball-bearing turbocharged engines report that they feel like they are driving a big, normally aspirated engine.
Tests run on CART turbos have shown that ball-bearings have up to half of the power consumption of traditional bearings. The result is faster time to boost which translates into better drivability and acceleration.
On-engine performance is also better in the steady-state for the Garrett Cartridge Ball Bearing
Reduced Oil Flow ¨C The ball bearing design reduces the required amount of oil required to provide adequate lubrication. This lower oil volume reduces the chance for seal leakage. Also, the ball bearing is more tolerant of marginal lube conditions, and diminishes the possibility of turbocharger failure on engine shut down.
Improved Rotordynamics and Durability ¨C The ball bearing cartridge gives better damping and control over shaft motion, allowing enhanced reliability for both everyday and extreme driving conditions. In addition, the opposed angular contact bearing cartridge eliminates the need for the thrust bearing commonly a weak link in the turbo bearing system.
Competitor Ball Bearing Options ¨C Another option one will find is a hybrid ball bearing. This consists of replacing only the compressor side journal bearing with a single angular contact ball bearing. Since the single bearing can only take thrust in one direction, a thrust bearing is still necessary and drag in the turbine side journal bearing is unchanged. With the Garrett ball bearing cartridge the rotor-group is entirely supported by the ball bearings, maximizing efficiency, performance, and durability.
Ball Bearings in Original Equipment ¨C Pumping up the MAZDASPEED Proteg¨¦¡¯s heart rate is a Garrett T25 turbocharger system. With Garrett technology on board, the vehicle gains increased acceleration without sacrificing overall efficiency and it has received many rave reviews from the world¡¯s top automotive press for it¡¯s unprecedented performance. 1. Wheel trim topic coverage
Trim is a common term used when talking about or describing turbochargers. For example, you may hear someone say "I have a GT2871R ' 56 Trim ' turbocharger. What is 'Trim?' Trim is a term to express the relationship between the inducer* and exducer* of both turbine and compressor wheels. More accurately, it is an area ratio.
* The inducer diameter is defined as the diameter where the air enters the wheel, whereas the exducer diameter is defined as the diameter where the air exits the wheel.
Based on aerodynamics and air entry paths, the inducer for a compressor wheel is the smaller diameter. For turbine wheels, the inducer it is the larger diameter (see Figure 1.)
Figure 1. Illustration of the inducer and exducer diameter of compressor and turbine wheels
Example #1: GT2871R turbocharger (Garrett part number 743347-2) has a compressor wheel with the below dimensions. What is the trim of the compressor wheel?
Example #2: GT2871R turbocharger (part # 743347-1) has a compressor wheel with an exducer diameter of 71.0mm and a trim of 48. What is the inducer diameter of the compressor wheel?
Exducer diameter = 71.0mm Trim = 48
The trim of a wheel, whether compressor or turbine, affects performance by shifting the airflow capacity. All other factors held constant, a higher trim wheel will flow more than a smaller trim wheel.
However, it is important to note that very often all other factors are not held constant. So just because a wheel is a larger trim does not necessarily mean that it will flow more.
2. Understanding housing sizing: A/R
A/R (Area/Radius) describes a geometric characteristic of all compressor and turbine housings. Technically, it is defined as:
the inlet (or, for compressor housings, the discharge) cross-sectional area divided by the radius from the turbo centerline to the centroid of that area (see Figure 2.).
Figure 2. Illustration of compressor housing showing A/R characteristic
The A/R parameter has different effects on the compressor and turbine performance, as outlined below.
Compressor A/R - Compressor performance is comparatively insensitive to changes in A/R. Larger A/R housings are sometimes used to optimize performance of low boost applications, and smaller A/R are used for high boost applications. However, as this influence of A/R on compressor performance is minor, there are not A/R options available for compressor housings.
Turbine A/R - Turbine performance is greatly affected by changing the A/R of the housing, as it is used to adjust the flow capacity of the turbine. Using a smaller A/R will increase the exhaust gas velocity into the turbine wheel. This provides increased turbine power at lower engine speeds, resulting in a quicker boost rise. However, a small A/R also causes the flow to enter the wheel more tangentially, which reduces the ultimate flow capacity of the turbine wheel. This will tend to increase exhaust backpressure and hence reduce the engine's ability to "breathe" effectively at high RPM, adversely affecting peak engine power.
Conversely, using a larger A/R will lower exhaust gas velocity, and delay boost rise. The flow in a larger A/R housing enters the wheel in a more radial fashion, increasing the wheel's effective flow capacity, resulting in lower backpressure and better power at higher engine speeds.
When deciding between A/R options, be realistic with the intended vehicle use and use the A/R to bias the performance toward the desired powerband characteristic.
Here's a simplistic look at comparing turbine housing geometry with different applications. By comparing different turbine housing A/R, it is often possible to determine the intended use of the system.
Imagine two 3.5L engines both using GT30R turbochargers. The only difference between the two engines is a different turbine housing A/R; otherwise the two engines are identical: 1. Engine #1 has turbine housing with an A/R of 0.63 2. Engine #2 has a turbine housing with an A/R of 1.06.
What can we infer about the intended use and the turbocharger matching for each engine?
Engine#1: This engine is using a smaller A/R turbine housing (0.63) thus biased more towards low-end torque and optimal boost response. Many would describe this as being more "fun" to drive on the street, as normal daily driving habits tend to favor transient response. However, at higher engine speeds, this smaller A/R housing will result in high backpressure, which can result in a loss of top end power. This type of engine performance is desirable for street applications where the low speed boost response and transient conditions are more important than top end power.
Engine #2: This engine is using a larger A/R turbine housing (1.06) and is biased towards peak horsepower, while sacrificing transient response and torque at very low engine speeds. The larger A/R turbine housing will continue to minimize backpressure at high rpm, to the benefit of engine peak power. On the other hand, this will also raise the engine speed at which the turbo can provide boost, increasing time to boost. The performance of Engine #2 is more desirable for racing applications than Engine #1 where the engine will be operating at high engine speeds most of the time.
3. Different types of manifolds (advantages/disadvantages log style vs. equal length)
There are two different types of turbocharger manifolds; cast log style (see Figure 3.) and welded tubular style (see Figure 4.).
Figure 3. Cast log style turbocharger manifold
Figure 4. Welded tubular turbocharger manifold
Manifold design on turbocharged applications is deceptively complex as there many factors to take into account and trade off
General design tips for best overall performance are to:
Maximize the radius of the bends that make up the exhaust primaries to maintain pulse energy Make the exhaust primaries equal length to balance exhaust reversion across all cylinders Avoid rapid area changes to maintain pulse energy to the turbine At the collector, introduce flow from all runners at a narrow angle to minimize "turning" of the flow in the collector For better boost response, minimize the exhaust volume between the exhaust ports and the turbine inlet For best power, tuned primary lengths can be used Cast manifolds are commonly found on OEM applications, whereas welded tubular manifolds are found almost exclusively on aftermarket and race applications. Both manifold types have their advantages and disadvantages. Cast manifolds are generally very durable and are usually dedicated to one application. They require special tooling for the casting and machining of specific features on the manifold. This tooling can be expensive.
On the other hand, welded tubular manifolds can be custom-made for a specific application without special tooling requirements. The manufacturer typically cuts pre-bent steel U-bends into the desired geometry and then welds all of the components together. Welded tubular manifolds are a very effective solution. One item of note is durability of this design. Because of the welded joints, thinner wall sections, and reduced stiffness, these types of manifolds are often susceptible to cracking due to thermal expansion/contraction and vibration. Properly constructed tubular manifolds can last a long time, however. In addition, tubular manifolds can offer a substantial performance advantage over a log-type manifold.
A design feature that can be common to both manifold types is a " DIVIDED MANIFOLD" , typically employed with " DIVIDED " or "twin-scroll" turbine housings. Divided exhaust manifolds can be incorporated into either a cast or welded tubular manifolds (see Figure 5. and Figure 6.).
Figure 5. Cast manifold with a divided turbine inlet design feature
Figure 6. Welded tubular manifold with a divided turbine inlet design feature
The concept is to DIVIDE or separate the cylinders whose cycles interfere with one another to best utilize the engine's exhaust pulse energy.
For example, on a four-cylinder engine with firing order 1-3-4-2, cylinder #1 is ending its expansion stroke and opening its exhaust valve while cylinder #2 still has its exhaust valve open (cylinder #2 is in its overlap period). In an undivided exhaust manifold, this pressure pulse from cylinder #1's exhaust blowdown event is much more likely to contaminate cylinder #2 with high pressure exhaust gas. Not only does this hurt cylinder #2's ability to breathe properly, but this pulse energy would have been better utilized in the turbine.
The proper grouping for this engine is to keep complementary cylinders grouped together-- #1 and #4 are complementary; as are cylinders #2 and #3.
Figure 7. Illustration of divided turbine housing
Because of the better utilization of the exhaust pulse energy, the turbine's performance is improved and boost increases more quickly.
4. Compression ratio with boost
Before discussing compression ratio and boost, it is important to understand engine knock, also known as detonation. Knock is a dangerous condition caused by uncontrolled combustion of the air/fuel mixture. This abnormal combustion causes rapid spikes in cylinder pressure which can result in engine damage.
Three primary factors that influence engine knock are:
Knock resistance characteristics (knock limit) of the engine: Since every engine is vastly different when it comes to knock resistance, there is no single answer to "how much." Design features such as combustion chamber geometry, spark plug location, bore size and compression ratio all affect the knock characteristics of an engine. Ambient air conditions: For the turbocharger application, both ambient air conditions and engine inlet conditions affect maximum boost. Hot air and high cylinder pressure increases the tendency of an engine to knock. When an engine is boosted, the intake air temperature increases, thus increasing the tendency to knock. Charge air cooling (e.g. an intercooler) addresses this concern by cooling the compressed air produced by the turbocharger Octane rating of the fuel being used: octane is a measure of a fuel's ability to resist knock. The octane rating for pump gas ranges from 85 to 94, while racing fuel would be well above 100. The higher the octane rating of the fuel, the more resistant to knock. Since knock can be damaging to an engine, it is important to use fuel of sufficient octane for the application. Generally speaking, the more boost run, the higher the octane requirement. This cannot be overstated: engine calibration of fuel and spark plays an enormous role in dictating knock behavior of an engine. See Section 5 below for more details.
Now that we have introduced knock/detonation, contributing factors and ways to decrease the likelihood of detonation, let's talk about compression ratio. Compression ratio is defined as:
or
where CR = compression ratio Vd = displacement volume Vcv = clearance volume
The compression ratio from the factory will be different for naturally aspirated engines and boosted engines. For example, a stock Honda S2000 has a compression ratio of 11.1:1, whereas a turbocharged Subaru Impreza WRX has a compression ratio of 8.0:1. There are numerous factors that affect the maximum allowable compression ratio. There is no single correct answer for every application. Generally, compression ratio should be set as high as feasible without encountering detonation at the maximum load condition. Compression ratio that is too low will result in an engine that is a bit sluggish in off-boost operation. However, if it is too high this can lead to serious knock-related engine problems.
Factors that influence the compression ratio include: fuel anti-knock properties (octane rating), boost pressure, intake air temperature, combustion chamber design, ignition timing, valve events, and exhaust backpressure. Many modern normally-aspirated engines have well-designed combustion chambers that, with appropriate tuning, will allow modest boost levels with no change to compression ratio. For higher power targets with more boost , compression ratio should be adjusted to compensate.
There are a handful of ways to reduce compression ratio, some better than others. Least desirable is adding a spacer between the block and the head. These spacers reduce the amount a "quench" designed into an engine's combustion chambers, and can alter cam timing as well. Spacers are, however, relatively simple and inexpensive.
A better option, if more expensive and time-consuming to install, is to use lower-compression pistons. These will have no adverse effects on cam timing or the head's ability to seal, and allow proper quench regions in the combustion chambers.
5. Air/Fuel Ratio tuning: Rich v. Lean, why lean makes more power but is more dangerous
When discussing engine tuning the 'Air/Fuel Ratio' (AFR) is one of the main topics. Proper AFR calibration is critical to performance and durability of the engine and it's components. The AFR defines the ratio of the amount of air consumed by the engine compared to the amount of fuel.
A 'Stoichiometric' AFR has the correct amount of air and fuel to produce a chemically complete combustion event. For gasoline engines, the stoichiometric , A/F ratio is 14.7:1, which means 14.7 parts of air to one part of fuel. The stoichiometric AFR depends on fuel type-- for alcohol it is 6.4:1 and 14.5:1 for diesel.
So what is meant by a rich or lean AFR? A lower AFR number contains less air than the 14.7:1 stoichiometric AFR, therefore it is a richer mixture. Conversely, a higher AFR number contains more air and therefore it is a leaner mixture.
Leaner AFR results in higher temperatures as the mixture is combusted. Generally, normally-aspirated spark-ignition (SI) gasoline engines produce maximum power just slightly rich of stoichiometric. However, in practice it is kept between 12:1 and 13:1 in order to keep exhaust gas temperatures in check and to account for variances in fuel quality. This is a realistic full-load AFR on a normally-aspirated engine but can be dangerously lean with a highly-boosted engine.
Let's take a closer look. As the air-fuel mixture is ignited by the spark plug, a flame front propagates from the spark plug. The now-burning mixture raises the cylinder pressure and temperature, peaking at some point in the combustion process.
The turbocharger increases the density of the air resulting in a denser mixture. The denser mixture raises the peak cylinder pressure, therefore increasing the probability of knock. As the AFR is leaned out, the temperature of the burning gases increases, which also increases the probability of knock. This is why it is imperative to run richer AFR on a boosted engine at full load. Doing so will reduce the likelihood of knock, and will also keep temperatures under control.
There are actually three ways to reduce the probability of knock at full load on a turbocharged engine: reduce boost, adjust the AFR to richer mixture, and retard ignition timing. These three parameters need to be optimized together to yield the highest reliable power.
Turbo Tech 103 (Expert) This article is a bit more involved and will describe parts of the compressor map, how to estimate pressure ratio and mass flow rate for your engine, and how to plot the points on the maps to help choose the right turbocharger. Have your calculator handy!!
1 Parts of the Compressor Map: ◊ The compressor map is a graph that describes a particular compressor¡¯s performance characteristics, including efficiency, mass flow range, boost pressure capability, and turbo speed. Shown below is a figure that identifies aspects of a typical compressor map:
◊ Pressure Ratio
Pressure Ratio ( ) is defined as the Absolute outlet pressure divided by the Absolute inlet pressure. Where: = Pressure Ratio P2c = Compressor Discharge Pressure P1c = Compressor Inlet Pressure It is important to use units of Absolute Pressure for both P1c and P2c. Remember that Absolute Pressure at sea level is 14.7 psia (in units of psia, the a refers to ¡°absolute¡±). This is referred to as standard atmospheric pressure at standard conditions. Gauge Pressure (in units of psig, the g refers to ¡°gauge¡±) measures the pressure above atmospheric, so a gauge pressure reading at atmospheric conditions will read zero. Boost gauges measure the manifold pressure relative to atmospheric pressure, and thus are measuring Gauge Pressure. This is important when determining P2c. For example, a reading of 12 psig on a boost gauge means that the air pressure in the manifold is 12 psi above atmospheric pressure. For a day at standard atmospheric conditions,
12 psig + 14.7 psia = 26.7 psi absolute pressure in the manifold
The pressure ratio at this condition can now be calculated:
26.7 psia / 14.7 psia = 1.82 However, this assumes there is no adverse impact of the air filter assembly at the compressor inlet. In determining pressure ratio, the absolute pressure at the compressor inlet (P2c) is often LESS than the ambient pressure, especially at high load. Why is this? Any restriction (caused by the air filter or restrictive ducting) will result in a ¡°depression,¡± or pressure loss, upstream of the compressor that needs to be accounted for when determining pressure ratio. This depression can be 1 psig or more on some intake systems. In this case P1c on a standard day is:
14.7psia ¨C 1 psig = 13.7 psia at compressor inlet
Taking into account the 1 psig intake depression, the pressure ratio is now:
(12 psig + 14.7 psia) / 13.7 psia = 1.95.
That¡¯s great, but what if you¡¯re not at sea level? In this case, simply substitute the actual atmospheric pressure in place of the 14.7 psi in the equations above to give a more accurate calculation. At higher elevations, this can have a significant effect on pressure ratio. For example, at Denver¡¯s 5000 feet elevation, the atmospheric pressure is typically around 12.4 psia. In this case, the pressure ratio calculation, taking into account the intake depression, is:
(12 psig + 12.4 psia) / (12.4 psia ¨C 1 psig) = 2.14 Compared to the 1.82 pressure ratio calculated originally, this is a big difference.
As you can see in the above examples, pressure ratio depends on a lot more than just boost.
◊ Mass Flow Rate
Mass Flow Rate is the mass of air flowing through a compressor (and engine!) over a given period of time and is commonly expressed as lb/min (pounds per minute). Mass flow can be physically measured, but in many cases it is sufficient to estimate the mass flow for choosing the proper turbo. Many people use Volumetric Flow Rate (expressed in cubic feet per minute, CFM or ft3/min) instead of mass flow rate. Volumetric flow rate can be converted to mass flow by multiplying by the air density. Air density at sea level is 0.076lb/ft3 What is my mass flow rate? As a very general rule, turbocharged gasoline engines will generate 9.5-10.5 horsepower (as measured at the flywheel) for each lb/min of airflow. So, an engine with a target peak horsepower of 400 Hp will require 36-44 lb/min of airflow to achieve that target. This is just a rough first approximation to help narrow the turbo selection options. ◊ Surge Line
Surge is the left hand boundary of the compressor map. Operation to the left of this line represents a region of flow instability. This region is characterized by mild flutter to wildly fluctuating boost and ¡°barking¡± from the compressor. Continued operation within this region can lead to premature turbo failure due to heavy thrust loading. Surge is most commonly experienced when one of two situations exist. The first and most damaging is surge under load. It can be an indication that your compressor is too large. Surge is also commonly experienced when the throttle is quickly closed after boosting. This occurs because mass flow is drastically reduced as the throttle is closed, but the turbo is still spinning and generating boost. This immediately drives the operating point to the far left of the compressor map, right into surge. Surge will decay once the turbo speed finally slows enough to reduce the boost and move the operating point back into the stable region. This situation is commonly addressed by using a Blow-Off Valves (BOV) or bypass valve. A BOV functions to vent intake pressure to atmosphere so that the mass flow ramps down smoothly, keeping the compressor out of surge. In the case of a recirculating bypass valve, the airflow is recirculated back to the compressor inlet.
A Ported Shroud compressor (see Fig. 2) is a feature that is incorporated into the compressor housing. It functions to move the surge line further to the left (see Fig. 3) by allowing some airflow to exit the wheel through the port to keep surge from occurring. This provides additional useable range and allows a larger compressor to be used for higher flow requirements without risking running the compressor into a dangerous surge condition. The presence of the ported shroud usually has a minor negative impact on compressor efficiency.
◊ The Choke Line is the right hand boundary of the compressor map. For Garrett maps, the choke line is typically defined by the point where the efficiency drops below 58%. In addition to the rapid drop of compressor efficiency past this point, the turbo speed will also be approaching or exceeding the allowable limit. If your actual or predicted operation is beyond this limit, a larger compressor is necessary.
◊ Turbo Speed Lines are lines of constant turbo speed. Turbo speed for points between these lines can be estimated by interpolation. As turbo speed increases, the pressure ratio increases and/or mass flow increases. As indicated above in the choke line description, the turbo speed lines are very close together at the far right edge of the map. Once a compressor is operating past the choke limit, turbo speed increases very quickly and a turbo over-speed condition is very likely.
◊ Efficiency Islands are concentric regions on the maps that represent the compressor efficiency at any point on the map. The smallest island near the center of the map is the highest or peak efficiency island. As the rings move out from there, the efficiency drops by the indicated amount until the surge and choke limits are reached.
2. Plotting Your Data on the Compressor Map In this section, methods to calculate mass flow rate and boost pressure required to meet a horsepower target are presented. This data will then be used to choose the appropriate compressor and turbocharger. Having a horsepower target in mind is a vital part of the process. In addition to being necessary for calculating mass flow and boost pressure, a horsepower target is required for choosing the right fuel injectors, fuel pump and regulator, and other engine components.
◊ Estimating Required Air Mass Flow and Boost Pressures to reach a Horsepower target.
¡¤ Things you need to know: ¡¤ Horsepower Target ¡¤ Engine displacement ¡¤ Maximum RPM ¡¤ Ambient conditions (temperature and barometric pressure. Barometric pressure is usually given as inches of mercury and can be converted to psi by dividing by 2)
¡¤ Things you need to estimate: ¡¤ Engine Volumetric Efficiency. Typical numbers for peak Volumetric Efficiency (VE) range in the 95%-99% for modern 4-valve heads, to 88% - 95% for 2-valve designs. If you have a torque curve for your engine, you can use this to estimate VE at various engine speeds. On a well-tuned engine, the VE will peak at the torque peak, and this number can be used to scale the VE at other engine speeds. A 4-valve engine will typically have higher VE over more of its rev range than a two-valve engine.
¡¤ Intake Manifold Temperature. Compressors with higher efficiency give lower manifold temperatures. Manifold temperatures of intercooled setups are typically 100 - 130 degrees F, while non-intercooled values can reach from 175-300 degrees F.
¡¤ Brake Specific Fuel Consumption (BSFC). BSFC describes the fuel flow rate required to generate each horsepower. General values of BSFC for turbocharged gasoline engines range from 0.50 to 0.60 and higher. The units of BSFC are Lower BSFC means that the engine requires less fuel to generate a given horsepower. Race fuels and aggressive tuning are required to reach the low end of the BSFC range described above.
For the equations below, we will divide BSFC by 60 to convert from hours to minutes.
To plot the compressor operating point, first calculate airflow:
Where: ¡¤ Wa = Airflowactual (lb/min) ¡¤ HP = Horsepower Target (flywheel) ¡¤ = Air/Fuel Ratio ¡¤ = Brake Specific Fuel Consumption ( ) ¡Â 60 (to convert from hours to minutes) EXAMPLE:
I have an engine that I would like to use to make 400Hp, I want to choose an air/fuel ratio of 12 and use a BSFC of 0.55. Plugging these numbers into the formula from above:
of air.
Thus, a compressor map that has the capability of at least 44 pounds per minute of airflow capacity is a good starting point.
Note that nowhere in this calculation did we enter any engine displacement or RPM numbers. This means that for any engine, in order to make 400 Hp, it needs to flow about 44 lb/min (this assumes that BSFC remains constant across all engine types).
Naturally, a smaller displacement engine will require more boost or higher engine speed to meet this target than a larger engine will. So how much boost pressure would be required?
◊ Calculate required manifold pressure required to meet the horsepower, or flow target:
Where:
¡¤ MAPreq = Manifold Absolute Pressure (psia) required to meet the horsepower target ¡¤ Wa = Airflowactual(lb/min) ¡¤ R = Gas Constant = 639.6 ¡¤ Tm = Intake Manifold Temperature (degrees F) ¡¤ VE = Volumetric Efficiency ¡¤ N = Engine speed (RPM) ¡¤ Vd = engine displacement (Cubic Inches, convert from liters to CI by multiplying by 61.02, ex. 2.0 liters * 61.02 = 122 CI)
EXAMPLE:
To continue the example above, let¡¯s consider a 2.0 liter engine with the following description:
¡¤ Wa = 44 lb/min as previously calculated ¡¤ Tm = 130 degrees F ¡¤ VE = 92% at peak power ¡¤ N = 7200 RPM ¡¤ Vd = 2.0 liters * 61.02 = 122 CI
= 41.1 psia (remember, this is absolute pressure. Subtract atmospheric pressure to get gauge pressure (aka boost):
As a comparison let¡¯s repeat the calculation for a larger displacement 5.0L (4942 cc/302 CI) engine.
Where:
¡¤ Wa = 44 lb/min as previously calculated ¡¤ Tm = 130 degrees F ¡¤ VE = 85% at peak power (it is a pushrod V-8) ¡¤ N = 6000 RPM ¡¤ Vd = 4.942*61.02= 302 CI
= 21.6 psia (or 6.9 psig boost)
This example illustrates in order to reach the horsepower target of 400 hp, a larger engine requires lower manifold pressure but still needs 44lb/min of airflow. This can have a very significant effect on choosing the correct compressor.
With Mass Flow and Manifold Pressure, we are nearly ready to plot the data on the compressor map. The next step is to determine how much pressure loss exists between the compressor and the manifold. The best way to do this is to measure the pressure drop with a data acquisition system, but many times that is not practical.
Depending upon flow rate, charge air cooler characteristics, piping size, number/quality of the bends, throttle body restriction, etc., the plumbing pressure drop can be estimated. This can be 1 psi or less for a very well designed system. On certain restrictive OEM setups, especially those that have now higher-than-stock airflow levels, the pressure drop can be 4 psi or greater.
For our examples we will assume that there is a 2 psi loss. So to determine the Compressor Discharge Pressure (P2c), 2 psi will be added to the manifold pressure calculated above.
Where:
¡¤ P2c = Compressor Discharge Pressure (psia) ¡¤ MAP = Manifold Absolute Pressure (psia) ¡¤ ¦¤Ploss = Pressure Loss Between the Compressor and the Manifold (psi)
For the 2.0 L engine:
= 43.1 psia
For the 5.0 L engine:
= 23.6 psia
Remember our discussion on inlet depression in the Pressure Ratio discussion earlier, we said that a typical value might be 1 psi, so that is what will be used in this calculation. For this example, assume that we are at sea level, so ambient pressure is 14.7 psia.
We will need to subtract the 1 psi pressure loss from the ambient pressure to determine the Compressor Inlet Pressure (P1).
Where:
¡¤ P1c = Compressor Inlet Pressure (psia) ¡¤ Pamb = Ambient Air pressure (psia) ¡¤ ¦¤Ploss = Pressure Loss due to Air Filter/Piping (psi)
P1c = 14.7 - 1
= 13.7 psia
With this, we can calculate Pressure Ratio () using the equation.
For the 2.0 L engine:
= 3.14
For the 5.0 L engine:
= 1.72
We now have enough information to plot these operating points on the compressor map. First we will try a GT2860RS. This turbo has a 60mm, 60 trim compressor wheel.
Clearly this compressor is too small, as both points are positioned far to the right and beyond the compressor¡¯s choke line.
Another potential candidate might be the GT3076R. This turbo has a 76mm, 56 trim compressor wheel:
This is much better; at least both points are on the map! Let¡¯s look at each point in more detail.
For the 2.0L engine this point is in a very efficient area of the map, but since it is in the center of the map, there would be a concern that at a lower engine speeds that it would be near or over the surge line. This might be ok for a high-rpm-biased powerband that might be used on a racing application, but a street application would be better served by a different compressor.
For the 5.0L engine, this looks like a very good street-biased powerband, with the lower engine speeds passing through the highest efficiency zone on the map, and plenty of margin to stay clear of surge. One area of concern would be turbo overspeed when revving the engine past peak power. A larger compressor would place the operating point nearer to the center of the map and would give some additional benefit to a high-rpm-biased powerband. We¡¯ll look at a larger compressor for the 5.0L after we figure out a good street match for the 2.0L engine.
So now lets look at a GT3071R, which uses a 71mm, 56 trim compressor wheel.
For the 2.0L engine, this is a much more mid-range-oriented compressor. The operating point is shifted a bit towards the choke side of the map and this provides additional surge margin. The lower engine speeds will now pass through the higher efficiency zones and give excellent performance and response.
For the 5.0L engine, the compressor is clearly too small and would not be considered.
Now that we have arrived at an acceptable compressor for the 2.0L engine, lets calculate a lower rpm point to put on the map to better get a feel for what the engine operating line will look like. We can calculate this using the following formula:
We¡¯ll choose the engine speed at which we would expect to see peak torque, based on experience or an educated guess. In this case we¡¯ll choose 5000rpm.
Where:
¡¤ Wa = Airflowactual (lb/min) ¡¤ MAP = Manifold Absolute Pressure (psia) =35.1 psia ¡¤ R = Gas Constant = 639.6 ¡¤ Tm = Intake Manifold Temperature (degrees F) =130 ¡¤ VE = Volumetric Efficiency = 0.98 ¡¤ N = Engine speed (RPM) = 5000rpm ¡¤ Vd = engine displacement (Cubic Inches, convert from liters to CI by multiplying by 61, ex. 2.0 liters * 61 = 122 CI)
= 34.1 lb/min
Plotting this on the GT3071R compressor map gives the following operating points.
This gives a good representation of the operating line at that boost level, which is well suited to this map. At engine speeds lower than 5000rpm the boost pressure will be lower, and the pressure ratio would be lower, to keep the compressor out of surge.
Back to the 5.0 L engine. Let¡¯s look at a larger compressor¡¯s map. This time we will try a GT3582R with an 82mm, 56 trim compressor.
Here , compared to the GT3076R, we can see that this point is not quite so deep into choke and will give better high-rpm performance than the 76mm wheel. A further increase in wheel size would give even better high-rpm performance, but at the cost of low- and mid-range response and drivability.
Hopefully this has given a basic idea of what a compressor map displays and how to choose a compressor. As you can see, a few simple estimations and calculations can provide a good basis for compressor selection. If real data is available to be substituted in place of estimation, more accurate results can be generated.
Wow, that was a heck of allot of information. Yes, you can turbo a 2.8L. "Decent" power is relative, what is decent for you? No internal mods for a high-mileage 2.8L? Don't plan on much boost, like 5psi tops. And the engine's life expectancy will drop accordingly. As a general rule, double the amount of air going into an engine will double the power, assuming fuel to match. (Very general rule as many things will decide actual numbers) So you will need 15psi (double atmospheric pressure) to get 280 HP assuming everything else is perfect (which it is not). You will need internal mods before even thinking of running that much boost.
Might be easier to just give the link to the garret site instead of copying and pasting that $hit.
actually i thought it was a great idea that he posted that all here instead of a link. this topic will eventually be archived for future info seekers. how long do you think a link will last before it is dead? most dont even last a year before they are no good. I can't remember how many searches i have done on PFF where good info is given in a post via a link that is dead, thus making the thread useless.
[This message has been edited by FieroMonkey (edited 02-15-2007).]
well thanks for the info, I read through it all and im still not sure when a T25 will hit full boost and plateu. I have a 2.2 T and I have an extra garetT T25 turbo for it with very little shaft play sitting on my desk here. I have the knowhow to do the kit, and I have 5 suite mates here at school and 4 of them have had or have turbocharged hondas with custom kits (i think they are stupid for putting that much money into a honda, but they know their stuff when it comes to turbocharging). one of them was pushing 450hp with CAM2 at 30psi. Now I know I wont get anywhere near that in a fiero 2.8, and if I do I will probably be doing a tranny swap. Im looking for over 200hp. 250hp would be nice but i realize pushing 250 will probably= engine work in the near future. but I can handle that too. Im going to school for automotive and we have a solid engines program with some good equipment.
heres my thing... I will have a good running 2.8L with about 80k on the clock. Its not enough power for me, plus im sick of my roomates talking trash about these things and me having nothing to back it up with. I know their cars; and 140hp isnt going to cut it. Even if its right wheel drive HP.
that 140hp is at the crank..about 110hp at the wheels on a 100% stock 2.8. Mine with aftermarket exhaust and ported manifolds put 115.8 hp down to the wheels. Over 200hp to the wheels out of a 2.8 Is alot to ask from that motor. I would suggest picking up a 3.4 block from a 93-95 f-body. everything will bolt up from the 2.8, except the starter will need to be moved to the other side. It's a much stronger block, better oiling system. and it's rated at about 160hp and 190ftlbs of torque so put a mild cam in and some different pistons and rockers and then turbo that and you should be pretty darn close, if not over your 200hp mark, and with the motor being stronger you could probably run a bit more boost than you could on the 2.8 with 80k
My turbo 2.8 has lots of mods but aside from a beter oil pump and new bew bearings on a reground the bottom end is stock. It has nice power and spoils so quick it almost seems like it donesnt have a turbo. Running only 7lbs boost but with 9.o:1 pistons and not the the 8.5:1 stcok pistons. It also uses a cut-down MR2 Intercooler, fan and Blowe-off. If you do go with your 2.8, drill out the oil passages on the crank.
I am so so sorry I did do an overload. on the thred The next is from extinsive junk yard search and use. I have tried the twin turbo Sabb 9000 They spool late 3800 prm and I have never seen them exhaust stack. the BOV if a great OEM product. 10 psi max till WG pops. The Audi Quatro 5000 is good for single turbo spools at 4200 rpm and will never exhaust stack 14 psi
The best is the chrysler Labaron garrett 2.2 and 2.4 turbo cars. The 2.2 Waste Gate pops at 11 psi the 2.4 pops at 15 psi 2.2 is 42 ar and the 2.4 is 43 ar. They both spool at 2800 rpm and exhaust stack at 6500 rpm On the Fiero 2.8 They spool at 2425 rpm and exhaust stack at 6025 rpm. they are ball bearings oil and water cooled, so they last. The exhaust stacking is good as they will not let engine over rev past 6100 rpm.
I used the above with 100 hp NOS in my stock 2.8 with 125k on it. it never over reved and run very good. True NOS was way to much should have used 50 hp. On the chasis dyno it hit 378 rear wheel HP and 402 lb torque. way to much NOS. W/O NOS it run 287 rwhp and 312 lb torque both at 4275 rpm.
I did blow it up on the dyno when I swaped in 150 hp jets. Lie NOS I Hit 504 HP at 3400 rpm when it came apart. And actualy I drove it home in a cloud of smoke 15 miles on 2 plugs 4 were burned off to the threds and 2 cyl were swapping coolant somthing fierce. The bottom held up the trans held up the clutch took a beating. Good luck
Just a thought not to try and suck some cash from you. I have 2 garrett T3ho turbo's water and oil cooled ball bearing. They have both been on Fieros. They were junk yard turbo's $75 and a rebuild for $125 They have O2 bungs stock location both from labaron daytona's. 5 speeds. 20 to 30 hours of use. absolutly no slop or any end play at all. looking to get $50 and shipping for each. They are heavy I bet 25 30 lb. I will send a free Intercooler from a turbo mustang or XR4TI they fit perfect in a coups engine vent location. there like 15 lb.
Forget about dual turbos (way too little space to do right and an overkill), just stay with a sane low boost and you'll still find the car a lot more fun to drive and it will live. And here's the biggie, go with a kit, dont DIY it! If your're dont have expertise with turbos (sounds like the case) chances are slim you'll pick the right parts and even slimmer that you wont pull your hair out.
If I had the money for a turbo kit, the 3800 SC in my driveway would be going into the car. I can DIY and I know I can do it very cheap DIY. the question is if I can get the performance that I want out of it without resorting to engine work, which again, if im dropping the cradle, I will probably just end up putting the 3800 in it. I have so many options here, I am just trying to weigh out what path I want to go down.
Formula 400 seems to have the same idea I do, make due with what you have, and what you can get for cheap and thats what I am trying to do here. By the way Formula 400, how did you run enough fuel to support boost and nitrous? what were you running for a fuel system/ tune?
If you want, I'll give u a ride in my 3800sc. You'll change your mind as far as the turbo. Unless you want to stay stock engine, that is.
The 3800sc has a lot of potential. The 200hp you'll reach on stock internals will be stressed for anything more. You can easily put down 240 with the 3800sc and thats just the beginning.
[This message has been edited by Jncomutt (edited 02-16-2007).]
The twin turbo Sabb I never dynoed sorry and I no longer have that car."Hang my head in shame" The owner wraped it up in a high speed run from the cops."fool"
The quatro turbo I sold on ebay it was tooo much turbo and the rebuild cost was $375 I did dyno it and it got a max HP at 6250 rpm of 173hp torque was way off at 183 lb at 5750. I don't like to spin engines that high.
The chrysler labaron daytona is a 1 turbo application not twin. It spools very fast yes and it exhaust stacks fast to. The turbo is not designed for the 2.8 at all but I tried it and love it. If your an all out racer you will not like it. You will never get more than 130 mph before it holds you back that is more than to fast for street use. You will never see low 10s at 1/4 mile. Sorry.
This application is "as I would say" stop sign racer. hitting 120 MPH is enough in my book. for the street. 1/4 mile times on a twin turbo VIA "Labaron turbo's" big hit of NOS on a 307 sbc tall 29-11-15 tires et drag will net you 8.92 167 mph not for the faint of heart or cheap pockets. The trans must be gone thru and almost all replaced with new High end parts cyro all of it. My trans rebuild was $1000.00 for parts and labor cyro was almost $900 center force clutch is not cheap. I had a v8 adapter that I had copied to fit the sub frame mounting solid as well as a front engine mount solid as well. trans hangs freely with only a torshion/ custom dog bone to keep it in place. all of this not easy or cheap. This Fiero is lost now. My cousin wadded it up on a late night when he decided to play night ridder.
In garage now is 88 formula 400 SBC same trans Holley projection efi and a Holset ht 60 turbo port injected NOS base plate injected NOS and a single port injected burn out box NOS. I hope when done if I can ever find all the grimlins. It will pull high 6 low 7 second passes at the 1/4 mile. All have called this my unicorn. Mytilogical car lol spelling sorry.
JMO Good luck
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01:25 PM
vafierro Member
Posts: 349 From: Newport News, VA Registered: Oct 2005
If you're still looking to see those turbos let me know. I can consider using both on my 4.9 build with twin intercoolers! Would look very 288GTO Ferrari I think...
I have the Design 1 (www.design1com) stage 2 on my stock 2.8. Kevin did a great job with this complete kit. 70K+ miles and no problems. Smoked 3800s/c on tracks in NJ and MD. Avendagor has seen this car on the track @ Watkins Glen. D1 turbos are fast, fun, and dependable.
5.9 = 359.9 360ci Max rpm at given boost 3850 100% volumetric efficiency cfm Required 401
4.9 = 298 300 CI Max rpm at given boost 6000 100% volumetric efficiency cfm required 520 at 77% 401 cfm
Using the 5.9 turbo you will exhaust stack at 4850 rpm
2.2 2.4 turbo 2.2 = 135 CI 6500 rpm at 100% VE = 253cfm 2.4 = 146 CI 6500 rpm at 100% VE = 274cfm
twin turbo application at 5830 rpm exhaust stacking on a 4.9 300 CI at 100% vel = 506 cfm
lets see the spool times and rpm versa boot psi
5.9 spools at 1450 rpm in stock dodge form at 8 psi 9psi at 1800 rpm 10 psi at 2000 rpm 11 psi at 2250 rpm 12 psi at 2325 rpm it takes awhile to get to 13 psi at 3250 rpm full boost at 3400 rpm 14 psi the Waste gate flutters at 3600 rpm and full open at 4000 rpm
lets apply this to your 4.9 the boost will come on at 1745 8 psi ramp up to 4861 true rpm when the waste gate blows Exhaust stacking true Max rpm 4334 rpm at full boost
OK this is not bad at all this would make a very good stop sign runner. you will never see 120MPH with out big tire
OK the Twin turbo lets look at it like 4.4 motor or 4.8 motor turbo spools at 4psi at 2150 rpm 6psi 2400 8psi at 3000 10psi at 3400 12 psi at 3600 14psi at 4200 waste gate flutter at 5250 full boost 15psi waste gate full open at 6000 rpm
on the 4.9 spool at true 1930rpm 4psi Max boost at true 4714 rpm 14 psi exhaust stacking Waste gate opens at true 5836rpm 15psi
not bad not bad at all a little high on the rpm map in my book but still good. you now need to weigh the cost factor twin cost $200 shipped fab work lets say $300 not to bad for $500 or a little more
Good luck v8fiero1988@aol.com
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07:08 PM
Firefighter Member
Posts: 1407 From: Southold, New York, USA Registered: Nov 2004
Well, 250 hp is not possible on a stock 2.8 with 80K on it, using any turbo. Oh, you will get 250 hp for about 5 seconds and then you will need a new engine, but the turbocharger will still be good. Turbocharging a good stock 2.8 gets you this, using a Garrett T/3:
At between 7.5 to 8 lbs. of boost; - 200 hp (engine hp) Over 200 ft. lbs. of torque 0-60 in less than 7 seconds Your basic overall acceleration will increase by 24% throughout acceleration range Intake air flow improvement of 51% Average increase in intake air temperature 94 degrees. With an intercooler, you can cool the increase in air temp. by 50% Top speed of, I don't know; but no less than it is now Ed
Jncomutt, I might take you up on that offer next time im home. What series 3800 do you have? mine is a series 1, OBD I, there is alot of information for OBD II swaps but i was looking a while ago and i couldnt find much for OBD1 swaps.
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07:48 PM
riverrat Member
Posts: 168 From: kansas city ks Registered: Oct 2004
How would one of those T3ho turbos work on a roller-cam 3400 block, 2.8/3.4 heads, turbo located in place of the muffler (aka STS Turbo style). I know the compression is only going to be about 7.66:1. Could I just run higher boost, should I use a larger turbo, any recommendations on what to look for? If one of those T3ho'swill work good, I am interested in helping you lose one.
Rjblaze I love to sell you a turbo but your talking about 1 liter more than turbo was designed for Thats 61 cubic inches I will do the math let me see After first math equasion I get a big no no exhaust stacking actual true 4238 rpm That is always my first test. 207.4 cubic in thats alot 140 to 160 ci is best math tells me spool 1421rpm at 4psi its looking ugly after that 1702 rpm 6psi 2125 10 psi 2408 rpm at 12 psi 2550 rpm at 14 psi 2875 rpm waste gate will flutter pushing 15 psi 3230 rpm full bost waste gate wide open
Most people do not understand exhaust stacking that is when turbo and waste gate can no longer handle any more. no they dont blow unless you hold foot feed wide open and have no regard for safe rules then after 5 or so min the turbo will grenade thus taking out engine.
riverrat off the top of my head I can not recall STI engine size let me do some searching for info EJ22 or EJ25 or EJ257 http://www.gruppe-s.com/Subaru/subeng.htm GT35r .63 .83 ar 650HP
The T30ho is a close second well 4th place it has no raiting for this engine as a stock replacement.
For a high tech engine doing a junk yard turbo swap is a bad idea
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12:47 AM
Firefighter Member
Posts: 1407 From: Southold, New York, USA Registered: Nov 2004
Jrgiehc - Am I to understand that after all these good folks have given you reams of turbo and other advice, that you are actually thinking about a 3800 swap? Let me ask you a few questions? 1. Why would you want to put in a 3800 and have a much cleaner looking installation than any turbo? 2. Why would you want a 3800 with better gas mileage and greater acceleration than any turbo installation would give you? 3. Why would you not want to constantly fool around with the 2.8 ECM and chip problems as we turbo folks do? 4. Why would you not want to be constantly tortured by the lingering question -Do I need an intercooler or not, can I afford to do it, and which one is best? 5. Why would you consider installing a more reliable engine, the 3800, than a 2.8 Tubocharged engine? 6. Why do you want to have something better than I do?
I have the turbocharged 2.8 with the garrett T/3 and a water alcohol injection system. But if I had to do it again, I would save my pennies for a Northstar conversion. Ed
Firefighter has a very good point of view. the 3.8 can be a better swap true the 3.8sc is even better the 4.1 4.9 ect are all very good swaps yes but were not talking about a swap. On swaps I would never do the 3.4TDC done it and the cost factor and stress you head feels is to much True very true I can get a 3.4TDC to scream 350hp 325 lb torque more than the 3.8 could ever think of doing.
What were doing here is is taking a stock engine apply a little cash make it feel big. Notice what I said little cash like $500.00 I'm not trying to just get rid of my turbos. No not at all. I'm trying to give options to those that do not want to do a swap, Or even try and give there swap a little bump for the buck. There are many power adders. methenal fuel lines fuel pump. Cheap but need to find it NOS Cheap but need to find it and pay extra each time Turbo fairly cheap. no need to ever buy extras Super charger not cheap at all, hp parisite bigger engine more cubes not cheap at all.
ok we got cams intakes ect. But nothing beats a turbo for the buck
JMO I do not want to offend anyone ever at all sorry if I do Good luck
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12:11 PM
rjblaze Member
Posts: 1159 From: Bethlehem, Pa., United States Registered: May 2006
Which turbo would you recommend for my 3400 hybrid idea? I am looking for the same kind of power as you put your "stoplight racer". Any cam suggestions? I know I can have the stock roller re-ground fairly easily. I am also planning an intercooler for this hybrid (BOV too), a 7730 ECM w/ knock conversion, customized stock intake tract, and a few other goodies (no NOS tho')....help?
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01:00 PM
riverrat Member
Posts: 168 From: kansas city ks Registered: Oct 2004
the ej25 is the best bet. closed deck will allow for boring. you can find them in legacys. outbacks. probably find one in the local yard for few hundy hell i know of one with a fresh rebuild for 400. go with a stand alone management. vf34. got hell of a ride
Im so torn, my olds with the 3800SC is on the freebie thread as we speak, but i dunno what i want to do now. im not confident enough to do the wiring and deal with all the custom stuff i need to do for the swap. and i dont really have the money for all the pre-made stuff. If i was forced to do it a at work im sure i could do it but im just not confident to do it on my own in my driveway, thats why i was thinking turbo. Firefighter really put it into perspective but im still on the fence. i guess i have some time to decide.
Jncomutt I don't want you to get me wrong at all nor do I wish to offend you at all.
Question. how is you can get 900 hp out of a simple honda motor. 2.0 4cyl easy big valves that is 4 per cyl "not 2" huge cams on valve no push rod no real lifter no real rocker arm. true they have lifters and a rocker arm but nothing like a standard oem engine they are OHC most 4v some 5v now take a huge turbo no good below 5000 RPM a huge intercooler run methanal for fuel spin that hoe up to 9000+ rpm you get the hp numbers
My point the stock Z34 3.4 TDC has the best of alot of worlds GM designed it at 345 hp out of the box. Problem they could not find a trans axle that could deal with it auto or manual.. now here GM has an engine that put out more than a small block screams to 7500 rpm and weighs less than a 2.8/3.1/3.4 pushrod in fact it should be scraped to be made better or worse or put it in a rear drive car. Its a shame they built it with shotty parts or shall i say off shelf parts. You put the TDC together right with extreem parts top it off with a huge turbo you will get 750 hp all day with no reliability. Now don't get me wrong the 3.8 is a fine engine reliable good power. It could and never will be able to perform like an Over head cam. Why can I get 650HP out of a STI 2.5 motor rock solid engine is why with 4 cams 4 valves.
Why can't you find many ZR1 vet engines. Easy Yamaha quit building it and the US banded it from production Why 1000hp rock solid all Day. Same reason the SHO Tarus was droped. huge HP numbers You seen any 3.4 TDC in new cars how about a Quad 4 HO a true SHO or even that nasty chrysler 3.5. The US has there reasons lets go to a motorcycle engine the Suzuki 1981 gs 1100 ES last year for the true TSCC engine WHY To much HP
All these engines have 1 major flaw reliability whats the fix DE Tune them make them work for the application you have problem. People tuned them back up to spec and blew **** up. got lawers involved and so the engines were scraped.
This is just my .02 cents sorry if I offend any one
