I know that a turbo 3800 has more power potential than any m-90 setup could.
I am trying to get my arms around why that is. Is the biggest reason because a turbo can be set up with a very large intercooler (aftercooler) to drop intake temps much more so than any M-90 could because of the limited space below the supercharger for the inlet charge to flow thru with minimal restriction? Is the secodary reason because the turbo can then be sized to more efficiently provide 10-20 psi of boost? Please chime in if I am understanding this correctly or if I am overlooking some characteristics of Turbos vs roots superchargers that result in the turbo 3800 having drastically more potential.

Thanks!

------------------
87 NB, 3800SC, 4T65E-HD, HP Tuners, 13.10 at 102.5 1/4 mile, Custom Dash.

turbos just move more air with less restrictions. roots and even centerfuge superchargers are parasitic and will at least for the roots type max out on amount of boost you can get form them. are they good for low end compared to turbos ....at one point they were but not so much anymore. while you will get the full potential of a turbo at higher rpms getting the right sized turbo will reduce power loss at low rpms. i promise you in the next 5 years you will not see any more roots superchargers from the factory unless its under very rare conditions appeling to a very select group of people that wont accept turbos on thier cars......mainly corvette owners but possibly camaros as if you were to put a turbo on the new ZL1 instead of a supercharger it would own a corvette ZR1 hands down, so they have purposely snubbed the engine design.

if you want power go with a turbo nuff said.

I may be wrong but here is what I have been told and it makes sense to me.

At, say 3000 rpm and cruising the blower and the turbo are both turning at a given rpm and producing little boost. Now imagine you are accelerating at fulll throttle. As you pass through 3000 rpm the blower is still turning at the same rpm as when you are cruising but the turbo has accelerated because of the increased exhaust gas pressure/flow therefore more boost.

Mechanical superchargers or blowers offer a more constant pressure vs RPM and quicker response. Turbochargers have lag but pressure increases with RPM.

Blowers also use hp from the engine they are mounted to whereas the turbo uses the energy from the exhaust gases which is mostly going to waste.

To answer you question simply, it is because the M-90 can only put out so much boost before you have to buy a new supercharger (high $$$$).
People who turbo charge them get bigger turbos to start with.


EDIT to add: Turbos are more efficent than superchargers, so for every lb of boost the turbo takes less HP to make compared to a supercharger.
Most peoples experiences with turbos are small 4 cyl cars, thus they relate turbos to lag, properly designed/sized systems don't have lag compared to the old days. With a properly designed/sized turbo system you can hit full boost long before a supercharger does. Turbos are load dependant, I can rev casual all the way up and never hit boost, or I can stab the gas and have full boost from 1800-2000 rpm (from idle that is a fraction of a sec)
When it comes to drag racing, turbos win hands down, (turbos were banned from pro racing long ago thus why you dont see them) But a good example my ex-father-in-laws Grand National launches at 21lbs of boost, what lag? Alot comes down to design/sizing, done wrong and turbos suck.


------------------
"DRIVE IT LIKE A FIERO"
'84 Fiero, engine to be determined
'87Blue GT 3.4L Swap Completed!!!!!!!! Boosted!!!!!!!
^^^^ Now in the Construction Zone^^^^
Las Vegas Fiero Club Parts/Sales/Service/Club
Fiero Road Club Of Northern Nevada

[This message has been edited by sardonyx247 (edited 10-06-2011).]

One big issue too is that a supercharger can only do so much until it is maxed out. When It reaches it's maximum output, it has to be upgraded (i.e., replaced with a different unit that can produce more power). The issue here becomes that doing this is not exactly an easy proposition. How many different blowers do you see available for the 3800? Exactly. This is one of the reasons why so much has to be done bolt-on and interally in the engine away from the supercharger itself to produce power because you're ultimately limited by the supercharger itself.

However, with a turbo build, there are SOOOOOooooo many turbos out there that possibilities and setups are virtually limited to what the engine can handle. You can build the block and drivetrain to withstand however much boost you wish to handle. Then from there build your setup. When your current setup is maxed out, you simply bolt on the next level turbo and construct & add whatever support modifications are required (more fuel, more intake, etc). Well, "simple" is probably the wrong word to use, but the idea is simple. The process is obviously anything but simple and can incur a very expensive cost if many components have to be upgraded.

The first response by Niterrorz also is good, in that ultimately a supercharger of this type is parasitic. It does take some energy away from the engine to produce energy - albeit the take-away is not a lot, but it is parasitic in nature. A turbocharger relies on what is essentially "waste" from the engine to produce power, and the only strain comes from if there is an issue with the tune or lack of properly upgraded components.

------------------
1986 Fiero GT... with REALLY high mileage

I think with a supercharger you have the advantage of better drivability, since you can modulate the throttle better. Also, it offers all the low end torque, which was great for a large car like the Grand Prix or Bonneville. You seldom had to get on the throttle, or rev past 3K RPMs. The turbo tends to come on like a light, all at once, and does not build boost linear like the supercharger, but exponentially.

The way i see a Supercharger VS Turbo is.... Superchargers are IMO better for driving.. if some punk wants to race me in a civic hatch turboed cruising 35 MPH i step on it i have almost instant power while his little turbo has to spool then he gets power but a turbo is better for the track IMO becuase you can rev it up and get some sort of boost before launch.....

------------------
1987 Black GT Custom interior with Mr. Mikes seats Series 1 L67 W/ 5 speed getrag! not running yet

Efficiency of a turbo is about the same as a m90...

The simple fact is size.... most any turbo I have EVER seen on a 3800 has been twice the size airflow wise than a M90. The turbo I have on my fiero moves 3x the amount of air than a m90 does.

quote Originally posted by RotrexFiero: I think with a supercharger you have the advantage of better drivability, since you can modulate the throttle better. Also, it offers all the low end torque, which was great for a large car like the Grand Prix or Bonneville. You seldom had to get on the throttle, or rev past 3K RPMs. The turbo tends to come on like a light, all at once, and does not build boost linear like the supercharger, but exponentially.

quote Originally posted by Celthora87GT: The way i see a Supercharger VS Turbo is.... Superchargers are IMO better for driving.. if some punk wants to race me in a civic hatch turboed cruising 35 MPH i step on it i have almost instant power while his little turbo has to spool then he gets power but a turbo is better for the track IMO becuase you can rev it up and get some sort of boost before launch.....

Like I said above, Most peoples experiences with turbos are small 4 cyl cars, thus they relate turbos to lag, properly designed/sized systems don't have lag compared to the old days.
I can control boost with my foot, the more I step on it the more boost I get up to the limit I set. It drives like a NA car.

EDIT to add: The 4cyls I am talking about also are usally high reving DOHC and don't make any power untill the hit high RPM anyway, that alone feels like lag.

------------------
"DRIVE IT LIKE A FIERO"
'84 Fiero, engine to be determined
'87Blue GT 3.4L Swap Completed!!!!!!!! Boosted!!!!!!!
^^^^ Now in the Construction Zone^^^^
Las Vegas Fiero Club Parts/Sales/Service/Club
Fiero Road Club Of Northern Nevada

[This message has been edited by sardonyx247 (edited 10-06-2011).]

quote Originally posted by garage monster: Blowers also use hp from the engine they are mounted to whereas the turbo uses the energy from the exhaust gases which is mostly going to waste.

Turbochargers create back pressure which can also be considered a hp draw from the engine. Either way, you are pumping air in and out. I would assume turbocharging would be slightly more efficient as a 'pump' than a drive belt supercharger.
Power comes from efficiency and the amount of air you're moving through the engine.

------------------
-Kyle
Email: kakagiraffe@gmail.com
Aim: Littlechugger
1988 Notchback 4.9 V8, 5spd Isuzu, Spec Stage 4
True Dual Exhaust, Delta Cam (212,000 Miles)
1992 Honda Accord LX (220,000 Miles) 5spd

quote Originally posted by sardonyx247: Like I said above, Most peoples experiences with turbos are small 4 cyl cars, thus they relate turbos to lag, properly designed/sized systems don't have lag compared to the old days. I can control boost with my foot, the more I step on it the more boost I get up to the limit I set. It drives like a NA car. EDIT to add: The 4cyls I am talking about also are usally high reving DOHC and don't make any power untill the hit high RPM anyway, that alone feels like lag.

The 1.4L Ecotec Turbo in the Chevy Cruze makes peak torque at about 1800 RPM. The turbo doesn't really ramp up until about 3000 though, and it's pretty much there to improve cruising speed efficiency. Most people are used to turbos installed by manufacturers, which aren't necessarily tuned to make the most power, most of the time. They are typically tuned for a healthy balance of power adding and fuel economy improvement, from the factory. With that type of tuning, the 'lag' is there for a reason.

This topic makes me wonder what a 1471 race blower would do on a 3800.

quote Originally posted by sardonyx247: Like I said above, Most peoples experiences with turbos are small 4 cyl cars, thus they relate turbos to lag, properly designed/sized systems don't have lag compared to the old days. I can control boost with my foot, the more I step on it the more boost I get up to the limit I set. It drives like a NA car. EDIT to add: The 4cyls I am talking about also are usally high reving DOHC and don't make any power untill the hit high RPM anyway, that alone feels like lag.

I had nitrous, centrifugal supercharger (Rotrex), turbocharged 3.1 and 3.4 on my Fiero. Turbos are peaky, again because of the way they build boost. The 3800sc is by far the most drivable, and it was that way when I had my GTP (grand prix).

Also, superchargers are low maintenance, or next to no maintenance. The oil is simple to change, along with the belt. Dont get me wrong, turbos are reliable, but they are a little more particular.

quote Originally posted by garage monster: At, say 3000 rpm and cruising the blower and the turbo are both turning at a given rpm and producing little boost. Now imagine you are accelerating at fulll throttle. As you pass through 3000 rpm the blower is still turning at the same rpm as when you are cruising but the turbo has accelerated because of the increased exhaust gas pressure/flow therefore more boost.

Not really correct. The belt drive supercharger has a linear increase in boost. At idle it is actually producing boost. It just produces more the faster it turns. It's maximum is only limited by the maximum engine rpm.

quote Blowers also use hp from the engine they are mounted to whereas the turbo uses the energy from the exhaust gases which is mostly going to waste.

Blowers can benefit greatly from headers that are well designed. Everything a header does for a naturally aspirated engine it does more of for a blower. The Turbo actually produces exhaust pressure which means it takes the turbo to power the air fuel mixture into the cylinder and force the exhaust out. In short, the engine is a little constipated with a turbo, and that means more pressure in the exhaust manifold and more pressure needed from the turbo. This is the reason a turbo'd engine can blow up so spectacularly. The pressures are higher to get the same effect

So there is a saw off. The turbo leaches power away and so does the blower, but, the blower generally leaches a little more because it is mechanical.

Arn

[This message has been edited by Arns85GT (edited 10-07-2011).]

The efficiency of any device used to create boost is the key. Turbos may build more horsepower on a 3800 but a large high efficency supercharger like a Whipple twin screw or Eaton TVS may work equally as well but at a far higher cost. The M62 and M90 Eatons used on 3800SC's at 90 C.I. are very small so you can only go so far with them.
Is turbocharging better than supercharging in the 1/4 mile? Although intercooled turbos have put up the better times on 3800's, the top fuel classes still run belt driven roots blowers. Having run both I tend to favor the positive displacement supercharger for the fast and immediate throttle response.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, ZZP Intercooler, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

If you look at the 10.5 outlaw class, almost all use turbo's.





I happily gave up "throttle response" for 300 more HP.

quote Originally posted by Dennis LaGrua: Is turbocharging better than supercharging in the 1/4 mile? Although intercooled turbos have put up the better times on 3800's, the top fuel classes still run belt driven roots blowers.

Top Fuel classes still run belt driven superchargers because they have a strict rule book to follow.

"...The forced induction engine is restricted to Roots-type supercharger, rotor helix angle not to exceed that of standard 71-series GM-type rotor. Turbocharger and/or centrifugal supercharger are prohibited..."
------------------
Turbo 3800 E85 5spd spec5
11.53@126.7

[This message has been edited by Justinbart (edited 10-08-2011).]

quote Originally posted by Justinbart: If you look at the 10.5 outlaw class, almost all use turbo's. I happily gave up "throttle response" for 300 more HP. Top Fuel classes still run belt driven superchargers because they have a strict rule book to follow. "...The forced induction engine is restricted to Roots-type supercharger, rotor helix angle not to exceed that of standard 71-series GM-type rotor. Turbocharger and/or centrifugal supercharger are prohibited..."

While you are correct that top fuel classes must follow the rules, I believe that turbos cannot be used in top fuel due to the feed through nature of fueling. The 21 or so nozzles are in the inector housing on top of the supercharger. Regardless tests were done to employ a turbo on top fuel years back and they were not sucessful. To my knowlegdde the best 1/4 mile with a turbo on any engine is in the six second range.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, ZZP Intercooler, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Let's talk streetability. The belt drive blower gives the lower end torque that gives much more flexible performance. You don't have rev the engine up into the power band to launch.

I would take a belt drive over a turbo for a whole host of reasons.

Not the least of which is that if the belt goes the engine still runs.

You can still put on a nice set of headers and dress the engine nicely as well.

It is also a much simpler system to install and set up.

They both work, but for the back yard mechanic on a street machine, the blower just works better. IMHO

Arn

I've never driven a supercharged car before and doubt it would affect my favoring a turbocharged engine. A good bit of the comments regarding turbo characteristics are not accurate regarding performance and efficiency. To start with, every car leaves the factory with an exhaust restriction via the converter and muffler, how much the turbo adds to it depends on sizing and changes to the exhaust after the fact and with normal driving a properly matched turbo does not add additional back pressure. Some wastegates have two ports, one of which opens it when the engine is not under boost allowing some exhaust to bypass the turbo all together.

You can put headers on a turbo car also.

Lag is hardly an issue anymore as new combustion chamber design has allowed for higher compression ratios with boost, better turbo technology and better turbo matching.

A properly matched and installed turbo causes no additional maintenance, you change its oil with the engine's and if synthetic is used you can bet on over 100k trouble free use, not to mention the life expectancy increase due to them being water cooled now.

The turbo on my 3900 is not twice as big as a blower but is sufficiently sized for the motor. The SC would have to grow to at some point to get more power.

Turbos and peaky performance, without proper controls in place yes, but factory cars have boost control solenoids that not only limit boost but can be programmed to command different boost levels at designated throttle inputs or rpm.

I have a sneaky suspicion that direct fuel injection is going to put the tendency to link turbos with lag to rest for good.

Although superchargers generally make boost quicker, they depend on rpm to do it, turbos can do this without additional rpm under load, like towing for instance. More throttle, more boost, same rpm, more power. This addresses potential
I found this article on the Ford Ecoboost engine after typing the above and it has pretty much confirmed much of what I stated. The durability test it was subjected to was down right brutal.

http://autospeed.com/cms/A_111422/article.html

Which of these methods of boosting is best is a matter of preference. Which is most efficient can be determined by crunching the numbers and I'm pretty confident it will be the turbo, definitively.

[This message has been edited by Joseph Upson (edited 10-09-2011).]

quote Originally posted by Dennis LaGrua: While you are correct that top fuel classes must follow the rules, I believe that turbos cannot be used in top fuel due to the feed through nature of fueling. The 21 or so nozzles are in the inector housing on top of the supercharger. Regardless tests were done to employ a turbo on top fuel years back and they were not sucessful. To my knowlegdde the best 1/4 mile with a turbo on any engine is in the six second range.

The real problem with turbos on Fuel cars is that the turbo would screw up how the exhaust works. Fuel cars don't use zoomies just because they look cool. Unburned fuel is actually lit and burned as it exits the headers, creating the flame fest that looks so cool. But this afterburning of fuel also creates thrust, which is why the zoomies are angled in the direction they are, so that the thrust also pushes the car down (to keep it on the ground) and forward (an extra boost of power from the thrust).

quote Originally posted by Arns85GT: Let's talk streetability. The belt drive blower gives the lower end torque that gives much more flexible performance. You don't have rev the engine up into the power band to launch.

Actually, that is just wrong, turbos give more low end torque than superchargers.

quote You can still put on a nice set of headers and dress the engine nicely as well.

Putting "fancy headers" on a supercharged car is a bigger pain than putting a turbo setup together on a 3800 fiero swap...

quote It is also a much simpler system to install and set up.

In a fiero, the M90 in stock form is fairly simple, but the second you want to get any type of performance similar to a turbo, it is MUCH more complicated than a simple turbo setup (that makes alot more power than a blower)

Turbos do not give more low end torque than superchargers, nor is the reverse necessarily true. Certain turbos may give more low end torque than certain superchargers. It all depends on setup and tuning.

Thanks for the good Civil discussion based on everyone's experience and opinions. It also seems clear that for HIGH horsepower cars, the M-90 has such a limited area underneath it for the intercooler that perhaps this affects its ability to efficiently cool the intake charge compared the larger surface area that would be afforded a centrifugal SC or a turbo. I would have to believe it is easier and more efficent to intercool the turbo/centrifugal SC?


------------------
87 NB, 3800SC, 4T65E-HD, HP Tuners, 13.10 at 102.5 1/4 mile, Regal GS Gauge Cluster.

[This message has been edited by DimeMachine (edited 10-09-2011).]