I recently got into a discussion with a fellow Fiero enthusiast about Turbo charging the 2.8. Neither of us were experts on the topic, but we did come up with some questions and points so I told him I would ask here and see what those who know more would say.

First off there are claims from 2.8 Turbo kits out there that will put the fiero 2.8 at 225 - 300 hp. It was my understanding that with the stock Fiero intake (i.e. upper, middle, and lower intake) and TB that you would not be able to move enough A/F to produce much more than 200hp because of flow restrictions, regardless of weather or not you had a 2.8 or 3.4 underneath it all. (or do these restrictions not apply so much when boost is present)

Second, he was of the impression that not only was there no modification needed to the computer, but that the stock fuel injectors were fine. My understanding was that the stock injectors and computer would not move enough fuel to prevent a lean mixture and melted pistons and valves. i thought at the very least a chip for the computer was needed.

Third, we disscussed the emisions capability of the kits offered out there. I never recall seeing a Turbo kit for the 2.8 that shows the EGR valve still inplace, and did not know for certain if the O2 sensor was still present. i told him it likey was but could not be seen below the turbo set-up, also, the SES error light would get annoying, and present another smog violation. Do these things pass smog in CA?

So lets hear it if anyone can clear some of these questions up.

you are correct on your first 2 questons. On an STOCK 2.8/3.4 you should expect 200hp, or a little more. You also NEED new injectors, the stock ones won't be even close for a turbo setup. You don't have to reprogram the computer, but if you want it running right, it should be done. The car will run without a reprogram, but you wont get very far.

On your last question, I am not too sure about the smog thing. I know the O2 stays, and you can also leave the EGR if you built your own crossover. Most kits take the EGR out.

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the stock Fiero intake system can't SUCK enough air to get 200 Hp's. Forcing the air in under pressure is a whole new story - yes, it can move enough for 300 HP's

the computer WILL need reprogramming if you go above roughly 4-6 PSI boost. but even at 2 PSI boost, you should have a chip made. the injectors should be sized based on final HP output. there are formulas & charts to work that out.

yes, still need the O2 sensor. gotta have it.

the EGR - not sure. how well will the EGR work in a pressurized intake....

You can get away with not re-programming the ECM when you start boosting. But you will have to have alternative fuel control, perhaps by a seperate computer with extra injectors, maybe an FMU (Fuel Managment Unit) witch cranks up the fuel pressure relative to the amount of boost. And you have to have a nifty way of preventing the map sensor from getting boost to it, many people use check valves vented to atmosphere. Some people (god help them) just get HUGE injectors and run it extreemly rich all the time, these people should not be allowed to install turbos.

The stock EGR system cannot operate properly with a turbo, Its reponces would be non linear, due to it requiring some sort of vaccum to operate, and the exhaust pressures are far greater then the EGR is normally designed to flow, so when spooling, at no boost conditions the EGR might open and dump high pressure exhaust into the intake, and that would cause all sorts of problems with the engines performance. Best eliminate it.

A) As has been mentioned above, with enough pressure difference, you can push as much air as you want through pretty much any orifice. While the stock Fiero intake is restrictive, especially at high RPM, it is by no means a brick wall limit to the amount of power an engine can make, especially a boosted engine.

B) Fuel flow requirements are proportional to horsepower. If you want to make a certain amount of power, you will NEED a certain amount of fuel flow. You get this fuel flow by installing injectors that meet your fuel flow requirements. I don't know what size they are right off (13 pph? 15?), but I would consider stock injectors marginal on a 200 HP turbocharged 2.8.

C) You should consider proper engine management (IE, proper computer tuning) a REQUIREMENT for turbocharging an engine that was N/A from the factory. FMU's, rising rate pressure regulators, etc, are all just bandaids that trick the factory computer. Remap the factory computer and you get better results more reliably, and probably with less cash outlay, considering the current state of the GM computer aftermarket.

The engine I originally put in my Ferrari kit was a race shop built (Jasper) 3.1 that used 2.8 intake and heads. I used the DS1 turbo. I used stock fuel pump, stock injectors, accel coil. It would turn over 7,000 rpm, dynoed when new at around 275 hp. I drove it for 8 years but on a lower boost for everyday use without any problems at all. I also eliminated the O2 sensor completely. It did run a little rich, so gas mileage was hurt a little im sure, but maybe that added the longevity of the engine. I put over 100,000 miles on it, and as many here will attest, I didnt nurse or pamper it.

here's some things you should never do

Never block off the wastegate because you want more boost. I have seen ppl do it ( im talking about seeing ppl block off the entire wastegate system all together)

Do a compression check, Running a turbo on a tired worn out engine with many mechanical problems won't get you far.

And some things you should consider.

There are many ways to feeding the engine more fuel at WOT, Bigger injectors is a easy way to get around that problem I guess. So many ppl use that method.

Try running a intercooler.... I see no harm in doing it no matter how much boost your running, A intercooler from a saab will fit nicely under the drivers side engine vent. You will have to remove the fuel vapor cansitor and relocate it.

There are 1000s of BOV's

colder spark plugs.

I have heard ppl running 8 psi of boost on 2.8s with no detonation problems. I would start off with 4 maybe 5psi to start out with.

oh yeah... However you mount your turbo make sure the oil feed line points up ( mounting it upside down will make your car into a misquito repelling smoke screen )

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4.9 under construction... To lay the smack down on any mid 80s truck that stands in my way.

[This message has been edited by 86fieroEarl (edited 08-05-2005).]

quote Originally posted by rogergarrison: The engine I originally put in my Ferrari kit was a race shop built (Jasper) 3.1 that used 2.8 intake and heads. I used the DS1 turbo. I used stock fuel pump, stock injectors, accel coil. It would turn over 7,000 rpm, dynoed when new at around 275 hp. I drove it for 8 years but on a lower boost for everyday use without any problems at all. I also eliminated the O2 sensor completely. It did run a little rich, so gas mileage was hurt a little im sure, but maybe that added the longevity of the engine. I put over 100,000 miles on it, and as many here will attest, I didnt nurse or pamper it.

Don't mean to hijack, but what boost pressure where you running to get 275 out of a 3.1???

OK - HERE'S THE SCOOP

The stock 2.8 can produce 200hp.
Yes you need a new chip.
Yes you need a 2 BAR MAP Sensor.
No you don't need new injectors, but it wouldn't hurt.
Yes, the EGR valve remains and there is a place for it on the kit I bought.
And in order to get more air in as compressed air, it needs to be cooled as in Intercooler or Water/ Alcohol Injection.
And yes, to get all of the above to work on a stock engine, it must be in great mechanical shape and you must do a compression check to find out.
If one cylinder reads low, you have piston, ring or valve problems and just like nitrous, your engine will fail, as either boost or nitrous will capitalize on any weakness.
On a "stock" 2.8 more than 200 hp requires some major engine rebuilding.
Ed

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quote Originally posted by Pyrthian: the stock Fiero intake system can't SUCK enough air to get 200 Hp's. Forcing the air in under pressure is a whole new story - yes, it can move enough for 300 HP's the computer WILL need reprogramming if you go above roughly 4-6 PSI boost. but even at 2 PSI boost, you should have a chip made. the injectors should be sized based on final HP output. there are formulas & charts to work that out. yes, still need the O2 sensor. gotta have it. the EGR - not sure. how well will the EGR work in a pressurized intake....

Exactly. Turbochaging or boosting pushes COMPRESSED air. Therefore you can move more air through a given space than normally aspirated. IN all actuality don't expect more than 200 HP with a turbocharged stock 2.8L with about 8 PSI of boost. The stock injectors can support 200HP at 100% duty cycle which can be put into the chip program. It's better to use larger injectors and stay at 80% duty cycle (or below) but keeping the stock injectors on all of the time for short 15 second bursts will not harm them. As for the EGR it works normally in a turbo engine. You only have boost with a turbo in a heavy throttl mode The ECM is disabled by the ECM during WOT and under heavy acceleration. Just leave it alone and no harm will be done..

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87GT 3.4 Turbo- 0-60 5.2 seconds -Best
Engine Controls, ECM goodies, Chip
re-programming & odd electronics stuff

quote Originally posted by rogergarrison: The engine I originally put in my Ferrari kit was a race shop built (Jasper) 3.1 that used 2.8 intake and heads. I used the DS1 turbo. I used stock fuel pump, stock injectors, accel coil. It would turn over 7,000 rpm, dynoed when new at around 275 hp. I drove it for 8 years but on a lower boost for everyday use without any problems at all. I also eliminated the O2 sensor completely. It did run a little rich, so gas mileage was hurt a little im sure, but maybe that added the longevity of the engine. I put over 100,000 miles on it, and as many here will attest, I didnt nurse or pamper it.

275 HP? At what boost? From a Jasper?
That would have to be in the 18 - 21 psi range...
Again... from a Jasper?

O2 is essential for proper fuel trimming. Removing it from a street car that will be tuned once and turned loose is exceedingly unwise.

Forced air makes up for poor intake (though we've sold quite a few of our intakes to turbo guys)

Larger injectors are better

While not a "must" at lower boost levels, it's probably just plain dumb not to change chips with such an engine modification.

I kept my EGR and it works fine, but I'm only running 7lbs of boost and it tuned to come in at around 3K

I also agree with using an intercooler. Like, why go through the trouble of turbocharging only to push hot air into your engine?

As siad by others, you best have an engine in really good shape to even consider a turbo.

Just don't put overly large injectors in. At small pulse widths they vary in flow and idle can suffer. Go big enough for the job but not any larger if you can avoid it.

quote Originally posted by FieroGTdude: Don't mean to hijack, but what boost pressure where you running to get 275 out of a 3.1???

That was 8 years ago, but they dynoed it before i picked it up, but I think around 14pnds ( ? ) I never drove it with that much, usualy around 5 pnds was where I left it. Remember it wasnt a stock engine. It was built by a friend who builds the engines for the Jasper Nascar stock car, and even at that it wasnt cheap.

quote Originally posted by Dennis LaGrua: ...... don't expect more than 200 HP with a turbocharged stock 2.8L with about 8 PSI of boost. The stock injectors can support 200HP at 100% duty cycle which can be put into the chip program.....

so then that under boost the stock 2.8's barrier of 200hp is because of the injectors? is 200hp surpassable then on a stock 2.8 by simply installing larger injectors, boosted, and chipped?

Are those claims of 225 - 300hp indeed possible with a stock 2.8 under boost with larger injectors installed? doesn't seem likely, but then i am not a boost expert by any means.

As far as engine condition, we were disscussing this because he has a 2k mile 2.8 he was kicking around Turbo'ing. I was just pooh poohing his claims of getting 225 - 300hp out of it. I might eat crow on this one....heh. but then I am schooled by more knowledgable folks.

I thought the 2.8 was 100% HP proof

How long do you want it to last? It's like cooking a turkey:

4 hours at 350
2 hous at 700
1 hour at 1400
30 minutes at 2800

Barring wise cracks. It was implied with terms like "good condition engine" in this topic that longevity was part of the equation.

If max hp were the sole goal, i am sure one could use a 500 - 1000 shot of NOS and break a record for highest hp from a stock 2.8 for about .5 seconds...

[This message has been edited by Roland (edited 08-06-2005).]

I just finished my turbo 2.8 project. And let me tell you!!!!!

Just build the engine correctly. I made a mistake with the cam, but that's not the end of the world, just more turbo lag.

For the record though... with aluminum pistons (to dissipate heat better) and larger injectors and a well-burnt EPROM, you can put more than 8psi into the Fiero 2.8. I had my block bored, honed, etc. And I built it form scratch last year. I installed a turbo this summer, and it take 12psi with NO DETONATION. I don't leave it at 12psi because it makes it a little undrivable. Very hard to move from a stop, but 10mph->60mph will snap your neck once that boost starts climbing. First time I hit 12psi, I froze. It was SOOO freakin' fast. Running at 8psi though, I get to 60 in about 5.0 seconds. Haven't taken it to the track yet.

Keep in mind though, this isn't REALLY a stock 2.8. It has a more aggressive (non-turbo) cam, and aluminum pistons. The exhaust is ported, and everything is new. I woudln't dream of 12psi into an engine with 100,000 miles on it.

Take this with a grain of salt for what its worth. I wrote it years ago.

Turbo's Turbo's Who's got the Turbo.

This page is a work in progress but this is what I have so far. It will give you some basic info that you may not have found on other pages.

Well if you are looking for turbo's and turbo info you have came to the right place. I am not selling anything, so if you think I am going to be giving you a turbo for your Fiero eeh don't count on it. LOL What I am going to try and show is really how easy or hard it is to turbo charge a V6 Fiero. I am going to try and show you a list of parts that just could save your motor in the long run. Everything that I am going work with will err on the side of caution. I will always try to run a little on the rich side, (rich = more gas than air) I will keep the boost levels under 10psi Especially with the stock Fiero compression ratio of between 8.5 and 8.9. Well enough chatter lets get right down to business

Parts who's got the parts. Well there are a ton of parts that you can and some that you will need to buy. Then there are some more that can be argued if you need it or not. Well getting right down to business

Fuel Injectors --Starting with the fuel system, injectors, it has been said that the stock 15# injectors when new can support 200hp with the right programming. The design one turbo kit has proven this. But if we flash to the real world here, none of us have brand new injectors in our cars. Some of them only perform as well as a new 10# injector. So we should be looking at some larger injectors. This can be a massive expense if you just run with credit card in hand down to the local tuner shop and say "Big Injectors Please" sure you could drop as much as 1000$ for a set of 6, but are we Bill Gates here. I don't think so. Well so where do we get our new injectors. FORD, yep FORD I hate to say it, but the 5.0 Mustang has created such a huge amount of buying power that you can get the Mustang injectors for Pennies on the $$ and they plug right into the Stock Fiero Fuel Rail. If you are lucky like I was, I managed to find a set of near New 19# injectors on ebay for a grand total of 28$, no I did not leave off a zero there. Some guy was upgrading his stock 19's because he had just bought the car new and was installing a supercharger so the 19's were useless to him. I believe if you were to buy this set brand new you could get it for about 300$. Well now you have injectors that will safely support up to 240hp on a 2.8 block.

Fuel Pressure -- Ok your stock regulator is set for aprx. 28lbs at idle and when your stand on it the fuel pressure rises to about 50psi. This is great and fine and dandy, but as you start to make boost, you no longer have an 50lbs of fuel pressure going to atmosphere you have 50lbs being pushed back by 10lbs. So you get 40lbs oops. That is not going to do, as you are making more power, but you fuel system is now flowing less fuel. That is the perfect recipe for lean out, and melted pistons as well as the possibility for detonation. The solution is a "Rising Rate Fuel Pressure Regulator" this is a neat little gadget that can either replace your stock regulator, or go depending on style that you buy can be hooked into your fuel return line going to your tank. As this gadget senses boost, it will block the flow of fuel to your tank from the fuel return line. When it does this, your fuel pressure will go up, this is a Very Good Thing. Now you think this is all fine and good, well it sorta is, but there is still room for the bigger injectors. So it is a good idea to keep those Ford Injectors in the back of your mind.

Pistons and Rings, hmm, well this is a debatable subject on what will and will not work.

Forged Pistons-- Obviously the best pistons are Forged Pistons, but they are also the most expensive, around 400$ for a set of 6.

Hyperutectic's-- Next in line is a set of good Hyperutectic's the only problem with hypereutectic pistons is they will crack under heavy detonation, but the plus side is that they will not burn or melt nearly as easy as a cast piston. Burning holes in pistons is a problem caused when your fuel system gets too lean, (not enough gas).

Cast Pistons-- Cast Pistons are by far the cheapest out there, and will work with a turbo motor. Many a person has done a low boost 7-10lbs of boost on cast pistons. You just have to be more careful with them and not run high boost as well as make very sure that you don't run lean.

Piston Rings-- This can get very argumentative. I personally have heard really good things and really bad things about the new Gap-less rings when used in turbo applications, so I can not recommend them or tell you to stay away from them. The rings I do know about are the Chrom-Moly rings and the Cast Rings.

Chrome-Molly are very hard, and when seated in your cylinder walls should not wear out EVER. In most cases you will end up wearing your motor out before you wear out the rings. These should give you a good safe guard against cracking a ring when running boost or even Nitrous. (more to come on that later)

Cast Rings again it is kinda the same boat as the cast pistons, they can be used, they will work, but if your motor has more than 100,000 miles on it, it is a good bet that your stock cast rings are wearing a bit thin and you might want to consider replacing them before you toss all your money into a turbo kit. If you don't you might end up with a 3000$ Fiero a 1000$ turbo and a 10$ blown motor that smokes like Mt. St. Helens.

Rockers-- Well the rockers are the things on top of the heads that change the cam shaft lobe motion into the valve motion. So for every time the piston moves up and down each rocker has to open and close a valve for that cylinder. The stamped steel stock rockers are all well and good, but if you plan to run your motor hard a set of 1.52 roller or roller tip rockers will save you a ton of grief in the long run. The roller tip rockers reduce the lateral friction on the valve guides this reduces wear and will keep your motor smoke free for a much longer time than the stock steel rockers. This is especially true with high revving turbo motor's.

Ignition System Oooh Spark's. HeHe.

Well your stock ignition if it is in like new shape will work, but it is recommended against it. There are several manufacturers of good aftermarket ignition systems, but I am a fan of the tried and true MSD series. I personally use the MSD 6A ignition box that hooks right to your Battery, it is triggered by your stock wiring to fire an MSD Blaster II coil that sends the juice out to your cap and rotor and on to your spark plug wires, Via MSD Superconductor Wires, out to Plain DELCO STEEL CORE PLUGS. This is what MSD recommends is the steel core plugs the regular ones you buy not some fancy platinum or other funny plug. I am considering giving the AC Delco Rapid Fire Plugs a shot though.

Intake and Exhaust. Now comes some more arguable stuff. When you "boost a motor" you are no longer trying to just let the air flow in and flow out. Your are cramming it down its little throat, and when it is burnt your are shoving it out like wild fire. Headers and bigger intake manifolds and porting is still of value but not nearly as important now.

Engine Electronics

ECM the good news is the stock ECM will work. Any and all Fiero ECM's will work. If you choose to go with the Stock ECM your best bet is to find an 85ECM as it is modifiable to work exceptionally well with a turbo. The only confirmed details I have are the fuel mapping on the 85 V6 is different (better) and the prom chip and be changed to work with a knock sensor)

Map Sensor. The stock MAP (Manifold Absolute Pressure) only reads 1 atmosphere negative that means it can read 14.7 pounds of vacuum but it can not read boost. A 2-Bar map can read + or - 14.7 pounds of Vacuum up to 14.7 pounds of boost. Unless you are building a full blow race motor and are shooting for over 15lbs of boost you will only need to buy a 2 bar not a 3 bar.

Ignition Timing Controls. MSD makes a neat unit that plugs into a vacuum source on your motor and can pick on boost conditions and retard your timing as boost increases. This is a really good thing as detonation is the leading cause of engine failure in almost any performance application. You can also get knock sensors these neat little guys screw into your engine block (the 2.8 already has the mounting boss for it) and listen to your motor, yes it can hear what is going on in your motor. When they hear detonation it starts retarding your timing. The nice thing about knock sensors is that you set your timing up at the most advance you would ever want to run. Then when you put say 100 oct.. race gas in your car it will allow the timing to be advanced on its own, but when you put say the cheap gas in your car it will retard the timing so it can save your motor.

The Boost Gauge, yes you will NEED a boost gauge, this will mounted in your car someplace within easy view. This will monitor how much pressure is in your intake when you first get this in your car, it will be hard to keep your eyes off of it. As you will be so proud to see your engine making boost. Aside from the huge grin on your face as you are sucked into your seat as the gauge reads higher and higher boost levels.

Air Fuel Meter, ah the never ending challenge to keep your motor from leaning out. This little doo-hicky plugs into your O2 sensor or can be hooked to a second O2 sensor that can be welded into your down-pipe. Generally they have a series of LED's (light emitting diode's) in 3 colours Red for too lean, yellow for getting a little lean, green for just right, and last one for too much fuel. Priced at around 100$ they are nice to have but are not needed. However I like lots of bells and whistles especially ones that show me what my motor is doing.

The Turbo---, Ok now for the biggie, you have all the stuff that you think you will need to have for this beast, it is time to start looking for a suitable turbo. Now this is where I get stuck myself, not being a turbo freak until about 6 months ago this is what I have learned so far. The turbo's on the dodge Daytona 2.2 and the turbo's on the Ford Thunderbird's are T3 turbo's and they are almost perfect for our applications. They are small enough that they will spool up at a relatively low rpm and begin creating boost at or near 2000rpms. The draw back is that they will run out of oomph at around 6000-6500 rpms. Don't worry if you are using a stock motor and stock fuel system this will be more than enough for a 2.8. If you have a modified motor you can still run this very well, and should be happy with it. The kicker to this is that there is a common swap with the T3 and that they take the compressor housing and exhaust housing apart, the compressor side is machined a bit and a larger compressor is installed, this allows the turbo to push a lot more air when the exhaust side is spinning at the same speed. This is called a (you guessed it) T3/T4 hybrid. A T3/T4 can be used to make up to 400hp, Just don't think your stock motor will do it. There are literally hundreds of variations of turbo's on the market today, ranging from Water Cooled, Oil Cooled, Oil and Water cooled. Ceramic bearing turbo's, ball bearing turbo's and the list can go on and on. I am looking into the Oil Cooled style myself. I understand that the water cooled is better but for cost purposes it will be an oil cooled unit. Prices can range anywhere from 20$ for a boneyard turbo up to as much as your wallet will allow. I have seen them for over 2000$ for a single turbo unit. You can count on spending around 100$ for a good used one or about 500$ for a new entry level model. Don't take this as the "die hard numbers" as I am new to this turbo thing myself. One thing that is nice about using a T3 turbo is there are lots of them out there, so the price is usually decent and you can find upgrade parts for less than some of the more exotic kits out there.

Getting Oil or water to the Turbo, as I know nothing about water cooled turbo's I am going to be talking about oil cooled turbo's. This was one thing that scared the heck out of me at first when looking into the designs of turbo's and Ya know what, it shouldn't. Why because as always the most confusing questions generally have the simplest answers. I have some pics of this that I will post someplace on this site. 1st you need to get your oil from someplace. That someplace is your oil pressure sending unit location, you use a T-fitting that runs splits off, one side goes to your turbo and the other side goes to your Oil Pressure sending unit. Ok that makes that easy, till you realize that all the oil is going into your turbo and on to your floor. Oops, quick hurry get the bucket. No No I am just kidding. The oil return line coming out of your turbo goes into your oil pan. You must punch a small hole in your oil pan and have a "bung" (bolt) welded onto your pan, that so that the oil coming out of your turbo goes back into the pan. The alternate source for oil is with a remote mount oil filter and you would get your pressure feed for the turbo from the oil filters exit side. This would give you cleaner oil and slightly cooler oil as it is no longer bolted to the block and has a chance to cool slightly in the filter. Especially if you use a filter cooler (filter cooler, is a large heat sink with fins that wrap around your stock filter and held in place with a large hose clamp) They do not do a whole lot, but it has been proven that they do reduce oil temps slightly.

Air Pressure its got to get into your motor somehow. Well most people use either stainless or aluminum tubing to duct the air from the turbo into the motor, this is a relatively straight forward thing. I am not to familiar with how the bends are set up or if you can get rubber or poly elbows to correct the problem of tight spaces.

Intercooler-- An intercooler will always help a turbo motor, but the question is do we need one considering we will be running under 10psi. For whatever reason 10psi seems to be the magic number for an intercooler to be used. I am sorta looking into using one on my car, but with the already awesome cold air intake that we have and the relatively low boost I plan to run it should not be a problem. I have seen intercoolers that were the size of a shoe box, and had the inlet and outlets in almost the perfect locations for us to use on our cars.

Exhaust Y-Pipe-- Ok here is some more things that are odd, well, from what I understand having the turbo as close to the exhaust manifolds as possible is your best bet, but with the Fiero 4 and 5spd cars, that is not always possible as the shifter linkage seems to plop right down between the 2. I have seen a couple of different ways to mount it, the best being near the cruise control location. It does make for the distance of the rear manifold to be much longer than the distance of the front manifold, but I think that will be alright. I have seen the easiest way to do this seems to be to go to your local "BIG CHAIN" auto parts stores and buy some raw exhaust tubing in different sizes and bends then go back to your car and play tetras for a little bit until you get an idea of what design your new Y-Pipe is going to take, then you take you designee to the local exhaust shop and explain what you want and how you want it routed and weld it all up and probably even show you a thing or 2 that you may not see. Like the way your EGR should be mounted and such. There are several different designs of y-pipes ranging from ones that will bolt a turbo right into your stock exhaust system right up to ultra high end ones that require a totally new exhaust system.

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85GT 5spd MSD Everything,4.9 With Nitrous. www.captfiero.com

everybody says you can get around the short comings of the stock intake manifold with boost but the fact is a shitty manifiold is still a shitty manifold no matter how you look at it. The compressed air still travels the same path as the non compressed air. An ineffecient intake is still ineffecient boost or not.

True indeed that a lousy intake manifold is a lousy intake manifold but the laws governing the movement of air regarding blowing air vs. sucking air are entirely different, and with forced induction the 2.8s problem becomes a non issue for the same reason the ram air induction system on the Trans AM adds an additional ~25 hp to the engine according to the documentation I read. It wouldn't return as a problem until you reached a boost level far to restrictive for the amount of air being flowed. My question is whether or not Capt Fiero is correct when he subtracts fuel pressure as boost increases, I do believe he has it backwards, the pressure increases as throttle opening increases and that's the purpose of the vacuum fitting to the housing. The spring loaded diaphragm allows less fuel to bypass as the atmospheric pressure increases or vacuum decreases so clearly at least to me as boost comes on the fuel pressure should rise a little with more pressure on the diaphragm which is the principle used on the adjustable regulators.

Everybody complains that the stock Fiero manifold is a crappy manifold, but in reality it is good for what it was designed for, low to midrange power and torque. Here's my 2. bored and stroked to 3.2L with the stock intake and exhaust:

http://www.etrackmasters.com/dyno/jamessa.gif

Notice that I generate 90% of my torque at just over idle, 1,250RPM? See how flat my torque curve is all the way to 4,000RPM? This means that I can start in second if I want, or start in first and shift to third at just about any speed. I have useable torque at 1,000 RPM so often times I just leave it in third and never shift when driving around town, and never take it out of 5th on the highway at any speed above around 35mph no matter how steep the climb. This makes it a very fun car to drive and I owe much of that to the long runner design of the stock Fiero intake.

JazzMan

quote Originally posted by JazzMan: Everybody complains that the stock Fiero manifold is a crappy manifold, but in reality it is good for what it was designed for, low to midrange power and torque. Here's my 2. bored and stroked to 3.2L with the stock intake and exhaust: http://www.etrackmasters.com/dyno/jamessa.gif Notice that I generate 90% of my torque at just over idle, 1,250RPM? See how flat my torque curve is all the way to 4,000RPM? This means that I can start in second if I want, or start in first and shift to third at just about any speed. I have useable torque at 1,000 RPM so often times I just leave it in third and never shift when driving around town, and never take it out of 5th on the highway at any speed above around 35mph no matter how steep the climb. This makes it a very fun car to drive and I owe much of that to the long runner design of the stock Fiero intake. JazzMan

You are correct you make good power all the way up to 4k.....then you lose power like no other. Your missing out on 2k rpms of powerband. If you get groceries in your fiero than that is perfect but if you race as I do then you will lose to the weakest civic.

quote Originally posted by Joseph Upson: True indeed that a lousy intake manifold is a lousy intake manifold but the laws governing the movement of air regarding blowing air vs. sucking air are entirely different, and with forced induction the 2.8s problem becomes a non issue for the same reason the ram air induction system on the Trans AM adds an additional ~25 hp to the engine according to the documentation I read.

This is incorrect. A restrictive intake is still restrictive even with boost. You would just require more boost to overcome the restriction.
As an example, Say you added a turbo to your totally stock 2.8L and pushed 10psi and the car dyno'd 210hp. Now change the intake to a less restrictive (higher flowing) intake. You would now only need about 7-8psi to make 210hp and at 10psi you would make more like 220hp.
Also, the engine making the same power with less boost would be easier to tune and run slightly cooler.

The "laws" of air movement are the same for normally aspirated and boost.

quote Originally posted by Oreif: This is incorrect. A restrictive intake is still restrictive even with boost. You would just require more boost to overcome the restriction. As an example, Say you added a turbo to your totally stock 2.8L and pushed 10psi and the car dyno'd 210hp. Now change the intake to a less restrictive (higher flowing) intake. You would now only need about 7-8psi to make 210hp and at 10psi you would make more like 220hp. Also, the engine making the same power with less boost would be easier to tune and run slightly cooler. The "laws" of air movement are the same for normally aspirated and boost.

My point exactly, less restrictive the air flow through the motor, less hotter it gets, therefore you will make more horse power with a good flowing intake with less restriction than a restrictive intake that requires higher boost to achieve the same result.

HTH
Prasad

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"Turbo Cars are like hot women. A little edgy, every guy wants one, some guys can't handle them, and if you throw a little alchohol in the mix they'll rock your world"
1986 GT (waiting for Buick GN setup trasplant)
1984SE 5 Speed W/SBC V8
1997 GTP
1987 Buick GN(10.70@124MPH)
1987 Trans Am SBC 355cid Twin Turbo(no track times yet)
1992 GMC Typhoon(13.20@ 99mph)
Other cars; JaguarXJR, XJ6 & Mercedes AMG 500SEC

What about plugging the vacuum on the fuel pressure regulator when running at the track to avoid pressure dropping from boost?
i.e. 50 lbs all the time?

I'd like to add my 2 cents on this manifold issue. A beter manifold is still a plus. We were surprised at how many intakes we've sold to people with turbos. I could be wrong on this, but I think not; I have 2.8 turbo with one of our long runner intakes and it's tuned for the turbo to come in at around 3k etc. Just by seat-of-the-pants, my car feels a lot more response and drivable when not in boost than it did with the turbo and the stock intake. Perhaps it's because the beter flow helps the larger injectors at lower non-boost rpm. BTW: 7lbs boost with 9-1 pistons, headers and lots of other mods.

quote Originally posted by BQUICK: What about plugging the vacuum on the fuel pressure regulator when running at the track to avoid pressure dropping from boost? i.e. 50 lbs all the time?

Because then your engine management would be screwed up. GM algorithms are based on the assumption that the pressure drop across the injector is always constant. If the gauge pressure in the fuel rail is constant, but the pressure in the manifold is changing, then the pressure drop across the injector is not constant.