From what I understand, you run the risk of leaning out if you exceed 80 or 85% duty cycle because the injectors don't have enough time to open and close, causing them to float half open. Not to mention that one or two of your injectors might not flow perfectly, so you could run lean in only one cylinder and hole a piston.

It's up to you. I'm just trying to offer advice that might keep you from blowing your engine. A used set of 24 lb/hr injectors can be pretty cheap compared to a rebuild. You'd also have that much more fueling capability, so if you wanted to turn up the boost, you could. But again, it's up to you. Good luck either way.

also - with high duty cycles - there is the chance of overheating & cooking an injector - they are just solenoids after all, and spending most of their time with current running thru them builds heat.

I bought a set of 24lbs injectors for 60$ off ebay. Of course they were "barely used". Now I'm happy with my purchase so far. The funny thing is all the injectors I saw on ebay are "barely used". YMMV.

This was in response to my question about the amount of non-intercooled boost one could safely run in a turbocharged 2.8L in good shape, with stock 8.9:1 compression, but not any special modifications to handle that boost:

quote Originally posted by SCCA FIERO: The amount of boost to safely run is probably around 7 PSI. It really depends on a bunch of different things (turbo size mostly - that is if timing and fuel are in check).

This is interesting. The 7 pounds of boost SCCA Fiero mentions above is in the same ballpark as what Design1Systems mentions for its mild, street-oriented, "Stage 1" turbo kit on its website. There, it says: "The Stage One System provides 7-8 PSI boost in manifold pressure to produce about 200 horsepower and a 0-60 time of under 6 seconds without sacrificing engine reliability." See http://www.design1systems.com/turbo/index.html

My understanding is that while pricey, the Design1Systems "Stage 1" turbo kit for the 2.8L supposedly is very similar to the old Miller-Woods turbo set-up. If so, that would be good, because for anyone who also is leaning toward a turbo kit, the discontinued Miller-Woods set-up, which the Design1Systems kit supposedly is based on, seems to have been a very well-regarded one.

Has anyone any experience with Design1Systems' mild, street-oriented "Stage 1" turbo kit, whether with the Fiero 2.8L V6, or with the corresponding 3.4L pushrod engine swap in a Fiero?

Let me chime in here with a comment on the turbo 3.4 pushrod. I am running a stock 3.4 L pushrod with a WCF 61 cam, larger injectors (19 lb Ford if I remember correctly), custom chip, and a Dennis L turbo kit sized for the 3.4. This setup runs at around 7 psi boost and does not have an intercooler. The block was a new factory shortblock with stock compression and now has about 10K miles on the engine.

I elected to sacrifice a bit of performance for the improved relaibility and did not tune for absolute best performance parameters or up the boost. However, I am quite satisfied with the car and the performance increase (even in 5th gear) is quite noticable as compared to the stock 2.8 engine.

I would supply a photo or two but do not have access to sizing software since I am out of the country right now and the pictures are larger than the 100 or 150K limit. If someone else wants to edit the photos for me let me know and I will e-mail a few to you for posting.

quote Originally posted by hnthomps: Let me chime in here with a comment on the turbo 3.4 pushrod. I am running a stock 3.4 L pushrod with a WCF 61 cam, larger injectors (19 lb Ford if I remember correctly), custom chip, and a Dennis L turbo kit sized for the 3.4. This setup runs at around 7 psi boost and does not have an intercooler. The block was a new factory shortblock with stock compression and now has about 10K miles on the engine.

Do you know exactly what turbo you have? Is it s T3/T4 hybrid? what trim?

quote Originally posted by Fiero Brick: From what I understand, you run the risk of leaning out if you exceed 80 or 85% duty cycle because the injectors don't have enough time to open and close, causing them to float half open. Not to mention that one or two of your injectors might not flow perfectly, so you could run lean in only one cylinder and hole a piston. It's up to you. I'm just trying to offer advice that might keep you from blowing your engine. A used set of 24 lb/hr injectors can be pretty cheap compared to a rebuild. You'd also have that much more fueling capability, so if you wanted to turn up the boost, you could. But again, it's up to you. Good luck either way.

Somewhere between 85 and 90% an injector will go static... this means that it doesn't have enough time to close and stays open all the time. This will give you a rich spike, followed by constant fuel delivery rate (will get leaner as airflow goes up). This is not an intelligent way to tune.

Also, as Pyrthian said, you can overheat and destroy and injector, although this is difficult. You can get away with static injectors for dyno pulls because the time involved is brief, but don't try any top speed runs that way...

quote Originally posted by timgray: Do you know exactly what turbo you have? Is it s T3/T4 hybrid? what trim?

If it is like the 3.4 turbo kit I got from Dennis it is like this.

Nissan/Garrett RB25DET (T3 style)
60mm compressor inlet and 38mm discharge nozzle. The compressor hsg is identified with a .40 A/R. The turbine inlet passage is 65x 45mm and the mounting flange measures 110 x 70mm. The turbo connects to the exhaust manifold with 4 bolts and the dump pipe is attached by 6 bolts.
They are relatively easy to find because they're factory fitment to the ever popular R33 Skyline GTS25T.,

I found that on a skyline forum somewhere when I was trying to figure out what kind of turbo it was that I got from Dennis.

quote Originally posted by Dgzfiero: the 3.4 turbo kit I got from Dennis

I realize Dennis LaGrua isn't selling those anymore, but out of curiosity, Dgzfiero, like hnthomps, are you also running stock compression on your 3.4L (which I believe is 9.0:1), and 7 pounds of boost, and without an intercooler?

I ask because I'm toying with the idea of doing something similar to what hnthomps reported having done, and I was wondering if you also have already done this:

quote Originally posted by hnthomps: I am running a stock 3.4 L pushrod with a WCF 61 cam, larger injectors (19 lb Ford if I remember correctly), custom chip, and a Dennis L turbo kit sized for the 3.4. This setup runs at around 7 psi boost and does not have an intercooler. The block was a new factory shortblock with stock compression and now has about 10K miles on the engine.

In terms of the direction I'd likely pursue with a turbo, it might be similar to what was mentioned below, and I'd like to know if this exemplified your thinking as well:

quote Originally posted by hnthomps: I elected to sacrifice a bit of performance for the improved reliability and did not tune for absolute best performance parameters or up the boost.

Has anybody else been thinking along those lines?

I have been trying to use a turbo-sizing calculator I found, but need help. Does anybody know the VE of the 3400 aluminum head/roller engine? How about the efficiency and pressure-drop for a SAAB 900 intercooler. I can't seem to find these anywhere.

quote Originally posted by rjblaze: How about the efficiency and pressure-drop for a SAAB 900 intercooler.

While I have no clue about official numbers on that Saab interheater, I can guess it's on par with a kinked hose. It's small, thin, and uses an extruded core. Air passes through a tiny inlet, through the skinny core, then hits a wall and has to find it's way to the other side to make a second pass through the same core (making the tiny core half it's size) and out a tiny outlet.

Throw that thing away. "Any intercooler is not better than no intercooler!" If you're using an intercooler that came from a car that had it installed from the factory, 99% of them are junk and will hurt performance, not help.

The 3400 flows better than the 3.4L. I'm just not sure how much better. Someone did post the flow numbers before. You could safely assume better than 83%. Maybe go 85-90%.

Myself, I have a '95 3.4L Camaro engine with a T3 turbo off an '84 T-Bird. It only needs the exhaust from the turbo to the cat and out the tailpipes to be complete. I am running stock compression and looking for 5-6psi boost with no intercooler. I'll post when I get it on the road in the next couple weeks. I do plan on dyno numbers to see how well she does.

[/QUOTE]
I realize Dennis LaGrua isn't selling those anymore, but out of curiosity, Dgzfiero, like hnthomps, are you also running stock compression on your 3.4L (which I believe is 9.0:1), and 7 pounds of boost, and without an intercooler?
[/QUOTE]
Yeah it is running stock compression, but I am using an intercooler, it is making around 5 pounds of boost. The GT has other problems right now so I ain't been playing with it much. I don't want to mess anything up.

quote Originally posted by Hudini: Myself, I have a '95 3.4L Camaro engine with a T3 turbo off an '84 T-Bird. It only needs the exhaust from the turbo to the cat and out the tailpipes to be complete. I am running stock compression and looking for 5-6psi boost with no intercooler. I'll post when I get it on the road in the next couple weeks. I do plan on dyno numbers to see how well she does.

Because different dynos often are calibrated differently, "pre" versus "post" turbo-installation horsepower reads on the same dyno would be ideal for determining the true level of improvement afforded by your new turbo set-up, although obtaining both the "pre" and the "post" reads certainly would be more time-consuming and expensive than a "post-only" horsepower read.

Nevertheless, even if you don't have that luxury, your upcoming post should be an interesting one for a number of people, including myself, as running stock compression (8.9:1 on the 2.8L, or 9.0:1 on the 3.4L swap) with a moderate level of boost (5 to 8 pounds) seems to be a prudent combination, especially without an intercooler (which I too would like to avoid using if I can).

Anyway, thanks for volunteering to post what happens when you get your project back on the road.

Will you be posting the dyno results you mentioned as well?

I did not spend the extra cash for the pre-turbo dyno simply because the 3.4L n/a is pretty well documented. Mine is all stock internally. Externally I have the ported exhaust logs and a custom intake manifold (home made) with 56mm TB (off Quad 4). Should be interesting if it works. It has started and idled very well so far. Can't run it more than a few seconds though without the full exhaust. Pretty quiet too. Turbo's make great mufflers.

quote Originally posted by Hudini: Pretty quiet too. Turbo's make great mufflers.

Interesting! I don't doubt your assertion that turbos make great mufflers; I just didn't realize that.

Will you be posting your "post-only" dyno result that you referenced? I think that would be very helpful to the rest of us, Hudinii, whether things work out with your 3.4L turbo project (which I obviously hope they do), or not.

I will post them, good or bad. The intake is a big question mark. I also plan on showing how I made the manifold in case anyone gets a wild hair (hare?) and decides to tackle something similar. I ordered the final piece of the puzzle on Thursday. I won't be home until next weekend so it should be finished within a day or two of that. Makes me feel like a kid at Christmas about to unwrap my toys. lol

quote Originally posted by Hudini: I will post them, good or bad. The intake is a big question mark. I also plan on showing how I made the manifold in case anyone gets a wild hair (hare?) and decides to tackle something similar. I ordered the final piece of the puzzle on Thursday. I won't be home until next weekend so it should be finished within a day or two of that. Makes me feel like a kid at Christmas about to unwrap my toys. lol

I'm assuming that you're referring to the custom intake manifold you've made that could be "a big question mark." In the unfortunate event that it doesn't work well, I suppose you could get around that limitation by using a Trueleo intake manifold with your turbo set-up (although that would certainly would move the engine further away from a "stock" appearance).

The tricky part could be figuring out much of the power produced with that custom intake manifold and turbo combination is from the custom intake manifold, versus how much is attributable to the turbo.

Of course, making that distinction could be academic if that combination obviously is a successful one.
On the other hand, if the combination doesn't work out well, that could present a more pressing analytical issue.

Whatever transpires, best of luck on your project, and I give you credit for having the guts to promise a post of your dyno results, whether good or bad!

It should work. I made some errors in placement of the injectors on the fuel rails so one is slightly canted. It sealed under vacuum but don't know if it will take boost. I can always order some more fuel rail. It was a 2 foot minimum order and fairly cheap.

I would like to ask Darth to burn me a chip to handle the 24lbs injectors and unhook the turbo for a n/a run. Then switch chips, hook up the turbo and see what it will do.

Here is a pic of it on my old 2.8L engine. It actually looks decent when the rails are on and everything is hooked up. It looks pitiful all by itself on that worn out engine:

[This message has been edited by Hudini (edited 10-04-2007).]

quote Originally posted by Hudini:

FrankenPlenum? good stuff. how did ya do the injectors/fuel rail?

quote Originally posted by Hudini: The 3400 flows better than the 3.4L. I'm just not sure how much better. Someone did post the flow numbers before. You could safely assume better than 83%. Maybe go 85-90%. Myself, I have a '95 3.4L Camaro engine with a T3 turbo off an '84 T-Bird. It only needs the exhaust from the turbo to the cat and out the tailpipes to be complete. I am running stock compression and looking for 5-6psi boost with no intercooler. I'll post when I get it on the road in the next couple weeks. I do plan on dyno numbers to see how well she does.

The rule of thumb that I use is that 85 ftlbs per litre is pretty close to 100% VE for an engine with pump gas compression, because that's what the current crop of ultra-high performance engines from BMW, Audi, Honda, etc are touching. By that rule of thumb, I'd estimate the VE for a 3400 to be about 70% and for a 3.4 to be about 65%.

quote Originally posted by Pyrthian: also - with high duty cycles - there is the chance of overheating & cooking an injector - they are just solenoids after all, and spending most of their time with current running thru them builds heat.

You can use injectors at 100% duty cycle (open 100% of the time) under the conditions that your engine will see. The 100% duty cycle doesn't represent normal operating conditions but a WOT condition that only occur for 10-15 seconds at a time. As such for only brief intervals your injectors won't overheat at 100%

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: You can use injectors at 100% duty cycle (open 100% of the time) under the conditions that your engine will see. The 100% duty cycle doesn't represent normal operating conditions but a WOT condition that only occur for 10-15 seconds at a time. As such for only brief intervals your injectors won't overheat at 100%

it is a solenoid, it does build heat. yes, the fuel flow does act as a coolant. but, the coils & the circuit's fuses will not like it.

quote Originally posted by Pyrthian: FrankenPlenum? good stuff. how did ya do the injectors/fuel rail?

That is a good name as it's made from the bottom 3.4L intake, 1/4" aluminum plate, 2 1/2" aluminum pipe, 1/2" aluminum plate for the throttle body to mount, and 3/4" solid aluminum rod drilled to 14mm for the fuel injectors. I'll post a little build thread when I get back home this weekend as I don't have any pictures with the rails installed.

There were no machine shop costs and everything was done with hand tools so it isn't the prettiest or most accurate. Basically, like Frankenstein, it is an experiment. I hope it's not an experiment gone bad though, lol.

[This message has been edited by Hudini (edited 10-04-2007).]

quote Originally posted by Dennis LaGrua: You can use injectors at 100% duty cycle (open 100% of the time) under the conditions that your engine will see. The 100% duty cycle doesn't represent normal operating conditions but a WOT condition that only occur for 10-15 seconds at a time. As such for only brief intervals your injectors won't overheat at 100%

Don't try any top speed runs like this, though. Not sure if the Fiero ECM does it, but between 15 & 20 seconds most GM ECM's will drop the EFR down to 10:1 or so to keep you from holing a piston. If you're injectors won't support that, you WILL hole a piston...

quote Originally posted by Pyrthian: it is a solenoid, it does build heat. yes, the fuel flow does act as a coolant. but, the coils & the circuit's fuses will not like it.

Yes fuel injectors are solenoids and if you leave them constantly on, they will get hot and may burn out or blow a fuze . However, we are talikg about using them for 10-15 secomds of the typical WOT run. In this condition the fuel injectors won't get hot enought for any negative effects. My original turbocharged 2.8L used a program that called for 100% duty cycle of the 15 lb injectors at WOT and the injectors worked fine and didn't burn out. The key is time. If you held the injectors on 100% for minutes at a time they might burn out. However, for short WOT bursts you will have no problems at all. All of the turbocharger kits made for the 2.8L Fiero ran the injectors this way

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Hudini: I would like to ask Darth to burn me a chip to handle the 24lbs injectors and unhook the turbo for a n/a run. Then switch chips, hook up the turbo and see what it will do.

If one accepts as the "baseline" the published horsepower numbers for a 3.4L, the above seems a straightforward, reasonably clean, "test" versus "control" experimental design where you'll then know roughly how much of the power increase is coming from the custom intake manifold, and more precisely how much incremental power is coming from the turbo. However, even if one doesn't accept the published 3.4L numbers as a valid baseline, at a minimum one would still know the incremental power provided by your turbo versus what was available with your custom intake manifold only.

I'm guessing from the photo that there is an increase in plenum volume with your custom intake manifold versus that of the stock intake manifold. If so, and since curiosity is killing me, do you know roughly what it is versus the stocker's?

I'm also guessing that your manifold eliminates that sharp 90-degree bend the stocker makes when transitioning into the cylinder heads. Does it in fact do that?

By the way, from the photo you've posted, I now better understand your earlier comment about feeling "like a kid at Christmas about to unwrap my toys." Before I saw the photo, for some reason I'd mistakenly thought you were feverishly grinding away on the stock Fiero intake manifold as others have done.

This project of yours should prove an interesting one.

quote Originally posted by Pyrthian: FrankenPlenum? good stuff. how did ya do the injectors/fuel rail?

I simply welded a small square piece on the intake and a small rectangle on the fuel rail with it in position. I then drilled a hole through both pieces so it would stay. The fuel injectors spray straight down about where the shark fin starts in the head.

Hudini, nice job for a shade tree mechanic. I don't know how much your new plenum will help horsepower. The stock Fiero plenum on my turbocharged 2.8L worked just fine but you then again might notice a difference. Did you open up the ports in the lower manifold around the fuel injector bosses? That area could use some help.

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

I ground them out to the same size as the heads. Just wanted to make sure the plenum was not a limiting factor.

I fixed all the little issues I had earlier but the blow off valve. I took it off and cranked the little adjusting screw almost all the way in. The starting position was all the way out. I can still hear the blow off valve opening when the turbo starts making boost. The little rubber hose on the BOV is hooked to the plenum at a vacuum/boost source. I am wondering if this is correct?

My boost/vacuum gauge is not lit yet until I get it secured into position so I could not see when the BOV was opening. It was pretty early as the car was just starting to spool up, then "whooooooooooosssshhhhh" and the car falls on it's face.

ok, which turbo do i get for my stock 3.4 pr? i keep reading t4 with .63 and 50 trim???

My origional calculations are a t3/t4 hybrid with a .50 trim but I am going for low boost as well.

Asking what turbo for the 3.4 is like asking what car you should buy. We need more info. like what boost level are you after? what are you going to do with the car? racing? are you going to beef up the engine to handle higher boost levels? etc...

I am very interested in Hudini's experience with the Ford T3 on his engine. all calculations show that turbo will peter out and run way outside the 60% efficiency island. but calculations and real world are different.... and if he get's success and does not have nasty intake temperatures it may be a good turbo for even the 3.4.

Hudini, you are going to add an intake air temperature meter so you can keep an eye on it? I am interested if your T3 on the 3.4 get's the intake temperature above 195.

I have TunerPro RT hooked up to the aldl connector. I need to modify the definitions because with the current definition files the MAT is reading in "units". What's a unit? Could be labeled wrong and it's Celsius but I'm not sure yet.

I just looked at one of my logs and under boost the MAT hit 58.75 units. If that is degrees C then it's 137.75* F. Realize that was just a quick couple seconds as the car is not tuned properly yet. I imagine it will go higher at higher RPM and sustained runs.

Wow, I am pleased to see this thread is still alive. I have decided to get a thunderbird turbo for my 2.8.

I will use a calculator to find how much power this turbo can give a 2.8.

quote Originally posted by goatnipples2002: It is in PDF format. So I can email it.

me too yamahamx4789@yahoo.com

So...we're kinda trying to avoid having to intercool these babies... what about a Meth/Water injection kit? This would also clean all the carbon and crap out of the combustion chambers in addition to boosting octane and decreasing Intake air temps... anyone put one of these systems on their 2.8 /3.4 Turbo setups to be able to crank the boost a little higher? I know wftb did it to his ecotec 4 banger swap... The 3.4 I have has heat coated headers on it, so I might just think about doing one of these setups if I can find the right T3/T4. I'd want to keep it around 12 psi TOPS, probably less, maybe 10 PSI, I don't want to destroy the engine, just want it to make a little more power above 4500 RPM. Btw I'm running the stock fiero intake and would like to keep it if possible. Think I could safely make 225 HP this way?

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1984 Fiero SE, White, first love, sold...
1986 Fiero SE 2M6, gold
1988 Fiero 2M4, the Fox
1987 Fiero GT, Blue, 3.4/4T40
Still looking for that perfect CJB 88 GT...

A basic rule of thumb is double the air, double the power. I think it assumes 100% VE. Using that WAG means 14.7psi gets you 320 crank hp. 10psi would be 2/3 of that or about 260 crank hp. I bet with VE losses it would be closer to the 225 you seek. Somebody here has done a water/alcohol injection on the V6 but don't know the specifics. I'm thinking you would need premium fuel at a minimum and a very good tune to avoid ping.

hmm, gears turning. So a T3/T4 hybrid is most desireable for a 3.4, I glean from the content of this (great ) thread, although the "trim" I'm not sure about. I looked on Ebay and there are a lot of turbos on there, men. I mean a LOT! They all say they're T3/T4s but have a lot of different brands on the snail shell part of the compressor housing. And they do't use exactly the same terms that have been used in discussing the A/R and the Trim, and such. I think I read that the .50 trim might be best for what I want to do with it, but would.63 be too much?

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1984 Fiero SE, White, first love, sold...
1986 Fiero SE 2M6, gold
1988 Fiero 2M4, the Fox
1987 Fiero GT, Blue, 3.4/4T40
Still looking for that perfect CJB 88 GT...

thnx