New to Forum. Has anyone here put a turbo on a Gen III 3400

[FieroGT87]

I just found this forum. I have a 87 Fiero GT I'm presently starting the process of upgrading the engine to a IHI turboed Gen III 3400 w/ Saab intercooler. I'm looking for any info anyone may have here pro's and con's for the turbo.

I plan on running about 5-9 lbs boost on the turbo.

The other problem is changing out the ECM for the PCM with a 5 speed Getrag.

The reason for the 3400 is I feel that if the Fiero had continued production that is the engine they would have put in it. I want the Turbo for a little more Torque and HP.

Thanks

[ikessky]

There is a guy over at n-body.net that just turbo'd his 3400 powered GA.

[Blackrider]

There is a guy over at n-body.net that just turbo'd his 3400 powered GA.

2 of them to be exact.

[bszopi]

The guy that owns and runs the GMPCM site (www.gmpcm.com) has a turbo'd 3400 (might be 3100) in a Fiero. No need to swap your ECM for the PCM. Much easier to just get a reprogammed MEMCAL for your current computer and run the engine MPFI vs SFI. The older computer is much easier to adapt to boost.

[ikessky]

2 of them to be exact.

phantom and who else?

[Mechanic]

Might want to consider using a top feeder turbo design such as those used by Mitsubishi for any turbocharged GEN III Fiero transplant. A 95' 3100 exhaust manifold will bolt right on to the 3400, and happens to have an outlet angle perfect for mounting a Mits. turbocharger to it directly. This has several benefits compared to the more exposed designs mounted at the crossover:

1) Saves considerable space in the area most prefer to mount an intercooler. The Saab 900 Blackstone works well in the stock air cleaner area, as long as you use a fan to supplement air flow at low speed/idle, and isolate it somewhat from the rest of the engine compartment. Side scoops are a big plus here.. Heres a pic with one in position, but without the fan and isolation shrouding: Initial Intercooler Install

2) The low mounting position reduces engine compartments temps significantly. All of the stock exhaust heat shields can be retained, which further reduces engine compartment temps. The exit side exhaust shield covers the top of the turbo quite well, with only some minor reshaping (i.e. bending) required.

3) The best performance from any turbocharger will be obtained by mounting it as close to the exhaust valves as physically possible. On a V6, this is as close as it gets..

4) Does not require welding in order to mount the turbocharger.

5) The total cost to mount the turbo is only around $50.

6) If emissions are not a factor in your area, the whole exhaust system after the turbo can consist of a $25 flange with a 90 degree mandrel bend welded to it. This can be routed to the existing stock cat back system, but a better flowing aftermarket (at least 2.5") cat back system should really be used here instead.

You will not be able to use the stock Fiero's ECM for a 3x00 swap as the 3x00's use a distributorless ignition system, you would be far ahead of the game by splicing in a 3.1 MPFI w-body harness along with its 1227727 pcm, and replacing the memcal's code with that used by the TGP (i.e. $8F program ID). Since you will likely need to modify several parameters in the code, VSS road speed constant, manual trans related critera, injector flow rate, etc. You would be well served to research what is required to do this yourself. Its really not hard at all if you spend a bit of time reading first. You can find lots of info on this at the GMPCM website (see sig).

[phantom505]

The other guy is Deek00 on GAGT.com

His is a custom rig. He's running low 14's in Las Vegas.

[FieroGT87]

Thanks for the responses everyone.

I've been reading as much as possible before pulling the 2.8.

This IHI RHB6 flows 592 CFM and with a engine capicity of 3360 @ 6000 RPM and 4 PSI boost I should be in the 290 HP rating with 290 BHP.

I'm also wondering if I need to change the pistons or anything else, or if I can keep the engine basically stock. Dennis LaGrua said someone here modified a 3400 "with minor modifications" to get somewhere around 330 HP. Were those Deek00 and Phantom?

The computer is a issue that concerns me. A couple of people on Pennock's have done this but I'm still unsure about the ECM. Some stated that I should find a early 90's Beretta and use that ECM and have a chip made for it.

Mechanic, thanks for the exhaust suggestion. I have Meecham scoops on my Fiero GT, so I have air flow through on both side to the rear engine compartment. I was planning on putting the intercooler on the drivers side with a fan and pull the air in to help keep it cool. The intake air I was either going to pull it from above the intercooler or the passinger side scoop.

This is a great forum, I'm glad I was pointed here from Pennock's Fiero Forum (www.fiero.nl)

Thanks,

Earl

[phantom505]

I'm so sick of people spreading stupid rumors about the 3400/4T45.

1) You don't need to change a thing about the engine other than spark advance and fuel tables. You need a table that will match the applicaiton, like all mods.

2) The stock pistons are weak, but not that weak. Most of the time some doofus with NOS blows one up. One person I am aware of blew one up on 24* of advance with his turbo at 10 psi, but I think there is much more to the story he never let out. I'm running 9 psi at 19-20* of advance and I don't have a degree of KR yet.

3) This doesn't apply to you, but the 4T45, although not holding up real well at this point is handling 320 HP and 340+ ft/lbs at the crank. It can't be that weak.

4) Some people think that you can't turbo and automatic, IDIOTS. You want an auto with a higher stall with most turbos or manuals with a really really steep 1st gear. Autos load turbos better. I've heard that from several reliable sources.

5) My engine is 100% stock other than the UD pulley. LIM, UIM, TB, heads, cam, pistions, all of it, stock. (not for much longer though).

[SappySE107]

Tiago has a camaro 3.4 that is basically stock with a turbo running the numbers you asked about (330+ hp). I dont know specifics but that bottom end is kinda close to what the 3400 has, minus pistons. Heads are different so that changes total boost you can run but thats not the question. Anyway, the stock bottom end can take it just fine as long as you tune the computer properly. Too much advance and not enough fuel are going to kill it, not the power with the boost itself. I would check the engine out though just to make sure it wasn't abused, has cracks or any other issues before you boost it.

Fiero.nl is a great site as well, but damn does it move! You gotta have it up like the stock market watching those posts scroll by

[brian89gp]

3) This doesn't apply to you, but the 4T45, although not holding up real well at this point is handling 320 HP and 340+ ft/lbs at the crank. It can't be that weak.

4) Some people think that you can't turbo and automatic, IDIOTS. You want an auto with a higher stall with most turbos or manuals with a really really steep 1st gear. Autos load turbos better. I've heard that from several reliable sources.

3) how long have you been running it? A great number of people consider "holding up well" as 80-100k miles. A lot of it is also driving habits, I know people that could toast any transmission behind any stock motor in a matter of a week.

4) My experience is the opposite, the manual loads the turbo faster (cept for first gear). Only thing is letting off of the throttle during a shift really sucks even with a BOV.

[phantom505]

Anyone that thinks you will get 80-100k on an engine/transmission that was not intended for boosting is smoking crack anyway (without lots of good maintenance). I have run it over 10k+ miles though.

It all depends on what kind final gear, how much that particular tranny loads the engine. In the case of the 4T45 I am at full boost at 3500-4000 RPM, in first gear. It verifies depending on gear, but so long as I stay on the throttle it never drops off, no drop in pressure when I shift. It's not a manual vs. auto issue, it's a loading issue. It's perfectly smooth with the auto too.

What engines/transmissions are you trying to compare here?

Most people also think that manuals handle power better. Also not true. You can build automatics to handle sick amounts of power simply because you can build them so they don't lock up. Manuals handle more power stock, and will handle more than a typical automatic transmission, but as far as beefing them up, there isn't much you can do to them when comparing to an auto. Just removing the lock up will let you handle more power than a 3.4L will ever hit, even with high winding.

Yes, it goes against conventional wisdom, but nearly everything on this car does. Just stay tuned in and see what sorts of fun things come out of this project. How about drags for a FWD that will allow us to use wider tires by changing their offset? The high winding 3400 (3500 or larger depending on the bore out), the suspension improvements, etc. It's going to be neat to see one of these cars supertuned.

[brian89gp]

It's not a manual vs. auto issue, it's a loading issue. It's perfectly smooth with the auto too.

What engines/transmissions are you trying to compare here?

Indeed, its all a loading issue. In my case it is a turbo 3.4 DOHC that used to be behind an auto that i then swapped to a 5spd. Nothing else changed besides for the transmission and what I found is that 2-5 gears load the turbo much faster then the auto ever did (except when the TCC was locked). Part throttle response is also much greater, the auto seemed kinda sluggish when it came to that. With the auto I had to be at 75% throttle to hit boost, depending on gear with the 5spd it can be anywhere between 15% and 50%.

[phantom505]

Hmmm.. I've heard similar complaints before on the 2.2L Eco. I haven't really noticed much of problem, except when it slips.

I'll let everyone know how the built tranny does. It has better clutch packs so it will grip so much better. For all I know I might full boost much earlier... that would be sweet. BTW, I'm going 3.69 gears too.

Another note, 1st and 3rd gear have the best load. It's takes longer to spool in 2nd.