what should I do with 3400 fiero?

[Froggx]

Hi everyone a couple years ago I was building a fiero up but then I moved away for a while to go to school and it sat in storage but now I'm back and looking at it. It's gonna take a lot of work but I think its got potential...

Here is what the car had on it when I acquired it: 1987 Pontiac Fiero GT with 2.8l motor and getrag 5-spd transmission, lowering springs/shocks (don't know what kind but it beats you up), ACT clutch (I want to say stage 3 but dunno it's excessively grabby more so than ACT stage 2 in my Miata), front tire 225mm low profile on 16" rim, back tire something like 275mm? on 17" rim, bigger radiator, blown motor (blew 3rd time I drove it first time was 6hr drive home from buying), it is painted all black and quarter panels are tinted, motor had full headers + exhaust (irrelevant, but it was true duals with each bank of cylinders getting their own header and full exhaust in such a way that the 2 banks exhaust streams never met), cold air intake (cone filter and some tubing I guess that's an intake that's what dude called it I dunno it looked like he bought like a crx intake off ebay and hacked it up and kinda twisted it funny to make it fit then put a lot of silicon couplings and what appears to be expensive duct tape on it and it looked kinda dangerous and I'm surprised it made it 6 hrs home but that's for another story...sorry for all that...), lightweight neutral balanced flywheel (if I remember correct only the '88 fieros used neutral flywheels all others had a weight bulge on it which makes me think that this is not the original 2.8 correct me if I'm wrong), the original interior is out of the car but it is available as is new carpet from fiero store, I think the motor was internally stock but cant be sure haven't taken it apart I just know it's dead, upgrade brake pads and rotors (and maybe calipers as well not sure), poly bushings...I think that's it...

sorry I know that's a bit much please keep reading I'll try to do better...

I saw this fiero with a blown motor as the perfect platform for an engine swap. I went to the junkyard and wound up getting a 3400 from a 2000 grand am. The motor was then rebuilt and slightly modified before it was installed in the car.

The motor has: pnp heads (the heads were "cleaned up" by the shop and the combustion chambers were polished), mildly reground camshaft (sorry I lost the cam card I posted it on this site back in the day dunno if it's still up), LS6 valve springs (with the proper supporting mods like valve seals and seats), 3500 upper intake manifold, all manifolds have been "port matched," pistons are thermal coated (sounded cool and shop threw it in with the heads), better than stock head gasket (no idea beyond that), new bearings and bolts, everything got checked out, I think it has a higher pressure oil pump or something, uses the light neutral flywheel of the 2.8, 36 lb/hr fuel injectors from grand prix 3800 supercharged (cleaned and flowed), I think that's about it. Pretty much all else is stock.

Things I need: throttle body (I have one from a 4.6 mustang but the linkage is all backwards and I can't figure it out really but it does bolt to the manifold and looks ok with ford logo ground off ), prolly gonna need an intake tract other than the crx thing, need an exhaust system from exhaust manifold-back.

What I have: access to a MIG welder (I don't know how to weld but I'm a fast learner), a garret T04B turbo (can't remember details I think a 57 trim compressor though), 3 intercoolers (4th gen supra, dsm, and mitsu starion), water injection kit (a decent one not a windshield squirter nozzle), blow off valve (hks super sequential, can vent to atomosphere or recirculate), a PCM from something (an early '90 grand prix I think can't recall specifically, I know it's capable of using code from the turbo grand prix and running a 2 bar map sensor thus being able to tune for boost), the items necessary to interface with said pcm using a laptop and programming it (I think I have a program called "GMPCM" has anyone heard of it?), electronic boost controller, skills at automotive electrical work, experience with boosted cars and ecu programing (turbocharged volvo 850, miata with m45 supercharger and standalone ecu), car-working-on ability (see miata), some other stuff I'm sure.

My goal is to basically put that stuff on that car and make it drivable. I'm not sure quite how to get there, so I'm going to ask a few questions:

What is the best way to physically attach my T4 turbo to the engine? Can I do it easily using the stock exhaust manifold? How? Would it be better to figure out some other manifold solution?

What should I do with the exhaust after the turbo? Wrap it around the engine? Snake it straight down and out the back? Use a 1 inlet, 2 outlet muffler or a y pipe or something else?

What should I do for engine management? Is using that PCM feasible? Will that program work? Should I use something else like mega-squirt?

Should I bother with an intercooler if using water injection? How do you put an intercooler on a fiero anyway?

Where would I get oil for a turbo? Best place to return oil?

What should I do for a throttle body? Is the mustang unit feasible or do I need to get something else? What else is there?

Imagine you were in this situation, what would you do?

[Bridgetown]

I am a 3400 Fiero owner. From what I have researched, the stock 3400 manifolds flow poorly. You should replace them first. Since you are going to turbo, you basically have two options. First, and simplest, is to get two front 3500 manifolds. You want the front ones because the rear 3500 manifold is angled away from the block making it harder for routing exhaust tubing, and may contact the trunk wall in the Fiero. Run both manifolds to a turbo flange located near where the cruise module/charcoal canister is (drivers rear corner of engine bay) This will give you the most room to do the rest of the plumbing. The second option is to build your own headers, this is obviously the better option, but requires some skill. As for engine management I would go with the 1227730 ECM. It is a well supported OBD1 setup and runs the 3400 very well. This is what I am using. You can actually use the Fiero(V6) harness, adding a few wires for DIS etc. to run the 3400. What size is the 4.6 TB? You probably want a 65mm unit like the TCE one or an lx5 (which requires an adapter) You are going to need to upgrade the fuel pump when you turbo too. And mabey a 3-core aluminum rad too. At 5-6 psi you probably don't need to intercool, but typically midengine cars have higher engine bay temps, so it is probably a good idea. Most guys run the intercooler low under the front of the engine, or cut the trunk out and put it there. That's all I can think of right now.

[mtownfiero]

Bridgetown i have a question,

I have a 3.1l mpfi now that im using 3x00 manifolds on since they are an upgrade over the older manifolds, but i have to run a block off on the rear one to keep the exhaust routing stock. I was wondering if i get a 3500 front manifold will it bolt up to my rear head and dump on the tranny side?

[Bridgetown]

Bridgetown i have a question,

I have a 3.1l mpfi now that im using 3x00 manifolds on since they are an upgrade over the older manifolds, but i have to run a block off on the rear one to keep the exhaust routing stock. I was wondering if i get a 3500 front manifold will it bolt up to my rear head and dump on the tranny side?

I am using stock 3400 manifolds on my car and built an exhaust sytem to exit to the trunk side of my engine (rear) it is a tight squeeze but it works. (You could do similar) Here is a pic of my exhaust. I also attached some pics of a 3x00 with two front 3500 manifolds (exhaust pipe setup for FWD car). You can see that the manifold that would be on the trunk side of your engine (in Fiero) is dumping towards the belt end of the engine, not the trans end. This is actually a good thing because it will give you enough space to loop the exhaust pipe back up and over the trans like the stock Fiero system. The other issue to look into first though, is if 3500 manifolds will bolt to 3.1L heads. This I can't answere for you.

[mtownfiero]

ahh i see now. The 3500 manifolds are similiar to the stock 3x00 manifolds but the dump faces straight down instead of vertical. I had my exhaust setup like that using the 3x00 manifolds but it constantly leaked so i blocked it off and made a y-pipe but id really like to get a tgp style rear manifold. I can tell even by the sound that having the rear blocked and the exhaust rerouted it is more restricted than before.
Love the car btw and im hoping to do a 3x00 top swap at some point, the 3.1l is a little more tq.y then the 2.8l but not a huge gain by far. 40 or so hp from the heads and intakes would be nice.

[mtownfiero]

also btw making a crossover with the 3900 manifolds would be a good start in a fiero. for the oil send and return you can T the oil pressure sender and run a line which is pretty straight forward, for your return you have to make a line into the oil pan that will allow the oil to flow straight down freely into the pan.

[Bridgetown]

I have been told that 3900 manifolds won't bolt to 3400/3500 heads.

[pocket-rocket]

I have been told that 3900 manifolds won't bolt to 3400/3500 heads.

I believe I've read this same thing.

[mtownfiero]

bridgetown dont you have 3900 manifolds on 3400 heads?



whoops i meant 3500

[Bridgetown]

Negative Ghostrider, the pattern is full. Nope I have 3400 manifolds on 3400 heads. The pic I posted of the exhaust (painted black is mine) the other two are someone elses 3400 (I think) with 3500 manifolds. The exhaust routing on the engine in the pics is for a FWD car not a Fiero. If you were to use the 3500 manifolds on a 3x00 in a Fiero you would run the exhaust the reverse of what you see in the pics. It would have the same routing as a stock Fiero. The pics were to show what two front 3500 manifolds look like. Disregard the pipeing on the last two pics.

[Superdave]

lol, that garage looks familiar..

Yes, 3500 exhaust manifolds will bolt to 3.1 heads. you'll have to use 3.1 gaskets though.