Iroc n roll

Just need a bit of sorting out of the differences between some of the blocks. The 3.1 block is basically a 2.8 with a larger crank...correct (besides the different pistons in many cases)? Now what is the difference between the 3.4 and 3.1? Same crank, different bore?
Now to pistons. How much boost would you trust the stock cast aluminum dished pistons in the 3.1's with? Just rough estimate psi wise.

CaliCamaroRS

Right.

Right. The 3.4 has something close to a 3.6 inch bore. The crank I pulled out of my 3.4 actually has "3.1L" stamped on it.

Dunno......you'll get a lot of mixed opinions on this subject.

KED85

Cheat
Spend $6 at ANY GM DEALER get the GM Performance Parts book.

Get their help to you with your questions.

pontiacguy1

The RWD 60 degree engines had a little bit better pistons in them than the FWD version. Of course, the FWDs got the better splayed valve heads. I would say that the stock pistons should handle 6 PSI pretty well. If you get very close to ten, I would guess that you will be rebuilding very soon. That's just my $0.02 worth.

My friend with the Shelby Charger ran his at 20 PSI on the factory pistons, which are cast. He had some port work done and was running a bigger turbo, too, so he was making about double the factory HP. The ring lands didn't live too long under that stress, and those things were made as turbos from the factory with much stronger pistons than the ones in our cars.

TomP

My "rebuilding the 60 degree v6" book says that in '89, the Gen I v6 (89 2.8 and 90-92 3.1) received lighter, "lathe-turned" pistons... and seems to me that lathe-turned might mean forged.

Iroc n roll

Thanks for the info. The motor in particular I'm refering to is a 1993 FWD 3.1. I believe the pistons were cast aluminum, dished pistons. If I were to run a very low compression (down around 7:1) do you still think closer to 10 psi would roast the motor?

pontiacguy1

If you are going to get new pistons to lower the compression, then make 8:1 as your target compression, and use forged pistons. That is about the optimum compression for a supercharged or turbo application. You can get some strong aftermarket rods from a 350, have the big end narrowed some, and use them in your 3.1 liter. I would probably stud the main caps, and have the crank reground and polished with a good fillet radius on there to reduce stress risers. Use a good head gasket. With those mods, you should be able to run 12+ PSI without trouble. If you don't want to spend the money on the 350 rods, at least polish the beams on the rods you already have. I think that the weak point is definitely the pistons, especially in the FWD cars. From what I understand, the dished pistons they used are very thin and prone to breaking, much more so than the ones in our RWD cars.

SlowCamaro88SC

what vehicle??

lookup w/ the Mc Laren 89-90 Turbo Grand Prixs used for pistons. try w-body.com

on a 3400, it's the same as the 3100 but with a larger bore. on a FWD application you can slip the 3400 right in your engine bay, and everything will hook up, provided you are useing the factory MPFI from your 3.1 -- the only drawback is that you're still losing 15-20 HP since you're not using the SFI, also the cams in the gen III cars are hydraulic roller.

just mentioning this, because a 3400 can be obtained pretty cheaply, the same price as a 3.1 or 3100.

Iroc n roll

It's for a fiero. The only reason I'm not going 3.4 is that I have a 3.1 engine here in front of me which by the way I'm only using the block so the entire upper half is for sale if anyone is interested, accesories too. Yeah I was trying to score some GTP pistons but I wasn't sure if they fit my block since they're engines were built by McLaren...did they use the same dished pistons only forgred? But anyway, I am still curious how much boost the stock block right now could handle with really looow compression, around 7:1.

SlowCamaro88SC

not GTP, Turbo GP. iirc the TGP were inhouse factory parts. @ least internals.

try to scrore some gen III heads from a 3100, or a 3400. the flow is much better. i don't know if it's possible to go to hydraulic roller cam either.

fiero has good potential.

if I were building one w/ keeping a v6, i'd go w/ the 91-96 DOHC 3.4liter GTP/z34/SL motor.

but that's high maintainance, but the 7k redline is to die for.

or there's the 90* 3.8 liter L67 3800SeriesII found in GTPs/Regal GS and Bonnie SSe and SSEI

oh dreams.

think if new GTPs can get gotten into the 13's fairly easily, I'd love to see that in a lighter RWD fiero.

Gumby

One little thing I know is the 2.8 is one of the best engines GM built. that and the 400 sb.

There is a formula of some kind, bore stoke cc something. and the number closest to 0 is the best, both the 2.8 and 400 are the only ones even close to that magic 0.

What does that means, not much but it tells you that its a possiable 14000rpm engine. yea 14000. course getting that is another story, just in terms of math its possiable.

I think its longer stroke than bore thing or vise versa, and there is a perferct combo in there some where.

Iroc n roll

Yeah, I've already looked at the DOHC, SC'd 3800, V8, Northstar, and all kinds of other fiero swaps. What it boils down to is that I'm just kinda tired of all this drag strip modding, which is the reason I'm going from Camaro to Fiero. What I want is a fun, small (and cool looking of course), turbo v6 which I can tool around in. I ask about the 3.1 because a friend of mine just gave me a motor free. What I want to do is use the 3.1 block with the fiero heads and intake. Two reasons: 1) The stock fiero valve covers and intake looks pretty cool; 2) The Fiero heads have the compression area in the heads while the 3.1 has it in the dished pistons, put it all together and you get loooooow compression, perfect for my boost plan. So all I really want to do is find the max boost I can shoot for with this project. With a guess of compression of 7:1 and cast aluminum dished pistons (if anyone thinks they know what compression would actually result please tell me) anyone else have an idea of the boost it can handle?

PS. Yeah I meant TGP, just mistyped it The Gen III heads won't fit the fiero's very easily, modding is necessary which aren't really worth the gains, anyways, I want the Fiero heads to get a good boost compression. I was originally going to start with a 3800 Series II SC'd block and build a serious turbo system with that, but then the 3.1 basically dropped on my doorstep.

SlowCamaro88SC

shhhhweet well, then go for it. heck, I wouldn't pass that up either.

KED85

Want quick simple?
Find a 3.4 RWD, adapt starter locations, swap on Fiero intake igniton system & valve covers, exhaust DONE

Iroc n roll

Dude....have you been reading the posts?

Iroc n roll

Ok, I've actually located a compression calculator. It turns out I was pretty close and my compression is going to be running at about 7.2:1. Now boost gurus, at that compresion with cast aluminum dished pistons, what boost would you max at?

KED85

Dude....have you been reading the posts?
Yes.
No replacement for displacement.

Iroc n roll

Then i'll gladly accept your free 3.4. You've missed the point completely.

If I wanted to spend money on going fast and displacement I'd stick with my 5.7. The 3.1 is sitting in my garage just waiting to be used.

KED85

For free I offer advice.
Sell the 3.1 & put funds toward a 3.4 mill.
Others have found theirs as low as $210 for a complete mill.
No replacement for displacement.
One guy here on the third gen board knows of 3-4 complete mills sitting around for about $400 each.

As long as the car currently runs you are ahead of the game (not thumbing it to work).
It's only offered as advice, for where it may go.

Iroc n roll

Anyway, back to the original question.

You guys have any figures for me? Even if it's just an educated guess now that we know the compression.

Iroc n roll

Anybody wanna take a shot?

pontiacguy1

The ultra low compression, you calculated it at about 7.2:1, will help you be able to use more boost. It will take more boost to make the same amount of power, because of the compression being lower. Since it is only .8 lower, I would say that you still couldn't go too much over 6 psi. I believe that I would set it on about 8 psi, and drive it for a while. If all seems well, then go up to 10. Using an intercooler would help a buch to control detonation, if you can get it in there. I would get one out of a Turbo 2 Chrysler fwd, or a Turbo thunderbird or SVO mustang. There are also some of the imports that have those on there too. You can also get a blowoff valve out of a mitsubisi turbo car and use that. The blow off valve will help your car between shifts, if it is a five speed, and will help your turbo live longer, too. Just passing on what little I know.

Iroc n roll

Excellent, now thats just the kind of info I needed. Yes, I was planning on running a intercooler and BOV, if only for that "whoosh" sound between shifts . I'm going to use a Saab 900 dual cell intercooler for space constraints.

KED85

Seek parts from a six cylinder factory engineered project, not just four cylinder parts.
Better suited to the size of our engines.
Should be easy to source out MANY businesses thru the back pages of the import tuner mags.
Next door buisness to my machinist does turbos on Hondas.
Under 10 secs things.

pontiacguy1

I hate to disagree with Ked, but I would actually use the four cylinder stuff for the following reasons: (1) It is cheap to get out of the junkyards, and pretty easy to find (2)Some of the common four cylinder chrysler turbo cars were 2.2 liters, and 2.5 liters, and some of the other cars mentioned were in the mid 2 liter range. That is only about 25% smaller than our 2.8/3.1 liter V6 engines. (3) most of those cars ran with around 15 pounds max boost, and the turbo was able to make more, if the wastegates would have been set differently. You should have no problems making as much boost as your engine can handle with the smaller turbo and intercooler.

I would definitely try to score as many parts as possible from the junkyards. I believe that I would use the turbo off of a Chrysler turbo 1 car, which was a non-intercooled 2.2 liter engine. They had a good Garrett T3 turbo on there, and made 15 pounds of boost on those engines stock. They were actually a better turbo than the Mitsubishi turbos that Chrysler later used on their Turbo 2 intercooled cars.

Oh, I know what little I know about it because a buddy of mine is into Turbo FWD Dodge cars. He has one with a stock bottom end and stock cam that ran a 8.785 in the 1/8th, which translates to roughly a 13.5 quarter mile. I helped him make some of the parts for converting it to the Turbo 2 setup, but we retained the better Garrett turbo. He didn't have very much money in it, either.

Camar_Hunter_c

Even with that low a compression, I would not go very high, like past 10 PSI. Reason being CAST. get FORGED at the same Comp ratio and you can probly push 16-17 easy.

KED85

My suggestion came from word on the street.

Cheap and easily available (from the yards) probably accounts for mostly twin turbo installations I've seen, for show circuit.
Why not one as large as I've seen for the Ford Mustang V-6 engines I've read about?
Just duplicate their receipe for duribility.
Is that wrong logic for making these 60* things work on a turbo set up?

Dale

iTrader: (12)

I'd love to see a supercharger on a 60deg v6 RWD. Seen them on the fwd, and I dont think they would fit.

Just something about the power always being their, and the sound.. OMG

However, turbo seems more doable.

Randy82WS7

well this sure is an interesting thread,
while im reading this thread i thought id stop to check to see if anyone wants a nice 2.8L FI for 100 bucks or something thats in an 88 bird here ? gonna go to waste in a few days if no one comes for it. i dont believe in V6 engines,

good luck

KED85

Can't blame ya if ya know of real engines from 1968.
Hundred is too much for a 2.8