Hi. I'm considering a turbo on my PR 3.4 87 gt. I've collected a lot of parts for the turbo setup but exhaust manifolds--do I need to fab up my own or is there some other easier method or a car I can strip them from? I'm not worried about max power but rather just a little extra kick without modding the engine bay too much. Thanks.
I think the usual way it's done is to use the stock manifolds (grind out the restrictions) or the Sprint manifolds from the Fiero Store, then make a custom Y-pipe and down-pipe for the turbo. That said, I suppose you could attach the turbo to the bottom of the stock Y-pipe. That should save you some work. But the stock Y-pipe doesn't flow very well, so you may want to replace it anyway.
Another thing I've seen people do (mostly on 3x00 and 3800 swaps) is to use FWD manifolds and crossover pipe, and attach the turbo to the crossover pipe. That puts the turbo on the trunk side of the engine. And you can run a short exhaust pipe back to the muffler.
You can use the stock manifolds but they will not hold up well without at least welding in bellows joints between the exhaust ports. I've traveled the boost route with stock manifolds enough times to know the best arrangement is something else in their place. They will glow intensely, expand and likely warp, or crack, or both before long. Try to find some cast iron manifolds from the 89-90 Turbo Grand Prix to fit in place, you will not burn those out. I made a matching back side cast iron manifold for a cast iron head using a 3400 front manifold which I mounted and cut the center section out of, turned around to line up properly with the middle port on the back side head and then welded it back together after all three sections were lined up and bolted down. I had to do a little grinding to clearance the bolts and used longer bolts with metal sleeves to keep the bolt heads far enough out to put a wrench on them. Understand that the front manifold exit would be pointing toward the passenger side when mounted on the back side cylinder head before modifying. I mounted with the outlet facing the driver side before modifying, as you know the center port does not line up in that arrangement.
I used stock 1988 exhaust manifolds on a turbo engine for more than 20 years and had no problems with them. I had relieved them, welded the outside and use custom Y pipe.
I used stock 1988 exhaust manifolds on a turbo engine for more than 20 years and had no problems with them. I had relieved them, welded the outside and use custom Y pipe.
That's no longer stock BillS and in line with the bellows expansion joints I recommended be added to the stock manifolds if used. Durability is key and stock manifolds as is in front of a turbo will not cut it for long on anything driven hard regularly. Cast iron was the only thing that allowed me to "set it and forget it".
I used the Fiero Store Sprint headers on my 3.4 Turbo build, we cut the flanges off and used a V band on both sides connecting the crossover pipe with a turbo flange. I wasn't happy with the power gained by the amount of time and money invested JMO.
Don't forget that one of the sources of issues with the manifolds cracking was the fact that they were rigidly bolted to the heads and then with expansion would stress and possibly crack. I used 1988 manifolds, which had the holes ovalled (only year they did that) to allow for at least a bit of movement with less strain. Possibly that contributed to the longevity of my manifolds.
I also use modified (ported and reconfigured to suit the front engine application) on my 1956 MG with a 3.4 in it. They are actually not bad in terms of flow if you hog out the extra metal the idiot factory left in the ports, and eliminate the crossover fiasco (I created a custom crossover for the engine swap job).
We (trueleoracing.com) use to make headers for the 2.8 & 3.4 engines, including those for turbo applications. That said, as someone pointed out, the stock Fiero headers are not worth trying to modify. They will crack and moreover they're woefully inefficient POS. You need to start out with a decent set of headers; else your turbo will not preform anywhere near efficiently. Additionally the poorly designed -low CFM- of the Fiero intake manifold will add to the problem. I suggest, as another had said: get a set of sprint headers and have someone make you a better Y pipe with a turbo flange etc. And by all means use a fan-assisted intercooler to help offset that awful intake manifold.
Additionally, forced induction is not free power, it takes energy to spin a supercharger be it a turbine or belt-driven. And that parasitic energy translates into additional wear & tear. You should thus start out with good engine; new bearings etc, else it may not live very long. The GM 2.8 is not your best choice for forced induction; not with its iron crankshaft, stock pistons -forged are much better- With steel crankshafts now like hen's teeth to find, Eagle made them, I got one of their last for my 87 2.8 build. I strongly suggest you limit you build to 7 lbs of boost max.
Lastly, IMHO you should not go the turbo route with a 2.8 or 3.4. Instead you can:
I- swap in a 3.8 or 3.8sc. In the long run it will probably cost you less, live longer, and give you a more fun ride.
2- see if you can find a small 4bb carb & intake manifold for the 2.8 & 3.4 Yeah, that intake is another hen's tooth thing, but worth the search; whereas that combo and ether sprint headers or opened-up stock headers can also make it a more fun ride with no 4.5k rpm power drop off.
good luck
[This message has been edited by Francis T (edited 03-15-2017).]
I used the Fiero Store Sprint headers on my 3.4 Turbo build, we cut the flanges off and used a V band on both sides connecting the crossover pipe with a turbo flange. I wasn't happy with the power gained by the amount of time and money invested JMO.
Same here on the expectation. We used a custom crossover pipe made from stainless steel with a T-3 mounting flange. My turbo 3.4L is peppy but doesn't seem to provide what the 3800 is capable of. Tuned properly (and that is a BIG challenge ) it should prove fun to drive but if you want a big step up a new cam ad some head work is needed. A while back there was a guy that built an intercooled turbo 3.4L , ran some high boost and made like 387 HP. You can find that video on You Tube.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Originally posted by Dennis LaGrua: Tuned properly (and that is a BIG challenge )
Not sure what this is all about; if you have the knowledge to tune a 3800 properly, you also know how to tune a 3.4. Likewise, if you cannot tune a 3.4, then I don't see how you would be any more capable of tuning a 3800.
An engine is an engine; they all work the same way.
I used Schedule 40 1.5" ID weld els from the local pipe supplier and expansion bellows from a junkyard find. It's still holding up years later:
As it is today:
90* Weld el
Expansion joints borrowed from a FWD car in the junkyard:
First attempt. Did not work as expansion would push the turbo flange to the drivers side. When it cooled there would be a gap between the exhaust manifold and the crossover connection:
[This message has been edited by Hudini (edited 03-19-2017).]
Not sure what this is all about; if you have the knowledge to tune a 3800 properly, you also know how to tune a 3.4. Likewise, if you cannot tune a 3.4, then I don't see how you would be any more capable of tuning a 3800.
An engine is an engine; they all work the same way.
It's not about the software it's all about the hardware. That was a huge hurdle in my 3.4 turbo, nobody around here burns chips.
It's not about the software it's all about the hardware. That was a huge hurdle in my 3.4 turbo, nobody around here burns chips.
If I might add, tuning a flash memory OBDII PCM is so much easier than trying to tune the Fiero C3 ECM. When you try to tune for a turbo with the Fiero ECM you must scale the fuel table by a factor of two for vacuum and boost (same table spaces for control of both conditions). With OBDII you have feedback tables of the LTFT. the STFT, and the KR's in addition to other parameters. Its tailor made for boost. OBDII program changes are done in minutes. Prom changes require removal, erasure, reprogramming and reinstalling. Doable but not very convenient. With even a good program like Tunercat, it takes hours to get a good ECM tune.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Kind of seems weird that one would do a 3.4 install (with turbo aspirations) and then saddle it with a difficult-to-tune ECU. That's no fault of the engine; that's poor ECU choice.
I have a tweaked MS2 on my Fiero-headed engine. It's easy to use, no?
[This message has been edited by pmbrunelle (edited 03-21-2017).]
I had a 3.4 PR Turbo build and it ran great, but I did have idle issues. It could be very frustrating. Sometimes I would pull up and it would idle fine and then sometimes it would stall.
I could never get it right.
I went with a 3800sc. More power and less frustration. I do miss the turbo, but drivability is important.
I ran a stock 87 ECM with slightly bigger injectors and higher fuel pressure on a 3.1 rebuild. Added a knock sensor and Buick ESC module connected to an MSD ignition. It worked but I ran out of fuel at 4500 rpm. Set at 8psi, boost kicked in at 1800rpm using a K3 turbo from a Volvo. Similar to a T3.
I have a twin turbo kit I'm thinking of installing on my stockish 3.4 rebuild (from a 3100 block 9:1 pistons). I want to do a 7730 upgrade first then at the GM turbo 3.1 code from the Grand Prix and go from there.
I also have a spare 3400 engine and harness+PCM (which is technically for sale)...I was thinking of using the harness to convert that 3.4 engine to OBD2 and then adding the twin turbo kit from there and keep the 3400 block in lieu of an overbore to 3.5L iron head build with a .510" for my next racing engine...
I ended up switching over to a 7730 pcm with DIS on my 3.4 Turbo, it took about a year of tweaking but we got it to idle and run perfect. Like I said before I just wasn't happy with the power.
I ended up switching over to a 7730 pcm with DIS on my 3.4 Turbo, it took about a year of tweaking but we got it to idle and run perfect. Like I said before I just wasn't happy with the power.
How much power were you making? Did you feel like you maxed out the 3.4 architecture, or there was still power left on the table when you decided to change to 3800?
[This message has been edited by pmbrunelle (edited 03-23-2017).]
How much power were you making? Did you feel like you maxed out the 3.4 architecture, or there was still power left on the table when you decided to change to 3800?
It was never dyno'd but if I was to guess, maybe 200whp. I think it was maxed out, although I was limited to 8-10psi boost due to stock internals on rebuilt 3.4 except for 272 cam. I was running with a 4T60 transmission and that was a nice upgrade, also headers to 2-1/2" exhaust ported intake and throttle body. It was intercooled and had meth injection, and as mentioned above 7730 pcm with DIS. A lot of time and money with not so great performance but it was very reliable.
[This message has been edited by JCircs (edited 03-23-2017).]
Originally posted by JCircs: It was never dyno'd but if I was to guess, maybe 200whp. I think it was maxed out, although I was limited to 8-10psi boost due to stock internals on rebuilt 3.4 except for 272 cam. I was running with a 4T60 transmission and that was a nice upgrade, also headers to 2-1/2" exhaust ported intake and throttle body. It was intercooled and had meth injection, and as mentioned above 7730 pcm with DIS. A lot of time and money with not so great performance but it was very reliable.
You would have been a lot further ahead on power had you chose a complete 3400 which dynoed over 300 hp at the wheels on stock internals and about 10-12 psi. Nice work with the 3.4L
You would have been a lot further ahead on power had you chose a complete 3400 which dynoed over 300 hp at the wheels on stock internals and about 10-12 psi. Nice work with the 3.4L
Thanks for the compliment but I ended up selling that as a complete drop out and opted for this. [/URL]
[This message has been edited by JCircs (edited 03-23-2017).]
The real limit on power I've seen from V6/60 engines is under-sized turbos. I too was making close to 200hp from my 8psi 3.1 conversion but in reality - a 3.4 needs a full T4 turbo to see 300+hp... The twin turbo setup I have sitting in a box uses 2 tiny turbos. My expectations are equally metered. Turbo experts will tell you that ONE properly sized turbo is all you need...but I bought it for $350 and came off a running car. I still am no where near to installing it...
The real limit on power I've seen from V6/60 engines is under-sized turbos. I too was making close to 200hp from my 8psi 3.1 conversion but in reality - a 3.4 needs a full T4 turbo to see 300+hp... The twin turbo setup I have sitting in a box uses 2 tiny turbos. My expectations are equally metered. Turbo experts will tell you that ONE properly sized turbo is all you need...but I bought it for $350 and came off a running car. I still am no where near to installing it...
Originally posted by JCircs: I used a Precision T3 58mm
Excatly my point. I think at 14psi, the limit of a T3 class turbo is about 250hp. It was nice having boost at 1800rpm, though ... A T4 probably won't make boost until 2400 or later but it will take you farther too. The reason people for hybrid T3/T4 is to make just over 300hp.. (air intake side uses T4 side but spools quickly since lower [exhaust] side is T3)...
I ended up removing the turbo 3.1 and having a 4.9 installed. Honestly, the turbo 3.1 made more power, just not consistently due to basically no proper tuning. I would have preferred a properly running turbo v6 over the 4.9 anyday...
Used to make so much power that before I put in a rear-bumpsteer correction kit that I could [unwillingly] spin myself out warming up the tires... But due to poor engine management would lose power at the motor got hotter... http://www.youtube.com/watch?v=AcT6YL7a-Mw
[This message has been edited by lou_dias (edited 03-25-2017).]
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... A T4 probably won't make boost until 2400 or later but it will take you farther too. The reason people for hybrid T3/T4 is to make just over 300hp.. (air intake side uses T4 side but spools quickly since lower [exhaust] side is T3)...
