Any help with 3.4L DOHC V6 Swap Advice would be greatly appreciated! (Page 1/1)
87PF-GT JUL 07, 12:41 AM
Hi all, just joined this Forum. Hoping to get some sound advice...

So just bought an 87 Fiero GT (5spd) about a month back. Am looking to get the engine swapped. Wondering if anyone can help out with this project as I'm looking to get a 3.4L DOHC V6 engine - aiming for over 300 HP (400HP would be sweet but not really sure if it would be possible). From what I understand, this engine runs high Revs and is quick making it fun to drive. Don't want to go towards the V8 Route as it's simply too costly for me. I would like to stay within my budget and get like some decent v6 engine with less headaches as I'm not a mechanic.

I know 3.4L DOHC can be taken out of 97 Chevy Lumina which is stock 215HP with 220 ft-lb Torque. Am looking to get a a good exhaust put in but which one? I'm assuming that in order to achieve the 300HP + would require a Turbo added to it? Also, would the 87 Getrag282 Transmission work with this?

If anyone can tell me what needs to be done to achieve this goal, then that would be really appreciated (like what hardware I would need: If I need a Spec Clutch and if so, then which one? or which Engine/Transmission Mounts, do I need to get Forged Pistons, or is there a Turbo kit I can get, which Flywheel, etc, etc)

I don't plan on taking this to the track or anything. Just want to enjoy this as a Street car and a little race here and there.

Really appreciate it, Cheers!
Patrick JUL 07, 03:13 AM

quote
Originally posted by 87PF-GT:

If anyone can tell me what needs to be done to achieve this goal...



I would suggest you look over the vast multitude of 3.4 DOHC threads here, get some idea of what you're up against, and then ask some questions about what you might still be unsure about.

[This message has been edited by Patrick (edited 07-07-2021).]

Dennis LaGrua JUL 07, 07:10 AM
With a custom exhaust, the 3.4DOHC engine should bolt right in with minor mods, but then you will be faced with the wiring harness and some basic ECM reprogramming. You will most likely have to replace the timing belt on a used engine as they must be replaced around 60K miles. To achieve your power levels, adding a turbo might be the most cost effective solution. Years back a member here by the name of Matt Hawkins built such a setup and made so much power that he blew his Getrag. As Patrick said a search of the archives will provide good info. This engine has never been a popular swap but several have been done. I must confess that I have not seen one lately.

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" 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, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, 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 "

87PF-GT JUL 07, 11:21 AM
Thanks Gents for the info. Will dig in to the 3.4 DOHC Threads.

If this seems too much of a hassle to atleast get 300HP, then may have to venture into 3.8L V6 Supercharge Series III.
ltlfrari JUL 07, 05:37 PM
See my web site, link in sig.
Not a lot of tuning stuff out there for the DOHC. In fact, not a lot of anything really. I had to design and/or make a lot of my own stuff.
It was a blast to drive, even in stock form and loped along beautifully on the highway mated to the stock Isuzu 5 speed which stood up well to it although I never dumped the clutch either. 1st was a bit low and the gap to 2nd was too big but the motor handled it no problem.
It was a fun swap and I am glad I did it but the 3800 seems to be the way to go now.

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Anything I might say is probably worth what you paid for it, so treat it accordingly!

Dave

www.ltlfrari.com

Raydar JUL 07, 08:19 PM
I am looking to begin this swap, in the not-too-distant future. (Still getting my garage sorted out.)
With that said, I have zero practical experience, and only know what I've read. There is very little aftermarket for the engine. Some of the mechanical bits are now unobtainium.
Without boost, I don't think you'll get much more than around 260 FWHP out of the engine.
Boosted? I've heard of them making absurd power.
Mine was built to withstand a turbo, but I'm not going to boost it. At least not right away. (The person I bought it from decided to go in a different direction, and is well into a 3.6 LF3 / F40 swap.)
Good luck with yours.

marc-alan JUL 08, 07:35 PM
I am in the middle of a 3.4 DOHC swap. I bought a long block many years ago and recently started the swap. The forum pages are helpful, I found you really need to dig in to find the information you need. I had to pick up another motor from a yard to get some of the missing pieces for the long block. I am also putting in power steering with the stock DOCH power steering pump. Additionally for the ECM going to going to use a megasquirt system.

Currently the motor and transmission is mounted on the cradle and I waiting on exhaust components before attempting the first fitment.

Shoot me a PM if you have any questions

Marc-Alan
87PF-GT JUL 09, 03:12 PM
Thanks everyone for the input. I decided to go the other route. After ample of reading, it seemed that going with 3.8L V6 Supercharged engine gives you more upgrade options, comes with 260HP stock and the engine is reliable. So with that being said, I've just purchased one complete engine assembly for 3.8L V6 SC Series III.

If anyone knows of any posts for building 3.8 SC Series III engine, then please do send me the links.

Again, thank you for your input. Cheers!
Dennis LaGrua JUL 09, 09:58 PM

quote
Originally posted by 87PF-GT:

Thanks everyone for the input. I decided to go the other route. After ample of reading, it seemed that going with 3.8L V6 Supercharged engine gives you more upgrade options, comes with 260HP stock and the engine is reliable. So with that being said, I've just purchased one complete engine assembly for 3.8L V6 SC Series III.

If anyone knows of any posts for building 3.8 SC Series III engine, then please do send me the links.

Again, thank you for your input. Cheers!



I've done a few 3800 SC swaps but only one series three that I chose to run with series II powertrain management ; a cable operated N* throttle body, LS1 MAF the 2003 GTP PCM and a few mods. If you go this route some PCM reprogramming is necessary. To begin a tune the new MAF tables need to be imported to the PCM, the TPS values changed and tire size chart modified. I did not go drive by wire as I disliked traction control and the way the drive by wire 3800 series III powertrains react to that. If you want to run with an auto (highly recommended) the series III transmissions mount differently using a rear trans mount. For a traditional mounting series III auto trans mount, WCF makes them. Any other questions just send a PM or email.