Engine swap in 86 GT (Page 1/1)
rkirkpatrick APR 15, 10:38 AM
I have an 86 Notchback with a iron duke (rebuilt)...5 speed.

I found an 86 GT with a bad engine (engine is available) with a 5 speed.

My notchback has a panel that is broken (from the last shade tree mechanic)...and I replaced the lights...

I am thinking about the conversion of putting the duke in the GT...

Any issues..????
skywurz APR 15, 12:13 PM
Depending on location engine swaps have issues come inspection time. Ignoring that and looking at this technically.

If you drop both cradles with engine harnesses attached. Swap the shift cables and ecu and bolt the cradles back into the opposite car the duke should fire up drive run in the gt.

You don't have to do a full cradle swap but its the least amount of work IMHO.

The shift cables are different between the 2 different transmissions and obviously the ecu is different between the engines.

I can't think of anything other than legal issues.

[This message has been edited by skywurz (edited 04-15-2021).]

Patrick APR 15, 12:31 PM
The fuel pumps (or the whole tank) would also need to be swapped as the fuel pressure required for a 2.5 and 2.8 is different.


quote
Originally posted by rkirkpatrick:

I am thinking about the conversion of putting the duke in the GT...

Any issues..????



The most obvious issue would be a GT with 50 less horsepower.

I personally wouldn't bother doing this swap. The end result would be less than appealing. Your notchie will have no engine, and be basically worthless... and the GT will be gutless. I see very little return on all your labor.

[This message has been edited by Patrick (edited 04-15-2021).]

Dennis LaGrua APR 15, 04:36 PM
A Duke 95HP engine in the heavier Fiero GT would result in very poor performance. I would just try to find a 3.4L 93-95 Camaro P/R engine long block that will utilize most of the 2.8L bolt on parts and provide 20 more horsepower. From what we read here this will pass the draconian CA emissions requirements.

------------------
" 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 "

skywurz APR 15, 07:45 PM

quote
Originally posted by Patrick:

The fuel pumps (or the whole tank) would also need to be swapped as the fuel pressure required for a 2.5 and 2.8 is different.




Per https://www.fierostore.com/Tech/Default.aspx?Id=423#:~:text=The%20pump%20will%20deliver%20fuel,via%20the%20fuel%20return%2 0line.

"The pump will deliver fuel to the pressure regulator which will limit the fuel pressure to 34-46psi(V6) and 9-13psi(4cyl). Any excess pressure is sent back down to the fuel tank via the fuel return line."

I figured because the GT has a higher psi pump it would just send the fuel back to the tank more. Not sure its really an issue or not so I did not bring it up.

Edit

Because this is an 86 i think the fuel line routing is all messed up and different. My main fiero is an 87 Duke. The 87 fuel routing would be adaptable but the 86 is not so yes what Patrick said swap the tanks because the lines are different.

[This message has been edited by skywurz (edited 04-15-2021).]

Patrick APR 15, 08:01 PM

quote
Originally posted by skywurz:

I figured because the GT has a higher psi pump it would just send the fuel back to the tank more.



Theoretically, it might appear to function in that manner... but I suspect in actual practice, a fuel pump putting 34-46psi long term into a system that only requires 9-13psi could be problematic. Why wouldn't Pontiac have used the higher capacity fuel pump for both engines then? It would've simplified production... if it worked.

no2pencil APR 22, 12:51 AM
it would be less effort to swap the fastback clip onto the notchback.

However I do agree, put a 3.4L into the GT.

Best of luck with whatever direction you go.