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Engine swap in 86 GT by rkirkpatrick
Started on: 04-15-2021 10:38 AM
Replies: 6 (490 views)
Last post by: no2pencil on 04-22-2021 12:51 AM
rkirkpatrick
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Report this Post04-15-2021 10:38 AM Click Here to See the Profile for rkirkpatrickSend a Private Message to rkirkpatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
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..????
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skywurz
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Report this Post04-15-2021 12:13 PM Click Here to See the Profile for skywurzClick Here to visit skywurz's HomePageSend a Private Message to skywurzEdit/Delete MessageReply w/QuoteDirect Link to This Post
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).]

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Patrick
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Report this Post04-15-2021 12:31 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
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).]

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Dennis LaGrua
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Report this Post04-15-2021 04:36 PM Click Here to See the Profile for Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
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.

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skywurz
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Report this Post04-15-2021 07:45 PM Click Here to See the Profile for skywurzClick Here to visit skywurz's HomePageSend a Private Message to skywurzEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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).]

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Patrick
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Report this Post04-15-2021 08:01 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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.

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no2pencil
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Report this Post04-22-2021 12:51 AM Click Here to See the Profile for no2pencilSend a Private Message to no2pencilEdit/Delete MessageReply w/QuoteDirect Link to This Post
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.
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