New member wants to instal a v8 (Page 2/5)
sourmash MAY 02, 07:36 PM
Another vote for the 4.9 or 4.5 engine. It's said to be one of the easiest swaps. Mine loves the interstate, gets good mileage and still has a bunch of torque down low for red lights. Having a V8 in a Fiero is an oddity to most people you meet.
Raymac85 MAY 02, 11:02 PM
Go with the 4.5/4.9 it is a awesome engine. I have a 4.5l in my 86GT that was built by johns 4.9 performance. Gobs of power and very fun. Super easy install.

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85 SE v6
86 GT 4.5l v8

Raymac85 MAY 02, 11:03 PM
Go with the 4.5/4.9 it is a awesome engine. I have a 4.5l in my 86GT that was built by johns 4.9 performance. Gobs of power and very fun. Super easy install.

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85 SE v6
86 GT 4.5l v8

cvxjet MAY 03, 12:34 AM
Just out of curiosity, what is the weight difference between the 2.8 and the Cad 4.9? Do you gain much weight?
sourmash MAY 03, 08:16 AM
This is from John's 4.9 site":

"The overall weight of the Cadillac 4.9 engine is 360 lbs.* A Chevy 2.8 V-6 engine weighs in at 350 lbs and a small block Chevy V-8 is about 550lbs.* With its square bore and stroke ratio, the 4.9 port fuel injected engine delivers 200hp and 275 ft/lbs of torque."

The footnote links to this site below:

*www.gomog.com/allmorgan/engineweights.html
Roger Walling MAY 03, 08:35 AM

quote
Originally posted by fieroguru:

The stock fiero ECM is normally removed when non-stock engines are swapped in. If the new engine is fuel injected, then the ecm to run the new engine is installed.



So when I buy the engine from a salvage yard, I have to get the ecm and cut out part of the wiring harness in order to connect it up?

Thank you fieroguru.
Roger
olejoedad MAY 03, 08:56 AM
Yes, the ECU from the donor engine needs to be used. It will fit in the stock Fiero location.
Roger Walling MAY 03, 10:54 AM

quote
Originally posted by olejoedad:

Yes, the ECU from the donor engine needs to be used. It will fit in the stock Fiero location.




Can you just plug it into the Fiero connections?
fieroguru MAY 03, 11:33 AM

quote
Originally posted by Roger Walling:
Can you just plug it into the Fiero connections?



If you buy a custom harness specifically designed to install engine A into a Fiero, then the answer is yes. Install the custom harness on the engine, put engine into Fiero, connect the Fiero 203, 500, battery, and ground connections and you will have an engine swap that will run electrically (still need to address mounts, fuel, cooling, exhaust, etc.).

If you want to go the DIY route, to connect any engine to the Fiero, there are 3 primary connection points.
ECM connections (most are different for each engine type, but these will come with the factory harness for whatever engine you are going to install).
Fiero 203 connector (this is in the center conlsole area by the ecm) is the wiring source for Injector power, fuel pump, check engine light, oil pressure gauge, Speedo, AC and torque converter lockup).
Fiero 500 connector (on the front engine firewall on the 84, by the passenger strut tower on the 85-87) is the wiring source for starter, ignition, alternator gauge, temp gauge, cooling fan, reverse lights.

At the bare minimum, the new engine and its donor harness will need to connect to the Fiero 203 and 500 connectors, but most other non-fiero engines do not use those specific connectors. The needed wires exist in the donor engine harness for all the systems and sensors that need connected to the 203 and 500 connectors, but you will need to isolate those wires in the donor harness and terminate then at the proper pin locations in the Fiero 203 and 500 connection points. It isn't difficult work, but it does require the ability to read wiring schematics, not be intimidated by a harness with 50 to 100+ wires, and have the skills and tools to make the proper electrical connections (twisted wire with tape won't work long).

There are many ways to do this. Strip the Fiero harness to just the 203 and 500 wires then splice them into the donor harness. Take the donor harness and repin its wires to fit the 203 and 500 connectors, a combination of the two, or a complete disassemble of both to reroute the wires where you want them to improve the overall appearance of the engine.

The time you take making everything neat, tidy, and clean looking will pay dividends every time you pop the decklid to show off your engine (and with a V8 in the back, people will stop you and ask to see it all the time!).

[This message has been edited by fieroguru (edited 05-03-2020).]

Roger Walling MAY 03, 08:21 PM
Thank you fieroguru.
I think the way that I will go is to buy the harness.

I would like to post a pic of my car, as it is not the most conventional car.
It is in fact, 4' longer and the passenger sits behind the driver in a compartment that is about 2' wide and the rear has been narrowed 8".
I tried to post the pic, but no luck so far.

I just posted a pic in the AACA web site (https://forums.aaca.org/ ) in the general discussion section with the heading below.

"84 Fiero now running.
By Roger Walling, Thursday at 06:52 PM"
Roger

[This message has been edited by Roger Walling (edited 05-03-2020).]