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Thread: Wants power

  1. #1
    Junior Member
    Join Date
    Apr 2009

    Wants power

    I'm recently in the midst of purchasing a lamborghini replica that needs some love on the interior since it was burnt to a crisp. My question though is what engine could I put into the fiero that is relatively cheap, but can produce alot of hp and torque so it can some what back up what it represents.

  2. #2
    Senior Member
    Join Date
    Aug 2007

    Re: Wants power

    There are many options for your car, mainly it all depends on how much you are willing to spend.

    A couple questions to help us help you.

    Do you want to keep the Fiero tranny?
    How much are you willing to fork out?
    Do you want manual auto?
    Carb or fuel injection?

  3. #3

    Re: Wants power

    There are a lot of options: in order from cheapest to most expensive:

    3.4 from a 93-95 Camaro/Firebird. Cheap, easy swap that uses the Fiero wiring and intake. Doesn't add much more horsepower, but is easy on the budget. Only parts needed are the engine, and a jig ($30 ) to drill new starter holes (starter is on the wrong side from the RWD donor.)

    3.4 DOHC
    3800 Supercharged or Naturally aspirated
    4.9 Cadillac
    All 3 of these will require fabricating new motor mounts, but will bolt up to the Fiero transmission. You will need to redo the wiring harness, using the donor engine's and merging it with the Fiero wiring. The wiring adds a lot more cost/time to the build. The wiring harness (unless it's a DIY) will cost between $400-700. The 3.4 DOHC has a higher rev limit, thus sounds more like a real Lambo, but doesn't have as much HP as the other 2. There's a long debate over which is better, the 3800 or the 4.9. Both increase the horsepower, but the 4.9 lacks aftermarket go fast parts. I'd say the 3800 SC wins.

    Small block Chevy
    -lots more horsepower, but requires an adapter (take a look at to mate the engine with the Fiero transmission. Fairly easy swap, but the kit is fairly pricey. You could use a fuel injected setup, again requiring wiring harness modification, or a carb setup. Most SBC swaps seem to have trouble with overheating issues. In the end, they seem to get solved (V8ARchie sells a 4 core radiator), but it's something to keep an eye out for.

    None of the previous swaps require any modification to the Fiero frame.

    LS1/LS6 swaps
    Best horsepower, but the engines are costly. It is longer than the SBC, so it may require frame modification. other than that it's the same as the SBC swap.

    Cadillac Northstar
    Aluminum engine, but requires frame modification. Still uses the Fiero transmission. I wouldn't recommend this swap.

    SBC or V12 with Audi transaxle
    Most expensive swap, requires adapter plate to mate the engine/trans. Not sure what you do with sourcing axles or hubs, wiring harness mods again. Engine will be longitudinal like the real deal.

    Take a look at :

  4. #4
    Senior Member jrslyrics's Avatar
    Join Date
    May 2008

    Re: Wants power

    how much horsepower can the fiero trans handle?

  5. #5
    Senior Member
    Join Date
    Sep 2006

    Re: Wants power

    I'll just tell you up front I'm biased toward the 3800 SC set up with the 4T65E HD transmission. That's what I have in my Fiero/ Finale kit car. It just "feels" right in these cars. Kind of like the further evolution of the Fiero if GM hadn't of killed it. V6 economy in an overdrive transmission that's just tooling around at 1500 r.p.m. most of the time but put it to the floor and you've got v8 torque with that vacuum cleaner from hell supercharger sound. Of all the kit cars I've built and owned my wife likes this one the best. You will indeed pay more up front getting it in but you'll be rewarded with a car that is rock solid reliable and you can drive anywhere.
    As for that question on what a Fiero tranny can handle, I'll assume you're talking about the Getrag 5 speed? With the age these transmissions have on them even a stock 2.8 can take one out if you abuse it much. You'd be better off matching up the original model tranny that came with your upgraded engine conversion.
    My only other engine/tranny combo of choice would be any of the LS series motors again combined with the 4T65E HD transmission. Just get ready to spend some much bigger bucks and a lot of time.

  6. #6

    Re: Wants power

    From regarding transmissions:
    Q How much horsepower can the Fiero Stick shift transmissions handle?

    A Generally speaking I have used the following engine/transmission combinations with great success, in fact, I haven’t broke a stock Fiero stick shift transmission yet. 1) With the 4-speed trans. (‘84 4 cylinder & ‘85-’86 V-6 4 speeds) I have used 300+ H.P. engines repeatedly with no problems. 2) With the ‘85 thru ‘88 4 cylinder 5 speed transmissions I have used 300+ H.P. engines repeatedly with no problems. 3) With the ‘86 thru ‘88 6 cylinder 5 speed transmissions, I have used engines rated at 460+ H.P. (One even had an additional 200 H.P. dual quad carb. NOS system on top of a 460 H.P. 383" Chevy stroker engine) With no failures yet. One final note on this subject: It is my opinion that: "even though we have had no failures, that any motor vehicle can fail if subjected to severe and constant abuse."

    Just from what I've read, IF you have any trouble (which doesn't seem common unless you abuse the car) you'll have more trouble breaking axles than transmissions.

    I put a Cadillac 4t60E in my car - it's an electronically controlled transmission. There were a few more wires, and had to make a bracket for the shifter (all detailed on Didn't really add much time, except I had to make a transmission mount too. I was lucky enough to have bought the whole donor car, so the transmission didn't add any cost.
    I do agree though - the best option is to use the transmission that was originally paired with the donor engine. Unfortunately, the only option there is to go automatic transmission - no manual transmissions that I'm aware of. You can use beefier axles though, bought off the shelf (again,

  7. #7
    Senior Member RCR's Avatar
    Join Date
    Jan 2002
    Shelby Twp Mi

    Re: Wants power

    Sounds like a 3800SC is up your alley. My preference is Northstar, but that's just me.

    Bob custom '84 Fiero SE --->>> custom F408

  8. #8

    Re: Wants power

    I researched this a few months ago and RHK pretty much sums it up perfectly. The 3800SC is going to be the all around best choice for a good balance between performance and price.

    On the other hand, if you have the time and the money, there are a couple of guys over at Kit Central that have successfully done the Bimmer V12 engine swap. HP isn't bad but it sounds sweeet. Check out this guy's Diablo: From what I understand Murci's can be outfitted as well.

  9. #9
    Junior Member
    Join Date
    Apr 2009

    Re: Wants power

    ;DWow u all are so helpful thank you very much. I have been doing some research and I have found LS1 Engines for 1,000, but I have also found a conversion for a 406 engine which was pretty bad ass. I know a guy in P.A who does work on theese cars, just i'm worried about tranny and rear differentials. I'm not much of a gear head so bare with me.

  10. #10
    Senior Member hnthomps's Avatar
    Join Date
    Jan 2004
    Columbia, SC

    Re: Wants power

    The 3.4 pushrod with a turbo is also a relatively simple installation that much improves the standard Fiero performance characteristics. Or you can go whole hog and install a 383 stroker that should be more than 400 hp at the wheels. That should provide adequate performance to back up your replica's looks.

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