need advice for fiero swap

[hookdonspeed]

so its been bout 2years since my fiero was stolen, im finaly picking up a new one, hopefully this friday

i was going to just do the 3.4 swap so i could keep everything prettymuch the same and get more power, but ive been reading some of the forums about the hybrid setups..

how much harder would it be to put the 3.4 with 3400 heads on it, and the 3500 UIM realy be? im not so much worried about changing over to DIS as i planed on doing that anyway, im more worried about having to re-do the fiero cooling lines, as that just seams like a HUGE headach...

also, how much more power would that be offering over the normal 3.4 swap?


p.s. please correct me if i messed anything up with sizes/etc

[IsaacHayes]

You could do a 3500 whole top end, heads on up and you'd have high compression if you kept the 3.4l RWD pistons, get a cam and headers and you'd have a screamer. Or swap a full 3500 like merlot did.

3.4 RWD is 160 hp, 3500 is 200hp stock.

Do a cam, headers, etc and you go over 200 quickly with the 3500. The 3.4 hybrid with 3500 top end would be pretty good too, and with the stock 3.4rwd pistons you got the extra compression for more power. You'll have to tune it but the extra work for the gen3 motor or gen3 top end is worth it.

[hookdonspeed]

what would the benifits of going to the 3500 lowerend be? i know its .1 more displacemnt, but do the actual blocks have a benifit to the 3500?

would 3500 heads fit on the 3.4rwd block?

also i though i read somewhere about someone having to drill pushrod guides or something for the hybrid engines?

[IsaacHayes]

oil squirters on 5 and 6 pistons. Other than that not sure what real benefits are other than stock compression. If you put 3500 heads on a 3.4 block with 3400 pistons it's lower than stock compression, but if you use the 3.4 rwd pistons it's 11: something.

Yes 3500 heads fit on both 3400 and 3.4l rwd.

Shouldn't need pushrod guides at all for the later year gen3 3x00 engines since they use roller rockers. The 3100 94-96 (some 96 got roller) had ball/pivot and had guides, but anything else (newer 3100, all 3400/3500) have roller and no guides.

[hookdonspeed]

id love to goto that kinda compression... so a total 3500 top-end swap sounds like it might be the way to go... at that point would i be using a cam for 3500 or 3.4? has anyone here done that swap yet? id love to read the build process.

ah, i see forcedfirebird has, ill have to read that thread.

what ecu would you recomend?

[IsaacHayes]

DIS swap with the 77300 (whatever it is) ECU is the easiest and then burn chips or use an emulator. You use whatever cam that the block you have uses. If you went with a 3400, you could get a roller cam regrind from the WOTTECH store here, or if you were going with the 3.4RWD block, you'd get a cam for that motor. (tappet)

[hookdonspeed]

soo sounds like ima get a 3.4RWD block, 3500 upper stuff, the new ecu..
im sure ima need some other minor stuff, hopefully no major fab stuff will be needed.
nice large cam, some forged pistons, cower rods, new spings, etc, this will be a slow long build lol...
dont look like ima be using low octane after this is done :P
at that compression NOS/turbo would be kinda scarry..

now i just gota pickup the car. $700 for a 86 fiero GT, looks good in/out and runs strong, just the guy is horrible about returning calls lol

[IsaacHayes]

why do so many fiero owners use the rwd block??? It's a FWD engine in the rear.. I don't get it.

I mean I guess it's a quick upgrade for the old iron head 2.8 top end, but if going to gen3 why not go full gen3?

[hookdonspeed]

from what i hear, its easyest becuase the motor mounts and all can stay the same, sensor locations, etc. and i belive on the gen3 blocks they moved some of that?
i know the 3.4 is almost a direct drop-in to replace the 2.8, just with more power nothing else needs to be changed..

i supose it might be something to look at just a full swap, would the mounts need to be changed? also, how well do them engines handle power-adders (super, turbo, nitrous)

[IsaacHayes]

Stock the 3x00 can handle about 10psi or so. Anymore than that and the pistons become the weak link. 3400-modified ran a 100shot of nitrous on a stock 3400 for a while. You can use machined SBC rods if you want to go really crazy too.

Engine mounts/etc I don't know check out on fiero.nl for merlot and see what he did. He is also on here. (3500 fiero)