Engine swaping

Asked by Jan 29, 2012 at 06:30 PM about the 1986 Pontiac Fiero SE

Question type: Maintenance & Repair

I have an 86 Fiero SE with a 2.8 that I destroyed.  I bought another 2.8 from a blaser just for the block, but today as I was ripping the original fiero motor apart I noticed that the right side motor mount does not bolt up the same.  Is there an adapter plate I can get so that it does or if I got a 3.8 engine block would that bolt right in and would the top side of the engine bolt to it?  Also I was going to bore the 2.8 30 over, how much bigger if any is the 3.8 and if I bored that 30 over would it be too thin?  With a turbo on it and the heads ported and a racing cam wil the tranny hold up, it is a 4 speed manual?

5 Answers


Oops. No adapter plates for that one. 3.8 does not just bolt in ( trans are totally different). We are Fiero guys, we recommend ( in order of ok to yahoo): 1) stock 2.8, clean up the heads a bit, etc. Don't bother with turbo. Nitrous maybe. With a shift kit the auto will hold up (Transgo kits only). Manual trans will hold up, but why bother shifting? 2) 3.4 Camaro, etc. Easiest -- you need the adaptor and drill bit and tap to relocate the starter, but doable. Engines are available at the junkyard, but getting harder to find. Bore it out and it has nicer torque, mostly bottom end. Don't bother with a cam. Car will run too rich, gas mileage will stink, for maybe 20 extra horse power. We learned the hard way on this one. 3) Northstar V8. Crazy fast, but the main problem is findin a good Northstar. Engine is essentially un rebuildable. Loads of work adapting too, mainly the exhaust system. Wiring is pain too but more in terms of hours needed. Compare the wiring system of the existing Fiero to the Northstar engine donor, it's all very doable. 4) 3.4 twin. My personal favorite just because I like having 4 cams under the deck. Revs like crazy up to 6500; it's lack of breathing which kills the stock 2.8. Still, a lot of work -- changing motor mount to frame points and the exhaust of course. Wiring, etc. Still, not a nicer engine note around (we use the original mufflers with free flowing cats.) 5) the best, hands down is the 3.8 turbo. This engine (A bad boy from Buick) is literally bulletproof. We love the roller lifters -- helps with top end rev limit. You must go for the Series II, upgraded supercharger, intake, etc. Doesn't take too much to get to 290 h.p. More than enough for Mr. Fiero. Don't waste time with Series I, too low on hp, even though there are more of them around. Basically an old persons car (Ultras, etc.) you can buy them with 75K used and you don't need to do anything. Check the supercharger though. Gear slop means lack of oil changes, and they should be rebuilt/replaced about 80K anyway. This is our best choice because of relative ease of installation (check for adapter kits) etc. Exhaust and wiring of course are up to you, but a certainly doable. And our favorite because of YAHOO!! Ain't nothing better than torque; when it slow the supercharger kick in. Almost unbeatable. Almost

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Well thank you for the info, I guess in the interest of ease I will try to locate a 2.8 that was in a feiro so that the mounts match. That really iritated me when I got a 2.8 and that the motor mounts are different. I expected them all to be the same but I suppose a rear wheel drive versus motor mouts for a front would make a difference. What if I made a template and drilled holes in the original motor mount to match the blaser block? That was an idea that I came up with today, if I can get it positioned in the same spt it is supposed to be in. What are the chances that would work, I just hate spending money on anote motor when I already have one.


Sorry. Rear wheel and Front Wheel drive blocks are different because of the different areas of the block the motor mount attaches to. Plenty of 2.8 Fieros still around (in Colorado junk yards anyway). You might be able to make an adaptor plate, but will the accessories clear the new bolts? Don't know, never done it. If you get a replacement Fiero engine, replace the bottom end gaskets. This engine lives in an enclosed oven (thus the cooling fan for the coil and alternator). After 60k these leak like sieves.

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My plan is to drill the holes that match up to the new block I have and to do a complete rebuild complete with boiling the block, boring it 30 over and getting the crank turned. I saw a supercharger that I can get for a fiero and I was planning on putting that on as well as new heads headers true dual exhaust. I want to squeeze as much horse power and speed out of th 2.8 as i can. It would help if my divorce would hurry up and get over with so I had more time to devote to it. Should be a fun ride when I am done. Any other pointers I can get would be a huge help, Ihave done this with a 350 for a camaro before but this is the first I have dealt with somehing with fuel injection and with a rear engne that is so light. Iam a little worried about how much torque and power the car can handle without twisting the frame or something. Any thoughts? And also thank you for all the info you have provided so far it has been a really big help!


Will be a killer ride. Something about 300 hp in a car weighing 2500 lbs. The Fiero can handle all the h.p you can give it (the separate carriage takes all the torque). Check out Pennocks (or Pennicks?) Fiero forum -- will give you all the Fiero info you can possibly handle. FieroGtchuck

1 of 1 people found this helpful.

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