2.8L Fiero looking for suggestion on Engine rebuild

[Scott205]

I have an 86 SE Fiero I bought with a bad engine. I was going to swap my 85 GT engine into (becuase there isn't a title for it) but I may rebuild. Looking for more HP and not to do a ton of work. I believe one of the piston rods broke (clanking sound) but i am stuck getting the oil pan free to be sure. Looking for mods i can do while i have it apart (probably still in the car)

I understand I can get a crankshaft and pistons from a Gen II RWD 3.1L Iron engine and make it into a 3.1L. (probably replace atleast one rod if not all 6). Anything else that is going to be easy to do? Higher compression is more HP? Any suggestions on rings or head mods for more compression?

Thanks,

No suggestion is too stupid, although we might laugh :P

Scott

[Will'sFiero]

Heh... Getting horsepower out of the 2.8 is so much work that if you want horsepower with minimal work, you ought to look at swapping in a 3400.

[Arns85GT]

the 2.8 can be built up

I did up mine, but I'll tell you what I did wrong too. I did not increase my compression. So the modifications don't get used to their full potential. (I'm going to raise the compressin soon) If I were you, basically, I'd raise the compression, port the exhaust manifold and the Y pipe and then port the intake and runners. This can all be done without buying alot of parts.

As for the 3.1 conversion, remember that the 3.1 has dished pistons and you are going to not get as much out of the engine as you think. The Fiero engine is 140 hp. I had a 3.1 Eurosport that was 130 hp. Hmm...

Here is the work I did with a carb conversion. If I had to do it again, I would have done it differently. Probably the Trueleo intake instead of the carb conversion. Check the Fiero Forum (fiero.nl).

2.9 liters (.050 overbored hypereutectic pistons)
ported heads
re-cut valve seats
roller-tipped 1.6 rockers
Edelbrock Torker II intake
Holley 390 carb
Blazer distributor set to open vacuum
ported exhaust manifolds into 2.5" mandrell bent
Magnaflow muffler
MDS coil
Power Pulley
11* initial advance with 36* overall advance

On the carb,
Black accellerator cam on #2 hole
#25 shooter
30cc Accellerator pump diaphram
#51 primaries (actually .50 thousanths)
#52 secondaries
Not sure about whether I'll end up on the yellow or the plain secondaries spring.

When I deployed the black cam, my #21 shooter suddenly leaned out and the engine took its time catching on to the kick I gave the gas.

When I deployed the black cam with the #25 shooter, the car started laying rubber from standing start. Remarkable difference for a very small change. I did, however have a bog develope.

In consultation with Scotty McLendon, I found the final answer to the bog. It completely solves the problem and the car now has a whole lot of snap from any rpm. The answer is reducing the shot. I took the orange accellerator pump cam but the white cam will do about as well. With the carb off the car, you remove the screw holding the cam in place. You then pivot the cam on the armiture so the #1 hole on the bracket is between the two holes on the cam. You then mark the cam with a magic marker and remove it. You then drill a hole the same size as the other holes through the spot you've marked. You then install the cam using the new hole on the #1 screw hole.

You then have to adjust the accellerator pump arm. If it is the metal one, you bend the tab until the arm returns to zero setting. If you have the plastic arm, you tighten the adjuster screw until there is some slack (very little) between the accellerator pump arm and the pump lever.

You will then have immediate throttle response with an overall shot of about 1/3 to 1/2 of the original cam. In my case, the new hole was about 40% of the distance between the two original holes. My shot is therefore reduced from 19cc to around 12cc.

Believe me when I say that this fix changes the response of the engine very noticably.

The plain secondaries spring that came on the carb seems to work well but is likely not aggressive enough. I will be trying out lighter springs.

Arn

[Guest]

Don't go carb whatever you do. Unless you want old school garbage that will fail and need constant adjusting. Look at arns setup. he hasn't stopped fiddling with it since he got it running year(s) ago. EFI would have been tuned from the beginning.

And arn you think you are going to gain like 50 hp by bumping your compression by half a point? HAHAHAHA YOu have 130 whp!! Wow dude bumping your compression will get you an extra 10 hp if you are lucky. 140 whp will make your car a damn rocket!!!

Swap in a 3400 and lay waste to any gay carb setup out there.

[Scott205]

well, i know of a few carb set ups that will gain you 100 hp. Say that 6 carb setup by Falconer.. but alas.. the rod that broke went through the engine..

don't know if i will swap for a 2.8 or what. I did buy the other car for the engine :P

[Guest]

only with a huge non streetable cam, lots of headwork, and 12.5:1 compression. Just bolting an itb setup on will not gain 100 hp. If you think that then I do have one of the falconer intakes so to speak. Its an itb for aluminum heads.

And fyi the falconer setup isn't a carb setup.

[x-thumpr-x]

I'd never thought I'd say this, but i'd have to agree with Shaun. (as the pit of my stomach is turning!) I swapped in a 3400 and have been doing well with it. When I did mine, there was no reference or resources to get info from, I did it all myself. Had a friend program the ecm for me who now has gotten into the Fiero scene. There is also the 3500 now with 20-30 more HP I believe, if you have more $$ fine a 3900 from a G6, stock is 245 HP (GM's rating so it's @ the crank) My 3400 came out of a Grand Am it gm rating it at 180HP (crank) and it dyno'd @ 175 WHP.

If you like old school, have the time and money. Try carbing out a 2.8L, when done right it will work good. It's just time, patience, trial and error. Arns set-up is a nice set-up and the carb has that look of a gas guzling power house when gas was cheaper then a whore. With time, Arns will have it running just right.

[Scott205]

OK, here are my big questions on this. I have my old 3.4L DOHC engine sitting under a bunch of plastic from my Cutlass. I am also thinking about perhaps finding a 3400 engine, or maybe one of those VVT engines (if i can find one cheap) My other thought is a Northstar v8 (say a 4.6L) what do i need for engine management on these? the orginal computer set up? Need thoughts and fast as I may be able to get the last cheap

[sharkey]

if your dohc is in good running condition, id swap that in there. it has been done several times, and is proven. its enough power to have fun with and not worry to much about killing stuff. a v8 swap is nice for power, but are a bit heavier, and are a pig on gas due to gearing.

honestly, there are so many engine swap options and kits avalible for all of them, i wouldnt even bother with a 2.8l anymore.

[Scott205]

ok, lets say i swap my 3.4 DOHC into it.. do i need to go find another wiring harness and ECM to run the thing? other options??

[Joseph Upson]

The easiest approach in my opinion for more power is to shop around for a 3.4L from a camaro or firebird and relocate the starter and upgrade the chip. It will be a drop in. Make sure you have the neutral balance flywheel for this.

If you have the skills and the time, install the 3.4 DOHC and relocate the necessary ECM plug pins and add the missing ones to install the appropriate ECM for that engine.

If you don't have the skills, don't even think about a Northstar, it's a task even for the pros.

The 3500 and the 3900 are excellent choices however they will require two things to keep them simple; a step up to a DIS ignition ECM and the 7x trigger wheel available in the store, the remaining necessities such as a replacement TB are non issues. The 3900 is the plan for my Fiero. If you want to keep it Real, again you need the skills, and all of the supporting electronics and hardware from the vehicle the engine is from and that my friend will be far from cheap and nowhere near easy to wire.

If you want more power the naturally aspirated 2.8 is out of the question if you intend to be practical in your approach. More displacement will do the trick everytime.

[sharkey]

pretty much anything other than stocking with a gen 1 motor is gonna need a wiring harness/pcm swap.

[no_doz]

...
As for the 3.1 conversion, remember that the 3.1 has dished pistons and you are going to not get as much out of the engine as you think. The Fiero engine is 140 hp. I had a 3.1 Eurosport that was 130 hp. Hmm...

eurosports only came with the 3.4 quad cam & were 4 door (unlike their z34 counterparts), you're thinking of a euro (even if they are considered the sport edition). sorry, i just had to be a smartass because its a simple thing that many people get wrong & it makes it a real pain in the ass when shopping for a true eurosport because everyone with EURO on the side of their car thinks they have one.

[Scott205]

ok, so how does this sound... get a wiring harness, ecm and the missing sensor we didn't use on the other engine. Put in new pistons rings and new gaskets for the heads (we had one pumping a bit of antifreeze into the piston) from the 92 DOHC and drop it in.. how do i integrate the 86 gauges into the 92 ecm? any tricks for the fact i am hooking it up to a manual?

[85maro]

If you're going to the trouble of an engine swap why not build it up some? If you just want some quick extra power go with the DOHC and a basic rebuild with .04" (iorn head 2.8L) gaskets, moly rings and have the cams reground, although a regrind may get a little more expensive for a DOHC. If you want to stick with the 2.8 it can be made to perform... if you don't mind running race gas. Using the stock flat top pistons you have now with aluminum heads and .06" (alum head) gaskets should give you about 12.5/1 compression. The pistons will need valve notches machined in, but it should'nt cost too much at a reputable machine shop. With a crane mechanical cam, headers and porting to the heads and intake manifold to make it flow you should have a real performer, but that's the extreme end for an N/A engine. It won't idle well and overheat if you're not careful, but in a lightweight fiero it'll scream. As for the tranny, try to find an ecm that came from a manual tranny car. Not sure if the DOHC's came with mauals, maybe a DOHC guy can jump in here? Either way you're going to need to reflash the ecm to get it to run with a performance build.