Edjumacate me on the 2.8-3.4 (Page 2/3)
zkhennings APR 24, 02:16 PM
The 3.4 block has way more webbing than the 2.8 and is definitely stronger. I also believe it has better oiling than the 2.8 but don't quote me on that. In addition, the starter is located on the opposite side, but the methods of redrilling the starter mounting holes on the correct side for the Fiero trans is well documented here. I think Rodney sells a jig, one of the holes is drilled on a not flat surface so a jig helps the bit keep from walking.

As someone who built a 2.8 and got 132whp out of it, I wish I had grabbed a 3.4 and swapped that in along with my mods as I would have made some serious extra power for next to no effort or weight penalty. They are also dirt cheap.

All of the Fiero stuff will bolt to the 3.4 long block and look OEM which is also cool. I believe the Fiero intake is the most performance limiting component if you do swap everything over. The 2.8 exhaust manifolds also have a pretty crazy restriction in each of the ports, requires re-welding them from the outside and taking a die grinder to the inside to open up the restrictions. I have all my 2.8 mods in the first page of my build thread.

[This message has been edited by zkhennings (edited 04-24-2023).]

sleek fiero APR 24, 08:50 PM
The 3.4 block is definitely heavier . The outside surface of the block has bulges for the cylinders where the 2.8 is flat.3.4 can be overbored at least a 2mm more than 2.8 . sleek
shemdogg APR 24, 09:46 PM
Appreciate all the replies fellas! Think im gonna get the 2.8 rebuilt to stock to pass emissions, and throw in a l67 in between smogs. Shop quoted me $1200 to assemble the shortblock, seems steep but it does need a cam, timing chain, oil pump, full gasket set, heads checked, head bolts, lifters, and maybe smore stuff. Thinking of doing myself to save funds, but rather have the shop do it.

shem
reinhart APR 25, 03:10 AM

quote
Originally posted by shemdogg:

Appreciate all the replies fellas! Think im gonna get the 2.8 rebuilt to stock to pass emissions, and throw in a l67 in between smogs. Shop quoted me $1200 to assemble the shortblock, seems steep but it does need a cam, timing chain, oil pump, full gasket set, heads checked, head bolts, lifters, and maybe smore stuff. Thinking of doing myself to save funds, but rather have the shop do it.

shem



With the engine out of the car, it should be fairly easy to work on. I'd definitely at least make an attempt at rebuilding it myself.
82-T/A [At Work] APR 25, 08:09 AM

quote
Originally posted by BillS:

The 3.4 is a stroked engine (longer stroke, same as the 3.1) with larger bores and still with cast iron heads. The following generation switched to better flowing alloy heads.

This is an original generation 3.4 installed in an old British car of mine.




Hi Bill... how does that MG run with that 3.4 in it? I bet it's quite a bit quicker than the older lower-revving 4 cyl that was in there. Was there any appreciable front-end weight bias due to the added weight? Did it affect handling at all?
zkhennings APR 25, 11:59 AM
Why not just buy a 3.4 and not rebuild it? Would be way cheaper than having all the machine work done. Just buy the motor, strip it down, re-drill for the starter, and reassemble with all Fiero stuff. It should pass smog no problem.

Should be cheap overall and then you can sell the motor on the mall later all ready to go for someone who spun a bearing on their 2.8.

Just my 2cents, seems like a waste to get the 2.8 all done up for all that money, not many people are buying 2.8s for if you sell it later.
82-T/A [At Work] APR 25, 12:16 PM

quote
Originally posted by zkhennings:

Why not just buy a 3.4 and not rebuild it? Would be way cheaper than having all the machine work done. Just buy the motor, strip it down, re-drill for the starter, and reassemble with all Fiero stuff. It should pass smog no problem.

Should be cheap overall and then you can sell the motor on the mall later all ready to go for someone who spun a bearing on their 2.8.

Just my 2cents, seems like a waste to get the 2.8 all done up for all that money, not many people are buying 2.8s for if you sell it later.




I would think the only reason why you'd want to do that would be if you wanted to keep your car numbers matching. But otherwise, yeah, I'd probably just get a Camaro/Firebird motor and drill for the starter.
Raydar APR 25, 09:17 PM
Were I in your position, I would spring for a 3.1 crank and pistons, and bolt the engine back together as a 3.1.
It won't have the power of the 3.4, but it will have a good bit of the torque, due to the longer stroke. A good cam would really help to wake it up.

I built up a 3.4, back in the day. Had $800 (in 2005 dollars) just in head work/porting. It would fairly scream, when it was done. Was almost as fast as my 4.9. But it cost me a fortune. Definitely not cost effective.
pmbrunelle APR 25, 09:32 PM

quote
Originally posted by shemdogg:

Appreciate all the replies fellas! Think im gonna get the 2.8 rebuilt to stock to pass emissions, and throw in a l67 in between smogs. Shop quoted me $1200 to assemble the shortblock, seems steep but it does need a cam, timing chain, oil pump, full gasket set, heads checked, head bolts, lifters, and maybe smore stuff. Thinking of doing myself to save funds, but rather have the shop do it.

shem



If you're willing to run the automatic transmission that comes with the L67, it may be possible to make the swapped powertrain California-legal, avoiding the hassle of swapping in a stock engine every time the car is tested.
shemdogg APR 25, 10:42 PM
All great calls, Think Im just going to get the heads checked out, sell the shortblock(good luck lol), and put in my 86 motor for now. It always ran great in the kit car. Only drove it a few times tho. Gonna order a new clutch now and start planning for the install.

Pmbrunelle im not willing to change it to an auto. Ill get an extra cradle/trans/rearend for the l67 and keep the pcm in the engine bay. That way i can slide it in, bolt it up and only have to connect fuel n power, bleed the brakes n clutch.

Thanks again for all the replies it really helped!

shem