hybrid 2800

[cooguyfish]

I know this has been gone over before but I have not seen a sufficient ending to the debate (and yes I searched on this).

As much as I really want to do a 3500 swap in my fiero, I can not get over the idea of swapping the 3100/3400 heads onto my fiero 2.8 block... I'd really love to do this and add a roller cam (if possible, and I have access to a machine shop if necessary). Raise the compression and see what it would do.

talk me into this.

1. How much power could be made with a 2800?

2. How many RPM's could this engine run?

3. What kind of fuel mileage would this get?

4. Could all off the shelf parts work on this build?

-Brandon

[Raffaelli]

Im new to this 6-60 stuff so bear with me....
I think (not often) that the 3x00 heads have too big a chamber for the 2.8. You might be lucky if im wrong.( Im I wrong people???)

Ive looked into a roller retrofit into a Gen 1 block. Not feasable in a practical sense.
Since your not limited to the RWD block (Like I am), a 3X00 swap is up your alley.

Plus that old saying of "No replacement for displacement"

[pmaniac69]

well, the heads should bolt on, should be the same thing as making a 3x00 hybrid with a 3.1, only problem your going to have though it the intake setup us different on a fiero is it no? compared to like a cavalier and what not that is

[IsaacHayes]

2000+ 3100 heads or any 3400 top end is the way to go. Later years had better castings though.

2.8 and 3.1 is the same bore. A 3.1 they stroked it out. The 3500 heads won't work on a 2.8/3.1 bore. Min 3.4L engine for those to work.

You'll need the whole top end, injector rail and intakes.

you're stuck with flat tappet cam.

A hot cam and 3x00 heads could make near 185+ or so, maybe more depending on cam and exhaust I'd guess... A 3100 large port makes 170.., a 3400 makes 185 roughly.

The flat tappet cam will be your limit on RPM I'd guess... a gen3 block with roller would help... But short stroke means high RPM... No idea what the cam could take but 7000 is all I would do on stock rods and that could be pushing the limit. If you wanted more then machining SBC rods would be the route to take.

6500 RPM I wouldn't see a problem with the bottom end, and with the 3x00 heads and a good cam and exhaust it could pull that high.

[cooguyfish]

How much different is a Gen3 block? The biggest reason I wanted to re-use my fiero block is just because i know it uses the existing mounts, well, and I have it and all that.

I was thinking about putting in a 3500 originally, but something about the idea of the 2800 makes me really want it in my car.

[ghrarhg]

I'm currently running a gen 2, 2.8 with a 3400 top end. I've added a cam as well, but I'm running a turbo. The 2.8 piston dish combined with the 28.6 cc (slightly larger than gen 2's 26.4cc) combustion chamber on the 3400 heads gave me around 8.5:1 compression ratio, so turbo was the best bet for me.

Being that you're doing this to a fiero (2.8 HO engine) you're compression ratio is going shoot through the roof by going to a 3400 head. 48.5 cc combustion chamber vs 28.6 cc puts you over 12:1. So if you're looking to raise the compression, this would do it. I thought about building a high compression 2.8, but went turbo instead.

Power numbers i'd expect to be a little better than what IsaacHayes suggests since your compression ratio is so high, as long as you can tune it.

[cooguyfish]

Yeah, I think I can tune it, I will be running a 7730 ECM, and I have tuning software for that.

High compression would be great btw

[IsaacHayes]

Ah yeah forget the Fiero stuff was gen1 which means pistons have less dish. You'll need a HOT cam for that high of compression. H272 at least, and 93 octane is a must. I'm going to try 91 octane with a moderate cam with 11.5:1, but I wouldn't do 12+ without 93 octane...

Use the compression calc and run the numbers.....

[cooguyfish]

I was doing some more searching, what is the oldest 3100 I could use to be able to have a roller cam? I know someone that has a malibu that has a bad tranny and I think it's a 98, I know it's a 3100 though. I could probably pick that up on the cheap.

[bszopi]

All 3100s had a roller cam, so starting in 93.

[no_doz]

2000+ 3100 heads or any 3400 top end is the way to go. Later years had better castings though.

2.8 and 3.1 is the same bore. A 3.1 they stroked it out. The 3500 heads won't work on a 2.8/3.1 bore. Min 3.4L engine for those to work.

You'll need the whole top end, injector rail and intakes.

you're stuck with flat tappet cam.

A hot cam and 3x00 heads could make near 185+ or so, maybe more depending on cam and exhaust I'd guess... A 3100 large port makes 170.., a 3400 makes 185 roughly.

The flat tappet cam will be your limit on RPM I'd guess... a gen3 block with roller would help... But short stroke means high RPM... No idea what the cam could take but 7000 is all I would do on stock rods and that could be pushing the limit. If you wanted more then machining SBC rods would be the route to take.

6500 RPM I wouldn't see a problem with the bottom end, and with the 3x00 heads and a good cam and exhaust it could pull that high.

and thats why Isaac's the man

also ghrarhg where are these highn umbers coming from for the size of the 3400 combustion chamber? on the CR calc it states 28.6 which is a bit bigger than the 3100's 26.4 if i remember correctly-can someone confirm or deny?

[cooguyfish]

Okay, I think I have done a sufficient amount of research. It sounds like I need to get a 3100 block and heads, and then I can use my 2.8 crank, rods, and pistons. I have a 3400 intake manifold, can I use 3500 stuff?

I still have a few questions

-I guess I can buy a WOT-tech cam still since I'll be running a roller cam?
-Do I need to worry about push rods?
-in my search I was reading about using 6" rods, are stock 2.8 rods 6"?

How much power would a 2800 make with a good streetable cam?

[cooguyfish]

also, out of curiosity, is it possible to put a 2.8 crank in a 3500 block? I do have a 3500 sitting in my garage right now, I planned on putting that in another car I have with just a cam, but a destroked 3500 might be cool too. I guess one problem might be that it would drop the compression with stock 3500 pistons?

[pocket-rocket]

Why would you want to use a different crank then what the 3500 has? If anything I would have that crank offset ground and get different rods because most of the 3500 (but not all, from what I have read) have a forged steel crank.

[cooguyfish]

Why would you want to use a different crank then what the 3500 has? If anything I would have that crank offset ground and get different rods because most of the 3500 (but not all, from what I have read) have a forged steel crank.

I don't know, which is why I am asking