How incompatible are those heads with the fiero intake manifold? Are we talking some bolts holes need adjusting, or is it "Really definitely not happening at all"?
Which is more restrictive, the fiero intake manifold, or the iron heads? If the intake is capable of supplying enough air for considerably more HP than the heads are capable of, than attempting to make the aluminum heads work is maybe worth the effort. But if they are similar or the intake is more restrictive, then it is not worth the effort.
Consider that the fiero intake manifold in question will have all mods. Potentially a Dawg intake if he's still selling them. Also consider both heads to be ported.
I have wondered about this...and admit I have never seen these two heads side-by-side.....I have thought that instead of trying to make a gigantic manifold that breaths better, why not make a LOWER manifold that ADAPTS the Fiero upper manifold to the 3X00 aluminum heads....Maybe it is physically impossible...but it would be a great option to KEEP the stock look but eliminate a few pounds AND gain some good breathing heads.
It would be nice to see the two heads in a picture, side-by-side.....Then I would know...something......
The Fiero V6 intake and the Gen.3 aluminum heads are completely incompatible. The intake ports aren't even in the same place.
Well that answers it then. Since you're here, would you happen to know if the 2nd gen 2.8l engine had a forged crank, and if it could be swapped into a 3400 to destroke it?
My opinion is that the Fiero 2.8 is not a good platform to modify. There are so many other engines that are better in many ways. The SFI engines, 3100, 3400 are MUCH better engines and relatively easy to swap in. If you want the aluminum heads, just put in the rest of the engine that they are bolted to and you will be much better off in the end. But, I understand why some do not want to part with the Fiero stuff, so I am not putting anyone down for it. If you want performance, look at other options outside of the 2.8.
Why would you want to destroke a 3400 V6? Does it generate too much torque? You want to rev it to 8000+ RPM? You're in a race class with displacement restrictions? Not trying to be a jerk. It's a serious question.
Why would you want to destroke a 3400 V6? Does it generate too much torque? You want to rev it to 8000+ RPM? You're in a race class with displacement restrictions? Not trying to be a jerk. It's a serious question.
Yeah, it's a definitely a legit question. I MIGHT want to destroke it (I haven't given it a lot of thought) because if I make an iron head 3400, then I have more displacement than my intake+heads can flow, which means torque drops off sooner than I want it to. If I reduce the displacement then I should be able to supply air up to a higher RPM. Not that I'd be making any more power - just that I could do so at a higher RPM, which I want primarily for exhaust sound.
So....a little bit of grinding and they'll line right up...? Jeez.....they don't even look like they come from the same company, let alone the same engine family....
What about the exhaust side....do the light-weight Fiero headers line up on the later heads or do you have to use the cast heavy 3X00 exhaust manifolds?
And, Rick, what actual engine do you have in your >CA< car? (I have a F-body 3.4 long block- which is fun but cuts off at 5000)(I'd really like to install the 3900...but they have an electronic throttle and BCM....)
Originally posted by Travis D: I MIGHT want to destroke it (I haven't given it a lot of thought) because if I make an iron head 3400, then I have more displacement than my intake+heads can flow, which means torque drops off sooner than I want it to. If I reduce the displacement then I should be able to supply air up to a higher RPM.
Hmm... that's actually a good point. Although the 3.4 V6 seems to do alright with iron heads. It runs out of breath around 5000 RPM, though. But some head porting and a lumpy camshaft should help with that.
Another thing to consider: The Fiero V6 intake is designed for mid-range torque (in the 2000-4500 RPM range). Above 4500 RPM, the intake starts to become restrictive. I know people like to open up the neck on the intake, to improve breathing. I'm sure that improves torque across the RPM band. But the intake still has long, thin runners (which is good for low RPM torque, but bad for high RPM breathing). So it's still going to run out of air around 5000 RPM. To get the most out of a high-revving engine, you need something different from the Fiero intake.
Just a thought.
[This message has been edited by Blacktree (edited 08-16-2017).]
Yeah, it's a definitely a legit question. I MIGHT want to destroke it (I haven't given it a lot of thought) because if I make an iron head 3400, then I have more displacement than my intake+heads can flow, which means torque drops off sooner than I want it to. If I reduce the displacement then I should be able to supply air up to a higher RPM. Not that I'd be making any more power - just that I could do so at a higher RPM, which I want primarily for exhaust sound.
Just an idea that might help.
The 3.4 DOHC revs to 7000, so there's no problem with the bottom end surviving that RPM.
Some displacement is good; more is better. Keep it!
So....a little bit of grinding and they'll line right up...? Jeez.....they don't even look like they come from the same company, let alone the same engine family....
What about the exhaust side....do the light-weight Fiero headers line up on the later heads or do you have to use the cast heavy 3X00 exhaust manifolds?
And, Rick, what actual engine do you have in your >CA< car? (I have a F-body 3.4 long block- which is fun but cuts off at 5000)(I'd really like to install the 3900...but they have an electronic throttle and BCM....)
The Fiero I have now has an LS4. I had 6 Fiero's at one time. One of the conversions I did was a 3100SFI. I used the 4 speed auto for a while then converted that over to a 5 speed. LOVED it as a 5 speed. The 4 speed auto alone was a huge improvement. But the 3100 is a great engine for the Fiero,...in my opinion. I would not bother modifying a 2.8. BTW, I don't recommend it,....BUT I did use the 2.8 exhaust manifolds on the 3100.
Well that answers it then. Since you're here, would you happen to know if the 2nd gen 2.8l engine had a forged crank, and if it could be swapped into a 3400 to destroke it?
I asked about this a while back... The 2.8 crank would fit in the 3.4 block, but the catch is with the pistons. From what Ive gathered the 2.8 and longer stroke 3.1/3.4 use the same rods, with a different compression height on the piston to make up for it. And since you cant get pistons with the 3.4 bore and the 2.8 compression height, you're sorta SOL
If Im wrong on this, someone else elaborate. Because I think a high RPM 3.0 60v6 would be cool as all getout.
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quote
Originally posted by Frank2:
here's the goal: Build a mid engine car 1/2 as good as a Lotus Elise at 1/10 the cost.
There no off-the-shelf pistons available for that application, because the 2.8 crank was never used in a 3.4 block from the factory. You'd have to get custom pistons made. Or you'd need to find rods that are 4mm longer than stock. Once again, there are no off-the-shelf rods for that application. You'd probably need to modify some custom-length SBC rods to fit.
Either of those two methods is gonna cost you a bunch of time and money.
I would think one just needs to be schooled in welding and some math and they could probably adapt just about anything. A fairly wild fab example from the web:
CLICK FOR FULL SIZE
[This message has been edited by 2.5 (edited 08-16-2017).]
Originally posted by cvxjet: A) Could the 3100 engine use a 3.4 block/displacement?
You mean swapping the top end of a 3x00 onto a 3.4 V6? Yep, you can do that. But with the 3.4 pistons and 3x00 heads, the compression ratio will be pretty high (around 13:1 maybe?). You could swap in some 3400 pistons to reduce the compression ratio. Or you could use a lumpy camshaft to reduce the dynamic compression. That's something you'd probably want to do anyway, if you want a high-RPM engine. Just be mindful of piston-to-valve clearance.
The biggest problem I have with engine swaps is that I live in CA...I actually successfully swapped a 5.0 into a 73 Mustang back in the 90s....Went to a referee station, had a sticker, etc....Nice thing with it was that CA liked and allowed the swap of a newer engine into an older car, but did NOT require the Cat- Because they knew that the older cars were not designed to have one and without a heat shield could catch fire...(Yes, my head was spinning because of the actual consideration and LOGIC of this law)(We're not in California anymore, Toto!(With the Twilight Zone theme playing)...
By far my favorite swap would be a 3500...But in CA they have to have been hooked to a manual trany to qualify for a MT car.....So then it comes down to the 3900....But the BCM and electronic throttle are two things that seem intractable......And reprogramming computers just seems impossible to me(I actually was trained as an Avionics tech in the Navy- and fixed computers at Atari in 1982....But I have to PAY someone to program my computer!!!)...I can fix electronics....with a hammer....
The biggest problem I have with engine swaps is that I live in CA...I actually successfully swapped a 5.0 into a 73 Mustang back in the 90s....Went to a referee station, had a sticker, etc....Nice thing with it was that CA liked and allowed the swap of a newer engine into an older car, but did NOT require the Cat- Because they knew that the older cars were not designed to have one and without a heat shield could catch fire...(Yes, my head was spinning because of the actual consideration and LOGIC of this law)(We're not in California anymore, Toto!(With the Twilight Zone theme playing)...
By far my favorite swap would be a 3500...But in CA they have to have been hooked to a manual trany to qualify for a MT car.....So then it comes down to the 3900....But the BCM and electronic throttle are two things that seem intractable......And reprogramming computers just seems impossible to me(I actually was trained as an Avionics tech in the Navy- and fixed computers at Atari in 1982....But I have to PAY someone to program my computer!!!)...I can fix electronics....with a hammer....
I live in California also, and have past a few cars through the certification process including the 3100SFI. It can be done, but not any engine/transmission combo can go in legally.
Hmm... that's actually a good point. Although the 3.4 V6 seems to do alright with iron heads. It runs out of breath around 5000 RPM, though. But some head porting and a lumpy camshaft should help with that.
Another thing to consider: The Fiero V6 intake is designed for mid-range torque (in the 2000-4500 RPM range). Above 4500 RPM, the intake starts to become restrictive. I know people like to open up the neck on the intake, to improve breathing. I'm sure that improves torque across the RPM band. But the intake still has long, thin runners (which is good for low RPM torque, but bad for high RPM breathing). So it's still going to run out of air around 5000 RPM. To get the most out of a high-revving engine, you need something different from the Fiero intake.
Just a thought.
I know you're right, but it's going to take me a long time to accept that I really should just leave the fiero intake on a shelf. It's a big handicap for the sake of aesthetics.
