fiero 2.8 manis on 3500?

[gar70614]

i know this is prob a newb question but will 2.8 fiero manis fit a 3500 and are the primaries way to small. i searched and think they said u could slot the holes. im unsure

[Joseph Upson]

i know this is prob a newb question but will 2.8 fiero manis fit a 3500 and are the primaries way to small. i searched and think they said u could slot the holes. im unsure

In all my fun fiddling with this hobby, one of many important things I've learned is never go backwards with technology unless it's absolutely necessary or it's convenient and there is no significant loss of performance.

The Fiero manifolds can be slotted however they will never match the area of the 3500 exhaust ports so you would end up choking the exhaust flow by doing so.

[gar70614]

yea didnt think they would have any gains jw if they would fit. asumed it would be a hp loss.

[Superdave]

that's like hooking a garden hose up to a coffee straw.. lol

[FallenZ24]

Definitely a bad idea using those manifolds. You can use the 3400 manifolds and build a custom exhaust. With some tight bends you may even be able to keep the trunk.
That's how my 3500 is setup and it runs okay. You can definitely tell that it needs headers though.

-Joseph

[Daguse5853Z]

Ok, I have def been debating a similiar scenario in my head for the past couple of months. TGP exhaust manifolds on a 3500. Now if you take a 3.1 exhaust mani gasket and place it on the 3500 head, the ports really arent much bigger than the gasket. The 3500 exh gasket ports are huge but the actual ports on the head arent. A pic would prolly explain myself better. I think they would seal and I'm prolly test it out. Id really like to see if anyone has tried it. Or maybe would the 3100 exh gaskets be a better comprimise?

[Superdave]

the gaskets aren't the problem, the manifolds are...

[Daguse5853Z]

have you tried using the manifolds, superdave?

[IsaacHayes]

Gaskets will always be larger.... manifolds should be as well for anti-reversion...

You absolutely do not want the ports larger than the gasket or manifolds. That is like hitting a brick wall! That is also why when you port exhaust ports on heads, you do NOT open them up to the full size of the gasket. You must leave them a little smaller so that gaskets/manifolds are larger...

[Daguse5853Z]

damn...Well I guess I should buy some flanges and build my own.

[americasfuture2k]

I have the truleo 2.8 headers modified to fit the 3500 on my car. Well, merlot did it when he built up the motor. I know he had to open up the bolt holes so the headers would fit and he also had the flanges gasket matched to the 3500. Or maybe it was have the flanges opened up as much as the tubes would allow. It works for now till we can design some better headers made to match the power band and cam of the engine.

These were the headers he had on his 3.4 swap.