building an intake manifold, input needed

[1988GTU]

Will the aluminum head 3.1mpfi intake bolt up? It's not that great of a performer either... Custom is best I guess since he wants to leave the heads and all alone.

That's what I dont remember.. They might, might not. Need someone that has recently tried it to chime in.

[IsaacHayes]

Will the aluminum head 3.1mpfi intake bolt up? It's not that great of a performer either... Custom is best I guess since he wants to leave the heads and all alone.

[1988GTU]

So you couldn't just use a 3.1MPFI lower & upper intake inplace of your current one? Then just port the hell out of that one?

[sharkey]

the lim is ported to match the heads already, however as i said earlier in the thread, its the middle and upper thats an issue. the trueleo intake is alright, however as far as i can figure its 3" taller (or more) than a fiero intake that already hits my hood. it also isnt a very good design, realy more of a one size fits all manifold.

im building my own, basicly mimicking the factory manifold idea, but better flowing and beleive it or not, shorter runners.

[montess408]

if i would have put all that time in the heads i would keep them thats for sure
maybe you should port the lim to match the heads and maybe think of a hood scoop of some sort and go with somthing like the turello model

[sharkey]

well, heads arent comming off to have them flowed. my dad has been porting heads for 30+ years now, he has done some amazing things with stock cast iron heads. the most impressive that comes to mind is the 446 he built (440 bored .030 over) for a 2900lb dart. many respected engine builders in the area said chrysler 906 heads would not be able to flow enough air to run even a high 10 in a 2900lb car. end result after years of pushing it was a 10.20. he also ported brads (treez24) 3400 head on his hybrid, and its currently the fastest n/a 660 at a 13.88. with results like this, i have no doubt that the way my heads are done that they will flow some decent ammount of air, and i dont need flow sheets to prove it. biggest concern he had when porting everything was the intake and the lack of what can be done to help the flow.

see id throw some other heads on this short block, however 3400 heads give me 12.5:1 compression, not very street/daily driver friendly. 3500 heads are atractive at 11.2:1, however the 3.700" combustion chamber of the 3500 on a 3.530 bore doesnt work.

[treeZ24]

the way his heads are worked i'm willing to bet the flow isnt that much less then 3400 heads. would be nice to have em tested to know for sure.

[IsaacHayes]

Then go for 3400 heads and LIM, and 3500 plenum. Then you need to add a lot of boost as your built bottom end isn't being taxed being N/A ya know.

[1988GTU]

If you dont mind swapping heads... Couldn't you swap 3x00 heads on it and inject some n2o? maybe not be a 3500 or full 3x00 swap, but it will be fast.

[sharkey]

its not a case of time or money, its the case of 2 years ago i put $5g into a motor, much of that into a bullet proof short block, and essentially getting nothing out of it. swapping a set of heads out isnt a huge deal. sure i have a ton of hours into porting, but i can sell those off.

selling the whole motor off is unlikly cause first off nobody is willing to pay anything for a 2.8 around here, and the only other car its a drop in is a fiero, and around here most fiero guys do v8 swaps. i dunno, mabey one day ill build up a 3500 (or a 3900), but i cant see that happening for a few years. ill stick with what ive got and continue to attempt to extract power from it

on another note, i figured out my oil cap clearance problem and brad (treez24) got the middle mostly welded up today. pics to follow

[ForcedFirebird]

Well the way I view it, custom pushrods, swaping covers, etc would bother me more than getting a custom motor mount, and just dropping in the 3400. He will still need the 3x00 style pump and coolant fittings if he keeps the 2.8 and goes to gen3 top end. Might as well just go to larger displacement and have the newer platform to build off of. _shrug_

Yeah, but I see the sentimental value of him building a motor he doesn't want to let go of. You will never get back what you put into it by selling it, especially when you dish out the cash for forged pistons.

I don't know that his swap would be any harder than mine, my problem is having 4 kids, cash and time is a commodity here my builds could go a lot faster if we had about 6 more hours in a day!

[IsaacHayes]

Well the way I view it, custom pushrods, swaping covers, etc would bother me more than getting a custom motor mount, and just dropping in the 3400. He will still need the 3x00 style pump and coolant fittings if he keeps the 2.8 and goes to gen3 top end. Might as well just go to larger displacement and have the newer platform to build off of. _shrug_

[ForcedFirebird]

Trying to get stuff to mate up to the 2.8 will probably be a PITA.

Why? If he took the timing cover and accy brackets from a 3x00, that wouldn't work?

Sharkey, which steering pump do you have? That might need to be change to a 3x00 as well.

[IsaacHayes]

Sharkey, I say build up a nice 3400 long block, with 3500 parts if you wish, cam it, run DIS, and sell your complete 2.8. I'm sure someone would like it for their circle track car or whatever.

You headers will still fit. Then you can be running somewhere in the low 14's high 13's hopefully. Trying to get stuff to mate up to the 2.8 will probably be a PITA.

[ForcedFirebird]

I'm upping the fuel pressure today to 55 PSI which takes the injectors up to 36#/hr.. hopefully that's enough to get me back under 80%.

The displacement is smaller on my engine, but my mods should really wake up. This way I can prove to the 90* V6 f-bods that .4 more liters isn't going to make up for the fact that we have it better at 60*!