building an intake manifold, input needed

[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.

[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.

[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]

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.

[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?

[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]

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.

[sharkey]

you cant swap intakes cross generation, they are all different. if i had a viable intake option that would bolt on and fit the engine bay, i would (that leaves out the trueleo).

[1988GTU]

Ok, like I said I was not sure. Now we know only Alloy design 2.8MPFI and 3.1MPFI LIM AND UIM can interchange (with slight mod) .

[sharkey]

as prommised




its still a bit rough. the runners end up being 15" total length, wich was what i was shooting for. if i wanted to go longer to try and hit the 2nd harmonic, i would have had to have some very tight bends to clear the hood, sacfrificing a lot of flow. i aimed for the 3rd and 4th harmonic, wich puts me right were i wanna be. now i know im gonna get comments on the shape of the top of the runners. basicly, i just pulledo ut the hammer and dolley and got them into a shape i throught would work with the top flanges. this shape also ended up with the runners being a bit of a velocity stack.

next thing is to get some aluminum and build flanges for the plenum. once i getthat done ill have the aluminum cut for the plenum (after i figure out the design), have brad weld it all up and itll be good to go.

[2.8RS]

Looks pretty good. The plenum is a box type?

[Superdave]

nice work!

[montess408]

lookin' good man !!!!

[IsaacHayes]

Cool. How does the lower look? Does it keep the flow straight from the middle part you just made into the heads? If so you'll end up with pretty much a 3x00 style lower with a 3500 style plenum..

[sharkey]

its actualy a rectangular port in the head, but the flow is straight to the intake valve. thats part of the reason i built it like this, to maximize flow with no restrictions. the plenum will basicly be a big box, much like a 3500 plenum. depending on how tall i go, the plenum may end up around 190 CI, wich is a bit large for my liking. i can build it lower, however im concerned about port flow if i go any shorter.

speaking of 3500 plenums, does anyone have any dimensions for the 3500 plenum. im interested in calculating the plenum volume to use just as a refference. it