This is pretty much my first project using TIG, so welds aren't great looking. I'm happy with how it turned out though. Car will be run by a motec m400 and tuning by Paul Yaw.

 

Pretty nice. Is that an 75 or 80mm mustang throttle body?

CJG

 

Nice job, man!

Any idea of the flow benefits over the stock manifold?

 

it's a 80mm q45 throttle body. I don't have any flow numbers on it so I can't say for sure how much better it would flow over stock. I tried to design it with the most gradual bends while maintaining the runner length I wanted, 15", and also tried to have the runners go straight as long as possible before entering the port to help with velocity. Also, it has velocity stacks going into each runner from the plenum, so that should help flow a bit.

 

Looking good.

 

congrats on doing something different. (sure, 'have seen plenums w runners before but it looks really slick). please keep us posted as to how it runs.

howard coleman

 

i like how the entry angle into the motor isn't so steep as the stock manifold. that way it's a more gradual turn, instead of basically a u-turn when the air enters the motor. port-match that thing to the block and it'll be GREAT!!

fitting a turbo around it might prove a little tricky, but i'd love o see some pice of that when you're done.

 

The only thing I see questionable would be the flange on the motor side. It looks pretty much on the thin side.

 

not a whole lot of heat in the intake though. once it's flat, it should stay that way.

it's not like building an exhaust manifold.

 

Yeah, after I welded it, I realized I should have gone a lil thicker, but I'm not too worried about it. If I remember correctly, its 1/4" steel. It bolts up nice and flat to the block. May look thinner than it really is w/o much reference.. the plenum is just under 6" diameter.

Guitarjunkie, it's been portmatched to the block, and yeah my goal was to get rid of that rediculous bend the stock manifold uses right at the block. The angle on my manifold is actually the same angle as the port runners in the engine. it seems like mazda made it that way so they wouldn't have to put as much of a bend in the intake manifold to make as much room for the heat soakers, err I mean stock twins...

Fitting a turbo is definatly going to be a bitch considering my original plan was to use a t6 hotside and run a 4" downpipe to move enough air for the bridge.. Looks like I may end up having to go w/ a t4 instead

 

thanks for the compliment howard.

 

looks like you've succeded in that with flying colors!!

one question though. with the runners so short, it's probably going to move your powerband up in the rpm range. i thought that the higher the rpm, the smaller the plenum. i'm not knocking you by any means--just curious.

 

hmmm, wont that thing crack when it heats up... it looks like it would need a brace of some sort

BTW great manifold, i love the creativity

 

crack?
it's not an exhaust manifold, man!

 

I went with this size plenum after discussing it with Paul. He did some calculations from the size throttle body and at 8k rpm, the air coming into the plenum would be traveling ~227 mph. What he told me is basically, the bigger the better since the air coming in past the TB will have more space to slow down and change directions rather than causing turbulence in a smaller plenum. And I doubt it'll crack, it weighs a good deal less than the stock manifolds, and shouldn't get all that hot. I might tie in a brace to the block at the TB flange for some added stability since I'm going to have to make a bracket to hold the throttle cable near there anyways.

 

Looks really good . What kind of engine and turbo setup are you going to be running this on??

 

engine is a 1/2 bridge w/ some meaty exhaust ports. Not 100% sure on turbo yet, but right now I have a gt4288 (gt4088 comp wheel and gt42 82mm turbine wheel, weird diesel turbo config...), 1.15 t6 hotside and dual wastegates. I've still got to build the exhaust manifold, but I need to figure out exactly what I'm going to go with first.

 

cool. i definately wanna see the dyno sheet when it's all done!!

 

I just wanna see it when its done, car's been sitting for over a year!! argghhh!!

 

halfie and shorty runners... you planning on a 9k+rpm turbo motor?

forget the pics and dyno sheet, i want a ride!!

 

what are the id's on the primary and secondary runners? also you said the plenum is just under 6 iches... can you be more exact? looks pretty sweet by the way!

 

Well, od on the primaries are 1 1/2 and 2ndaries are 1 3/4, I wish I woulda gone a bit smaller now. So at .049 wall that puts the primaries at ~1.402 and 2ndaries at ~1.652. I think the plenum ended up being 5 3/4 or so in diameter, I'd have to go measure it to be more exact, tho.

 

but where are ur injectors going to be placed?

 

Look under the secondary runners.

The injectors for the primarys are in the block.

-Alex

 

It's gonna leak under boost. Even the factory intakes are prone to leaking on the primary ports at high boost. I always use 3/4 inch to 1 inch 6061 to help with that problem.