Building Custom Intake

[mag_pbg]

On the R&D page, there is a thread about building a custom intake manifold and I would like to try and do this since I have a welding class and I have access to all the equipment. I just a few questions, 1.) I want a good top end, so should I go with 9 inch runners¿ 2.) I have no idea how long to make the pluem (sp)¿ 3.) Where the heck can I find 4 inch exhaust tubing, I have looked everywhere for it on the net, even diesel places¿

[86LXItooFAST4me]

do what now? lol. 4"?? 9" runner? huh?

[mag_pbg]

Sorry about that here is the link for the thread https://www.3geez.com/showthread.php?t=16237 But The runners will be 2 1/2 inch in diamiter, and 9 inches long, the pluem will be 4 inches around but I need to know how to make the pluem.

[shepherd79]

well, the shorter the runners the better the top will be but your low end will suffer a lot.
i guess you just have to search around for 4" pipe, but try this place. http://www.onlinemetals.com/
they have anykind of metal you need.

PS. you may want to build it out of aluminum. since the steel will be very heavy.

[smufguy]

imo, get a B series manifold. why? its because not only the finish is good its built right. The only problem with self building is that you dont wanna induce turbulance in ur manifold before the runners and that will cause bad AF mixture. The how-to on the linked page looks alright, but thats not how most of the manifold builders build their stuff. the runner intersection with the plenum needs to be tapered, as in, it should resembel a venturi. We have done intake manifolds for our formula one car, but we used carbon fiber on the inside and fiberglass on the outside, but this was on a CBR motor and everything is outside so there is no heat buildup. Even our plenum was made out of CF and FG but the runners were aluminum tubings. I machined the injector bosses outta 6061 solid stock and the injectors base holders and the fuel rail itself was actually made from thinner steel. We also had mill and laithe in our school and it made things a lot easier.

[mag_pbg]

Now that you said that I might not build one, my spare intake manifold is port mached and I made covers to go over the EGR valve so I won't have to use it, but I think I will look into getting a b series manifold.

[smufguy]

if you wanna go for a forced induction later on. I would suggest that u get the Edlebrock or even the Skunk2 manifold (B series) to begin with to save money later on.

[Andrew]

A20A1 made an exhaust anifold, might be a good person to ask.

[smufguy]

yeah mike made and exhaust manifold i also remember he adapted the stock carb manifold and made his own. But EFI manifold, is a whole different story. But as it always goes, if you know what you are doing, then you are good. If you have no clue, then leave it to the professionals or just get off the shelf one.

[mag_pbg]

I think I will just stick with the stock manifold sice it port matched, it seems like the b series intake takes alot of work to adapt, and there isn't really detailed instructions how to fit it to our cars.

[smufguy]

I think I will just stick with the stock manifold sice it port matched, it seems like the b series intake takes alot of work to adapt, and there isn't really detailed instructions how to fit it to our cars.

if you think about it, its actually simple. THe only problem is overcoming the egr and stuff, but if ur gonna go turbo, that manifold is the best. Besides, u can put larger TBs on it. As long as you have a good intake manifold gasket, just match it to the mani. U have done this before, same concept.