intake manifolds

[bhearts]

whats keeping everyone from making unique intake manifolds. what design flaw would i get if i flipped a nice appropriatly sized exhaust merge collect around backwards and used that for my intake manifold dividing area. instead of just a plenum and perpendicular runners like some cars have.

[DON SVO]

Most intakes are aluminum. Most exhaust merges are steel. That's a total PITA to weld. The gains on a NA motor with a custom manifold for our motor sizes is rather negligible. I could see using runner length and cam timing to move the torque curve but the $$$ isn't there for a $400 manifold to gain 5whp.

[blkfordsedan]

There have been some members that have fabricated their own sheet metal intakes. Rocketman has even cast his own design. Intake manifolds are "tuned"...much more than exhaust manifolds. Runner length determines the rpm intervals of optimum torque, based on the wave pulses. Plenum volume is also tuned based on on RPM, CID, etc.. You can fab your own, but there are specific design parameters.y

[festyfreak39]

I think people need to think more about intake manifolds, lots of honda guys run aftermarket ones. There are also lots of mturbro.net guys welding b18c5 intake manifolds to bp intake flanges and seeing good gains. You bring an interesting point sir, stock b6T intake manifolds are junkola.

[bhearts]

ive seen some interesting designs for the 280z motors. when guys keep the flange and injector portions but add their own length of pipes and their own plenums. what specific rpm do you think the aspire b3 intake is tuned for?

[Huli]

I have seen a math formula for figuring out how long the runners need to be and then how long between the throttle body and the filter. Its not hard to do if you can get your hands on a TIG welder. I have built a few exhausts but never an intake.

You can get the tubing delivered from cone engineering.... if you don't mind stainless steel. Talk to Rich.

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[Festy46]

I make my own carbed intake for the 1.8L SOHC by using the intake off the 1.6 Ford Escort carbed manifold. This is the engine where everybody gets the Escort carb to put on the carbed B3 and B6 engines. The Escort runners are perfectly spaced to match the intake holes on the 1.8L SOHC head. All you need to do is cut off the original Escort flange and weld on an aluminum plate and drill and gasket match the intake ports. When you cut off the intake flange, make sure the carb flange is sitting level and cut the intake flange at a 90 degree angle to the carb flange. Apparently the Escort engine (or the head) does not sit at the same angle in the Escort car. If you cut the runners off the flange parallel to the old flange and weld the new plate to the intake on the 1.8L, the carb will not sit level. The best part of the whole deal is you don't need a carb adapter. You can use the Escort carb or go with a "true" Weber.