modifying intake manifold, how high should it be 1

[bear1a]

I have a 6.1 liter dodge hemi, i need to modify the intake manifold to accept a twin screw or roots blower. I want to keep the height above the hood as low as possible, so my question is, when cutting the manifold is there a minimum height it should be for performance, or does it not matter?..right now the runners are about 4-5 inches high, if i cut them to 1" ..will it work..thanks

 

[MikeHalloran]

The supercharger should make the plenum size irrelevant, but remember to leave enough metal and enough clearance to bolt it on.



Mike Halloran
Pembroke Pines, FL, USA

 

[patprimmer]

Blower manifolds need to be quite robust due to the weight of the blower and the belt tension.

Also blower manifolds can expand quite a bit due to heat from the air being compressed (depending on boost level and what fuel and where it's added). This can change belt tension quite a bit.

Runner length and plenum volume are much less important with a blower, but runner cross sectional area should be maintained. Air flow from the blower discharge point into the runners should not be obstructed and should have reasonable radius and some bell mouth shape if possible.

If you look at street and race manifolds for more common engines (like small block Chev) you will get some tips.

Race manifolds are designed to optimise performance above all else.

Street manifolds make a reasonable compromise on performance for the sake of convenience, particularly with regards to mounting height.

Are suitable engine internal parts available for the boost and power levels you intend.

Mikes point re actually being able to access mounting bolts is very important.

Also access to other regularly serviced engine parts is important, like ignition system and tappet covers.

Take care not to obstruct water flow from the heads as cooling may be more critical.


Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[sbc438]

One thing to keep in mind. Other engine components need to be up readed. Just had a 6.1L hemi come through the shop that had head work done and a procharger. The result...the rods were in a hundered peices. This wasn't even a real agressive tune-up but the factory rods were way too weak.

 

[bear1a]

good point, Indy Cylinder Heads is building the engine to handl e 1200 hp...