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Author Topic:   Has anyone considered H.P. loss from crankcase vaccum
Dirt Maniac

Total posts: 141
posted December 10, 2001 07:22 AM
I was reading a book and this engine builder claims to have gained 50 - 60 horsepower on a 400 smallblock race engine, from crank case ventilation. (rough diagram)He had a tee with one hose running to intake (high vaccum @ idle) and the other hose to the header collector (low vaccum @ idle/ High vaccum @ High RPM's). He performed a few modifications here and there. This was a drag motor not a circle.

Dirt Freak

Total posts: 467
posted December 10, 2001 10:04 PM
Yes , pulling a vacuum in your engine is worth power ! The dyno testing that I've done , usually with 5 stage dry sump systems , has shown on average between 15-30 horse power gain . I'm not saying that 50-60 is out of the question , but a lot of articles are exaggerated a bit .

I don't suggest trying this on a dirt engine though ! Though the power gains are really cool , the dust that gets sucked past all the seals is not good !

Hendren Racing Engines
Rutherfordton , NC

Dirt Full Roller

Total posts: 33
posted December 11, 2001 06:55 AM
In drag racing they actually sell a pump to boost the vaccum.This way an engine builder can loosen up the rings,witch will cause less friction in the cylynders, whitch in turn gives out more horsepower.But it is just like sdhnc29 said it is'nt much good on dirt, due to the dust.I still use a stock vaccum resivior to boost up the vaccum and it works good until one of the plugs rattles out in the middle of a feature race and leaves your car sputtering off the track.

Dirt Maniac

Total posts: 141
posted December 11, 2001 07:39 AM
Thanks, guys I appreciate it

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