how much crank case vacuum should i run?

[quick coupe]

Just wondering how much i should be running with my vac pump. I have a 357ci windsor that i shift at 8k and trap at 8300. Any advice would be great..this vac pump thing is all new to me. Thanks

[andydallas]

it really depends how the engine builder setup your motor, but I was told for my nitrous motor to not let it get over about 10 lbs of vacuum or I could be taking oil away from the motor

again, I think it really depends on your exact engine specs, and how the motor was setup, I'd talk to your engine builder

andy

[quick coupe]

Originally posted by andydallas
it really depends how the engine builder setup your motor, but I was told for my nitrous motor to not let it get over about 10 lbs of vacuum or I could be taking oil away from the motor

again, I think it really depends on your exact engine specs, and how the motor was setup, I'd talk to your engine builder

andy im my own engine builder and i have no clue:D :confused:

im gonna post this in the forum with the hot street racers...my engine is basically a slot hot street motor.

thanks

[Cobramust]

Originally posted by quick coupe
Just wondering how much i should be running with my vac pump. I have a 357ci windsor that i shift at 8k and trap at 8300. Any advice would be great..this vac pump thing is all new to me. Thanks

It must be getting blow-by, Right ?. 8K and traps 8300.

By have this blow-by you need to releive the PSI build up in the crackcase, faster then most (I assume).

So how much (in hg) of vacuum do you need ?.

You can asnwer this by knowing how much Blow-by you have.

This is what I did - I have a screw in cap on my valve cover on each side, So I tapped one side - cap and put a PSI guage sensor in it, putting the guage inside the car, then found out what PSI build up I got, From ideal to 6000 + - Started out with 5 in hg. and went to 10 in hg. Vacuum and found that was good enough for me - This may not be for you ( Do not know).

I found that having a little + PSI is Better then having - Vacuum in the Crankcase, by having a little on the - vacuum side I could fill up a quart of oil out of my catch can, this to me is not good - I need that oil somewhere else (Lubication and Cooling).

This test was done on a :
351W Sprotsman 9.200" Block, Stroked to 408cid
4.000" Crankshaft
6.125" Con Rods
1.078 C.H. Pistons
AFR 205 Heads Pro Ported
540-550HP all motor
700+ @ 7000rpm NOS

I hope this helps.
:)

[quick coupe]

thanks for all the advice guys

[Cobramust]

Originally posted by quick coupe
thanks for all the advice guys

Your Welcome, Just try and = the pressure with vacuum.