Crankcase evac question

[weedburner]

Originally Posted by BTR69

Curious on crankcase evac systems. About to put the money into one and looking for what works best for most of y'all. Looking at preferred brand/model and also belt driven vs electric. Seems to me less pulleys running off the crank would be a better option, but do the electrics pull enough vacuum?
Will be going on 355CiD SBC. Roughly 450 hp, powerglide & 3400lb car.
Primarily raced, but will ne street driven a time or two monthly.

My 355 sbc powered street/strip car uses a hybrid pcv/electric crankcase vac setup. Pcv provides all the vacuum around town and on the hiway, only use the electric pump when spraying. Here's a link to a page about my system (put up the page 7-8 years ago, still use basically the same system today)- http://grannys.tripod.com/evac.html



The above data/graph is from a NA WOT 3rd gear pull (2650-6000rpm / 43-99mph) using only the pcv valve shown on the webpage as it's crankcase vacuum source (electric pump was not switched on for this pull).

...Yellow trace is crankcase vacuum
...Red trace is engine rpm
...Blue trace is the WOT switch for the nitrous (nitrous system was dis-armed)

When I started rolling into the throttle at the 4 sec mark, crankcase vacuum was 12.3"Hg. By the end of the ~6 second pull, the crankcase still had 3.9"Hg of vacuum left. As you can see, there's no reason to even turn on the electric vac pump unless it's going to make a pass.
This is a well sealed flat top 355" sbc street engine w/ gapless rings. Well over 800hp on 91oct pump gas when spraying, spins past 9k.



Here's a link to the car's webpage... GSS Shop Mule Webpage