Stimey131

I built a new engine 415 stroker with a ECS big blower cam and procharger D1SC. I'm planning to one day get a bigger supercharger, but no rush on it. it's making a ton of power and I'm having a blast with it. My only real problem is the very low vacuum I'm getting of 5 to 6 inhg and because of this I can't get a blow off valve to operate very well because if the low vacuum I have to use a lighter spring. Most of the BOV for sale require 11 to 15 inhg to operate. I'm thinking if I add a electric vacuum pump to my system it should solve this problem. I've also read it that they have other benefits as well. some of the ones I've looked at are fairly easy to install and are supposed to work automatically to maintain 12 to 15inhg. Has anybody else had to do this. Thanks for any help on this.

neutron82

bov's work differently on a supercharged car, since the blower is always moving air being belt driven it needs to vent the air when at idle and part throttle hence why you need a lighter spring to allow vacuum to keep it open in these situations... they are typically around a 2lb spring and once you reach -2in/hg of vacuum the valve will close to allow you to build boost... a heavy spring may be too strong to keep the valve open at idle and they can also cause flutter and you don't want either of those... the bov's you see for sale with heavy springs were probably on turbo cars, if you get one of those you will need to swap the spring out but other than that you should be fine

Stimey131

OK. Thanks for the info. I also talked to a tech at procharger and he told me I also needed to upgrade to a larger BOV as my original was only using s 1.25" outlet. This is to small for the my new setup. I planning I getting one of there Big Red BOV. Thanks again for the info.