Random thought. Vacuum controlled Cutout?

**benner** · 04-21-2011

One of the guys on my local forum is building a Modernized 69 Camaro and I noticed he posted images of mufflers with a butterfly valve that's vacuum controlled.

So I'm wondering if it would be possible/feesable to make a vacuum controlled cutout. You'd need to be able to have a switch to be able to control whether it'll operate or not. AC controls would work.

Something like in this pic but in the piping so there'd be no restrictions at hard throttle. Anybody ever tried?

(I take no credit for the work in this pic.)

**matt5112** · 04-21-2011

Did you see that other guys 500 WHP dyno that was posted today?

He lost 28.5 WHP to having his cutout closed.

http://www.grandprixforums.net/back-...lts-45626.html

503.4 HP / 619.4 T with cutout on DP open @ 20 PSI (small touch of KR - damn sh*tty gas)

474.9 HP / 580.5 T with cutout closed @ 19 PSI

take it as you will

**benner** · 04-22-2011

yeah I saw that. Basically what I'm thinking is it'll open under boost situations when needed but when it's not it'll close. So for instance you take off it's gonna open but you pull up to a stop light and there's a cop. no worries unless you get into to much boost.

**Bio248** · 04-22-2011

Originally Posted by matt5112

Did you see that other guys 500 WHP dyno that was posted today?

He lost 28.5 WHP to having his cutout closed.

http://www.grandprixforums.net/back-...lts-45626.html

take it as you will

on a turbo car. that runs more than 12 pounds of boost.

also, if you research 'boost activated cutout', they make these already.

**SlowNA06** · 04-22-2011

A 5.7% difference at ~20lbs boost. On a car running 8lbs? I'd say it might make a 2% difference, tops. So, at 242hp, you might gain 4.8hp with the cutout. Whoopdeedoo.