NPP question
Thread Starter
Safety Car
Joined: Aug 2017
Posts: 4,243
Likes: 1,133
From: North Myrtle Beach SC
NPP question
Has anybody just connected their npp mufflers directly to vacuum source without any controller/module?
obviously, at light throttle( high vacuum) valves would stay closed then open at heavy throttle (low vacuum). Almost the same as factory except for the rpm requirement to open.
obviously, at light throttle( high vacuum) valves would stay closed then open at heavy throttle (low vacuum). Almost the same as factory except for the rpm requirement to open.
Le Mans Master
Joined: Apr 2013
Posts: 5,376
Likes: 1,118
I did it for a while after my original NPP controller solenoid **** the bed. It works good too, except that the flaps open earlier than with the factory controller, since the only thing keeping them closed is vacuum, so it functions more based on load/throttle opening rather than being RPM based. Once you crack the throttle open, it’s going to open the valves.
All you have to do is bypass the solenoid behind the right taillights and remove the one-way valve from the NPP vacuum line up front by the firewall on the drivers side.
All you have to do is bypass the solenoid behind the right taillights and remove the one-way valve from the NPP vacuum line up front by the firewall on the drivers side.
Le Mans Master
Joined: Dec 2005
Posts: 6,998
Likes: 1,681
From: Southeast TX
I've been running on straight manifold vacuum for over a year. I like it. I have an NPP in a box for sale if you're interested. I bought it a year ago and never installed it. I like it how it is. The only downside, and it's minor, is that the flaps will open on an uphill grade in 6th gear. That probably has something to do with a bigger than stock cam that I'm running. If it is a bother, just down shift going up the hill. Otherwise, you can accelerate fairly briskly and never have them open. Push a little harder on the right hand pedal and they will open instantly.
