Force bi-mode mufflers closed without vacuum
Thread Starter
Heel & Toe
Joined: Feb 2016
Posts: 22
Likes: 0
Force bi-mode mufflers closed without vacuum
Hello. I know this is probably the opposite of what most people want but Is there a way to force the flaps closed on the bi mode mufflers without having vacuum to it? Reason I ask is because I ordered the NPP in a box but it has not come in yet! Ahhh very frustrating because it hasn't even shipped yet! But I will be installing the mufflers on my car tomorrow and do not want to run it open all the time until the kit comes in. I want the quiet mode for early morning drives and around town and that's why I am retrofitting this set up on my car now that I have headers and an x pipe. Any help would be very much appreciated! Thanks!
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,631
Run your vacuum line from the back of intake manifold port, then using a T at the back of the car, split the single vacuum line with a T to connect to the two valve ports on the muffler.
Note, if the car did not come with NPP to start with, on the end of the intake port will be a winged plastic piece. Turn the wing section to snap it off the end of the nipple, and make sure that the inside of the nipple port channel is open so you can get the needed vacuum out of the intake manifold port to start with.
Connected this way, when you start the car, will create the needed vacuum to close the gates on the mufflers. When you get on the throttle to go WOT, the Vacuum in the intake drops to zero, and the muffler gates will open up to put you into loud mode then.
Down the road when you install the vacuum solenoid in the vacuum line for the Controller to control the vacuum solenoid, you can have the loud mode at less than WOT instead.
Note, if the car did not come with NPP to start with, on the end of the intake port will be a winged plastic piece. Turn the wing section to snap it off the end of the nipple, and make sure that the inside of the nipple port channel is open so you can get the needed vacuum out of the intake manifold port to start with.
Connected this way, when you start the car, will create the needed vacuum to close the gates on the mufflers. When you get on the throttle to go WOT, the Vacuum in the intake drops to zero, and the muffler gates will open up to put you into loud mode then.
Down the road when you install the vacuum solenoid in the vacuum line for the Controller to control the vacuum solenoid, you can have the loud mode at less than WOT instead.
Last edited by Dano523; Apr 7, 2016 at 02:29 PM.
Safety Car
Joined: Jul 2009
Posts: 3,755
Likes: 190
From: Baton Rouge LA
St. Jude Donor '14, '16
Small 12v vacuum pump mounted in the rear fascia
Just kidding! I would find some way to just force the flaps closed by interfering with them, or the pushrod that controls them.
Just kidding! I would find some way to just force the flaps closed by interfering with them, or the pushrod that controls them.
Thread Starter
Heel & Toe
Joined: Feb 2016
Posts: 22
Likes: 0
Awesome information right there! Thank you everyone. I may run the vacuum lines right now because I have to anyway. Or I'll just be lazy and zip tie them shut until I do the entire install. Thank you!!
