anthonyrb98

iTrader: (45)

so i've reading up a lot lately on test pipe cutouts and dumps, particularly electric cutouts from companies like qtp, dmh, badlanz, etc.

a lot of the domestic guys, both turbo and non-turbo, are making pretty big gains with these - one 650whp corvette reported a 50whp gain with dual cutouts. even those with aftermarket 3" exhausts have reported huge gains when they bypass their entire catback system.

from my understanding, even a single 2.5" cutout will flow enough to reduce backpressure TREMENDOUSLY, resulting in better engine VE, and ultimately more power.

this is my next project and my plan is to install a wastegate actuated cutout (instead of those crappy motor operated flapper valve cutouts that leak) and get tuned for it.

for those of you who are running cutouts, what kind of gains are you experiencing?

i just don't understand how even a 3" exhaust system could create enough backpressure that a test pipe cutout would alleviate and make even 10+whp gains.

BluEVOIX

iTrader: (69)

First you should ask the question is that "3 inch" exhaust people are running a true straight flow through system? Many people have so called 3" exhausts but they dont know that there is a drastic taper or bottle neck inside .

Anyways, on a forced induction car a cutout near the turbo will give you a little more gain because the exhaust doesnt have to travel and eventually be pushed through 10 feet of piping. But the gains shouldnt be that large as 50 whp unless your current setup is max'ing out your exhaust diameter. Even 3" exhausts have a optimum max hp rating...

A 2.5" cutout is not the same as 3" cutout but it may still help. Although a cutout valves opens up 2.5" it still reduces the volume and the rest of the exhaust becomes less of a bottle neck and for the reduced left over volume of gas.

I do agree with you that boost actuated cutouts are better than electronic. But I plan to have one made right behind my muffler. Current setup includes full 3" exhaust mated to stock muffler. I dont want to put the boost actuated cutout under the car but rather right before the stock muffler in the rear. Running them under the car brings too much resonance in cabin. And yes I care about that even in WOT conditions.

Anubis18

iTrader: (31)

What exactly is a cut out and an electric cut out? Interested.

Raptord

iTrader: (10)

Basically it's a device that allows exhaust gases to bypass the whole exhaust line by allowing them to exit much closer to the front of the car. My friend has one on his Evo, the cutout is pretty much under the passenger seat. His is electric, so he presses a switch inside the cabin and the cutout opens, allowing exhaust gases to exit right under the passenger seat instead of going through the whole exhaust system.