Exhaust Cutouts?

[Grendel]

Hey all,

A while back, A guy at my work was telling me about how he was putting exhaust cutouts on his trans am... he said you put them right after the headers, and have them hooked up to a lever inside the car...

You flip the lever, and open cutouts, which bypass the mufflers and basically makes it like running straight pipes...

I was thinking about putting one of these in the exhaust piping after the turbo, so I would be basically running without any backpressure...

How much would one of these things cost? less than 50 bucks? Would running one of these give me a noticeable horsepower increase?

What if I just sawed off my muffler? I know that would be loud... but would it be too loud? Someone told me that since I have a turbo, my exhaust wont be *too* loud since the turbo absorbs a lot of the sound or something... I dont really believe em tho

-Grendel

[texan]

The turbo does significantly deaden sound waves from the exhaust, but depending on the airflow it'd still be quite to very loud with no muffling or baffling at all. Moreover, bypassing the catylitic is against the law in all states when driving on public roads, but of course that's not an issue at the track.

If you want to create a bypass valve I recommend you have a local muffler shop weld in a dropout just upstream of the cat, which is opened by removing a metal plate from the end. It's very cheap to do... you just need a 2" section of pipe the same diameter as the current downpipe with a mounting flange welded to the end, along with a similarly drilled metal plate complrete with gasket that mates to the flange.

Of course the real answer here would be to sort out your exhaust system so that it's no longer a real restriction, that way you'd have nearly all the power of a dropout exhaust all the time, and without any of the noise, safety or legal ramifications of an open dropout.

[454Casull]

Under the hood there's going to be hell.

[Grendel]

Hey guys, thanks for the replies...

Ok, so its gonna be louder... will it be a lot more powerful? I dont know how restrictive stock Z exhausts are...

The thing is... I am pretty low on cash, and wanna find a cheap way to get hp...

Texan: The way you are talking about... do you need to be outside the car to open that, or is there a way you can set it up to open from inside the car? I wanna be able to open it up just to let people hear it, or to race someone, then close it back up to make it civil...

454 Casull: What do you mean that under the hood there's going to be hell?


Are cutouts safe?

A kid at my school used to run his bronco with straight pipes, he just left a muffler inside his car... he said if he ever got pulled over, he would tell the cop it just fell off, and he was going home to weld it back on :P

-Grendel

[boosted331]

Originally posted by texan
The turbo does significantly deaden sound waves from the exhaust, but depending on the airflow it'd still be quite to very loud with no muffling or baffling at all. Moreover, bypassing the catylitic is against the law in all states when driving on public roads, but of course that's not an issue at the track.

If you want to create a bypass valve I recommend you have a local muffler shop weld in a dropout just upstream of the cat, which is opened by removing a metal plate from the end. It's very cheap to do... you just need a 2" section of pipe the same diameter as the current downpipe with a mounting flange welded to the end, along with a similarly drilled metal plate complrete with gasket that mates to the flange.

Of course the real answer here would be to sort out your exhaust system so that it's no longer a real restriction, that way you'd have nearly all the power of a dropout exhaust all the time, and without any of the noise, safety or legal ramifications of an open dropout.

Why would he put a cutout AFTER the cat? The whole purpose of a cutout is to bypass all the restrictive piping and the mufflers to free up horsepower. On a turbo car it should make a fair bit of difference as far as spool up time and power goes, and at idle with a cutout you get a nice whistle/whine like that of a centrifical supercharger I was running a cutout that I had midas make, and it had 3 lug nuts on it that I would have to crawl under the car to uncap every time I wanted to race. If you want something really good, take a look at the McCord Power Plate. I ordered one, and i'm putting a little covered toggle switch and a LED on the dash board to open it.

http://www.mccordcg.com/mpp/mpp.htm

[texan]

Originally posted by boosted331


Why would he put a cutout AFTER the cat? The whole purpose of a cutout is to bypass all the restrictive piping and the mufflers to free up horsepower.

Upstream of the cat means closer to the engine, not further from it. My theoretical dropout is located just before the cat.

[The Dude]

ON TURBOCHARGING OR ANYTHING NOT NATURALLY ASPIRATED EVERTHING IS BACK PRESSURE. The turning of the pipes can cause flow to stop a little, the muffler,headers,cat converter anything. Because the turbocharger pushes air in and out you want the cutouts to be a close up as they can. With turbo charging you want the exhaust out as fast as you can. So the cutouts are cool and cheap like 20 bucks i think.

[texan]

Backpressure is always a negative thing, regardless of induction method or exhaust setup. You never want backpressure.

[Steel]

hehe, the loudest thing you can do is set pipes straight from the engine to right behind the front wheels. Course it'll prolly melt the asphalt, along with ruin your paint, start grassfires, and get you pulled over faster than you can say "wowthisisloud!" But it WOULD be cool.

[GPrince]

you could set up the cut outs with a vacume pot . when the intake presure reaches close to 0 it would open the cut outs for you.
if you dont want to be hear don't push so hard on the pedal.

[Grendel]

Originally posted by GPrince
you could set up the cut outs with a vacume pot . when the intake presure reaches close to 0 it would open the cut outs for you.
if you dont want to be hear don't push so hard on the pedal.

That would be cool, but I would want to be able to floor it w/o the cut outs opening... just wanna be able to flip them open once in a while...

-Grendel