I know of a guy that installed my Security system in my Tahoe & he had offered me to try out some exhaust cut outs to make a complete open exhaust system & I thought I had read that with the Cobalts we need to keep some back pressure for best preformance is this true ???

Here is the link check out the lower picture as thats what I was thinking of installing along with proper switchs to open & close the blowout.

I was thinking of installing it after the cat but wanted some feed back as to if that would be stupid as I can install it before but it would be more of a pain as I would have to trick the 02 sensor or thats what I'm told!

 

that is nifty, but i dont know how it would affect performance

 

not trying to flame but i think they are called exhaust cutouts.


Rick

 

No problem as I think your right

Well I know with V8 engines the less restriction the better HP gains hence Headers & open exhausts on race cars & such but I think it would have ot be properly tuned to run with open exhaust so then when you open it you actually benifit from the free flow of the exhaust but then what happens when you run the stock exhaust again ???

 

Ya there called cut outs. I know with my current set up ive lost about 2 psi so back pressure is deffinetly important for low end torque. But I think you gain the hp and tq later on in the power band.

 

backpressure is important in street cars to a point....some in our car will build boost and TQ at a lower RPM.

but it will hurt top end power...

in my 3in system i lost a little bit of low end but my mid/top end power is much improved...some low end tuneing is needed.

 

Ok so if I was to run this I would run the stock system 99% of the time but when I wanted more power I would flip a switch & open up the cut out & be able to add top end from what you are saying right

This whole set up has been playing with me as I know if I add this my warranty is gone so I might just wait fro a couple years but I thought it would be a nice mod for track nights & just playing with the Honda's

 

Just talk to your dealer and see what they think of the whole warranty issue. Just remember when you open up the exhaust it should sound like ****.

 

Yeah i had an '81 malibu with a 355 puting down about 400hp. i put cutouts on it, sounded bad ass. but they where the manual ones with 3 wing nuts on each cutout. I put those on cause i heard the automatic kind had a problem with thier cable binding up and then your screwed, so, just so you know that.


Rick

 

I know someone who got one...lost 5whp

 

I'm getting a header with 3" exhaust and a quicktime electric cutout before the cat, it should be badass!

 

So does that mean that if tuned using HPTuners, you could somehow keep your low end from losing performance?

 

Thanks for the heads up but these are new & he just got his pattend & they have been tested for 5 years to hold up as he had a set with cables & they were junk so he built these & people started wanting a set & now I guess he sells quite a bit of them.

I can't see losing hp but this is why I'm asking as most motors like breathing but I do know some that need back pressure

 

So I guess you will be the Guineepig huh Let us know if it helps!
Waht brand of cut out are you using is it actually called Quicktime ?

 

Quick lesson in exhaust systems...

Aside from many factors including vortexing, balanceing, scavaging, and resonance, backpressure is proably the main thing to consider when selecting an exhaust system. Here the basic rundown as far as backpressure goes:

More backpressure means:

Runs quiter (usually)
Makes more low-end power
Makes less high-end power
Runs richer

Less Backpressure means:

Runs Louder
Make more top end power
Makes less low-end power
Runs leaner

Keep in mind that a car that is tuned to run a high backpressure system will FALL ON IT'S FACE with an open system in the lower RPMs, and will make marginal, if any gaines up top.

A car tuned for a low backpressure system will fall on it's face up high with a high backpressure system and marginal, if any gains down low.

This is the bad thing about cutouts...you an't tune the engine for both.

 

Guys with exhaust cut-outs like those, on a 4 cylinder you will loose a lot of bottom end and that's not good.

 

Yeah, all they do is make it louder. Now if it were in a big block Chevy, different story, but in our cars, waste of money.

 

no....a tune cant fix the looseing power in certion RPM's but you do have to tune the car for less back pressure becase the car will lean out...thats what you have to worry about and fix.

 

rite on!...i was going to scan one of my books at school here that had a write up on back pressure and exspected results from changeing it....but you beet me to it!!

 

A four cylinder that has cut out will sound like ****. Have you ever heard a honda that has the exhaust cut? The srt might sound good though becasue of the turbo.

 

you may gain some top end..you prob will gain a little bit BUT to take full advantige of the much free'er flowing exhasut you will have to adjust your tune to bump your commanded AFR's becasue the car is going to lean out.

 

Yea thats sort of what tought as me & a friend have built pulling tractors with motorcycle engines & it's been our experiance that some back pressure is required to maintain low to top end HP as we gained top end but when the sled gets heaver at the end of the track & starts to bog the motor down we would just lose all power & die out quicker!

Thanks for the trplys guys as I think I will just stay with the stock exhaust for awhile yeat