Open exhaust on track vs. muffler

[Invictus]

as the title says... im taking the GTR to the strip on friday, and it is very easy for me to unbold the portion of the exhaust that bolts together just underneath the passenger seat. I have driven with it off before, but haven't really felt a change in pull. would unbolting the back half reduce turbo lag and yield a better 1/4 mile time?

[Adam2326]

do you mean unbolt from the cat back..as in the cat and then nothing.. also is your cat gutted..

because dont forget you wont have any back pressure

[Invictus]

there is no cat, just a test pipe. so yes, cat-backless... so to run the set up that i want to correctly, it would have to be a straight pipe all the way to the back of the car??

[Adam2326]

sorry i meant the less back pressure the better..as like nascar and dragsters..they try to reduce back pressure to get more hp. One important characteristic of mufflers is how much backpressure they produce. Because of all of the turns and holes the exhaust has to go through, mufflers produce a fairly high backpressure. This subtracts a little from the power of the engine. here are other types of mufflers that can reduce backpressure. One type, sometimes called a glass pack or a cherry bomb, uses only absorption to reduce the sound. On a muffler like this, the exhaust goes straight through a pipe that is perforated with holes. Surrounding this pipe is a layer of glass insulation that absorbs some of the pressure pulses. A steel housing surrounds the insulation. These mufflers produce much less restriction, but don't reduce the sound level as much as conventional mufflers. or you could just go strait piped yes which will defer more noise to the rear and sound amasing..haha

[Turismo]

i don't think there's anything wrong with shortening the exhaust like you're thinking, i would still want it routed to the side though. That's a lot of nasty crap just coming out of that pipe under the car, plus probably a few fireballs if driving it really hard.

[Invictus]

then i will run straight piped on friday. lol

[Adam2326]

vids!

[Invictus]

Turismo, I have driven the car about 60 KM straight piped as i have described, and where the exhaust comes out from underneath, there is no sign of carbon build up or burning or wetness from unburnt fuel or grime. I guess my motor runs very clean

[Invictus]

I have a videographer taking vids of it on friday. straight piped, you guys don't even know how loud the turbo spool is haha.

[Dragon Humper]

You need to unbolt it and remove it to get the best result. The catback will weigh at least 30lbs but more likely 50lbs. This and the extra little bit of hp should give you about 1mph more.


Jon.

[Invictus]

i can't tell if there's sarcasm there or not, so ill only say this. 50 lbs = approximately .05 seconds off the quarter mile time. five minutes of work is worth this.

[mcfly]

dont be a ricer. keep your exhaust on.
If you had to ask this then you can gain the .05 seconds just by driving better I imagine.

Unless you have a stock exhaust you wont find any gains in actual engine performance.
The restriction is the dumps and downpipes once you have a cat back.

[Invictus]

ty ty

[Dragon Humper]

An improvement of 1mph could translate into 2 tenths if you can drive. Don't underestimate the benefits of loosing weight over gaining horsepower to improve your times. The less weight you have the easier it is on parts. Take an hour before you go and gut the interior/trunk of the rear seat and anything else readily removable (spare tire and jack) and you could pick up 3 to 4 tenths.



Jon.

[DarkCaporaL]

That's a lot of nasty crap just coming out of that pipe under the car, plus probably a few fireballs if driving it really hard.

I would love to see a fireball blow up the gas tank.