Ditching a cat?

[sceneiskeen]

Ok i do not have a cat on my exhuast setup

Ive read around and here is a few things ive read:

"Ditching your cat, kills your gas milage" If this is true how so?
"Ditching your cat, gives you more hp, but a little less torque" Again if true how so?

"Ditching your cat, kills your higher rpm speed" IF so again how is this true

again i know nothing about cats, or exhaust just basics.so can you guys explain?

[zoideraserb]

Re: Ditching a cat?

Well a rule of thumb i've come across is that stock cats are usually somewhat restrictive. So removing it would allow better flow and in turn logicly let you make more power, and with more power comes more fuel use. I've never heard of lsing tq but gaining hp though.. just by losing the cat. and as for the higher rpm band, i would think better flow would help it..

[kristen]

Re: Ditching a cat?

it will not hurt your gas miliage. your car will be come more free flowing when it comes to your exhaust which will help you out a little bit. nothing noticable

having no cat can give you a couple more hp since there is less air restriction. and If your exhaust is too freeflowing, you loose backpressure which effects low end torque.

i don't know how it will effect the speed but the back pressure issue will end at higher where exhaust velocity will overcome the tendency for reversion.


read this. it explans exhaust very well

http://auto.howstuffworks.com/car-ex...ns-channel.htm

[techsan23]

Re: Ditching a cat?

the o2 sensor in front of the cat reads air/fuel ratio, the one behind it tells the computer if the cat is working properly. every once in a while my check engine light comes on because of this so i just keep reading and clearing the code.

[kristen]

Re: Ditching a cat?

just get an o2 sim and then you won't see that code anymore

[crushedout]

Re: Ditching a cat?

Actually on my SUV the cat was going bad and I got a new one put on per federal law that they will last 80k miles. My gas milage dropped in it and the only thing that was really diffrent was the fact that I added a K&N filter which in theory woulda got me a little bit better gas mileage. So I don't see how having no cat will hurt gas milage but help it because its more free flowing.

[greasemonkey]

Re: Ditching a cat?

If your exhaust is too freeflowing, you loose backpressure which effects low end torque.

I've always dreamt about a world where this fallacy ends.

O.P.
Engine mods and vehicle speed have really nothing to do with each other. The engine has no idea how fast the car is going. You could have 2.29 gears, or 4.60 gears. Both have very different mph/rpm relations.

[IDoVoodoo]

Re: Ditching a cat?

She's talking about the torque band of the engine. nothing to do with your mph.

[zymose]

Re: Ditching a cat?

O.P.
Engine mods and vehicle speed have really nothing to do with each other. The engine has no idea how fast the car is going. You could have 2.29 gears, or 4.60 gears. Both have very different mph/rpm relations.

???

So let me get this streight, all these performance mods that people do, don't actually make our cars faster?

[kristen]

Re: Ditching a cat?

Engine mods and vehicle speed have really nothing to do with each other. The engine has no idea how fast the car is going. You could have 2.29 gears, or 4.60 gears. Both have very different mph/rpm relations.

say what now.....

[Blue02]

Re: Ditching a cat?

[QUOTE=greasemonkey]I've always dreamt about a world where this fallacy ends. [\QUOTE]

Read this sticky: http://forum.camarov6.com/showthread.php?t=77275

It's about understanding the VELOCITY.
Lower backpressure is good, UNLESS there is also a decrease in velocity.

Confused yet?

IMHO, no cat should be better, mpg, low end torque, and top end. BECAUSE the backpressure is lowered and velocity should be unchanged. (unless you do the cat delete with a 5" pipe!) :omg:

[greasemonkey]

Re: Ditching a cat?

^ .... I agree. And I know that. Just like I said - It is wrong to assume that lower backpressure kills torque. Torque only starts to fall off if the exhaust slows down. Did I once say otherwise?

???
So let me get this streight, all these performance mods that people do, don't actually make our cars faster?

Thats not what I said. Your referring to acceleration. I'm saying you could redline at 50 mph in first gear, or you could redline at 35 mph in first gear. It all depends on your rear ratio (and trans ratio, but those are less commonly changed). So, therefore, engine power/torque and vehicle speed (how fast the car is going) are not directly related. Really it doesn't matter anyways, since I misread the OP's post - which was a reference to rpm speed, not vehicle speed. And voodoo corrected me on this already.

[Blue02]

Re: Ditching a cat?

That post wasn't directed at you Greasemonkey, I was agreeing with you ! :)