brownrx

I am planning to take my car to get a new exhaust next friday and the guy is going to just bend pipes for me. there wont be any catalyic converters and I am assuming he is just going to tap a whole for the 02 sensor but i was wondering if that would be ok or would that make my car run bad since the 02 sensor wont be in the catalyic converter?

brownrx

i just want to make sure that my car will run ok without catalyic converter

coldy13

Yeah, it'll be fine.

anthrax

Most of the cars on this forum run with out any emissions control equipment, and wide open straight through exhaust...

They stink and they are noisey...

You just gotta love it

brownrx

where is the o2 sensor located on the gslse

riofrio

Right on the exhaust manifold. Open the hood and look from the passenger side, it's hard to miss.

brownrx

when you guys took off your catalyic converters and just ran pipe did you notice much of a difference. I am assuming that it would make a big difference because it will take away so much restriction.

TurboIIGuy

I've dynoed a quite a few cars in the past few years. What year is your car and what motor do you have? I'll try and give you a ball park on horsepower gains.

brownrx

1985 gsl-se 13B

TurboIIGuy

Well if you use the stock exhaust manifold and stright pipe after you should see about 12-17 horses extra at around 6500 rpm. if you have headers add about 5 to that and your peak will start at around 5800 rpm and level out only slightly but still increase. I will try and find some dyno sheets and post them.

riofrio

What happens to the low end torque after this conversion?

Hades12

Dont you have to rig the 6th ports if you take out the Cat?

TurboIIGuy

Actual low end torque feels only slightly less, not to bad since the flywheel is so heavy thoug, and the throttle response increases so much it won't even be a factor. You may need to rev about 200-300 rpm higher when taking of from a standing start but it's no big deal.

MosesX605

I should caution you that your setup is going to be unbearably loud. When I did the exhaust on my RX-7, with headers/RB presilencer and a Magnaflow muffler, I got pulled over for excessive noise. With two presilencers I just barely squeaked under the legal noise requirements.

If you are running just a straight pipe to a free-flowing muffler, I don't think you'll last too long before you:

A) get pulled over

B) go deaf

Just my .02.

BMS2004

yea he will have to rig the 5th and 6th ports. otherwise they will just be closed all the time. backpressure in the system is what opens them. you can rig it up with the air pump but i've lost the link to that.

TurboIIGuy

if you buy the racing beat presilencer it has a connection for the port actuator.
Yeah it'll be loud as hell. My last straight pipe RX7 was a 12A. I had a header straight piped into a magnaflow stainless steel oval tipped muffler it was to loud. I ended up swapping to a stock exhaust manifold instead of headers but still leaving the rest of the straight pipe and magnaflow and it improved alot. It didn't have a hi pitch ear killing sound and I recovered a little bit of lost low end. The tone was a lot smoother and not as pulsing. It sounded good.