Question about exhaust...

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Originally Posted by nofive-0

What we have always done for a "race" type exhaust is this: We took a straight piece of tube and weld it to a collector and bolt it to the header where the cat used to bolt too. Then weld in a bung as close as possible to where the O2 sensor was. Then just use the hanger by the cat. Lastly put a turndown on the end of the pipe. Litterally we would have these things done in like half an hour. If you wanna use it for weekends and stuff it will definitly be the cheapest, fastest, and easiest route.

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That's the advice I'm lookin' for :goodjob:

Curious, though. What exactly is the point of the turndown at the end? Also, I was looking at doing the side exit simply because NA engines require a LITTLE bit of backpressure. I know it's been argued many times whether backpressure matters or not...but I think that an NA build requires just a little bit. Either way, that aside, I would have just thought that having a pipe THAT short wouldn't provide any at all... I'll probably try it though. Damn, that's gonna be loud, haha.

Thanks for all advice. You're a big help.

put a resonator on it.

Meh, it's at a track. I may just run it open unless the noise gets unbearable...

Through your BS, was the theory of backpressure on a combustion engine ever tested?

If I assume your engine is fairly stock straight pipes will not be much difference in power than with a resonator.

Yes it is true in N/A applications a little backpressure is good. Really the most important thing for an exhaust is the exhaust gas scavenging ability. That is basically all in the header, and doesn't have that much to do with afterwords.

My advice to you is to come off the header where it bolts to the cat. just use some 2.5" or 2.25" tubing for a foot or so. Im pretty sure on efs the 02 sensor is in the header so you shouldn't have to worry about that. On the end of that first piece put some kind of resonator, then a turn down on the end of that. It really shouldn't take more than an hour.

Quote:

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Originally Posted by nofive-0

If I assume your engine is fairly stock straight pipes will not be much difference in power than with a resonator.

Yes it is true in N/A applications a little backpressure is good. Really the most important thing for an exhaust is the exhaust gas scavenging ability. That is basically all in the header, and doesn't have that much to do with afterwords.

My advice to you is to come off the header where it bolts to the cat. just use some 2.5" or 2.25" tubing for a foot or so. Im pretty sure on efs the 02 sensor is in the header so you shouldn't have to worry about that. On the end of that first piece put some kind of resonator, then a turn down on the end of that. It really shouldn't take more than an hour.

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I'll probably follow your advice. On EF's, the O2 sensor is located on the header. However, the LS motor (obd1) is built with the o2 sensor being in the downpipe.

Currently, yes, the engine is stock. In time, however, it will be built. If I build NA, my goal is 200 at the wheels. If I build turbo, my goal is 300 (give or take) at the wheels.

Quote:

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Originally Posted by JokerTypeR

That's the advice I'm lookin' for :goodjob:

Curious, though. What exactly is the point of the turndown at the end? Also, I was looking at doing the side exit simply because NA engines require a LITTLE bit of backpressure. I know it's been argued many times whether backpressure matters or not...but I think that an NA build requires just a little bit. Either way, that aside, I would have just thought that having a pipe THAT short wouldn't provide any at all... I'll probably try it though. Damn, that's gonna be loud, haha.

Thanks for all advice. You're a big help.

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The turn down is so you don't melt the entire undercoating of your car while boiling your brake fluid in the lines and anything else that happens to be in the exhausts path, don't forget about the fuel line too.

THEN you can do all the custom piping in the world but ever heard of noise regulations/ordinances at just about ANY sanctioned event? Think it's 96 decibals in SCCA. If you're not within their guidelines then you don't get to run again, period. You want the tip facing down in the center of the car and use one you can rotate depending on which side of the car the sound meter is on ;)

I run a factory cat and high flow stainless steel resonator and it's not enough back pressure. It's great off the line but my topend runs out. On our honda race cars [205-210whp] we run an SMSP header with two CRV resonators in line to a turn down. Dyno'd just about every imagineable exhaust out there and this setup is just as good or better than any of them...

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Originally Posted by speedminded

The turn down is so you don't melt the entire undercoating of your car while boiling your brake fluid in the lines and anything else that happens to be in the exhausts path, don't forget about the fuel line too.

THEN you can do all the custom piping in the world but ever heard of noise regulations/ordinances at just about ANY sanctioned event? Think it's 96 decibals in SCCA. If you're not within their guidelines then you don't get to run again, period. You want the tip facing down in the center of the car and use one you can rotate depending on which side of the car the sound meter is on ;)

I run a factory cat and high flow stainless steel resonator and it's not enough back pressure. It's great off the line but my topend runs out. On our honda race cars [205-210whp] we run an SMSP header with two CRV resonators in line to a turn down. Dyno'd just about every imagineable exhaust out there and this setup is just as good or better than any of them...

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Wow...common sense didn't kick in about that turndown melting shit...LoL

Thank for the tip on having an "multi directional turndown"