Custom exhaust questions for 98 Camaro?

[augie1209]

I have a v6 98 camaro... yea yea i understand its an LS1 site, but i always have been getting better advice and imput here then any other camaro forum site... so keep the good info coming people!!

Anyways... I plan on gettin a LS1 sometime in the near future when i get the funds.. but i just bought a v6 camaro recently and would like to experiment and have some fun with it before i go to the ls1... with that being said, instead of spending God knows how much on a custom exhaust setup, I plan on taking this on myself and had a few questions before i do it...

1. From the headers on back to the rear, how many and where are all the sensors (i plan on getting underneath and checking it out, but just wanted to get a confirmation so i'm not missing one)?

2. I've had different responses to a Cat-delete setup, yes i know its not legal, but i want to know how it will affect hp, mpg, and take off torque?

3. If i do a Cat-delete, is there any way i can avoid having the engine light come on (i have read that there is a sensor connected to the cat converter and that when it is taken out it makes the computer loopy)??

4. In a exhaust system, other than the cat and the muffler, is there anything special about the piping that would affect performance and sound compared to if i used piping from say lowes or whatever hardware store? (not sure i'll go this route just yet, but wanted to get imput on this)

I would appreciate all your help and advice, once I get some more info I'll probably start on the exhaust and make a thread with detailed piks!!

Thanks

[pajeff02]

Hey Smittro! He's our resident V6 expert and should pick up on this thread eventually. Anyway, there should be both upstream and downstream O2 sensors. The upstream sensors control fueling and you don't want to mess with those. The downstream sensors simply tell the PCM if the cats are working. These can be tuned out or simmed to avoid a CEL. Removing the cats will actually increase power and mpg as they are an exhaust restriction. This will also have an effect on the sound of the car as well.

[Smittro]

The Doc is in..lol

Whomever told you that the rear o2 will make the computer go "loopy" is a moron.. The rear o2 is totally useless except for catalyst efficientcy codes. Which yes will trigger the SES light, you will gain some power by getting rid of the cat. The old piping is junk from the factory. The down pipes have a "kinked" profile with a DIA. that's too small and the kinks run the length of the pipes which then turn and come together @ a 3" collector and then into the cat. The rear o2 can be removed and the code can be tuned out.. There is only one rear o2 sensor.

Can't go wrong with a custom system. I built a custom system in a few hours @ my shop. Unfortunately I hate how the muffler sounds and the fact that I had to reinstall a cat. I'll be doing an all new system soon and then another one for the blower later down the road when my other project gets done. If you have any other "?'s" post up I'll help you all I can..

[Smittro]

Oh and the rear o2 is just after your cat. It can be seen without jacking it up..

[Smittro]

Hey Smittro! He's our resident V6 expert and should pick up on this thread eventually. Anyway, there should be both upstream and downstream O2 sensors. The upstream sensors control fueling and you don't want to mess with those. The downstream sensors simply tell the PCM if the cats are working. These can be tuned out or simmed to avoid a CEL. Removing the cats will actually increase power and mpg as they are an exhaust restriction. This will also have an effect on the sound of the car as well.

Correct! But just like you lsx guys o2 sims are'nt worth your/our time.. Best to tune them out. I will be emissions exempt this year (finally!) so guess what's comming back off..lol

[Smittro]

To add. If you'd like to gain/make usable some more off the line torque I recommend a 45 side wall.. I run autocross competion kumho 265/45/16 not a wet wheather tire tho. But it acts like it's on rails now. A good upgrade for our cars too is the Moog (HD) rear sway bar linkages. If you have stock linkages imho get rid of them the driver side stock linkage is prone to breakage.. Part # K5252

[augie1209]

wow thats awesome info thanks guys.... hey smittro, did you happen to do custom lts? Or did you already have an ls1? I wanna try to do lts for the sixer and see if they increase any power... Should i might as well buy a tuner for my car and do it myself to make all the custom settings? What tuner is good for the sixes? You said the piping is to small, should i go with 3 in piping throughout the whole thing? I plan on bending a custom piece to make quad outlets in the center, like the vettes, slp makes this part but its like 280 or something like that, i can probably get piping and bend it for 20-30 bux..!!!

[Smittro]

wow thats awesome info thanks guys.... hey smittro, did you happen to do custom lts? Or did you already have an ls1? I wanna try to do lts for the sixer and see if they increase any power... Should i might as well buy a tuner for my car and do it myself to make all the custom settings? What tuner is good for the sixes? You said the piping is to small, should i go with 3 in piping throughout the whole thing? I plan on bending a custom piece to make quad outlets in the center, like the vettes, slp makes this part but its like 280 or something like that, i can probably get piping and bend it for 20-30 bux..!!!

I'm on factory mani's. Lt's will give you a good boost in hp maybe 10-20 crank hp. The problem is the heads they don't even match the openings in the mani's. They are too small too. 3" out of headers will flow very nicely even if you don't mees with the heads. I was originally going to do a lsx project. But after tons of research and seeing 3.8's and 3800's pull wheel stands on a single turbo I found there's no need for an lsx swap other than status among the v8 gods. You start pulling wheel stands on a blown 3800-II, frankly you ARE a god!.. You'll have to find a tuner near you I don't put much stock in hand helds. I have a buddy running in the high 12's on a stock well tuned duramax. He'll be doing all my tunning for nothing but the price of the software for the Camaro.. Have fun with her. In my honest oppy you can't go wrong building the Legondary 3800...

[augie1209]

thanks that helps alot.. yea i know what ya mean about the v8's, but i found an amazing deal on my car when i bought it, 80k original but has brand new 3800 II series engine and transmission, and many other things were replaced brand new as well so it basically a brand new car pretty much.... any1 got a thread anywhere online on custom building lt headers for the sixers? Am i going to need access to a shops machined pipe bender or is there any other way i'll be able to do that? The welding aint a problem at all, mostly thinkin about the bending

[augie1209]

also just wondered what the best muffler and tips combo out there with a lt head and no cat converter set up... thanks

[c5z28]

http://www.ls1.com/forums/showthread...48#post2345648

[Smittro]

http://www.ls1.com/forums/showthread...48#post2345648

Yeah but the 3800 sounds all together different than a v8.

[augie1209]

yea thats wut i was thinkin as well.. so gotta couple more questions... i plan on mig welding then smoothing out the tacks.. is this a good way to weld the headers if i decide to customize some lts? Also what kind of metal piping should i use? I plan on using 3" from headers back, but what measurements should i make the lts? Also, are the lts essentially just longer versions of the manifold??

[Smittro]

thanks that helps alot.. yea i know what ya mean about the v8's, but i found an amazing deal on my car when i bought it, 80k original but has brand new 3800 II series engine and transmission, and many other things were replaced brand new as well so it basically a brand new car pretty much.... any1 got a thread anywhere online on custom building lt headers for the sixers? Am i going to need access to a shops machined pipe bender or is there any other way i'll be able to do that? The welding aint a problem at all, mostly thinkin about the bending

also just wondered what the best muffler and tips combo out there with a lt head and no cat converter set up... thanks

Can't beat that. I have a little over 80k too but mines the whole package with that mileage. As for headers custom headers are on my list of to do's as well. If you deside to build your own you'll need axcess to a pipe bender for sure.. Custom pipes are the only type of exhaust I use. In my honest oppinion it's where the power is @.. However places like summit carry ready mades.. If you keep the cat I'd run strait pipes no muffler. If you ditch the cat, I'd run strait pipes and a set of custom internal baffles... Yeah it will be loud.. I'm going dual chrome 4" x 24" fed by 2.75" and a set of internal custom 3" baffles with interchangable set of 2.5" ,2.0" baffles for when it needs to be a little more quiet..

[augie1209]

where on summitracing is there lts for the 3.8?

[Smittro]

yea thats wut i was thinkin as well.. so gotta couple more questions... i plan on mig welding then smoothing out the tacks.. is this a good way to weld the headers if i decide to customize some lts? Also what kind of metal piping should i use? I plan on using 3" from headers back, but what measurements should i make the lts? Also, are the lts essentially just longer versions of the manifold??

Mig will work fine. I only arc weld "stick". One is not better than the other in this instance imho. Arc is just what I'm good @.. Pipe should be of good to excellent steel. Or you can go stainless 1/16th will work but wont last as long as pipes of the 1/8th wall thickness.. Tube inlet should be the exact shape of the exhaust ports for the best flow results. But 1-3/8" tubes will do just fine you could even push it to 1-1/2 but that's way bigger than nessasry(sp) imho.. Now if you're gonna go and build your own headers theres some options with the exhaust ports that can be done if you want to really dig into it. The castings allow for exhaust ports to be opened to 2 inches or more now you're talking flow Unfortunately you realy can't do much with the intake side except a mild to full polish. Porting the intake is a no no, UNLESS you build a custom untake then they can be elongated.. BUT NOT widened the water jackets are far to close and thin walled so you're kinda stuck there..

[Smittro]

where on summitracing is there lts for the 3.8?

Pm sent.

[Smittro]

My play thing and some stuff...