i started with a pacesetter 4in1 then went to the exhaust shop and bought some hangers and a new colector flange 3in i made a complete 3in mandral bent exhaust system front to back i did not install a cat. engine lite was off all day in till i got off the highway and stoped at light then it came on and i know why its the second o2 thats kicken the light on becouse one is in the header and the other is after the cat with out a cat there is no difference in the reading so the computer is saying there is something wrong.

this is my question how do i rid my self of the last o2 like a o2 elimiator that can b put on mustangs. or do i have to have a cat. and dont even say its the law becouse kentucky doesent have VET testing any more and can i just unplug it .( the second o2 that is) and leave the first o2 in the header colector.

 

HPTuners will take care of that once we're supported. There are O2 sims out, not sure if they would work for us though.

And I hope you realize that a full 3" catback exhaust is hurting your cars performance SEVERLY. The MAX a 2.2 should go in exhaust size is 2.5" and recommended is about 2.25".

Sorry to break the news to you

 

yeah, i'd say 3'' is too much, but theres a dude on here with a 2.75 and he claims he's gotten some good gains up top

 

Yeah..that's just way too big and sorry but you're losing more power than you think you're gaining.

I believe most GM vehicles use the same 2nd O2 sensor, so if you can find an O2 simulator for another GM vehicle, you should be able to use it.

But yeah, take that exhaust off. It's not helping and probably sounds terribly loud and nasty w/o a catalytic converter.

 

i know 3in is too big but its not to big for STC witch should be about right. the exhaust system i made is a 3 piece and can be removed . the system not helping me in the performance part yet but after the supercharger is in stalled with a turbo ( stc ) it should be great. it has a great sound but its a bit to loud and hard to cruse becouse i put a dynomax racing muffler at the end with a chrome tip im moving the muff just behind the down pipe and adding a stupid high flow cat.

 

Yeha I have a 2.75 inch exhaust on mine but it is not mandrel bent its press bent. The only reason I went with 2.75 is because when you press bend pipe you need to go a quarter of an inch larger then the size your actually wanting.

 

the part over my axle is crush bent 2.25

 

Good luck with tuning...

Can I ask why you're trying to put both on?

 

I hope you realize doing your "STC" setup will have to wait for at least 6 months if you choose to have the car run right. Without tuning support and a piggyback that works your not going to get far

 

i know tuning will be the hardest part of this project. thats why i havent started it just yet . so check this out i said i was having a problem with the check engine lite becouse of no cat and it was real loud i fixed all that today i pulled the down pipe off and cut it right past the curve the i took my stock cat and cut both ends off in till the 3in pipe fit perfect then welded it back moved the rear o2 behind the cat 6in then i cut the 4 wires on the o2 1 at a time and exstended them 10in longer so it would plug up now its great u cant here it runing at idle to 1500 the it becomes i little louder in till 6800 its not nearly as loud and on he high way at 65-75-ish its a low hum and me and my lady can still have conversations with out the anoying sound of the engine as she puts its. so now its quiter and no check engine lite with a stuped cat. the total cost was 300 $ for header 3in mandral pipe 4 hangers 1 chrome tip and dynomax race muffler and some misc. sawzaw blades and i could have used 2in-2.5-3.0-3.5in size piping for the mandral so it was 1/3 of the price to do it my self and the left over piping im usen for a cold air intake with a k&n bell filter and a rubber elbow from homedepot

 

the reason for both is why not its not somthing u see every day and i cant resist on pushing the envolope

 

You do realize that right now your stock cat is a major restriction on your exhaust system right now and is about the equivalent of your stock exhaust system?

 

It's your car but I'm just saying, it's not necessary and I think you're going to get over your head.

 

hmm, a twin charged 2.2

good luck with your engine, tranny, and drivetrain build lol

 

twin charge = too restrictive...the s/c can only throw so much air into the engine and the turbo wont have much exaust fumes to spool...both = low boost numbers...and the best way(performance wise) is to run a open downpipe...you want back pressure to leave asap thus making down pipe peek performance...it attaches to the exaust manifold...when ever it will be made.turbo at 12-15 psi will own all...well probally low 14s mid 13s. actually you probally wont be able to boost that much due to being owned by high compression...pistons, rods, cams, and ring them pistons to **** and you should be able to boost high numbers...hell even upgrade turbos.

 

The open downpipe only works like that in theory, believe it or not you do want some back pressure even with a turbo. Open downpipe helps up top, like highway speeds. I have a friend with a srt and he runs his dp open ALL THE TIME, sounds like a tractor and pulls like hell 80+.....

 

Yes and No.

On my Sunfire, I was running open downpipe and I will say when you're in vacuum pressure it's a bit weaker as far as reacting power. When I was in boost pressure, it was defenitley good though. Now I say it was a bit weaker cause I eventually got it connected and it was more responsive in vacuum pressure.

But the point of running open downpipe is to have no backpressure to help the turbine spin easier. It's the same theory as exhaust cut-outs except this is all the time open.

Oh yeah, I loved my tractor Sunfire

 

You always wont at least SOME backpressure, especially on a 4 banger. Otherwise your robbing horsepower, in this case with a 3 inch exhaust.

 

Yeah...you'd get probably better gas mileage too but if people are all about power with a turbocharged vehicle, it can have its benefits

 

LOL backpressure

ah kids

you want velocity, backpressure is bad mmkay. where you reach peack velocity in the powerband is going to be dependant on the breathing ability of your engine, in this case the header and exhaust piping. the smaller the piping the lower in the rpm range the exhaust gas volume is going to reach peak velocity. the larger it is the higher it will be and longer it will take. I'm not going into this any further because it's been brought up before and I'm sure at least one idiot will try to argue against concrete proven physics theory of fluids lol

a properly sized turbo setup is going to be far superior to this clusterfuck you're attempting, but yes it is possible, just not very cost effective.

 

ok as far as the factory cat being restictive i can agree but this is a good choice for what im doing the stock cat will stay in there in till i figure out how to tune my car with out blowing it up still reserching on the tuning of stc with the stock cat back in there i can feel the power from the new exhaust its more then what it had to begin with and it sounds so good now . in the future weather i go with sc or turbo the stock cat will come out and a free flowing one put in. but cant right now becouse the check engine lite will come on and it makes a big difference becouse i drove 35 miles with out a cat with engine lite on i burned 1/4 tank of gas i was like ow no! so i put the stock cat in for back pressure and to muffel the sound and to keep the check engine lite off so far no problems and i still have my factory gas milege . any questions ill try to answer then.

 

please stop using stc in reference to a twincharged vehicle. stc is the name of a respected group of automotive enthusiasts, not trying to overcomplicate the process of making an engine with positive manifold pressure.

a high flow cat if it's not oversized is not going to trip the rear o2

you burned more fuel because you were probably out of the efficient area of the rev range with that much flow capability on the exhaust side. if you were cruising at higher speeds you would have been fine.

you might as well expect to have an engine light on right now, because with what you're trying to do it would almost take a grace of god for it not be there, aside from removing the bulb.

 

not trying to be an ass, but punctuation would make this thread so much more bearable.

 

You burned more gas because without the cat the rear o2 sensor sent the computer into a "what the hell, need more gas?? whatever" mode.

 

lol I love that mode.