I know someone who did it an it's good for a nice gain in HP.
__________________ Red Bull Drift Team 2008
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[I believe] if not properly accounted for, it will throw codes from the ECU. Doesn't the car burn exceptionally rich at the beginning to warm up the cat as well?
I believe you can work around this either IN the ECU or with a controller on the O2 sensor on our cars but i do know it's a cheap trick of the O2 sensor on an Evo to keep it from throwing a code.
Very interesting, I didn't think it would throw a code. I read some people say that you can get a few extra horse, but I wonder how hard it would be to trick the ECU?
I know I will probably catch some flack from some of our more environmentally conscience members here, but I have to ask...
Has anyone here gutted their cat or just replaced it with a straight pipe? I am wondering what the consequences of doing something like this would be?
Other than the obvious emissions test failure.....
I've had a good deal of experience with this. Before I start though, I DO consider myself an environmentalist. I won't bore you with everything I do, but I do also consider myself Republican, so with that perspective, take what I say with the understanding that I don't want to give any bias.
A car's engine is designed to perform at certain RPMs. Most engines can only perform well in the low to mid-range power, or the mid-range to upper rpm power. This is why VVT is so great because it takes advantage of the entire range! However, taking that into consideration, the whole package must be designed to make the car perform with an acceptable performance range (with no major bias). At the same time, they need to contend with a number of restrictions (like CAFE, etc...).
When they designed the stock catalytic converter (along with the stock piping) they did so, so as to optimize performance while meeting emissions, sound, and cost restrictions.
Replacing the cat with a straight pipe WILL give you significantly more power in the upper rpms, but it WILL affect to some extent the lower rpm power range.
An IDEAL solution to this is to get a higher flowing cat. The Clear Image one is nice as it's nearly 200cfm more flow than the stock catalytic converter. This gives you something in the range of 95% of the optimal performance you'd see in the top-end, but with no loss whatosever to power in the bottom end. This makes your car ultimately a faster vehicle in every respect, and makes it a more well rounded modification for the street.
Going with a straight pipe will be ideal if you plan on racing the car full time (where you'll spend 90% of your time in the upper rpms). But for a daily driven car, put a high-flow cat on.
Emissions will be relatively the same in day to day driving with a higher flowing cat, but when you really get on it, you'll be putting out significantly more emissions in the upper rpms than you would with a stock cat. However, you should still pass standard emissions tests (if your state has those) where they ask you to keep it at 2,000 rpms for a couple of minutes.
__________________
Todd,
People for the Ethical Treatment of Automobiles
@ http://www.PETACar.ORG
------------------------------------------- 2006 Pontiac Solstice (#1267)
- GM Cold Air Intake
- Clear Image Hi-Flow Cat
- Clear Image Shorty Header
im selling my straight pipe cat replacement by Clear Image if your interested, it definetly freed up some horsepower.. felt much more open on all rpms.. not just the higher rpms, although i will admit that with the stock cat back on the car feels more responsive..if that makes sense lol .. believe it or not i got better gas mileage too..
it took my car 1200 miles to throw a code.. most likely because of an exhaust leak over the straight pipe..
you will be heard. theres no getting around that..
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Last edited by jinsoku3g : 05-14-2008 at 04:28 PM.
im selling my straight pipe cat replacement by Clear Image if your interested, it definetly freed up some horsepower.. felt much more open on all rpms.. not just the higher rpms, although i will admit that with the stock cat back on the car feels more responsive..if that makes sense lol .. believe it or not i got better gas mileage too..
it took my car 1200 miles to throw a code.. most likely because of an exhaust leak over the straight pipe..
you will be heard. theres no getting around that..
I mean no disrespect, but "feeling" more power at all RPMs and having power at all RPMs is completely different.
You WILL lose some power in the low-end, basically off-idle and into the lower mid-rpm range. This is because the additional back-pressure does improve the lower torque (the "more responsive" feeling you're getting when you put the cat back on).
It's really hard to judge SOTP when the car is extremely loud, and it's making all that noise, and you're nailing the gas...
It's like that old Nissan 300ZX that I saw slamming through the gears. The rear shocks were totally shot, so when the guy would floor it, the car would lurch forward with the front end shooting up and the rear bumper scraping on the pavement. The guy probably thought he was running some ridiculous times, but he was no match for my mid-16 second quarter mile 1997 Pontiac Grand Am Sedan with the 2.4 TwinCam... hahah...
This is different of course for Turbos... since the turbo provides ample backpressure in itself and a straight pipe is the most ideal setup you could get.
Bottom line, if you're looking to make your car more well rounded, (which INCLUDES quarter mile and 0-60 times), then install a high-flow catalytic converter.
I guarantee to you... that a car with a shorty header and a straight pipe is slower in a quarter mile drag than the same car with a shorty header and a higher-flowing catalytic converter (in the case of the Solstice about 150-200 more cfm).
On the other hand, the car with the straight pipe would probably run a slightly better track time at Silverstone than the car with the high-flow cat.
But lets be honest, 99% of the races you do on the street are going to be a drag race (hopefully).
__________________
Todd,
People for the Ethical Treatment of Automobiles
@ http://www.PETACar.ORG
------------------------------------------- 2006 Pontiac Solstice (#1267)
- GM Cold Air Intake
- Clear Image Hi-Flow Cat
- Clear Image Shorty Header
lol i wasnt starting a arguement, apparently im the only one whos has actually experienced it tho, it really didnt sound faster (just louder)..it felt faster... im not saying that it definitively had more power in lower rpms, just felt more open, "throaty" if you will.. but like i said with the stock cat back on the car definetly feels more responsive.. which is probably that low end power your talking about on the straight pipe..
__________________
THE SKYSTICE
A big Thank you to my Friends, Family, God, Solsticeforum.com, Autoloc, Meguiar's, Dunlop, Installer Institute, and Team Jinsoku!!
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