decat pipe?

[Winston Kodogo]

Somebody suggested to me that if I replace the cat pipe on my 1995 Civic LSI Coupe with a straight-through de-cat pipe I could enjoy better fuel economy. Was he lying like a cheap watch?

TIA!

[wiseguy01]

its a bunch of nonsense first its illegal and if u go smog car and smog tech sees this u will redtag ur car for an inspection station only second you make your car smell like a stinky 66 chevy yeah u like that smell. and third you can buy high-flow cats for like 150$ and still get better gas mileage so think before u do anything

[Alex37211]

Okay, no disrespect to "wiseguy" but the question at hand is wether or not eliminating that cat would provide better mileage. This is a question that has sparked my interest too because I spoke with a gentlemen about this topic and he told me that a motor needs a certain level of back pressure to operate most efficiently. This doesn't make much sense to me. It seems more like a henderence than a help, but I don't know much about the mechanics of a motor or which variables may effect power or efficiency.
Maybe some one could shed some light on this subject for "winston kodogo" and I.
And as far as the legality of the "test pipe", it is well known that no car will pass emmissions whithout a cat; but it's not that much trouble to put it back on once a year.

[wiseguy01]

Originally Posted by Alex37211

Okay, no disrespect to "wiseguy" but the question at hand is wether or not eliminating that cat would provide better mileage. This is a question that has sparked my interest too because I spoke with a gentlemen about this topic and he told me that a motor needs a certain level of back pressure to operate most efficiently. This doesn't make much sense to me. It seems more like a henderence than a help, but I don't know much about the mechanics of a motor or which variables may effect power or efficiency.
Maybe some one could shed some light on this subject for "winston kodogo" and I.
And as far as the legality of the "test pipe", it is well known that no car will pass emmissions whithout a cat; but it's not that much trouble to put it back on once a year.

OK heres the answer then it will not help because u have oxygen sensors before and after the cat that adjust the air\fuel ratio for better gas mileage so like i said you will burn too lean because the ecu will think less gas more air so yeah it will reduce your gas mileage plus destroy your oxygen sensors you are better off buying a high flow cat and it is a hassle putting the cat on every year because one most hondas have bolt on cats and second 95 percent of the time the pipe you have to replace it with has to be welded back on unless u have one fabricated for a pretty dollar.. so with that in mind lets just say you go through with this when it comes time for smog check you gna find out that you have to replace o2 sensors because they are too contaminated with rich\lean mixture and not to mention the CEL that will come on everytime

[Greenblurr93]

The only time you have an o2 sensor after the cat is on OBD2 cars. I test pipe will give you more peak horse power, but you will lose low end torque which will in turn hurt your city fuel economy, however, if you spend most of your driving on highways, you may actually see a greater fuel economy due to the engine having to work less to keep the speed.

[Winston Kodogo]

Originally Posted by Greenblurr93

The only time you have an o2 sensor after the cat is on OBD2 cars. I test pipe will give you more peak horse power, but you will lose low end torque which will in turn hurt your city fuel economy, however, if you spend most of your driving on highways, you may actually see a greater fuel economy due to the engine having to work less to keep the speed.

I'm not sure about OBD2, I'll search the forum but I do do 1,000 motorway miles a week, cruising at 90 to 100 mph - so I may give it a try. Thanks.

[Greenblurr93]

if your cars is a 1995 or older.. its OBD1

[Alex37211]

I'm obd1 (95 eg)
From a performance standpoint, would a test pipe allow for a better 0-60? 1/8 mile? Would it cause a slower launch? Would it all depend on the motor or setup? Also, is the fuel octane level a factor?

[Greenblurr93]

everything is a factor