Catalytic Converters:
The catalytic converter, as it was originally introduced, was a large chunk of exotic metal that would in theory catch unburned fuel and combustion byproducts and break them down to produce cleaner running vehicles. They were also, at conception, MAJOR exhaust system restrictions causing severe loss of power. After many people gutted or removed their cats, the NHTSA stepped in and set a standard that the cat can NOT exceed 10% of total exhaust system backpressure. What does this mean? This means that the catalytic converter today is of minimal flow restriction and will always, when functioning properly, outflow what the engine is capable of producing in terms of airflow. The catalytic converter still functions basically as a honeycomb of exotic metals that, once heated creates a second combustion event burning unburned fuel, breaking down NOX, HC and CO emissions. Removing the cat, aside from being a federal offense, punishable by extreme fines, as well as in some states, impound and siezure of your car, is not going to magically free up horsepower as it would in days past. It will usually hurt performance to remove the cat, as well as severely impact your wallet if caught. There are numerous high flow, aftermarket cats available for very reasonable prices if you require one with larger than stock inlet and outlet diameters, and I would strongly encourage anyone looking for more flow to check them out.

I forgot where I got this from. But test pipe won't get you more than a few hp...

 

LOL, higher octane fuel doesn't make you faster man...stop being a slave to the hype.

 

[quote:ee3cf7727f]as for race fuel, nah, not unless you've minimized da variables in the car like excess weight, and plus its only a track day, if its a battle for top times then maybe[/quote:ee3cf7727f]

I'm hoping you meant "not unless you've got some sort of FI on your motor" ... :wink:

 

HUH? :?

 

There's different types of high octane petrol offered, and some of the highest octane will damage your cat. There's really no point in running higher than normal "premium" fuel.

[quote:8350da4474] one more thing is it worth it to empty the stock cat?[/quote:8350da4474]

In a word, no. You make a lot of noise w/out making any horses unless you're willing to tune the car for the extra flowthrough...and the "extra" flowthrough isn't going to be as good as you think because an empty cat is not an efficient transporter of exhaust gasses.

For whatever it's worth, my ITR is almost exclusively a track vehicle, and it still has a cat and runs on normal street premium fuel.

 

Not even "a few."

The only place I've seen "a few" defined was in the Bible ("...a few, that is eight."). So you won't be anywhere near "a few."

:P

LOL...

 

HUH? :?[/quote:e7382eda44]

What? Unless you have some crazy high compression, or some high hp boosted setup...high octane gas does nothing. N-o-t-h-i-n-g....there was a dyno floating around from Austin who dynoed his car on premium, and then on race gas, and his car was worse on race gas.

Race gas burns slower, that's because it's higher octane...simple idea if you ask me.

 

Don't waste your money.

You won't be able to tell.

You could advance your timing a bit more, but without testing it all on a dyno, what is the point?

Higher octane only works if your engine is set up to support it. That is, higher compression, stuff like that.

 

Not to stir anything up, just state another's opinion-

Dave Rock, a very competent AZ autocrosser who drives an '03 Celica GTS in STS, uses race gas for almost every event he attends. He puts it in, drives about 50 miles to get the ECU "used to" the higher octane, and races. He claims that not only can he feel the difference, but he'll break the tires loose when the big cam comes on in 1st.

:shrugs:

I don't know, as I've never tried race gas, but he firmly believes that his and our higher compression really benefit from higher octane gas.
Mind you, we only get 91 octane here in AZ as our best pump gas.

 

Sweet! He goes by butt dynos!