Cat delete gains

[btwilson86]

I've driven one Supra (GE) with a hollowed out cat, and then the same car after a used cat was installed... Although there *may* have been more power with the hollowed out cat (nothing that we noticed), the car ran better with the cat in place. The power built up much smoother than without the cat, and it helped the car have more pull in the higher rpm's (with the hollowed cat, it would fall on it's face around 5500ish RPM).


So I say keep the cat.

[Supra Saiyan]

Originally Posted by btwilson86

I've driven one Supra (GE) with a hollowed out cat, and then the same car after a used cat was installed... Although there *may* have been more power with the hollowed out cat (nothing that we noticed), the car ran better with the cat in place. The power built up much smoother than without the cat, and it helped the car have more pull in the higher rpm's (with the hollowed cat, it would fall on it's face around 5500ish RPM).


So I say keep the cat.

With this being said.. High flow cat would be better than stock right? I would still get a similar build up with out the "falling on the face around 5500ish RPM".. Yes, no?

[btwilson86]

Well, I wouldn't really be able to say for sure; never drove anything with a high-flow cat on it. Exhaust systems are tricky, too much free flow and you don't build the pressure differences between outside air and the gases within the pipes that is required to help suck the exhaust out of the system, too little flow and exhaust backs up in the pipes and chokes the engine. Both scenarios will hinder performance.

I feel it should be noted that it's not about how much hp you can gain, but how the car drives. That extra 2 hp at XXXX rpm for a split second could translate to less hp throughout the powerband. In this scenario, you have more peak hp but performance will suffer due to the lower overall hp.

Oh, I also forgot to mention that the Supra I was referring to above had an unknown brand 2 1/2" cat-back system on it, both before and after the cat change.

[Supra Saiyan]

Originally Posted by btwilson86

Well, I wouldn't really be able to say for sure; never drove anything with a high-flow cat on it. Exhaust systems are tricky, too much free flow and you don't build the pressure differences between outside air and the gases within the pipes that is required to help suck the exhaust out of the system, too little flow and exhaust backs up in the pipes and chokes the engine. Both scenarios will hinder performance.

I feel it should be noted that it's not about how much hp you can gain, but how the car drives. That extra 2 hp at XXXX rpm for a split second could translate to less hp throughout the powerband. In this scenario, you have more peak hp but performance will suffer due to the lower overall hp.

Oh, I also forgot to mention that the Supra I was referring to above had an unknown brand 2 1/2" cat-back system on it, both before and after the cat change.

Hmm, I see..

[Supra Saiyan]

Thanks for all your input.. I have decided the only way to find out if I will in fact lose or gain will come down to trying the high flow cat and the test pipe on a dyno. This way I can see where I gain or lose along the power band...

[btwilson86]

That's a good idea, be sure to post your results once you're able to do this

[fantasma87]

nice topic, i`m interested now because my fantasma doesn`t have the cat and its a straight 3" pipe from the downpipe to the muffler. i will run 550cc injectors and some mods on it "7mgte". post the results to see the diferences. thanks

[Ranma]

I took my Supra without cat for a run down the mother road on Saturday. Had the top off and the engine sounds get annoying real quick. I do not think he has any more power than my Supra with the CAT. If anything there seems to be less power. Well put enough money into her, suppose it is time to replace the exhaust system or at least from the block to the cat.

[gordyordy]

My supra is a 87 7mge non turbo...I live in oly washington so I'm not worried about emission problems. I want to delete my cat...where do I find a tube to replace it? Should I install it myself? How much would it be if I had the shop install it?