Cat delete gains

Supra Saiyan · 11-22-2010, 04:04 AM

I been searching around and have found a few different things out there for numbers upon deletion of the cats... One thing I found said there would be like 3-5hp gains, another said up to 15 per cat..?

Listen, I don't want to take the chance and have a cop find out I deleted the cat. So I am interested in doing the method another member here used. They chiseled out the honey comb inside the cat to keep the visual effect for cops. They claimed their gains where noticeable as well..

Can anyone help confirm this, or give some incite to using that method..? Also, I passed my emission with my catz with flying colors. Will I not pass with this mod or a test pipe.. (I mean its pretty much a test pipe)

Please reference this link to see one post I took some info from..
http://www.toyota-supra.info/forums/...test-pipe.html

bassboy3313 · 11-22-2010, 06:15 AM

yeah theres no way you will pass emissions with a cat delete or the mod that you described. if you live in a state that older than 1995 cars still have to get emissioned, theres no way around it. im so glad we dont have to emission test cars older than 1995.

CanadianBak'inSupra · 11-22-2010, 06:21 AM

couldnt help ya, havnt had a supra with a cat.

Supra Saiyan · 11-22-2010, 06:24 AM

Well, its just a few bolts. I could delete for now, or use that "special method", and then when time comes I could put it back..

Would it be about the same to just do a high flow cat though?

btwilson86 · 11-22-2010, 06:25 AM

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 · 11-22-2010, 06:33 AM

Quote:

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 · 11-22-2010, 06:47 AM

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 · 11-22-2010, 06:59 AM

Quote:

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 · 11-22-2010, 07:02 AM

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 · 11-22-2010, 07:29 AM

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

11-22-2010, 04:04 AM	#1
Supra Saiyan 3" Exhaust Join Date: Feb 2010 Location: Oregon Posts: 225	Cat delete gains I been searching around and have found a few different things out there for numbers upon deletion of the cats... One thing I found said there would be like 3-5hp gains, another said up to 15 per cat..? Listen, I don't want to take the chance and have a cop find out I deleted the cat. So I am interested in doing the method another member here used. They chiseled out the honey comb inside the cat to keep the visual effect for cops. They claimed their gains where noticeable as well.. Can anyone help confirm this, or give some incite to using that method..? Also, I passed my emission with my catz with flying colors. Will I not pass with this mod or a test pipe.. (I mean its pretty much a test pipe) Please reference this link to see one post I took some info from.. http://www.toyota-supra.info/forums/...test-pipe.html Last edited by Supra Saiyan; 11-22-2010 at 04:08 AM.

11-22-2010, 06:21 AM	#3
CanadianBak'inSupra Official hall monitor / search nazi - NO SOUP FOR YOU! Join Date: Oct 2009 Location: Canada, BC Posts: 837	couldnt help ya, havnt had a supra with a cat. __________________ 1984 supra - 1uzfe - w58 - 4.10 - 1 piece aluminum shaft.

11-22-2010, 06:25 AM	#5
btwilson86 Super Moderator Join Date: May 2007 Location: Billings, Montana Posts: 1,034	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. __________________ 1989 7MGTE R154 Targa Top White Package w/Blue Interior Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels

11-22-2010, 06:47 AM	#7
btwilson86 Super Moderator Join Date: May 2007 Location: Billings, Montana Posts: 1,034	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. __________________ 1989 7MGTE R154 Targa Top White Package w/Blue Interior Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels

11-22-2010, 07:29 AM	#10
btwilson86 Super Moderator Join Date: May 2007 Location: Billings, Montana Posts: 1,034	That's a good idea, be sure to post your results once you're able to do this __________________ 1989 7MGTE R154 Targa Top White Package w/Blue Interior Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels

11-22-2010, 06:15 AM	#2
bassboy3313 Stock Join Date: Oct 2010 Location: Wisconsin Posts: 27	yeah theres no way you will pass emissions with a cat delete or the mod that you described. if you live in a state that older than 1995 cars still have to get emissioned, theres no way around it. im so glad we dont have to emission test cars older than 1995.

11-22-2010, 06:24 AM	#4
Supra Saiyan 3" Exhaust Join Date: Feb 2010 Location: Oregon Posts: 225	Well, its just a few bolts. I could delete for now, or use that "special method", and then when time comes I could put it back.. Would it be about the same to just do a high flow cat though?

11-22-2010, 07:02 AM	#9
Supra Saiyan 3" Exhaust Join Date: Feb 2010 Location: Oregon Posts: 225	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...

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