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

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.

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

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?

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?:dunno:

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.. :outahere:

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...

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

:bow: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

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.

so you feel more power with the cat?

I would have to do a series of objective tests. I do hope to get transferred to Hawaii or return home to Japan. The Cat is needed for both, do wonder if I can get in trouble for running without the cat.

I will post the results for sure.. Currently my car is....

Full 3'' Cat back exhaust from MaganFlow, and AEM intake..

Unfortunately the test may include a 3'' down pipe w/3'' turbo elbow.. Sorry, but it just may end up that way.. ;)

Oh I like a car that performs and thus loud is not required. Loud impresses teenagers and draws police attention. Having tinnitus from my military service and loud for loud sake is annoying.
The max speed limit is 75 mph 120 km in Oklahoma, I do not race but wants to have a good ride that makes the most out of the trip. Again Loud or giggles "load" is for children :rofl:

:naughty:i`m with you , BUT i want to have a ride that when those mustangs , camaro, :ghey:etc .. starts to accelerate next to you , showing off , you step on the gas and there you go , kicking some muscle ASS!!!!!!!

大きい廃物
 

I will leave it up to you to race the young boy in his GM or Ford sodai gomi "mussel car". I just to not have time to play with the kiddies ;)

Do keep in mind that the changing of the cat will only heavily influences N/A's on powerband issue. With a Turbo, all of the back pressure required by the car is supplied by the turbo, no further back pressure is needed.

So, If you got a turbo, sure, you can take the cat off and see a considerable gain.

With an N/A, I wouldnt, the car runs alot smoother with it on and it smells better.

One more thing to keep in mind, the oxygen sensor on this car is not heated, I have been to told by mechanics that beack pressure created by the cat helps to heat up the oxygen sensor, and that little guy controls up to about 8% of your fuel economy...

F' it all.. I'm either hollowing the cat or doing the test pipe.. Anyone know what kind of noise a hollow cat will make? something nasty added to my 3'' system? or will it not sound bad?

There you go with your sound fetish again.

The previous owner put headers on my Supra and butchered the exhaust system. I find the noise annoying

You must be one freaky girl.. the kind you don't bring home to mother! I'm not going for the sound being louder, but more performance gains. I was asking about sound because I didn't want it to sound like a rattle can or worse.. HONDA Xb

pm me about fetishes.. lol jk jk.. Got's me a super freak already!

Hold
On
Not
Done
Accelerating

:eek3:You must mean the SCION Xb - The wanna-be's car.
:rofl:Or the Honda Escape? - Butt-Ugly, but with a power-washable interior?

i enjoy a good growl as much as the next American. but id rather hear the whine of my turbo spooling.

Just get a bigger turbo and your whine will be heard over anything!
like me :D

Giggles, my Supra is stock 86.5 thus it has no turbo charger. He is fast enough for me. It might be that I get more horsepower with the stock system than this butchered one. I do like to hear my music and or friend in the seat next to me. Am at the limit of loud, the police give me funny looks when I pass. The city needs ticket revenue so I have to be careful.

I think the police are just checking out your friend!! :rofl:
Maybe they are wondering what's up with the Gragorian Chant music.. :nuts:

lawl......

really, would I be better off with a stock system? admit to having a stock fetish :)

Oh my friend is a guy so that would make the police ah suspect? :p I lisen to Japanese music, can't understand all of it but it has a nice sound :D

+1 on the direction this thread has taken! :rofl:

The vectra has a butcher's shop special system on it (Irmscher back box and a bunch of 2 1/4" tube tacked loosely together, and no cat which is 'naughty' for a 2000 registered car) which actually sounds quite good thrashing round the back lanes, bit like a WRC super 1600 car on steroids! :redx:

quiet but powerful
 

MA70-3.0GT, at least you have the wheel on the right side of your Supra. Am thinking about returning to Japan but my Supra has it on the left side :(
Anyhow to bring her back to Japan will need a CAT among other things. The Supras are becoming rare in Japan.
Oh I want mine to be as quiet as possible but without losing power.

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?

On your 7mge without a cat you may actually lose some power since the main gains are on the 7mgte that is turbo and does not need backpressure like a 7mge does.

used to have headers and full 3 inch on my 7mge with no cat.

sounded sexy, and with the headers i felt a good difference...
if your not going for many other AM parts slightly smaller woulnt not hurt maby a 2.5 or 2&3/4 would be perfect

No 7M-GE sounds sexy with that kind of setup.... sounds more like a Civic with straight pipe after getting fisted.

no a civic will have a 1&3/4 inch to a 4 inch muffler haha

what if i just put headers on it? would it sound as sexy?

I don't think the sound changes that much with the header atleast not for me. The problem is that there are only 2 headers made for the 7mge and they are basically the same just made from different materials. Pacesetter and obx are the 2 and they are so so. Both will have to be modified to fit, o2 sensor moved and either wraped or ceramic coated to reduce under hood temps.

Turbo, resonator, cat, muffler.... in that order are what affect the sound the most. Pipe diameter affects both pitch and volume but isn't something you should screw with much if you're worried about performance and you car is mostly stock (and there's not a single upgrade you can make on a GE to justify larger than 2.5", turbo'd engines are a whole different ball game).

Turbos, cats, resonators and mufflers all smooth out the oscillations in your cars exhaust. The exhaust exits the header as a continuous series of little bubbles. The pockets of lower pressure and then the jump back up are what cause that wicked lovely ricer fart sound... there's no performance there, just someone with no clue how it works or is looking to be loud and obvious for the cops just for the sake of it.

Now there are different and better types muffler and resonator... the stock cat flows VERY well, but you can get even better flowing ones pretty cheap. As for mufflers and resonators you want to look for free flowing but from a company with a clue... I like Borla's ProXS series and Magnaflow, but I find I prefer the sound of the Borla most. Both are straight through mufflers, to level the tone more and reduce at idle and low load volume a dual outlet model is preferred. With resonators you'll be hard pressed to find a straight through model. There is one made by AeroTurbo which is a straight through, helmholtz resonator... the only way to go. Smooth deep sound with an increase in exhaust velocity.

One more thing you can do to help the exhaust system is to increase the pipe size after the resonator by about 1/4" this provides extra volume to allow for the increasing density of the cooling exhaust gasses.... but don't jump up in size too quickly. The ideal pipe diameter is actually a very small and steady increase in size... a VERY long narrow cone. Kind of hard to get that fabricated, but you can use a couple small steps up in size as the pipe gets closer toward the back of the car.

No headers have very little affect on sound.... at least on a car with such a long exhaust track, any interruptions and piping anywhere near the stock diameter. Don't buy headers for sound.... don't buy any upgrade just for sound, it's a waste of money, IMO.