does removing the catalytic converter add HP? Options

[nate95]

Hey i was just wondering if i were to remove the catalytic converter if it would add any horse power? or what about getting a "Y" pipe before the cat. so i can still have the cat. but have it go straight out when i want to race?

[hitcachi]

No it doesn't. Sorry. You can argue better flow all you want, but......no it doesn't.

[malpaso]

Sorry for question from someone with low english... Is "catalytic converter" same as "calorifier" (direct translation of "katalizator")

[BLADDER_MASTER]

No it doesn't. Sorry. You can argue better flow all you want, but......no it doesn't.

So turbo cars don't gain HP when they removed their cats?

[94wrc]

Wrong,

Or certainly wrong on JDM cars, when you remove the cat you should see around a 3-5 BHP increase due to the exhaust gases exiting the system quicker, this has been proven on rolling roads. I removed mine on my GT-4 and there is a huge difference, the turbo spools up a lot quicker and it now spits flames out of the exhaust

Nathan

[alexjb]

Wrong,

Or certainly wrong on JDM cars, when you remove the cat you should see around a 3-5 BHP increase due to the exhaust gases exiting the system quicker, this has been proven on rolling roads. I removed mine on my GT-4 and there is a huge difference, the turbo spools up a lot quicker and it now spits flames out of the exhaust

Nathan

True, get rid of the gas quicker works for cars that are highly tuned and especialy blown.

however it sounds like the 5Sengine in the base model over there is neither, so may not make any difference to that motor.

[94wrc]

Good point, it may not help the N/A engines as they do need back pressure however turbo cars would run best with no exhaust or a tiny one as they need to get rid of gasses as quick as possible.

I stand corrected (maybe)

Nathan

[alexjb]

Good point, it may not help the N/A engines as they do need back pressure however turbo cars would run best with no exhaust or a tiny one as they need to get rid of gasses as quick as possible.

I stand corrected (maybe)

Nathan

Zactly,
we were both right

[malpaso]

Fine fellas, I'll try again...

my exhaust has four parts:



first... right names for right parts

Is in english right:

1 - horns
2 - calorifier
3 - silencer
4 - muffler



and second... if I remove part number 2, I will NOT have any HP addition really?

[bindertch]

Fine fellas, I'll try again...

my exhaust has four parts:



first... right names for right parts

Is in english right:

1 - horns
2 - calorifier
3 - silencer
4 - muffler



and second... if I remove part number 2, I will NOT have any HP addition really?

1 - horns - or flex pipe
2 - calorifier - actualy this is the catalitic converter.
3 - silencer
4 - muffler

Actually there is two cats' on the american 7AFE. The first is mounter off of the manifold right below it and the second as malpaos's picture shows is after the flex pipe. I have noticed significant gains from removing both but replacing the second with a hi-flow one and addind a hi-flow muffler, header and CAI.

[Insanity-74]

Come on guys...get yer brains into gear ...of course removing the cat will gain you BHP...be it in an N/A car or a turbo.....whats the first law of modding????? better breathing for the car, be it inlet or exhaust...the CAT restricts the exhaust gas escaping from the engine, remove ANY restriction to flow and the car is going to breath easyer.....and get more BHP (to get more air in, you have to get the spent air out etc)...in stock form there will be only a slight difference on a N/A car....turbos get much bigger benifits. Can be around 15-20BHP released from getting rid of the CAT (I got 16BHP increase from removing the CAT from the Faff...but I have seen the same type of car gain 30BHP) ...as soon as the mods start to appear, then the benifits of removing the CAT will increase Exponentially.
Also as CATs get old they start to block up with crap etc....do yourself a favour get rid of the CAT...but beware at MOT time.(Brits only)

This post has been edited by Insanity-74: Mar 28, 2006 - 6:46 AM

[94wrc]

Ahh you frequent over here too Nial, I did think that getting rid of the cat would give increases but didn't want to start an arguement

Nathan

[Bitter]

Actually there is two cats' on the american 7AFE. The first is mounter off of the manifold right below it and the second as malpaos's picture shows is after the flex pipe. I have noticed significant gains from removing both but replacing the second with a hi-flow one and addind a hi-flow muffler, header and CAI.

that depends on the emissions spec, fed spec has one and no egr i think, after 95/96 the cali spec would definatly have 2. my fed spec has ONE cat, no EGR, and NO post Cat O2 sensor.

[crismillencolin]

Got a de-cat pipe put on last thurs and i can safely say seems to make no difference at all - sounds good but thas it . (disapointed)

[94wrc]

You are the only person I know who has said it makes no difference, mind you I only know people with turbo's that have changed them and on turbo's it makes a huuuuuuuge difference. It should increase your top end though.

Nathan

[crismillencolin]

You are the only person I know who has said it makes no difference, mind you I only know people with turbo's that have changed them and on turbo's it makes a huuuuuuuge difference. It should increase your top end though.

Nathan

really . damnit , maybe its just me.....the rest of the exhaust is becoming SS on friday - maybe then it'll be a bit better . My top end is 112 anyway need that restrictor off asap

[Insanity-74]

Another good thing I tried for the first time at the weekend (slight topic change here) Toyota`s own brand injector cleaner. (as recommended and supplied by Ian Smith - anyone who knows him ... Ian is the GT-four Guru) Well it worked wonders...try some of that if performance is ****e, but it must be Toyotas own brand, I have tried others with nowhere near as good results as this stuff.

Also, try cleaning the filters, plugs dizzy cap etc

Ahh you frequent over here too Nial, I did think that getting rid of the cat would give increases but didn't want to start an arguement

Nathan

You know me mate.....always one to wade in....dont mind an argument and I think I should know enough by now to back up what I`m saying

[Vacchus]

This was the first thing that i did to my car, and i can tell you for sure that it is the easyest way to get +5 to 10 hp without any money.. You will only need to make a tube to replace it or you can make a fake catalytic converter for the case that the police look under your car. That worked for me!!
The only problem is with the inspection of gas, but you can always put the cat back in order to pass the test, and remove it again. If you are unlucky enough and when they stop you, the have a portable gas meter, then you have a big problem... So the best you can do is make a fake converter and claim that it propably dont work.. Maybe you will leave without a penalty!!

[94wrc]

Ahh the pesky restrictor, get rid, I did and I have seen 150 in mine with about 1000 revs to go on a private airfield of course you should be able to see the high side of 130 the worst thing on the stock system is the flexi, it is so restrictive, once you get a full system on there you will see a difference.

Vacchus: luckily in the UK we dont normally get the police looking under the car for the cat (they don't like getting their hands dirty ) although they sometimes do roadside emissions tests which is when you can get in trouble

Nathan

[nate95]

how hard is it to remove?what do i have to do to take it off? im not worried about getting pulled over for it, is it worth doing?