Decat & Exhaust

Hello,

 

Appologies if this question has been asked before. Did a search but I'm still alittle confused.

 

As far as I understand the Supra has 2 cat's fitted as stock.

 

1) When the term "De-cat" is used which of the 2 cats is bypassed ?

 

2) I guess you need to have 1 cat still on there for the emissions for the MOT ?

 

3) With my Supra TT decat-ed & a Blitz Nur Spec R exhaust fitted what kind of performance would you expect - that these 2 bits of kit would give ? Just rough guesses.

 

Many Thanks!

C.

1) You have to Get 2 De-cat pipes, one for the 1st cat and one for the second cat.

 

2) Correct most places require one or you can find a Friendly MOT place that does not mind

 

3) if you De-catted wit both cats out, u would need a Fuel cut defender and a restrictor ring to keep the boost low. Sorry to say i dont have a TT so cant tell u rough BHP you would get from a Decat

Thanks for the info.

I'll be happy with decatting 1 cat - if it doesn't effect the MOT.

 

Has anybody here de-catted only 1 of their cats and fitted a decent aftermarket exhaust system ? Would be interested in your point of view.

 

Cheers,

C.

I have had the second cat removed and a decat pipe stuck in it's place, the work was done by the boys at JPS in Bletchley.

 

It was done because the second cat was getting rattly, but it's supposed to help the turbo's spin up a little quicker as well.

 

The rest of the exhaust back from the new decat pipe is GReddy and seems to be quite a straight system with not too many bends, this is also supposed to be a good thing

 

Seems nice and quick to me and pulls well.

 

Sherriff.

Got both cats took outa mine recently at a local custom exhauste place put a restrictor ring in as well,the car now runs 14 psi just before fuel cut and its a lot fekin faster and more responsive than before,:flame Dev although i'v now found out my clutch slips on full boost

Thanks for the info guys!

It will depend on whether you have a JSpec or UK spec car.

I've just had my car de-catted(Both removed) and a Nur Spec exhaust.

It had a restricter ring fitted, and it ran 15 psi. This gave 346 bhp on the Thor dyno which is measured at the hub. I was told that there is roughly 20% transmission losses on power, so this gave 414 bhp at the flywheel, which is where the power is normally quoted.

 

Looking at most threads I've seen in the past there seems to be a wide spread of boost pressure from just de-catting and changing the exhaust. It just seems to be pot luck as to what you'll get:blink:

 

Are you feeling lucky....

 

Dan.

Just had the second cat removed, second hand de-cat pipe fitted and a HKS hiper exhaust put on. The difference is phenominal :eek: low down torque in town is instant.

Throttle response instant. Get it done mate. Check out http://www.tdi-plc.com who quote the BHP gains. I got a very noticable 24 bhp, your TT wil get 45 bhp if you do the exhaust at the same time Pretty good £ per BHP:cool:

The difference is phenominal low down torque in town is instant.

Must agree, the first turbo seems to spin up as soon as you touch the gas:p . Lag seems to be non-existent....

Thanks guys!

 

I guess that's it then! Will get it done next month after pay-day And treat my J-Spec TT :-)

 

Can't wait now!

Does removing the cats shorten the turbo or engine life? (or any other component for that matter)

The only purpose the cat serves is to reduce emissions, thus stifle back pressure. Both Japan and the USA have very stringent emission laws hence the 2 cats on a supe. By removing one cat, the engine becomes more efficent and breaths better. this would have no bearing on engine or turbo life. However as the car will go faster you mave drive it harder as it becomes more fun :D But the best bit is you still keep in one cat on and pass the mot

Been working out some figures - cheapest I've found is buying the kit at Fensport.

 

For a Blitz Nur Spec exhaust with a pipe for the removal of the 2nd cat - inc vat = £780

 

Does anyone know of a cheaper supplier ?

Also - I've got a J-Spec TT ... am I right in thinking that I don't have to muck about with a lambda sensor ?

 

As far as I understand - that's only for UK spec Supes ?

 

Thanks guys!

Christian.

Did u look at the link I posted earlier on this thread. TDi actually quote the prices anb BHP gains for both a TT and NA

Opps - sorry! Need stronger glasses!

Hi guys,

just an interesting point, yous guy had a fancy exhaust with fitted a restricter ring to get 15psi just before the fuel cut, and get some where 340bhp,

 

My jap tt just stock with an induction kit on, I put a manual boost controler on to get 15psi just before the fuel cut as well, both cat still there, stock exhaust, and what sort of bhp am I getting out of?

 

thanks.

Originally posted by 200SX Boy

Does removing the cats shorten the turbo or engine life? (or any other component for that matter)

Removing cats will cause an increase in boost pressure and that will probably shorten the turbos life somewhat.

Originally posted by 250horses

By removing one cat, the engine becomes more efficent and breaths better. this would have no bearing on engine or turbo life.

See the above reply to 200SX Boy

Hi i have Jspec TT Supra 94 i have removed both cats and got the powerflow exhaust put on i dont know if they will have put on the restricter rings an anybody help

 

if they havent put on the ring will this affect the engine or turbos??

Originally posted by SUPRA2000

Hi i have Jspec TT Supra 94 i have removed both cats and got the powerflow exhaust put on i dont know if they will have put on the restricter rings an anybody help

 

if they havent put on the ring will this affect the engine or turbos??

Do you have a boost gauge? Running the stock turbos at more than 1.2 bar is not a good idea.

 

Is the car suffering from fuel cut at all?

i dont have a boost gauge

im thinking of buying one which one is better the 52mm or 60mm

also do you know the size of the clock and vents just to see if i can fit a gauge in that hole,

 

so if theres a restricter ring on the exhaust it should be fine???

and no im not getting fuel cut off, how would i be able to check???

Originally posted by SUPRA2000

i dont have a boost gauge

Get one. How else will you know if the boost is creeping damgerously high?

which one is better the 52mm or 60mm

Which one is better? The one that fits the hole you're trying to put it in.

do you know the size of the clock and vents just to see if i can fit a gauge in that hole

The air vents will take a 60mm gauge. I think the clock can take a 52mm but I'm not 100% sure. Measure it.

so if theres a restricter ring on the exhaust it should be fine???

Not necessarily, it needs to be the correct aperture for your car and your preferred level of boost.

im not getting fuel cut off, how would i be able to check???

You'd know if you were, at least you'd be on here asking a lot of questions about your car cutting out at WOT and all the dash warning lights being lit.

Originally posted by Jake

Which one is better? The one that fits the hole you're trying to put it in.

 

LMAO :D :D

Supra2000:

 

Why dont you buy pillar pod ? Paul E of Miami GT sells them. They're made specificly for the Supra as far as I know.

 

A EGT gauge & a boost gauge are a good buy - the pods come in either single, dual or triple gauge housings.