Cats out

[Phil Wall]

After changing the auto fluid yesterday, I decided to rip the front cat out and put in the nice shiny pipe provided by Mr C Wilson. (Thanks Martin see post below)

 

Getting the cat out is fun!  Three hands and one-inch diameter forearms are required.

Even with the correct tool it is quite difficult to get at the three nuts holding the cat to the manifold pipe.  My flexible coupling came in very handy here.  Once out the new pipe fitted in quite easily, Thanks to advice form Chris about the sequence of tightening the whole system slotted nicely into place.  The front Exhaust stabilising bracket did not fit exactly as it should, about half and inch out one end, but was soon reshaped when torqued up.

 

I started her up, once everything was double-checked and the car was off the axle stands.  The note was noticeably different at tick over, more rumble than burble.  Once on the open road it was sweet, as Andy will confirm.  As for performance, at the moment boost is spiking high, so the boost gauge warning light played an important safety function. Before the final decat I could keep my foot flat and only hit 1.15 bar as a max, in cold air and about 0.95 bar in warm 20 degree air. No I am only using my toe ever so gently. Quite a difference from just the one cat out, notably more torque on number one turbo, slightly fast number one spooling, very fast number two spooling and much bigger torque surge at 1.0 bar and above.    

 

I have spoken to Chris Wilson, who is making me a restrictor ring to help reduce the excess boost caused by my 3" HKS pipe.

 

I had got used to the car and did not really notice the power anymore, but now I have a new car.

 

 

 

 

(Edited by Phil Wall at 12:33 pm on April 4, 2002)

[Guest Martin F]

Hey who's 'Ms C Wilson' ?

 

Doh!!! :o

 

Glad you are having fun.

 

(Edited by Martin F at 10:35 am on April 4, 2002)

[FaithStalker]

As i'm totally bored here at work,

Can someone explain how this exhaust thing hangs together...

 

Supra has 2 cats, one at the front and one at the rear.

 

What are the 2 box's that are around the middle of the car then?

Is the big box just before the rear of the exhaust cat #2 ?

Can i see cat #1 from looking under the car (no jacks!) ?

 

When you guys talk about pipes / exhausts etc... what does :

'cat-back' mean ? An exhaust from cat#2 to the rear of the car?

       isnt this going to be just the tailpipe then?

'full system' is this an entirley NEW exhaust from exit of the engine

      through to rear of the car without cats?

'Chris Wilsons pipes' do they come from the engine through to

      cat #2 (therefore removing cat#1) and then whatever

      exhaust you have from that point on to the rear of the exhaust.

removing 2 cats = high boost + boost creep , unless you buy extra bits?

removing 1 cat = slighlty higher boost, no creep, ok for mainly stock

when you remove 1 cat , is it cat1 or cat2?

 

thanks for any info and relieving my boredom !!!!

 

 

 

 

 

 

[AJI]

I'll try and answer the simpler questions you posted.

 

The TT Supra has three baffler boxes, one on the back box and the other two you have identified in front of the rear axel.

 

A full system is indeed a full exhaust from the downpipes right to the tail pipe.

 

CAT 1 is the most restrictive CAT out of the two and most people remove this one to see most difference in performance. The Supra will need at least one CAT to pas MOT so most people only remove one CAT. I believe that CAT 2 is realy easy to replcae with a straight through pipe. This will give a noticable exhaust note difference and a slight increase in performance, but not as much as CAT 1.

 

As for the other parts of your question I sure other people will answer those.

[Lee Burley]

Quote: from ajefford on 11:14 am on April 4, 2002[br]

When you guys talk about pipes / exhausts etc... what does :

'cat-back' mean ? An exhaust from cat#2 to the rear of the car?

       isnt this going to be just the tailpipe then?

'full system' is this an entirley NEW exhaust from exit of the engine

      through to rear of the car without cats?

'Chris Wilsons pipes' do they come from the engine through to

      cat #2 (therefore removing cat#1) and then whatever

      exhaust you have from that point on to the rear of the exhaust.

removing 2 cats = high boost + boost creep , unless you buy extra bits?

removing 1 cat = slighlty higher boost, no creep, ok for mainly stock

when you remove 1 cat , is it cat1 or cat2?

 

thanks for any info and relieving my boredom !!!!

 

 

 

Cat Back: From the back end of No2 Cat backwards. You keep both cats, example would be a HKS Hiper. Gets rid of the twin pipe section and the nasty backbox, replacing it with an outrageous drainpipe with little regard to silencing!

 

Full System: Right from the manifold to the tailpipe, example would be the mongoose, or a Hiper + Cat replacement pipes.

 

Chris Wilson Pipes: Two pipes to replace No1 and No2 cat. Can be added separately or in pairs.

 

HKS Cat pipes: only replaces one cat, so you can use one CW and the HKS. All quite straightforward.

 

UK Spec: Take out both cats, and boost should still be reasonable.

 

Jap Spec: Take out both cats and you might get creep, unless you fit Chris's 2.5" pipes. It varies from car to car. Its still better to get both out, even if you need a restrictor plate, since your EGTs will be a lot lower (engine not needing to pump exhaust through the cats)

 

My opinion: Get the cats out. Both of em. Big grin guaranteed.

[Phil Wall]

Oh yes very big grin:biggrin:

 

:biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin: :biggrin:

[FaithStalker]

EGT's?

 

I thought it would fail the MOT if you take out both CAT's?

 

Essentially in the future i think i'll be going for cat#1 replacement,

whats the best thing I should do to do this?

Get a cat-back system, then chris wilsons pipes to remove cat#1 ?

 

I want performance with a little sound but no major screaming !

 

With the above , would i need boost controllers, restrictor plates,

etc etc. or can i just leave it as is (with a boost guage obviously!)

and it should also pass its MOT with flying colours !

 

[Lee Burley]

Yep EGTs, the lower the better.

 

As for the MOT, you are on the verge of not needing CATS on a '93. Even if you do need to put them back on, the other 364 days of the year can be catless.

 

Before you do anything, get a decent boost guage fitted. I cant stress this enough. Without one, you are too much in the dark about what the car is doing.

 

 

If you do just get rid of No1, get a CW pipe fitted. It will still get through emissions that way, and boost should be nicely controlled.

 

But I still think you should get rid of them both.

 

 

(Edited by Lee Burley at 2:32 pm on April 4, 2002)

[MONKEYmark]

hi

 

is the cat 1  the main cat from the turbos

i have replaced the middle cat (cat 2 i think) and have seen a big increase in power but got fuel cut, so have fitted the trl fuel cut.and it cured it then i got fuel cut again other day think i had it the  trl limit then of 18psi so wont be doing that again. got a boost gauge but dont know where to t into anyone have a pic of where to t into.

 

next on list is a egt gauge then boost controller.i have saved my old exhaust so can put back on for mot times.

 

its good site to learn from.there is lots of helpful supra owners too

 

i would like to go catless too.would a boost controller keep it under control.dont want to be melting pistons.

 

thanks

[Steve Cargill]

Below are a couple of pictures of how I plumbed mine in.  I got the basics off the MKIV.COM site.

 

http://www.cargills.demon.co.uk/supra/mods.html#BoostGauge

 

[Phil Wall]

I fitted mine with the help of some digi pics from Martin. It is not difficult and an essential if you are increasing boost.

 

My old one cat system; first cat in, second cat out replaced with HKS pipe, and HKS Hiper cat back system, was boosting to 0.95 Kg/cm or 13.5 psi, just below stock fuel cut in 20 degree ambient air.  At 3 degrees ambient air I hit 16.5 psi well over stock fuel cut.

 

With the removal of my remaining front cat and the addition of a very well made, Chris Wilson, front pipe, the boost potential has shot to 1.45 Kg/cm or 21.05 psi which is a tad on the high side . So I am keeping my foot off a bit at the moment until Chris knocks up a restictor plate.

 

 

(Edited by Phil Wall at 11:10 am on April 5, 2002)