Toyota V8 - Cat or no Cat?

Submitted: Tuesday, Jun 03, 2014 at 08:44
ThreadID: 108081 Views:8675 Replies:5 FollowUps:4
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While looking into getting a less restrictive exhaust for my V8 Dual cab, I found that you can get them either with or without Catalytic converters.

What are the positives or negatives with having them on a diesel exhaust? & why do you need them.

Also is it legal to fit an exhaust system without one?

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Reply By: Bludge - Tuesday, Jun 03, 2014 at 10:00

Tuesday, Jun 03, 2014 at 10:00
Ozrover, I have recently seen the Redback system on the 79 V8 straight through (no cat, resonator/muffler) and while it sounds great I don't think I could stand it as a daily drive.

The Cat is optional and from what I was told not a requirement, as diesels are in a different category.
From what I have read, it is not so easy.

Gov regulations

I was told that the difference in through put is minimal so it does roduct full flow and turbo spin up and power.

So for the extra $120 it is worth having the Cat so that your vehicle is sure to EPA test.
AnswerID: 533645

Follow Up By: Road Warrior - Tuesday, Jun 03, 2014 at 10:51

Tuesday, Jun 03, 2014 at 10:51
Could it be due to the changeover in emissions regulations in 2010? I.E. pre 2010 79 Landcruisers may not have to have them but 2010-onwards might have to. Euro 4 came into effect here in Oz on 1 July 2010
FollowupID: 817062

Reply By: AlbyNSW - Tuesday, Jun 03, 2014 at 10:49

Tuesday, Jun 03, 2014 at 10:49
I have the same vehicle Jeff and looking to do the same. From what I am told it is illegal to not run a cat if it is standard fitment on the vehicle, you will see on most ads that sell the exhausts online have a note saying "for offroad use only" for the models without a cat as it is illegal onroad

Also from what I have been told it does not effect performance either as most supply a 'Hi-flow' version, likewise you can go straight through after the cat without a muffler or resonator and they do sound great but as a tourer the noise may get to you at some stage as I know a couple that have done this and later fitted a resonator because of the drone.
Hope this helps

AnswerID: 533650

Reply By: Ozrover - Tuesday, Jun 03, 2014 at 12:00

Tuesday, Jun 03, 2014 at 12:00
Thanks all, makes my choice easier now.

AnswerID: 533655

Reply By: The Bantam - Tuesday, Jun 03, 2014 at 17:04

Tuesday, Jun 03, 2014 at 17:04
If it is petrol and it came with a cat converter the vehicle will be illegal without one.......the belief that cant converters are restrictive is not accurate...if they are in good order they should make no difference to the air flow.

If it is a diesel it should not have a cat converter...if it has anything it will have a diesel particulate filter...again same legality issues......don't know about the restrction issue if in good order.

IF however the DPF is clogged due to not reaching high enough temps for long enough to burn the particles, they most certainly will become restrictive...solution a highway run.

AnswerID: 533666

Follow Up By: AlbyNSW - Tuesday, Jun 03, 2014 at 17:17

Tuesday, Jun 03, 2014 at 17:17
DPF's are on euro diesels, Toyota uses a cat
FollowupID: 817075

Follow Up By: Ross M - Tuesday, Jun 03, 2014 at 18:44

Tuesday, Jun 03, 2014 at 18:44
To be legal a diesel has to have a CAT. If large enough it won't affect the gas flow. Any aftermarket offering ie, 3" system or bigger will allow easy flow through.

If you get stopped and it doesn't have a CAT and you are hundreds of KM's from home, they may insist you get a Taxi or friend to pick you up. There is always tilt tray towing too.
I think Cats are cheaper.
FollowupID: 817082

Follow Up By: Member - DOZER - Tuesday, Jun 03, 2014 at 20:33

Tuesday, Jun 03, 2014 at 20:33
when i built my exhaust for the 200 series, i found the std exhaust has 2 cats per side....the systemi put in has a high flow cat purchased off ebay, which has stainless mesh inside and is see through.
Cost me $99 and is 3 inch stainless.
FollowupID: 817088

Reply By: Emerging I.T. - Wednesday, Jun 04, 2014 at 11:18

Wednesday, Jun 04, 2014 at 11:18
Yes go with a hi flow cat and all is good. I recently did my Hilux and it peaked at 624nm with the Steinbauer and hi flow cat so there is no restriction on performance.
AnswerID: 533715

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