race cat

quick question guys, i have the opportunity to buy a race cat(not sure if it is 100 or 200 cell yet), but was wondering will this damage my standard turbo seals just like de-catting would??

Some would say it may exaggerate already worn seals but to say removing a cat and creating less restriction in the exhaust will cause seal damage is possibly a little misleading. The standard turbo doesn't have a full 360' bearing so that is the weakest part of your turbo but a race cat still offers some back pressure so you should be fine.
If it were the case then the guys running 3" exhausts must be going through turbos like there's no tomorrow.

If it helps you decide, I ran a decat on a standard turbo with 70k miles on it for 3 years with no issues at all.

I also ran decat on a standard turbo for nearly a year with no problems.

a few have on the 20v na bravs without problems too. scoobies and evo owners do too.

So how is that related in any way to the 20vt???

aparantly the 5 pots arnt good without a cat (even though 20v na's havnt a turbo) they seem to run fine. but still most scoobies and evo's do. All the power those lads run without a cat,im sure they wouldnt if they had problems. im guessing itd be the same for us??

Mickey, the suggestion is that removing a restriction in the exhaust you may be at risk of reducing your turbo life due to the reduced back pressure, which could mean the seals don't work in the correct manner and the bearings may not be oiled correctly.

The big power turbo cars tend to run different turbos that have different seal/bearing arrangements that aren't as dependent on back pressure to seal.

But as Jimbo pointed out there seem to be a good number of standard cars that last well with a decat.

The non turbo cars shouldn't have a problem with a decat as they only have one lambda sensor before the cat. The only time you'd run into problems is if the car had a second sensor after the cat.

right

The standard 20v without a turbo likes a bit of back pressure. You'll lose torque without it. At least without looking into other stuff.

A race cat should eliminate so called "back pressure". That is the point.

Back pressure isn't good on any engine.

Pressure differential.......

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On my Punto HGT, removing the cat was a very bad idea. I lost 15 bhp. If an engine is tuned for a certain exhaust, then removing the cat can be a bad idea because it changes the exhaust line the car is tuned for. Indeed, less backpressure SHOULD see you more horses, but there are other effects (heat difference, scavenging effects,...) that also come into the equation. Which is why I said 'without looking into other stuff'.

PS - so my use of 'backpressure' wasn't very good.

Exactly. Naturally Aspirated engines need a bit of back pressure IIRC. With turbocharged ones the less pressure the better.

I'd love to see an explanation of why NA engines need a bit of back pressure....... what does it do that's of benefit?

Well, it's not back pressure, but exhaust scavenging

Exhaust scavenging I can roll with but what does back pressure have to do with that?

The tuning of the exhaust takes the cat in account. Remove it and you'll alter the effect. In this case, removing the cat - and thus some backpressure - might reduce the power.

I would suggest that the cat acts as a stop end (as far as exhaust pulse activity is concerned)which would return a compression pulse (higher pressure) towards the exhaust valves rather than the more desirable rarefaction type (lower pressure).

Anybody got any pictures of a 20v exhaust system I can look at?