RX Turbo Cat Converter positioning .

discopotato03 · Post by **discopotato03** » Sun Apr 08, 2007 6:53 pm

Hi all , been around turbo engines for a while (not Subaru) and I can't say I'm keen on the way they did it with RX Turbo's . Has anyone fitted a fabbed non cat up pipe and fitted the cat down stream of the turbos turbine housing ? It seems logical that getting the engine pipes unrestricted pulsing direct to the turbo should make it more responsive , and if a reasonably low restriction cat and exhaust were fitted down stream of the turbo it should be a win all round . Todays cats would have more effective/efficient catalist materials than was available in 1986 so I doubt emissions would be an issue , by todays standards 86 era engine management is fairly dirty anyhow so better cat would mean cleaner exhaust .

Ideas ? Cheers Adrian .

BlackMale · Post by **BlackMale** » Tue Apr 10, 2007 3:02 pm

Mate, getting another fabricated is easy and I would think that any zort shop would wack 1 out for you (with the cat being basically parallel to the floor pan, near the gear box as apposed to the vertically near the fire wall). I am assuming that this is what your talking about. Alternatively you could have the cat removed all together it will give you more power however its not legal.

Gremlins · Post by **Gremlins** » Tue Apr 10, 2007 3:22 pm

Are you saying your car has the cat coverter before the turbo?? There should be nothing in the up pipe to the turbo, and the cat should be in the down pipe after the turbo.

discopotato03 · Post by **discopotato03** » Wed Apr 11, 2007 10:08 am

Yes my mistake - steep learning curve ATM .
Can see how it would not be too difficult to make a better engine pipe/s but would prefer having another std one to play with . 1986 was early in the days of cat converters and being nearly 21 yrs old means it would not be difficult to improve upon . The metalic matrix cats are now legal and far better flowing than the ceramic type .

Later .

Gremlins · Post by **Gremlins** » Wed Apr 11, 2007 1:06 pm

You might want to check out this thread for some more info on modded engine pipes:

showthread.php?t=3644

If you get a free flowing cat converter then you may get issues with over boost (depending on how free flowing the cat actually is) as the standard waste gate can't bypass enough exhaust gas to prevent overboost with a free flowing exhaust downstream of the turbo. This may or may not be a good thing depending on your point of view.

discopotato03 · Post by **discopotato03** » Thu Apr 12, 2007 8:24 am

Already watching that thread .
Low restriction cat would not be an issue on my RX as the tail pipe is a real pea shooter .
From an engineering point of view using a restrictive exhaust to limit boost is a bad idea . Backpressure (turbine inlet pressure) between the exhaust valves and turbo is bad because it creates all kinds of reversion and thermal issues for the engine . From all reports EA82T's are not too robust when it comes to withstanding large doses of either so anyone wanting serious power from one would have to find ways of being kind to the engine along the way . There are ways but generally those with the resources play with more sophisticated machinery .

Cheers A .