I thought I had seen a discussion on here before, but why have WRC and the various rally groups decided to place their catalytic converters at the rear of the car vs closer to the engine? Is it for debris protection, quicker turbo spool, etc..?
I thought I had seen a discussion on here before, but why have WRC and the various rally groups decided to place their catalytic converters at the rear of the car vs closer to the engine? Is it for debris protection, quicker turbo spool, etc..?
I think it is so they don't shoot flames and light the forest on fire. Correct me if I'm wrong though.
When I asked the question, the answer from a Rally America driver was "makes tech quick and easy".
It keeps the catalyst cool.
The farther back it is, the less rich the car has to run to keep it from failing. So all race cars that are required to run catalysts have them as far back as they can get them.
they make them run catalysts?
i suppose they don't want to pollute the air as they tear ass and dig up ruts thru the forest...
If you leave it in the stock location it will take a hit, break up the matrix, and give you a DNF.
alfadriver wrote: It keeps the catalyst cool. The farther back it is, the less rich the car has to run to keep it from failing. So all race cars that are required to run catalysts have them as far back as they can get them.
Makes sense...the hotter your exhaust is the further back you'd need to move the cat to keep it from getting too hot.
novaderrik wrote: they make them run catalysts? i suppose they don't want to pollute the air as they tear ass and dig up ruts thru the forest...
Sounds legit to me, ruts and flying dirt aren't environmentally harmful 
Learn something every day :)
novaderrik wrote: they make them run catalysts? i suppose they don't want to pollute the air as they tear ass and dig up ruts thru the forest...
Rally America requires cats, too.
As been said, they're run at the very back of the exhaust system so they don't melt down. You've gotta figure, they deliberately ignite air and fuel in the exhaust manifold (okay, not so much anymore, but still) to spool the turbo when off throttle, there's a lot of EGT happening and that's instant cat death.
Carbureted N/A cars in the US have been known to melt their floors when they have a cat in the stock location, as well. Mounting the cat at the rear is a safety measure.
Plus, at least at the professional level, those are motorsports cats. If an OEM cat was an air filter, grid size wise, then a motorsports cat is a screen door. They're technically catalytic converters in that they have a honeycomb coated with catalyst metals, but they wouldn't allow a street car to pass emissions.
(Now, I like the R-A rule that said a cat can be determined legal if there is at least a 1degF temp rise from the front to the rear. You can do that with a straight pipe that is double thickness at the front, so a temp gun sees a hotter aft temp than front temp... SHH!!)
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