Removing the CAT on SLR exhaust

[allegro]

Could somebody who has removed the cat from an SLR tell me if there is any performance change after the cat has been removed. Is it worth the 160GBP caterham charge for the replacement collector. question.gif Is there an alternative to the caterham collector question.gif If so where can I buy it question.gif 160 quid seems a bit steep.

 

Thanks in advance.

 

Andy Mac

 

 

[Mike Bees]

No direct experience, but I do know that Caterham use high-flowing converters so the losses are very small (like less than 1 bhp so they say). It could be worth putting the cat pipe in to preserve the converter for MOT time.

 

Mike

[jonhill]

I can't comment on the performance aspect, as I changed mine before the car was properly run in. However, an R500 owner told me that he'd been advised that the CAT on his car would be knackered after 2 track days, and he was advised to take it off. Apparently Caterham did not disagree with this when he asked them. I would imagine that if this is the case, it would apply to the SLR too, if not in exactly the same number of miles.

 

Also, the CAT is significantly more expensive to replace that the 4-2-1 pipe, should you have a knock on that side of the car.

 

Jon

[V7 SLR]

I've replaced the Cat on V7 with a 4-2-1 pipe supplied by Caterham for the following reasons:

 

1. It's lighter. About half the weight of the Cat.

2. The 4-2-1 collector irons out a little inconsistency in the torque curve at 4500rpm that is found with the Cat's 4-1 collector.

3. It's prettier. Not quantifiable.

 

Myths:

 

The replacement pipe gives more power. No it doesn't. Well it may add up to 2bhp at max revs, but nothing more.

 

The Cat won't last more than 2 track days. Rubbish.

 

The replacement collector produces a louder noise than the Cat. Nope. I've measured before and after at 96dB at 1 metre on the same tool at 4000rpm.

[Geek]

Silly question time :o)

 

The CAT is replaced for the MOT, yes? I'm assuming that you unbolt the non-cat exhaust and bolt the cat one back on.

 

What about if you've had the engine mapped with the new exhaust? Do you keep the old map and replace it at the same time as the exhaust?

 

Would the car need mapping for both exhausts to enable easy switching?

 

Um, not all that clear I think.

 

1) Simply swap them back for the MOT?

2) Load the old map for the MOT?

3) As a result of 1 and 2 emissions/whatever are fine and the car sails through the MOT.

 

Oh, and doesn't the long 4-2-1 exhaust need a bigger hole in the bodywork than the standard 4-1 (on a 1600SS in my case)?

[V7 SLR]

I think we're confusing the two types of 4-1. There's a 4-1 collector that's located inside the engine bay, which has a single pipe exiting from the bodywork, and 4-1 collector where all 4 manifold branches exit the bodywork and then enter the 4-1 collector. The latter type is on the SLR, and it's the collector part that is the Cat.

 

You simply replace the Cat collector with a 4-2-1 collector.

 

 

There's no remapping required as the standard Caterham SLR Cat flows very well already.

 

To swap between one of the former, single exit, exhausts and a "sports" pipe would require a bigger hole in the bodywork, yes. I don't know about remapping, because it depends on the general state of tune of your engine I guess.