Re-Cat more power or in my head?

Rich H · Post by **Rich H** » Fri Jul 17, 2009 7:43 pm

I have jsut refitted the cat (Going more deaf) and my instant feeling was I had more torque, is this in my head due to the noise or cold it actually be true?

It is actually louder at idle with the cat in, but a bit more civilised at speed.

Rich

tut · Post by **tut** » Fri Jul 17, 2009 9:53 pm

I am sure that there has been comparisons between Cat off and on on a R/R, but do not have them to hand. Probably 2-4hp depending on the state of tune, ie you would not feel it, and a little loss in weight.

There used to be a good reason of running a high powered S1 without a CAT because a number of them went up in flames thought to be caused by a flash back through the CAT, but not seen that happen for a while.

tut

robin · Post by **robin** » Fri Jul 17, 2009 10:56 pm

Depending on manifold design and cam timing you may indeed have more torque at the low end by putting the cat back in - you've changed the resonant frequency of the exhaust system.

Top end power will never go up as a result of fitting it, though.

Cheers,
Robin

Rich H · Post by **Rich H** » Fri Jul 17, 2009 11:26 pm

I so rarely get to open up properly (Criminal I know) that I won't notice top end...

The change was marked though at least I thought so... Definitely louder at idle too

fd · Post by fd » Fri Jul 17, 2009 11:43 pm

I mitigated MOT hassles this year by buying the cheapest cat I could find to fit for MOT time (50 quids inc next day delivery), I run a motorsport cat all the time and it usually only just passes the MOT with a lot of revving to heat up and a friendly tester and year on year it's been getting more and more marginal . . . what was immediately obvious with the ebay special was the car felt very flat above 5K, normally it revs to the limiter at 7.2 very freely . . . refitted the motorsport job after the MOT and we are back to normal . . . I also recently put a very quiet tubular on which certainly makes the car 'feel' better in the midrange, no conclusive figures but I know my car very well . . . Interestingly the 4-2-1, motorsport cat and tubular pipe all have the same ID whereas the ebay special is a reduced ID . . . so perhaps no surprise it restricts . . .

Fd

Scottish Elises

Re-Cat more power or in my head?

Re-Cat more power or in my head?

Re: Re-Cat more power or in my head?

Re: Re-Cat more power or in my head?

Re: Re-Cat more power or in my head?

Re: Re-Cat more power or in my head?