N/A Horsepower
03-06-2012, 09:41 AM
#4
i pulled the cat on my 924s when i did the headers. (the cat was only a year old) and i did notice improvement in topend speed but you do lose lowend torque(no back pressure). when inspection time came around i had to put the old setup back in and ended liking it more with the cat in so now my plan is to splice in a hiflow racing cat into my delete pipe. my 2 cent
03-06-2012, 09:57 PM
#5
Race Director
i pulled the cat on my 924s when i did the headers. (the cat was only a year old) and i did notice improvement in topend speed but you do lose lowend torque(no back pressure). when inspection time came around i had to put the old setup back in and ended liking it more with the cat in so now my plan is to splice in a hiflow racing cat into my delete pipe. my 2 cent
Reducing backpressure does not lower the torque. The header moved the powerband.
Reducing backpressure lowering torque is an old wives tale.
03-06-2012, 09:58 PM
#6
Race Director
03-06-2012, 10:05 PM
#7
Rainman
Rennlist Member
Rennlist Member
That said, I just found a 944 header collector pipe cut off after the O2 sensor. I'll let you all know if it feels any faster, or just louder
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03-06-2012, 10:31 PM
#9
Does removing the cat result in an increase in exhaust noise? I would gladly remove my cat as long as the engine/exhaust tone remained the same.
And, to set this straight, simply placing a straight pipe where the cat once was WILL NOT result in a loss of low end torque? In the eight years I've been here, I've never seen a clear cut answer to that question.
And, to set this straight, simply placing a straight pipe where the cat once was WILL NOT result in a loss of low end torque? In the eight years I've been here, I've never seen a clear cut answer to that question.
03-06-2012, 10:51 PM
#12
Race Director
03-06-2012, 10:54 PM
#13
Race Director
Removing the cat does make most cars louder. But not more powerful.
The late Sport Compact Car magazine (when its editors were automotive engineers - I know a few of them) did a great dyno test with and without cat on a S13 240SX (similar engine to the 944). No change in power, and a loss of 1 ft/ft of torque w/o the cat and that is well within the degree of error on a chassis dyno.
Now, and old cat may cause problems, but a good cat (aftermarket is fine), especially a high flow cat (as most modern cats are), will NOT hurt performance.
The late Sport Compact Car magazine (when its editors were automotive engineers - I know a few of them) did a great dyno test with and without cat on a S13 240SX (similar engine to the 944). No change in power, and a loss of 1 ft/ft of torque w/o the cat and that is well within the degree of error on a chassis dyno.
Now, and old cat may cause problems, but a good cat (aftermarket is fine), especially a high flow cat (as most modern cats are), will NOT hurt performance.
03-06-2012, 10:57 PM
#14
03-07-2012, 12:43 AM
#15
Rennlist Member
Does removing the cat result in an increase in exhaust noise? I would gladly remove my cat as long as the engine/exhaust tone remained the same.
And, to set this straight, simply placing a straight pipe where the cat once was WILL NOT result in a loss of low end torque? In the eight years I've been here, I've never seen a clear cut answer to that question.
And, to set this straight, simply placing a straight pipe where the cat once was WILL NOT result in a loss of low end torque? In the eight years I've been here, I've never seen a clear cut answer to that question.
By comparison, before this I had an MSDS header, hi-flow cat, magnaflow muffler, and 3" tubes to connect it all) and it was substantially louder than stock.