Horsepower/exhaust equation information
01-18-2002, 03:04 PM
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Horsepower/exhaust equation information
Does anyone in this group have specific dyno. information on how much horsepower is lost in a stock (very early model year) 964 catalytic converter?
I've been told that the later (1995) 964 cats only cost a few H.P. (less than 5) but I'd really like to know the figures for my 1989 C4 cat. (my understanding is that the early 964 cat is different than the later version)
Any input or guidance would be most appreciated.
Thanks...
I've been told that the later (1995) 964 cats only cost a few H.P. (less than 5) but I'd really like to know the figures for my 1989 C4 cat. (my understanding is that the early 964 cat is different than the later version)
Any input or guidance would be most appreciated.
Thanks...
01-18-2002, 06:37 PM
#2
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Hi Tim:
I do not think that you find any hard data on this as there are truly very little differences in flow & capacity between cats on these cars. There are bigger differences between a new and used cat and if you had a flow bench and could flow a used one compared to a new one, you could see some small changes in airflow.
Now,.....in context, one cannot always make direct comparisons between airflow and HP so this is largely academic. I would tell you that when a cat starts to get plugged up from excessive heat or rich mixtures, the power will start to drop off at higher RPM.
This can be checked by reading exhaust back pressures before and after the cat. There is a spec for what the allowable back pressure is supposed to be.
Some time ago, I went for a ride in a fellow's 964 that he'd installed a pair of 993 heat exchangers and cats, along with a custom-made set of flowmaster mufflers. Man that thing sounded great and went like hell. Stock motor, too (chipped). Passed smog with no worries,.......
I do not think that you find any hard data on this as there are truly very little differences in flow & capacity between cats on these cars. There are bigger differences between a new and used cat and if you had a flow bench and could flow a used one compared to a new one, you could see some small changes in airflow.
Now,.....in context, one cannot always make direct comparisons between airflow and HP so this is largely academic. I would tell you that when a cat starts to get plugged up from excessive heat or rich mixtures, the power will start to drop off at higher RPM.
This can be checked by reading exhaust back pressures before and after the cat. There is a spec for what the allowable back pressure is supposed to be.
Some time ago, I went for a ride in a fellow's 964 that he'd installed a pair of 993 heat exchangers and cats, along with a custom-made set of flowmaster mufflers. Man that thing sounded great and went like hell. Stock motor, too (chipped). Passed smog with no worries,.......
02-07-2002, 06:42 PM
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I think that you can find a recent dyno thread in the 964 area. They found the exhaust did not make any difference.
[quote]Originally posted by SuperCarrera:
<strong>Does anyone in this group have specific dyno. information on how much horsepower is lost in a stock (very early model year) 964 catalytic converter?
I've been told that the later (1995) 964 cats only cost a few H.P. (less than 5) but I'd really like to know the figures for my 1989 C4 cat. (my understanding is that the early 964 cat is different than the later version)
Any input or guidance would be most appreciated.
Thanks...</strong><hr></blockquote>
[quote]Originally posted by SuperCarrera:
<strong>Does anyone in this group have specific dyno. information on how much horsepower is lost in a stock (very early model year) 964 catalytic converter?
I've been told that the later (1995) 964 cats only cost a few H.P. (less than 5) but I'd really like to know the figures for my 1989 C4 cat. (my understanding is that the early 964 cat is different than the later version)
Any input or guidance would be most appreciated.
Thanks...</strong><hr></blockquote>
