Exhaust options?
12-15-2011, 07:22 PM
#31
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i like your efforts to solve the issues with the resonator's flow. what do you think about the stock muffler ? had a guy from a large Porsche repair shop tell me the weird double exhaust tubing is so nobody could run other parts, but have to keep buying Porsche, (without installing a complete cat back or test pipe and new resonator and muffler).
including parts, in san diego about $550. country hick town about $400 tops.
and run the biggest CENTER OFFSET muffler.... (i don't recommend buying the muffler i'm running, as it is gigantic).
instead get the next size down.....
this. http://www.magnaflow.com/02product/s...e=main&id=9331
and either 14 or 16 guage pipe.
including parts, in san diego about $550. country hick town about $400 tops.
and run the biggest CENTER OFFSET muffler.... (i don't recommend buying the muffler i'm running, as it is gigantic).
instead get the next size down.....
this. http://www.magnaflow.com/02product/s...e=main&id=9331
and either 14 or 16 guage pipe.
12-16-2011, 10:56 AM
#32
Burning Brakes
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Exhaust is a tricky thing to tune on NA motors...especially 968's. Go too big, and you will lose power (especially in the low end). Stay with stock on a semi-built motor, and lose your performance potential.
A common misconception is that bigger piping with little or no backpressure is best. Wrong.
Exhaust can have the same effect as headers, which is properly scavenging exhaust gasses. Proper tuning is crucial.
As for why our cars have Twin pipes from the factory....a few manufacturers do this (including BMW with many of its models). They provide a smoother underside without having the exhaust hanging lower then necessary. Look under most BMW's or your 968 and you will see a generally smooth surface compared to many other cars. Dual Pipes are also better heat sinks because of the higher surface area. Two smaller pipes will also produce a higher velocity air flow. Porsche and/or BMW dont install dual pipes so people cant run other parts. That is myth.
A common misconception is that bigger piping with little or no backpressure is best. Wrong.
Exhaust can have the same effect as headers, which is properly scavenging exhaust gasses. Proper tuning is crucial.
As for why our cars have Twin pipes from the factory....a few manufacturers do this (including BMW with many of its models). They provide a smoother underside without having the exhaust hanging lower then necessary. Look under most BMW's or your 968 and you will see a generally smooth surface compared to many other cars. Dual Pipes are also better heat sinks because of the higher surface area. Two smaller pipes will also produce a higher velocity air flow. Porsche and/or BMW dont install dual pipes so people cant run other parts. That is myth.
12-16-2011, 04:30 PM
#33
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yeah Dino,
but nobody's dumb enough to run fat pipes. backpressure does not make power. scavenging does. big heavy breather and 2.5" straight pipe isn't going too big. it makes decent power. as excruciatingly difficult as it may be to believe, i got the old beater all the way to 161 mph. Van did an acceleration test and estimated 240 hp at the flywheel. which is in the ballpark. i'm willing to bet that with the old exhaust and a new oem cat, i would have been about 12~18 hp less than that...
now all i need is four more cylinders.
.
but nobody's dumb enough to run fat pipes. backpressure does not make power. scavenging does. big heavy breather and 2.5" straight pipe isn't going too big. it makes decent power. as excruciatingly difficult as it may be to believe, i got the old beater all the way to 161 mph. Van did an acceleration test and estimated 240 hp at the flywheel. which is in the ballpark. i'm willing to bet that with the old exhaust and a new oem cat, i would have been about 12~18 hp less than that...
now all i need is four more cylinders.
.
12-17-2011, 05:45 PM
#35
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[QUOTE=odurandina;9105479]i like your efforts to solve the issues with the resonator's flow. what do you think about the stock muffler ? had a guy from a large Porsche repair shop tell me the weird double exhaust tubing is so nobody could run other parts, but have to keep buying Porsche, (without installing a complete cat back or test pipe and new resonator and muffler).
I think the rear muffler is not the worst offender. Probably with the resonator gone, there may be some restriction from the rear muffler but the breathing on the 3.0 would need some major upgrades to find it.
I think Porsche engineered an exhaust system that via compute modeling, hit their objectives of not choking the power and sent it out to bid. Once prototypes came back to engineering, they went though their selection process and crunched the $$ and we see the result as the production exhaust. The plate that I talk about removing was an afterthought and clearly was not originally in the design.
Think back to 1992...Porsche was fighting to stay in business as a private company and had a pretty stale lineup. My 1994 M030/220 car had a sticker of $51XXX. Who in their right mind was going to spend that sorta money for a 4 cylinder Porsche? I think V8 Corvettes were $35K and A 300ZX was under $30K . My point is that Porsche didn't do much with the exhaust on this car and probably looked at the 968 as a holdover 944 platform that was long due for replacement. JMHO.
I think the rear muffler is not the worst offender. Probably with the resonator gone, there may be some restriction from the rear muffler but the breathing on the 3.0 would need some major upgrades to find it.
I think Porsche engineered an exhaust system that via compute modeling, hit their objectives of not choking the power and sent it out to bid. Once prototypes came back to engineering, they went though their selection process and crunched the $$ and we see the result as the production exhaust. The plate that I talk about removing was an afterthought and clearly was not originally in the design.
Think back to 1992...Porsche was fighting to stay in business as a private company and had a pretty stale lineup. My 1994 M030/220 car had a sticker of $51XXX. Who in their right mind was going to spend that sorta money for a 4 cylinder Porsche? I think V8 Corvettes were $35K and A 300ZX was under $30K . My point is that Porsche didn't do much with the exhaust on this car and probably looked at the 968 as a holdover 944 platform that was long due for replacement. JMHO.
