Benefits\Loss' of Straight pipe on NA 944
10-04-2004, 07:31 PM
#2
Race Director
Check out the dyno charts on my website.
Most all cars don't have cats. 138 hp car has just stock headers. No cat or muffler. Not sure it if that is what gave him th 138 hp peak, but the car is even all they way to 5000 RPM and then keeps going while the other cars seems slow loose power. That motor seems to be breathing better. I can only guess that the low restriction exhaust influences this.
Most all cars don't have cats. 138 hp car has just stock headers. No cat or muffler. Not sure it if that is what gave him th 138 hp peak, but the car is even all they way to 5000 RPM and then keeps going while the other cars seems slow loose power. That motor seems to be breathing better. I can only guess that the low restriction exhaust influences this.
10-04-2004, 08:35 PM
#5
Campeck Rulez
Rennlist Member
Rennlist Member
ok...someone needs to get some serious data on this stuff.
I might go to a dyno. and put stock exhaust. then gutted. then straight one day.
If no ones else has done it by then then I might as well. just need a job first..sheesh.
I might go to a dyno. and put stock exhaust. then gutted. then straight one day.
If no ones else has done it by then then I might as well. just need a job first..sheesh.
10-04-2004, 08:41 PM
#6
Addict
Rennlist Member
Rennlist Member
Try just looking at M758's site Campeck, the 944 Spec guys have already done way more testing on this than you could ever do. When it's a spec class like this, they've already booked a dyno and tested everything possible.
Sam
Sam
10-04-2004, 08:52 PM
#7
Campeck Rulez
Rennlist Member
Rennlist Member
well...I looked and the only mods I saw were straight pipes with stock tube headers.
I would really like to see what the cat does by itself. what an MAF does..by itself. what headers do. and such.
when your in a "class" there are restrictions. therefore there are restrictions on the info you can gather.
I would really like to see what the cat does by itself. what an MAF does..by itself. what headers do. and such.
when your in a "class" there are restrictions. therefore there are restrictions on the info you can gather.
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10-04-2004, 09:05 PM
#8
Rennlist Member
Campeck, if you do a dyno run for every single mod, youll quickly run out of your allowance money.
Im gonna be blunt, the straight pipe will take a little power from the low-end, but itll scream above 3700rpm. Sounds nice too, as long as you dont have the bursch which vibrated like a ****.
Im gonna be blunt, the straight pipe will take a little power from the low-end, but itll scream above 3700rpm. Sounds nice too, as long as you dont have the bursch which vibrated like a ****.
10-04-2004, 09:11 PM
#9
Campeck Rulez
Rennlist Member
Rennlist Member
Originally Posted by Serge944
Campeck, if you do a dyno run for every single mod, youll quickly run out of your allowance money.
.
.
or get to know him a little and pull some strings
10-05-2004, 11:32 AM
#10
Race Director
Most 944-spec cars run without cats. Most also run with mufflers of one form or another, except for the 138 whp dyno car.
Now... I can't say that no muffler did that, but given the power curve maybe.
For the street I would NOT run without a cat and certainly not without a muffler.
Too noisy and the gains do not THAT great (5-10 hp at best).
On the race track it is differenet story. I would ditch the cat since they tend to crack at the forward weld. As to the muffler it depends on local sound restrictions. I run a stock muffler since I heard of, but never saw a back to back dyno results that showed NO GAIN from a removing the muffler. The 138 hp dyno was not done back to back. The apparently is another 944 spec that did some muffler testing and found power with it off the car. Nothing definitive however!
Now... I can't say that no muffler did that, but given the power curve maybe.
For the street I would NOT run without a cat and certainly not without a muffler.
Too noisy and the gains do not THAT great (5-10 hp at best).
On the race track it is differenet story. I would ditch the cat since they tend to crack at the forward weld. As to the muffler it depends on local sound restrictions. I run a stock muffler since I heard of, but never saw a back to back dyno results that showed NO GAIN from a removing the muffler. The 138 hp dyno was not done back to back. The apparently is another 944 spec that did some muffler testing and found power with it off the car. Nothing definitive however!
10-05-2004, 11:39 AM
#11
Race Car
wouldn't a benefit of an aftermarket muffler be less weight (assuming the power was the same)?
hell, my stock exhaust from the headers back must weigh 60-70 pounds
hell, my stock exhaust from the headers back must weigh 60-70 pounds
