dprantl

This is exactly what my sound preference is on my GT. On an NA GT, I would give up that 5 - 8hp for the right sounding car since it's a daily driver. With the supercharger, I'm not sure it would help or hurt.

Dan
'91 928GT S/C 475hp/460lb.ft

BC

I'm glad that the differences are there for boosted engines. That means with headers, an x-pipe, and whatever mufflers, that if its too loud you can add more mufflers resonators and maybe not lose too much power. I'm done with REALLY loud cars. The 81 exhaust I had with spintechs was just too damn loud. The stock exhaust on the 85 Euro I had when I put in the X-pipe was perfect. I will always have headers on my cars, but I will add more mufflers to take back any raspiness or too-loudness that was added. A loud car on a trip over 50 miles gets irritating. It adds wear and tear to you and your ears. Its not fun. If I find it too quiet I will hadd some electric cut out valves and put straight pipes on the side. Push a button, rev a bit really loud, and then turn it back to civil for 97% of the time.

Crap is that maturity? oh well. I drive these cars every day when I am not working on them, so I need something civil.

Jim bailey - 928 International

Just one small step !

BC

Its just ridiculous Jim. I was praising my wife's car for its "comfort" on the way to and from Houston. Insane.

hacker-pschorr

You have been in SoCal too long. My father will turn 66 in April and recently asked about taking the CATS off his Ferrari. It already has a Tubi exhaust, he said it's too quiet.

BC

Being in SoCal, there is more time to enjoy the car, hence more driving, and more time to contemplate not hearing yourself think. Weather says it was 18 today in Green Bay, and will be 0 by Friday night. 0. That's not a tempature - that's definition of hell. Have fun with that.

hacker-pschorr

All the warm days driving even the best mountain roads in SoCal do not compare to a weekend driving Road America. I'll stick with what I have.

Not to mention I cannot remember the last time in 10 years I've been "stuck in traffic" not counting game days. Took me over an hour to get from downtown San Diego to Del Coronado.

So we get three months to work on all the cars.

To keep this on topic......this is what a supercharged exhaust should look like:



If even a little backpressure was a good thing, they would strap on a muffler or two

Louie928

Brendan,
0 deg F, as long as you aren't in California, is just fine.

ddarnell

It's funny we (I) spent at least a hundred hours and several hundred dollars attempting to make her car (78 928) nearly as quite a my car (01 740i). It's getting close. I guess it must be middle age..........quiet on the inside is good. BUT it must have that perfect sound on the outside. I've been wondering how much sound/noise is being generated or radiated out of the length of the exhaust system. The ideal, as I see it, is to have that exhaust note at the rear opening of the pipe and no where else. Anyone have any insight on insulating/blocking noise from the length of the system? How much noise is coming directly out of the components?
David

BC

True. But there must be a way to keep the back pressure as low as possible but not wake the dead.

toofast928

If the system is designed correctly then little (acceptable) HP is lost. I'm using 4 mufflers and 2 cats. Dynoed 405 HP with just the right roar.
* Acceptable means I'll trade 15 HP to hear my radio at speed.

hacker-pschorr

You would not like my 79 then.

Down the highway open pipes are not an issue. My exahust is not loud at all in the 81 at 80mph in 5th with only one straight through Borla muffler (no cats)

I'm not sure where this picture came from. The dual muffler's on the left shouldn't be very restrictive and should kill a lot of sound

Z

If it's the same supercharged car that I'm thinking of, the before exhaust modification dyno numbers were very optimistic. At least part of the reason for that was due to an impossible correction factor having mysteriously gotten used somehow, and artifiicially inflating that dyno number by probably around 10% or maybe even more.

I don't remember the individual helping the dyno operator ever addressing how that impossible correction factor could have occurred when it was noticed on the dyno chart and he was asked about it. I don't think that car has ever made as much power again as it did the time that one particular guy was helping to run the dyno's computer. Yes, that guy helping with the computer did have an interest in the car showing as much power as possible.

Louie928

Thanks Z. That explains a lot. Does anyone have good data on SC engine exhaust mods? Such as using headers, or dual 3" rear exhaust vs stock exhaust or stock with X pipe?