HP junkies: too much noise?

beepbeep · 02:46 PM

Friend of mine is swapping out his original 930-muffler to simpler "straight trough 3-inch excuse for a muffler" ...

I'm thinking of using the same concept. What do you think?

Plan is to use early-style headers into turbo, and this thing on the pic from turbo...with mild 90-degrees bend after "muffler" into one pipe on the right side.

Any risk for flame-throwing/too much noise?

Thanx.

Picture: Original muffler sompared to new one

1bar · 04-14-2002, 03:07 PM

My guess would be definitely YES. The PO of my '77 930 took a torch and cut a slit in the bottom of the muffler, pulled everything out of the inside (baffles, etc.), bent the flap back up and welded it shut.

The car sounds really cool at idle, but it's so loud anywhere else I'm embarrassed to drive it around the neighborhood. At 3000 RPM there's a terrible resonance, which is pretty hard to avoid, and is really really loud.

Oh, yeah - I've set off someone's car alarm on two occasions.

Of course, on a balmy spring day flying through a canyon pass in the Cascades with the roof back and the windows down, the sound IS awe inspiring. I'd just be really pi$$ed if it was me who was following some OTHER bum making that much noise...

On the other hand, if you have tolerant neighbors and you don't mind if your kids realize you're on you way home from 2-3 blocks away, go for it. It's a turbo, it has a reputation to maintain.

JohnC · 04-14-2002, 05:04 PM

beepbeep

No need to wonder. Go listen to what it would sound like
at http://members.rennlist.com/magisterc/dump_pipe.html

The sound clip where the tires break loose is a real hoot!

"Muffler!?..... We don need no stinkn' muffler!"

JohnC · 04-14-2002, 05:16 PM

After listening to the sound clip of the car "warmed up" it kind of sounds like a Focke Wolf 190 sitting on the grass landing strip ready for takeoff.

RarlyL8 · RarlyL8's Garage

This thread is very timely.
I got on this evening to post just this question. I'm looking for creative short 930 muffler options myself.
Anyone else?

jkcrewsn · jkcrewsn's Garage

I listened to the clips with my girlfriend, I even turned it up loud. She says mine is louder. I am constantly setting off car alarms. In garages, driving by parked cars...you name it. It is seriously loud. The only modifications I have is a few broken welds on the pipes, and a borla muffler (if you can call it that). I am kind of curious why you couldn't hear that distinctive ripping sound that mine has when the boost comes on.

beepbeep · 04-15-2002, 12:16 AM

Jeff:

"distinctive ripping sound" on boost probably comes from your open-air wastegate. Not all run open dump on wastegate.

jluetjen · jluetjen's Garage

If the objective is flames, then I believe that the carb/injection settings may have a bigger affect then the muffler. Why?

A lot of us have often seen 935's throwing flames while slowing for turns. A great place to see this is the entry to "Big Bend" at Lime Rock. But there are a couple of other cars that have also been known for do the same thing: TransAm cars and on occasion Mazda rotories. In the case of TransAm cars, I believe that it happens because their carb settings run rich on over-run which combined with a lot of camshaft overlap results in raw fuel being pumped out the exhaust and burnt there. I believe that Mazda's do it for the same reason, but they will do it even in spite of the fact that they often have extensive mufflers to keep the noise below the pain threshold (if you've ever heard one of the Mazda RX7 race cars from the '70's you'll know what I mean!).

So if the objective if flames, you might want to look at your carb/injection settings in addition to just your muffler configuration. I suspect the rich on overrun settings might also help throttle response.

juan ruiz · juan ruiz's Garage

I dont know if im much help but anything that saids HP JUNKIES I have to be part of It ! In my car we took the catalytic and install a J pipe to the custom muffler everyone seems to agree that is loud to what extend? Well the only thing that i have to compare is that when i go racing at nite i have to push the car out of the garage and the same back in, other wise i wake up the family

it does seems a little loud to me at times but i get over it quick i just push the gas in more.

Not related i just return from the NHRA Import Races and oh boy if i can only get my 911 like that 9s STREET SUPRA it was awesome! a lot of 10s cars 9s and the Pros in the 8s the final was all Toyota Celica vs Toyota Tundra and yes that Chevy Cavalier well it did choke!

Ok guys see ya, Going to the camp to see how the proyect is comming.
Regards Juan

beepbeep · 04-16-2002, 09:16 AM

Well, his objective isn't flamethrowing but good exhaust path. I think i'll also go this route. I'll just let him test it all first

Plan is: Early-style headers into 2:1 pipe into turbo, "stump with muffler-excuse" out from turbo...

Imagine two 930's running on full boost, both with open wastegate-dump and this "shorty" exhaust...should be pretty "musical" expirience :-)))

Yeah baby yeah!

JohnC · 04-16-2002, 10:29 AM

Has anyone here run a short equal length header as opposed to the "shorty" headers?

The reason I'm asking is that I have a design on paper (3D) that has approx 17" length primaries (equal length) 1-1/2 OD tube. I was wondering what the difference in power(torque curve) and turbo spool would be compared to the "shorties".

beepbeep · 04-16-2002, 12:11 PM

JohnC:

Yes, "equal length header" better know as "extractor header" is better than ordinary headers ... we are also thinking about making our own "extractor headers". Those equal length headers are helping to extract gases from cylinders , but it's more important on N/A engines than on turbos (which always have some back pressure).

If you have 3D-model of how it should look like, and wouldn't mind sharing it with us, please feel free to mail it to me at: goran@virlab.com

I can open 3DS, Maya , Lightwave etc. files...

Cheers!

sammyg2 · 04-16-2002, 01:50 PM

A couple years ago I built a turbocharger system for a 2 liter 914 (yeah I know, NARP).
I used a 2 1/2" pipe from the turbo to the rear of the car, with a 2 1/2" x 24" glass pack type of muffler. It wasn't loud at all. Granted it was much longer than what you guys are talking about.
Oh, one more thing, old racer's trick:
mount the glass pack backwards so the flow goes in the out end.
The inside of a glass pack looks like a cheese grater. If you put it in backwards the grates do not disrupt the pulses and allow for better breathing but still knocks down the resonance a bit.
I would think that a straight pipe on a 930 would not be that loud if it were long enough. But then again, that may defeat the purpose :-)

dean · 04-16-2002, 05:58 PM

This winter I built a quad outlet SS muffler for my 930 motor. That was a lot of work. It is not too loud, but I do have a resonance at 2900 rpm. I also built a small SS wastegate muffler. I think that you should try the muffler out, if it is too loud then do something else.
Dean