ThePhranc wrote: Isn't exhaust pulse savaging important and effected by back pressure hence the need for some?
No. Backpressure is sometimes a side-effect of sizing the header primaries and collector for sufficient exhaust velocity, but backpressure is not the objective and gives no benefit.
Can someone explain to a newb how to add a thread to your watchlist? I can't figure it out...
In reply to eyesoreracing:
Click on the heart at the bottom of the page.
eyesoreracing wrote: Can someone explain to a newb how to add a thread to your watchlist? I can't figure it out...
dave... there is a heart shaped icon at the bottom of the thread... not sure if it emails you when it updates or what...
I never even knew there was a watchlist.
Any other cool stuff on the page I've missed too?
eyesoreracing wrote:chandlerGTi wrote: I had a ceramic coated aluminum exhaust from autotech back ten years ago on my MKI GTI. it sounded wild.Really? I had no idea that existed! So no problems with it? How long did you have it?
Well.... It saw two track days and about three months of street use before I parted it out. Guy in Wisconsin bought the shell and the exhaust. Someone in Indiana bought the Bertils beetle cup engine. I loved the car but I'm a cheapskate and I could not justify the cost I had tied up in a Rabbit.
In reply to donalson:
Wow, thanks guys. I NEVER would have found that.
Regarding the e-mail part of it, I DID find that. When you go edit your profile, there's a check box that makes it e-mail you when there are updates on your watchlisted threads.
ThePhranc wrote: Isn't exhaust pulse savaging important and effected by back pressure hence the need for some?
Velocity = good.
Sometimes, velocity = backpressure.
Retarded logic thus says backpressure = good.
The fellow with the yellow ST ZX-2 has an aluminum back-half exhaust.
Hopefully he'll chime in with a durability update.
I'm doing my best to remember an SCC article, somewhere in the last decade, giving heed to the "backpressure is BS" camp. Something about dyno tests with a B16 Civic mounted up with 3ft of 3" pipe after the header. Favorable gains, etc etc, it's Black Friday and I'm mentally shot, wish I could remember more.
Of everything I ever lost, it's my mind I miss the most. After that, is SCC. Long live Dave Coleman and GRM.
eyesoreracing wrote: That's why my aluminum starts halfway down the car. Back half of the exhaust is much cooler. I've had titanium exhaust before. It was incredibly light, but titanium prices are insane.
This. I think that you are on stable ground here. Temps mid way back are fully low enough that you need not worry about melting something. I would also say that aluminum exhaust would look cool on a Subaru Brat. 
Titanium or carbon is the way to go, yo. $$$$$$
The back 1/2 of the exhaust on the ZX2 is aluminium. Works well...no issues after 3 years of racing.
The front 1/2 is stainless, as is the resonator. Whole thing weighs about 17# including the cat and the resonator.
Video/sound: http://www.youtube.com/watch?v=itVuu7OaRrQ
Results from that day: http://www.waiautox.org/2011/event5_fin.htm
This thread is so empty of illogical B.S. and fanboi cr*p that the remaining volume is composed entirely of "win." THIS is why I come to GRM about five times a day.
Any other Stainless-connected-to-aluminum exhausts out there? Very interesting idea.
81cpcamaro wrote: I guess the next rage is titanium exhaust?
http://www.vanguard-performance.com/research/benefits-of-titanium-exhausts/
A typical Ti exhaust for my E46M3 is quoted to save something like 45 pounds over the factory exhaust, not counting the weight of the $1000-1500+ it will remove from the contents of my titanium money clip also. That's a tough cost-benefit ratio to justify.
Way back in the late 1980's, the Meineke muffler shop I worked in installed aluminum exhaust systems almost every day. All fabbed and bent right there in the shop. The lead installer was amazing, he could look at a car and have most of the pipe bent before the car was up in the air. Anyway, using aluminum for exhaust is nothing new.
ncjay wrote: Way back in the late 1980's, the Meineke muffler shop I worked in installed aluminum exhaust systems almost every day. All fabbed and bent right there in the shop. The lead installer was amazing, he could look at a car and have most of the pipe bent before the car was up in the air. Anyway, using aluminum for exhaust is nothing new.
Aluminized (steel) is not the same as aluminum. Aluminized steel is common...and is what they use at Meineke and Midas. I highly doubt they used true aluminum tubing.
I saw the title of this thread and had a link to some "Dave Coleman Miatabusa" build ready to go.
I have nothing to add on the durability, never tried it, but if the aluminum does turn out to be too fragile, have you thought of just making a turndown somewhere before that problematic rear subframe?
Seems like a simpler method to get the weight savings you're after.
pigeon wrote: A typical Ti exhaust for my E46M3 is quoted to save something like 45 pounds over the factory exhaust, not counting the weight of the $1000-1500+ it will remove from the contents of my titanium money clip also. That's a tough cost-benefit ratio to justify.
Especially when you can just do this.
There's a DSP MX6 GT on the west coast that has aluminum in his exhaust. Don't remember how much of it was, though. I'll try to find it here in a little bit.
But as for personal experiences? No, i haven't. Yet. After seeing how much weight will be saved on the Escort buid going from cast i4 manifold and stock exhaust to tubular steel V6 manifolds with aftermarket stuff, i'm intrigued by the idea, and think i've got a good 30lbs to save with aluminum.
Eh, i was wrong. It's all 304SS. Carry on. 
I've tried dumping exhaust under the car and out the side before. Both cause problems.
Under the car makes it really loud inside. Even having the tailpipe a few inches too short gives the exhaust noise a direct path into the trunk, which carries a shocking amount of noise back into the interior. I was amazed how much quieter my Silvia got when i added 4 inches of tailpipe to it.
Side exit just causes endless ground clearance problems. Been there on my 510 rally car. That exhaust was ripped out from under the car at least 4 times before I gave up and went out the back.
I for one sorta like the nascar style side exit... long thin slots.
Doing that in aluminum sheet may in fact be possible if you have tig and some time...
eyesoreracing wrote: Side exit just causes endless ground clearance problems. Been there on my 510 rally car. That exhaust was ripped out from under the car at least 4 times before I gave up and went out the back.
+1 to that. Hit a realy big speed bump, side exhaust gets pushed into rear tire and flattened. Hit a really deep pot hole, side exhaust scrapes ground and gets pushed into rear tire. Hit a giant Appalachian raccoon at 75 mph, side exhaust gets pushed into rear tire and covered in blood. Bad idea.
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