Aluminum exhaust vs. stainless exhaust

[Dylan0123]

Found this pic of a 1g w/ aluminum pipe after a stainless downpipe

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I like the idea, less weight and less materials cost

 

[outlawdsm]

An aluminum exhaust will not sound any different than any other material, the muffler and resonators affect the sound, not the material of the tubing.

Also I wouldnt worry about anodizing the exhaust, there are tons of non-anodized aluminum parts on many cars on the road today with no issues.

 

[TSi Kid]

An aluminum exhaust will not sound any different than any other material, the muffler and resonators affect the sound, not the material of the tubing.

The thinner material wouldn't have a different sound at all?

 

[outlawdsm]

The thinner material wouldn't have a different sound at all?

Typically the SS would be thinner than the aluminum. I have no exact proof that it wouldnt sound different, I only have my experience on my car and there was no audible difference.

 

[TSi Kid]

Typically the SS would be thinner than the aluminum. I have no exact proof that it wouldnt sound different, I only have my experience on my car and there was no audible difference.

Hmm, I would've thought aluminum to vibrate more and give off a different sound due to the density differences. I'll have to try it out..

 

[snowborder714]

I have run an aluminum cat-back exhaust on my car for about 20k miles. It has been daily driven, drag raced, and road raced. Only issue I ran into was how I made the hangers at first (out of alum. bad idea) I have since changed the hangers and have no issues.

Do you know what wall thickness your tubing is?

Also, what did you change the aluminum hangers to? I'm guessing the aluminum hangers were too soft and bent too easily with flex?

 

[Ludachris]

Hows an aluminum exhaust sound in comparison?

If the car is being built for road course events, most sanctioning groups require the exhaust to exit behind the driver door, at least NASA did. It can be a down turn or side exit, but it must be to the rear of the driver window.

 

[snowborder714]

I'm guessing you may have meant to quote Jake's question on open downpipe, which would be an issue with some of the rules. Here are the rules for reference. Let me know if you want me to pull rules for any specific classes.


NASA HPDE/Competition
11.4.23 Exhaust Exit
The exhaust must exit behind and away from the driver.

RTA - Street Tire Class
4-1.9 Exhaust must exit behind the front axel.
4-1.10 Vehicles must be equipped with functional catalytic converter(s). All exhaust gasses must pass through the functional catalytic converter(s).

RTA - Modified Class
5-1.10 Exhaust must exit behind the front axel.

RTA - Super Modified Class
6-1.5 Exhaust outlet location is unrestricted.

SCCA Solo
15) Exhaust must exit behind driver or to the side of the car.

 

[Ludachris]

I'm guessing you may have meant to quote Jake's question on open downpipe, which would be an issue with some of the rules. Here are the rules for reference. Let me know if you want me to pull rules for any specific classes.


NASA HPDE/Competition
11.4.23 Exhaust Exit
The exhaust must exit behind and away from the driver.

RTA - Street Tire Class
4-1.9 Exhaust must exit behind the front axel.
4-1.10 Vehicles must be equipped with functional catalytic converter(s). All exhaust gasses must pass through the functional catalytic converter(s).

RTA - Modified Class
5-1.10 Exhaust must exit behind the front axel.

RTA - Super Modified Class
6-1.5 Exhaust outlet location is unrestricted.

SCCA Solo
15) Exhaust must exit behind driver or to the side of the car.

Side exit or down turn rearward of the doors and you'll be fine.

 

[outlawdsm]

Do you know what wall thickness your tubing is?

Also, what did you change the aluminum hangers to? I'm guessing the aluminum hangers were too soft and bent too easily with flex?

I do not know the wall thickness. I had issues with the hangers tearing off at the weld, so I switched to using SS t-bolt clamps on the tubing and running hangers from the t-bolt clamps.

 

[snowborder714]

Side exit or down turn rearward of the doors and you'll be fine.

I'd like to make this option, in addition to a full exhaust to the rear.

I do not know the wall thickness. I had issues with the hangers tearing off at the weld, so I switched to using SS t-bolt clamps on the tubing and running hangers from the t-bolt clamps.

Good to know! I saw that in the Miatabusa project and thought it was a pretty slick idea.

 

[TSi Kid]

Quote:
Originally Posted by TSi Kid
Hows an aluminum exhaust sound in comparison?
If the car is being built for road course events, most sanctioning groups require the exhaust to exit behind the driver door, at least NASA did. It can be a down turn or side exit, but it must be to the rear of the driver window.

Hmm, I would've thought aluminum to vibrate more and give off a different sound due to the density differences. I'll have to try it out..

I wasn't thinking it would sound different because of the location, but because of the density of the material and the different frequency it would be vibrating at (making it sound more "tinny")

Outlaw, could you get a video of your exhaust? I'd love to hear it.

 

[turbotalon1g]

There are clips of DSMs with aluminum exhaust out there, the owners say the tone is different and a bit higher tone I believe.

Once I have the abilities I'd love to go to this.

 

[TSi Kid]

There are clips of DSMs with aluminum exhaust out there, the owners say the tone is different and a bit higher tone I believe.

Once I have the abilities I'd love to go to this.

Could you link some? I can't find any. I fully believe that the aluminum would be of a higher tone, doesn't make sense that it wouldn't sound different.

If I flash around my mechanical engineering degree will people believe me?

 

[yzfgsx]

You can listen to my aluminum exhaust here.
http://www.dsmtuners.com/forums/philadelphia-area-dsm-forum/395396-my-91-gsx.html

 

[snowborder714]

brad gst stm aluminum exhaust - YouTube

Pictures of ^ exhaust. Really has me wondering if my car is too low to run it under the rear end and not over the axle
STM GALLERY - Brad's 99 GST




kelford 280 4" aluminum exhaust - YouTube

 

[Calan]

I wouldn't worry about coating it (much less anodizing, which = $$$), unless you want to coat the outside up close to the flex area to prevent heat transfer during low speed. Aluminum both gains and loses heat faster than steel, so at highway/racing speeds I would expect it to actually run a bit cooler than steel.

Raw aluminum is immediately "self-coating" when exposed to air (alumina, or aluminum oxide), which prevents corrosion. If you did want to paint it for some reason, you need to use an etching primer and quality paint.

I can't imagine it sounding much different (if you compare apples to apples), unless there were large variations in how much it could flex compared to steel, or you measured it with some sensitive equipment.

 

[91stocker]

I bookmarked this page a while back, when i thought off doing my exhaust in aluminum. Pretty interesting stuff.

TD Autowerkes 4 inch Aluminum Exhaust, Child-proof - Honda-Tech

 

[TSi Kid]

Pictures of ^ exhaust. Really has me wondering if my car is too low to run it under the rear end and not over the axle
STM GALLERY - Brad's 99 GST

That last video you link sounds like it was recorded with a calculator

You can listen to my aluminum exhaust here.
My 91 GSX

This sounds good, what's your setup on it? Is it just piping?

 

[yzfgsx]

It is aluminum 4" pipe from the down pipe back, with a Burns stainless steel muffler. They started making an aluminum muffler after i bought mine.

 

[Hal]

Here is an under shot of mine before I painted it.

The rings are thick aluminum bands which are welded to the tube.

The hangers are steel and bolted to the bands.

The muffler is steel with a steel vband flange and mates with an aluminum companion flange.

It's hung using the oem hanger points.

The sound is a little more "tinny" than normal.

 

[TSi Kid]

The sound is a little more "tinny" than normal.

Video of your setup? should sound similar to yzfgsxs i'm guessing. How much did the full thing weigh?

 

[Hal]

Hooker maximum flow 3" in/3" out, no cat, no resonators

Nov 24, 2011 10:26am | Facebook

 

[arrowhead]

What is the big worry about the sound, what diff does that make, are you building for the track if you are, the only worry is if it will pass the decibel rules wherever you are racing.

Dont worry about heat or anything else go with the lightest thinnest alum you can get, dump it behind the doors so fumes will not bother or kill you, use slip on with the springs as someone already mentioned, if in 3 or 4 yrs you have to replace it well fine.

arrowhead

 

[TSi Kid]

What is the big worry about the sound, what diff does that make, are you building for the track if you are, the only worry is if it will pass the decibel rules wherever you are racing.

Because physics tickles my fancy

Hal, thanks for the video, sounds great and nice numbers!