Aluminum exhaust vs. stainless exhaust

[Hal]

I'm not sold that 3.5 is any better than 3.0

The 1g in the garage had a Buschur 3.5 on it and the only thing it was good for over the 3.0 was increased decibels.

Granted that it's a 600 hp car and you might see gains at higher levels.

 

[99gst_racer]

The car that I built it for was aiming for about 800 WHP. Though he was making great power through the 3" system prior. I agree that 3" diameter is good for quite a bit more than most people give it credit for.

 

[TSi Kid]

A copper exhaust is probably gunna run a few hundred at best.. But why is it even being seriously discussed . TSi Kid is trolling hard in this thread .

Nah when I troll it's funny and satirical (I'm facebook famous). This is just me trying to learn more about different sounding exhausts with materials.

What's the contrast to aluminum vs titanium for sound and weight?

 

[snowborder714]

I'm trying to figure out why you're "littering" my thread with the sound questions

This is a road race forum and the only sound data should be loudness (not tone, pitch, etc.).

Here's a calculator I just found that can give you approximate weights (not sure how accurate it is, but it might get you an idea).
Maryland Metrics: Metals Weight Calculator

 

[TSi Kid]

I'm trying to figure out why you're "littering" my thread with the sound questions

This is a road race forum and the only sound data should be loudness (not tone, pitch, etc.).

Here's a calculator I just found that can give you approximate weights (not sure how accurate it is, but it might get you an idea).
Maryland Metrics: Metals Weight Calculator

Thank you sir!

 

[ACM]

If cost is no option I would go with Beryllium - just don't snack on it

 

[UofACATS]

..hot exhaust gasses..

Aluminum's melting point is 1220° F

Aluminum has a high thermal conductivity. The heat from the hot exhaust gas will quickly transfer to the aluminum, however this heat will be just as quick to dissipate. While the exhaust gas temperature could exceed the melting point of aluminum, this would only be during a WOT pull, which lasts ~10 seconds on the street or even at the drag strip.

Aluminum exposed to the atmosphere is coated with a layer of aluminum oxide, which has a melting point of 3,600 °F. Although thin, this provides a protective barrier against temperatures higher than that of the melting point of the aluminum itself. Anyone that has tried to weld aluminum without removing the aluminum oxide knows that the protection it provides is "significant." Having said that, exposing aluminum to its melting point for any significant amount of time will still melt the aluminum underneath despite the oxide coating. I believe the oxide plays a modest role in aluminum piping withstanding the rigors of the exhaust system, still I consider it noteworthy.

Another consideration is the cooling effects of the airflow surrounding the exhaust pipe, as speed increases under WOT.. but what's most important is that F/I vehicles have successfully used aluminum for (at least) the "catback" portion of the exhaust, and that's all this guy needs to know.

 

[eviltsi]

I just called STM and got some more info on this exhaust.

Pipe size: 3"
Wall thickness: 1.5mm (0.059")
Muffler: Vibrant
Clearance issue running under rear end for FWD car? Nothing yet
How much of exhaust is aluminum? After downpipe is when the aluminum section starts (SS downpipe)

Clearance was not an issue and his car is pretty low, going over the axle would make it a lot more difficult and another flange somewhere. And yes its from the downpipe back.

Also we are now making 3" 2 bolt aluminum flanges so theres no longer a need for the expensive and heavy v band connections.

And ive had an aluminum exhaust on my car for a long time without any issues at all....cept for when the rear end decided to fall on it....

 

[snowborder714]

Thanks for the input, Cory.

Do you happen to have a weight difference between the v-band and 2 bolt flange? I personally think I'd sacrifice the weight to have the exhaust easily removable, but I'm curious how much of a difference there is.

 

[eviltsi]

not off hand, i could prob weigh them monday.

Mine is vband and yes its great to have the entire system off the car in about 30 seconds, just another option and less welding.

 

[Raph]

visit akrapovic.com for titanium exhausts and their pries..8k for an m5 v10 exhaust, gtr costs alot too..evo x was 2k i think.

not exhausts,but works of art made of titanium really

Akrapovi? - top-quality exhaust systems for motorcycles and sports cars.


###### not for the us market tho.(because it costs too much)

 

[T is for TURBO]

Brian, did you ever decide what route to take with this?

 

[snowborder714]

I haven't fully talked through it with some people that I'd like to, but right now the plan in my head is to go with a stainless o2 housing/partial downpipe to get me back behind the oil pan (for heat purposes). From there, it'll be a full 3" aluminum exhaust.

I'll probably put a v-band connection before the rear crossmember for a few reasons. I'm considering making 2 sections for the rear - one over and one under the crossmember. I don't know if I'll actually go through with it, as it'll probably not be cost effective, but they each have pros and cons. The one over the axle would be more ideal for aero and a future rear diffuser. The one under the axle would be more ideal for straight-through flow.

Then if/when I get a diffuser, I could just put a very short turn down piece at the v-band so the exhaust wouldn't interfere with the airflow, but would still meet rule requirements of being dumped behind the driver.


But I've just acquired my 12cm twin scroll Holset exhaust housing, so the next step is to send the turbo off to have a manifold built for it. The builder will also be doing the o2/downpipe piece, so at some point soon I'll have to figure out at least that portion of it.