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Alloy exhaust vs SS
l0rd - 22/12/11 at 04:58 PM

What do you lot think?

Off you go

myke pocock - 22/12/11 at 05:20 PM

Alloy exhaust? Can you get them? Never heard of them before but prepared to be edicated.

blakep82 - 22/12/11 at 05:25 PM

hmm, never heard of an alloy exhaust either,can't think why it wouldn't work... sounds an interesting idea

Confused but excited. - 22/12/11 at 05:38 PM

I take it you are referring to aluminium alloy? If so why? IMHO it wouldn't last very long.
SS by preference on cost. Monel if you win the lottery.

l0rd - 22/12/11 at 05:56 PM

quote:
Originally posted by Confused but excited.
I take it you are referring to aluminium alloy? If so why? IMHO it wouldn't last very long.
SS by preference on cost. Monel if you win the lottery.


Yes aluminium alloy.

Why wouldn't it last very long?

Costly but light.

mark chandler - 22/12/11 at 06:05 PM

I think the acids will hole it pretty quickly, I know you cannot use copper as it will produce poisonous gases !

MakeEverything - 22/12/11 at 06:17 PM

Depending on what grade, but I suspect a lot of oxidisation and also a lower melting point than steel?

indykid - 22/12/11 at 06:22 PM

I'm not sure which alloy you're proposing, but most melt at about 650°C.

A puddle below where your exhaust should be doesn't sound good to me

l0rd - 22/12/11 at 06:37 PM

I have been reading different forums and there are a lot of people who don't have problems running them

Volvorsport - 22/12/11 at 06:49 PM

drag racers use them to good effect , but obviously not right at the manifold , it would be ok for silencers .

gingerprince - 22/12/11 at 06:56 PM

Neither - mild steel. Absorbs the noise better than SS so works better as a silencer, which is what its supposed to do.

l0rd - 22/12/11 at 07:14 PM

quote:
Originally posted by Volvorsport
drag racers use them to good effect , but obviously not right at the manifold , it would be ok for silencers .


most of them are back from the manifold. One even claimed that he used one for a turbo downpipe and back

Grimsdale - 22/12/11 at 07:40 PM

is it possible? sure. would it last? No.
Creep and oxidation would be the main two worries, especially as the exhaust gas has to be approaching the melting point of the material.

Confused but excited. - 22/12/11 at 08:22 PM

quote:
Originally posted by l0rd
quote:
Originally posted by Volvorsport
drag racers use them to good effect , but obviously not right at the manifold , it would be ok for silencers .


most of them are back from the manifold. One even claimed that he used one for a turbo downpipe and back


Drag racing is a totally different ball game. The exhausts would only have to last a one/couple of runs. Top AA Fuel rails have million dollar engines and they don't last long. They are looking to shave a thousandth of a second off a run time, so look to save a gram in weight, antway they can. A bit like, if a F1 engine lasts two races, it's been over-engineered.

jimmyjoebob - 22/12/11 at 08:34 PM

You can use aluminium exhaust manifolds, even before turbos, but only if they are water cooled. Marine engines use them, especially those on jet skis.

Aluminium cylinder heads can cope with the exhaust port temperatures only because of the cooling passages within (or around if air cooled).

In fact, in boats the water cooled exhaust manifolds can pass the exhaust gases into silicon hosing after a very short distance because the water cooling is so efficient.

[Edited on 22/12/11 by jimmyjoebob]

Chippy - 22/12/11 at 11:06 PM

No evidence that its correct, but have heard that a silencer made from alloy tube is quieter than one made of stainless. Problem seems, to me at least, finding alloy tube big enough. Cheers Ray

TAZZMAXX - 22/12/11 at 11:33 PM

Hope this link works. It's for a drag car that a guy called Robbie Ward is building in New Zealand. The engine is a twin turbo Nissan V8 and has aluminium exhausts (Post #28)

http://www.gtr.co.uk/forum/151739-6s-200mph-pump-gas-nissan-thats-goal-2.html

welderman - 22/12/11 at 11:51 PM

I made a huge alloy exhaust. Passed SVA at the time. Was quiet and light. But the 90 deg bend on the outlet was changed twice. Until I made a huge stainless one.
So I would go stainless.

Canada EH! - 23/12/11 at 12:22 AM

Neighbour had a 289 Ford in a Donzi boat, cast ali exhaust manifolds. Even with water cooling the exhaust ate through them in a few years.

MikeRJ - 23/12/11 at 09:39 AM

quote:
Originally posted by Confused but excited.
A bit like, if a F1 engine lasts two races, it's been over-engineered.


They have to last at least 2 races!

MikeRJ - 23/12/11 at 09:45 AM

quote:
Originally posted by TAZZMAXX
Hope this link works. It's for a drag car that a guy called Robbie Ward is building in New Zealand. The engine is a twin turbo Nissan V8 and has aluminium exhausts (Post #28)

http://www.gtr.co.uk/forum/151739-6s-200mph-pump-gas-nissan-thats-goal-2.html


Which part of the exhaust is made from alloy? Definitely not the manifolds, they are steel.

TAZZMAXX - 23/12/11 at 10:08 AM

quote:
Originally posted by MikeRJ
quote:
Originally posted by TAZZMAXX
Hope this link works. It's for a drag car that a guy called Robbie Ward is building in New Zealand. The engine is a twin turbo Nissan V8 and has aluminium exhausts (Post #28)

http://www.gtr.co.uk/forum/151739-6s-200mph-pump-gas-nissan-thats-goal-2.html


Which part of the exhaust is made from alloy? Definitely not the manifolds, they are steel.


The turbo outlets are aluminium

Confused but excited. - 23/12/11 at 11:24 AM

quote:
Originally posted by MikeRJ
quote:
Originally posted by Confused but excited.
A bit like, if a F1 engine lasts two races, it's been over-engineered.


They have to last at least 2 races!


I was quoting a Williams Team design engineer, because I know FA about F1. Don't shoot the messenger.

[Edited on 23/12/11 by Confused but excited.]