[batou]

One thing I've noticed (more so since fitting the manifold) is the big difference between the sound of the exhaust note when cold to when it's fully warmed up.

From a cold start the exhaust is raw, raspy and will crackle and snap for a good 200 yards. This is not good because thats how I like it and it's egging me on to give it some beans when it's cold.

When it's up to temperature it's a deeper, lower note and it pops rather than crackles.

It's this just the difference in the exhaust temperature affecting the note or the way ECU protects the engine when cold (i.e more fuel)... or a combination of both?

[DaFlake]

It is like anything that produces sound. As it warms the tone will change.

[neilobe]

As it warms up it expands and makes more deeper tone, on my R56 S when cold you would hardly notice it has the Milteck on it, but when its warmed up the exhaust gives a nice burble sound

[batou]

I thought as much, looks like I'm going to have to look at under car cooling to keep the raspyness lol!

[DaFlake]

Strap a fan to the underside with a big chunk of ice.

[MINI-Morgan]

Its due to the pipe expanding and also the fueling changing You wil be on open choke startup a certain temp and open loop standard map until the O2 sensors get upto temp and then it will settle quick. 600degress in the sensor takes a moment to build. Roughly 30 seconds.

[MINIMANIAUK]

sound waves travel at a different speed with temperature changes -the speed of sound changes with temp
the exhaust gets hotter and the exhaust gas travels faster and further down (heat) the pipe -hence tone change

[MINIMANIAUK]

The pops and crackles are unburnt fuel .You get more pronounced pops with higher octane fuel
The tubular manifold amplifies sound and the cast manifold dampens sound -A cast trumpet would sound cr-p

[DaFlake]

So what you are saying is that people with hot air toot better?

[batou]

I use V-power on every tank, pops and bangs are easily worth an extra 2p per litre imo

[MINIMANIAUK]

especially after beans on a hot day

[batou]

I know something else that pops after beans on a hot day too lol

[James@fomsport]

Quote: Originally Posted by batou (original)

I use V-power on every tank, pops and bangs are easily worth an extra 2p per litre imo

only an extra 2p im moving where you live then, i topped up yesterday and it 10p more up here

[batou]

I'd happily pay 10p extra per litre to avoid the M4 corridor and have Scotlands roads to enjoy!! I must go up to Mallaig, Arisaig and over to Skye again at some point

[DaFlake]

I'm moving back to the USA and dreading driving there. I will miss Germany in that aspect.

Guess I'll be saving fuel soon.

[James@fomsport]

Quote: Originally Posted by batou (original)

I'd happily pay 10p extra per litre to avoid the M4 corridor and have Scotlands roads to enjoy!! I must go up to Mallaig, Arisaig and over to Skye again at some point

true i used to live south a couple of years back was a nightmare sometimes now its only 2 miles form the house to nice open country roads (and i wonder why my tyres dont last)

im going up that way trough torridon and up applecross pass when my m7 coilovers get here and i get round to putting the new BBK on

me thinks weve gone off topic again today well i blame that Friday feeling and that i have nothing to do today, self employment has its perks.

back on topic, i was chatting to a mate who put a millteck on his s a few months back and he said he was amazed at how much it dose expand and contract when cold to hot, and now the metal has bedded in (his words) he was going to have to adjust it as its gone a touch wonky.

[MINIMANIAUK]

No more hooning down the autobahn ,only to be flashed by a M5 ,to get outta the way -you will think the traffics stopped on your return home !