David_Wallis

Why do I want heat in the exhaust...

what egt's is too high for a turbo?

can someone prove that gas moves quicker with higher egt's?

what temp does oil carbonise (sp)?

David

Edited when sober.

[Edited by David_Wallis - 11/6/2002 11:07:12 AM]

nom

Heat for faster gas, so heat good.
Is hot gas fatster? It's how the typical turbo (centrifugal) works - intake gas is accelerated to a high speed and then expanded rapidly (within the snail-shaped conical thing wrapped around it); as the gas expands it cools and slows.
So, turn that round the other way - and hot air flows faster. And any expansion leading up to the turbo (larger up-pipe) may cool the gas (and so slowing it) leading to longer/later spool-up as well. So keep it all hot & it should all work nicely!

But, as you say, how hot is hot and what is too hot?

I wouldn't have thought that the oil carbonising would be a problem as long as the cool-down thing after a blast is observed. It doesn't exactly hang around for long enough to get hot enough, if everything's working, I'd have thought.

My brain has been ticking slowly, as is its way :rolleys: and I think I have a simpler explanation...
Hot is is thinner/less dense (so lighter) than cold, as proven by hot-air balloons going up rather than not. So, in a certain volume, there's less hot air than cold (mass). The engine shifts an amount of air on each stroke, which needs to make it out of the various tubes. On leaving the engine, that air has a certain mass. That mass is what needs to be shifted. The less dense the mass is (so, the hotter the mass is), the faster it needs to move to 'get out' in time for the next one. So, hot air moves faster .

[Edited by nom - 11/6/2002 1:11:11 PM]

David_Wallis

Anybody use these?

Wheres the cheapest place to get them from.. am I more likely to kill the turbo with them?

Is there any physics / laws behind the 'gas moves quicker' when egt's are higher??

Page number in corky bell's book? or 21st cent.??

Anybody lagged there up-pipe??

Also how thick did you put the exhaust wrap on..

David

jim litten

I was thinking of putting on a turbo blanket when I finally get round to going full decat. Demon Tweeks do a couple of different ones but they're a bit of a rip off really, so I'm just going to modify the heat shield and lag the downpipe, as for how any layers one should do or just til the rolls run out!


Jim

flat4

being a tight barsteward i lagged the turbo with exhaust wrap seems to do the job, also lagged every other bit of exhaust i could find, manifolds, uppipe, downpipe

i don't care if the manifold falls to bits like everyone says it will, i'll just get one off a scrapper for a couple of quid when/if that day comes


kev

ustolemyname??stevieturbo

iTrader: (1)

Dunno about the cheapest place, they all seem pretty damn expensive. Most books do claim better spool up etc, but would it really be noticeable??
I havent seen anyone ever do tests with them.
I notice in some pics that Andy's seems to have one in the condensed FMIC

David_Wallis

top

SMG

I love a bit of lagging, but be careful not to trap to much heat in the turbo, oil can carbonize and ive seen a T4 non roller bearing turbo running just over 2 bar melt the bearings. This was not a prob before the turbo was lagged.Just keep an eye on things.
Steve.

hypoluxa

I would suggest monitoring your temps straight after the turbo especially if your planning on using any form of anti-lag.

You basically want to keep as much heat in your exhaust system as possible - obviously within reason

Exhaust bore size also plays an important part in your resulting egts.