Heat wrap?

[FSP]

How much heat wrap do I need for the exhaust manifold and down pipe? Manifold is the one from the group buy and down pipe is standard.

Thanks,
Martin

[HAndy]

How much heat wrap do I need for the exhaust manifold and down pipe? Manifold is the one from the group buy and down pipe is standard.

Thanks,
Martin

do not heat wrap a tubular exhaust manifold, build a heat sheild around it to protect from heat using something like nimbus lite or something similar but less expensive like http://www.thermalvelocity.co.uk/Heat-Shields/c-1-113/

heatwrap the down pipe
maybe a turbo blanket also if you want to control under bonnet temps even more
might be hard finding one for a t25 though

[FSP]

Didnt know that wraping manifolds is no good, why is that?
Was thinking to make the bonet open for only 2-3cm on button in the cabin, anyone done this?

Thanks!
Martin

[chipis]

im also interested why wraping exhaust manifold is not good?

[Ashy]

Nowt wrong with wrapping your manifold, I've done it on all my 5's and never had any problems...

[Matt Cole]

Wrapping cast manifolds can be problematic and may crack. Nothing wrong with wrapping a steel manifold, infact it can help with gas velocity.

[JP Racing]

Exhaust wrapping will cause pipe material to cycle repeatedly thru extremely elevated temperatures as the radiant and convective heat transfer to atmosphere is blocked. Since pipe contains stresses from manufacture and welding and since it is often made from steel or stainless with relatively low strength at high temperature the metal can degrade very badly. This is the effect of thermal stress as it's called.


The only possible benefit - if you are prepared to accept severe deterioration of the pipes themselves is reduced under-bonnet temperatures. The massive flow of heat coming off the exhaust - especially in highly tuned front-wheel-drive installations when not moving at reasonable forward speed - can cause the fuel in the carb to boil, the oil and engine to overheat. The underbonnet temperature can be easily surveyed with an inexpensive hand-held probe from Halfords or other auto shop and will shock anyone who has never done it. Certainly cold air ducting is great when your vehicle is moving but not so effective when it's not. If you must use wrap to reduce underbonnet heat - give the insulating material some stand-off from the pipe to avoid those high metal temperatures.

One must also remember that the heat doesn't just flow outwards radially thru the pipe and down the pipe - it gets into the port, the valve and seat - even piston - region and can cause all sorts of dramas: seats cracking, detonation etc etc. General increases in head temperature are going to degrade the inlet charge density too. And, if, for argument sake, you have a very highly tuned motor and you wrap your exhaust tightly and you're running a cooling system with plain water and no water-wetter or antifreeze your cooling system on the ex side of the head is likely to be totally overloaded due to nucleate boiling = no heat transfer at all to the coolant system - and the first thing you'll know about could well be a blown head gasket, or worse.

Do you want to wrap ex header/manifold on turbocharged units? No, no way just speculatively, even if it brings a performance gain - unless you know for sure by means of traceable metallurgical data and via accurate thermocouple measurement in the pipes etc that you are not exceeding the maximum rated temperature for the turbine blades and casing and exhaust port/valve region too. Never mind all the nuts and bolts that hold it together. Otherwise you put the whole unit at risk.

Just using a "turbo blanket" on a car with a turbo installation can cause damage to the engine from heat and damage to the turbo from overheating. While it does prevent radiant heat damage to other parts of the engine bay (most notably wiring) this is all preventable by rerouting. Your final solution is to use a sheet of metal held at about 2 inches from the turbo to protect other parts from heat. So the you can choose what ever you like to wrap or make heat shields

[SCHWARTZ]

What he said

[GTphil]

Good posting, a lot of things you mention hadn't even crossed my mind when I wrapped my manifold

[FSP]

Got some wrapings for sale, anyone?

[GT TURBO BEN]

thats the most in depth thing i think ive ever read you could have made it a bit simpler for the likes of me that was hard work

[JP Racing]

Sorry it was deep and heavy going its just I was thinking of wrapping my manifold and downpipe and also putting a blanket on the turbo until I did lots of research into it. I also found most people have wrapped manifolds With no real problems so each to there own but I even saw a post on another forum stating that he had wrapped the entire exhaust system except for the back box. The back box had been coated in vht paint and the paint had started to be charred in Places which shows how well the wrap worked but also how hot the gases were even at the end of its cycle. So to protect the engine components and hopefully the longevity of the engine and turbo too I will put a few heat shields in place to protect other parts from heat instead of wrapping.