exhaust wrap ?

[SGHOM]

"quote"

Exhaust Wrap:

When used to wrap tubular exhaust manifolds the reduction in under bonnet temperature may increase horsepower & increase fuel efficiency, ( not suitable for cast iron as it may crack!).


mmm.. /Hmmm not advisable to do the front & rear manifolds then ??
& I thought most manifolds were cast ?? /yes

[SGHOM]

perhaps this answers my question ? /yes

the other thing about heat wrap, don't put it on cast iron manifolds I found that out after the previous owner put the stuff on, and then a tie to hold it in place.


I have a Morris Manifold which is neatly cracked in 2 in the back of my garage now. Still, only £50 to replace it. Horrible to say, but it made me feel much better when I was told Wildfire S3's was £330 for his TVR S3 (not as in, he's having to pay more but, thank god mines that expensive. ]


how close to the manifold should I take the heat wrap then ?? the front [ which I'm starting on ] is the easiest to get at !! :embarasse

[enigma]

The problem with cast is that it holds A LOT of heat, tubulr steel ones radiate it quite well! I would stay clear of the manifold.............

[SGHOM]

mmm ? /Hmmm
some conflicting opinions here ?? :rolleyes4

http://www.clubvr4.com/forum/showthread.php?t=9961&highlight=ako

[Wodjno]

Hmmm .. Interesting debate this.. I was going to wrap up my Exhaust and manifold a few months back( after talking to Bloke wiv Focus RS who had it done at the Sheffield meet) but then to read about that cast wrapping can create to much internal heat and crack them. :rolleyes4 So i put that on hold. Also read that insulating your turbo's makes them more efficient by retaining heat and making them spool faster.. /yes But then if theTurbo's are hotter then isn't the air that paasses through them hotter ? /Hmmm And Obviously the hotter the air the less dense and so les power.. :inquisiti There seems to be so many ( to many) variables as to increasing power and efficiency and finding the right balance is a bit of a mare.. You cool 1 thing down, but it heats another up.. Or you heat one up to make it more efficient, but this affects something else further down the line in a bad way.. /help
Maybe i'll just get myself a Diesel and be done with it all.. /pan /pan

[SGHOM]

If you just wrap the downpipe, how far do you go back ??
& as you say Glenn, wrapping the turbos is also an option, but that's also part of the cast manifold ?? /Hmmm

[Wodjno]

If you just wrap the downpipe, how far do you go back ??
& as you say Glenn, wrapping the turbos is also an option, but that's also part of the cast manifold ?? /Hmmm

Well my the reason i was first going to wrap the Zorst and manifold was to keep underbnnet temps down .. Then i found that it could also increase the speed in getting the gasses out. And then the cracking bit appeared.. I reckon by wot i have read that you need to be staying 4-6in away from the manifold, so your keeping the gasses flowing out on the way out .. But yur nt heating the manifold up to much and allowing it cool a little where it is fixed rigid to the engine.. This is where the problem is with to much heat becuse it is bolted to the engine it can't expand with the heat and it cracks..

With the Turbo's, keeping them hot with jackets might actually be beneficial if your running standard boost, but were not.. So increasing the heat in the Turbo's on higher boost is in my eyes giong to have a detrimental affect.. So i ain't going there ..!!

[colVR4]

By the way, air temperature and air density are two separate things. You can have dense hot air and thin cold air, and vice-versa. The denser the air the better. Heat is related to pressure not density, IIRC. Never was much good at physics

[Wodjno]

By the way, air temperature and air density are two separate things. You can have dense hot air and thin cold air, and vice-versa. The denser the air the better. Heat is related to pressure not density, IIRC. Never was much good at physics

Hmmm .. But doesn't 2 different densitys of air at the same temperature depend on atmosheric pressure.. ?? You can have a hot air that is more dense than a colder air but to have this the atmospheric pressure would have to be higher to achieve this.. At the end of the day if you have your car running at the same atmosheric pressure for most of the time, of which i think we do then keeping the air cooler that is entering the inlet manifold is only going to be beneficial .. /yes I Think ..?? :inquisiti /help

[RED]

The way I understand it is that wrapping the manifolds, turbos and downpipes is not primarily to reduce underbonnet temps but it is to retain the heat in the exhaust.

The engine produces power and energy. A certain amount of that energy is transferred and lost as radiated heat. If you can retain that heat energy then it is able to be used elsewhere ie at the wheels. Of course it also has the benefit of reducing underbonnet temps aswell.

The manifold and downpipe on the rally car are heatwrapped and we have not had any cracked manifolds after 4 seasons hard use.

Marcus