Originally Posted by KevinD

uh huh. keeping the heat inside is why you heat wrap it. keeping the heat inside the manifold will help the turbo spool faster. and i doubt you have seen any quality manifolds crack for the sole reason it was heat wrapped. more then likely there were a number of other reasons, such as an unsupported turbo, or to thin of tubing.

ironically, wrapping the downpipe i can't see a reason to do. i've tracked my car many times, without a heat wrapped downpipe and never had any problems at all with overheated oil.


oh, and before heat wrapping the mani, i thought the radiator hose was going to melt it was so hot in the engine bay after a 30min track session. after wrapping it, i could literally touch the header immediately after a 30 minute session. engine bay temps dropped enormously. next time i need to wrap my manifold, i'll be sure to log some temps.

Originally Posted by KevinD

prolly not. the manifold opperates at 1000 degrees+ at WOT. even at idle it operates at 3-400. water boils at 213 deg. therefor, even after idling for a minute or so, all the water has been boiled off (even if you have a saturated heat wrap), the manifold will be dry any time it is at operating temperatures. so explain to me why moisture would cause it to crack?


do exhaust pipes crack when you drive in the rain? they are hot, and they certainly get when when it it rains... why would the wrap make any difference?

Originally Posted by KartaRailed

There are different schools of thought on this one. The main reason I see for cracking in the rain with exhust manifolds are as follows. Most people who run a manifold run an aftermarket o2 housing as well. With the ebay o2's there is no longer a suppourt brace on the o2 housing to hold the weight of the turbocharger up, thus putting stress on the hot (1000+ degree) exhaust manifold, the metal is already weakend by this, then rain water coming thorugh a hood vent with no black metal vent insert gets on the manifold, causing fluxuations in temp. which then results in cracking.