Engine/Transmission (1994 - 1998) Heat wrap exhaust or not?

[FreeBMW]

I am about to purchase a new turbo back exhaust (4inch all the way).



my question is: is there any benifit to heat wrap the new pipes? some companies call it header wrap but lots of other tubro car owners are wraping the downpiep at least some folks all the way back to the muffler.





anyone done it? any differance?





Thanks

 

[Eric_77]

Yes we do it to race bikes all the time. it helps a lot on several points it keeps heat in the exhaust thus keeping underhood(bodywork) temps much cooler. Other it helps in the scavenging effects of the exhaust. Might help with boost response and turbo temps but I don't know about that.



It should only be done to a stainless exhaust though, mild steel will rust out quickly as the header wrap keeps pipe moist for a long time after it gets wet. Other thing it helps with is sound not much but it might help with drone you can get with aftermarkert systems.

 

[HEMI®Dart]

My downpipe is wrapped like a mummy. I also have Geno's exhaust blanket. I won't run without either. I think it makes a difference.

 

[Ben Rumson]

Ditto

Keeping the heat in the pipe longer will help "Draw" the exhaust and add effeciency.



I'm in the process of making my own exhaust blanket and will include a sleeve to blanket the down pipe to at least the horizontal bend.



Reduced under-the-hood temps, cooler air intake (no stock box), and better draw/air flow.



I concur with applying to SS vs mild steel - unless you provide ample slits for road spray to drip down and away from the pipes and this becomes iffy. They WILL get wet.

 

[y-knot]

I suspect that if you don't use a good stainless steel down pipe, and you live anywhere never a snow state, your fancy warp won't be long for this world.

 

[Diesel Freak]

I wrapped the downpipe for the first four feet. I coated it with silver VHT paint.

 

[chrleb1]

Depending on how high your EGTs are before the turbo, the temperature can drop as many as 200 - 300 degrees a little way down the pipe. Keeping the heat in the pipe doesn't help air flow sometimes. When the pipe is uncovered the exhaust gases cool faster, creating a lower pressure (hot air expands). It basically just comes down to a matter of preference. Most of the heat you are going to get in your engine compartment will be from the block, radiator, exhaust manifold, turbo housing.

 

[Diesel Freak]

Originally posted by chrleb1

Depending on how high your EGTs are before the turbo, the temperature can drop as many as 200 - 300 degrees a little way down the pipe. Keeping the heat in the pipe doesn't help air flow sometimes.

Most of us that are doing this, are at the point where EGT's are high enough to do damage if held there for an extended period of time ie. over 1450F @WOT.



Keeping the gasses hot, can help it move easier... . but it depends how hot they are to begin with. I am sure you already know this, but the hotter the gas, the more elastic the molecular colisions become, and therefore it will flow easier. Dropping the temp on the exhaust won't lower the pressure... . the exhaust system is not a sealed container... PV=nRT does not work in this case.



Most people that do this, are just trying to keep the gasses hot, to make it easier to move them out of the way