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Re: Thermal Coatings

Never ever never ever wrap cast exhaust pieces unless you want to replace 
them.  I also would think long and hard about the risk to the turbo 
verses the gain in hp concerning wrapping it also.  I raced a 2.3l ford turbo
(no flames, it was and is a powerhouse of an engine with a bullet proof 
bottom end.  It also has not dropped any valves unlike my audis have) 
from 85 to 88,  I could not tell any improvement or turbo response.  It 
helped to cook the bearings fairly quickly and sometimes I would notice 
hairline type cracks on the exhaust outlet of the turbo.  I would try to just
insulate the air intake from the engine heat and pursue other hop ups.  
I would also like to hear about the hop ups that some people have done to 
their audis to get 350+ hp,  seems kinda high to me, we were getting 
about 340-350 out of the 2.3 and it was, no way in hell,not streetable at all
I would love to see some dyno numbers and see one driving on the street 
with stock crank and rods, etc.  Also with that kinda of power it should
, with stock gearing, tires, etc. , be turning low 13s to high 12s in the 
1/4 mile.  hadn't heard about any 5000s doin that.  

On 18 Apr 1995 glen.powell@smc.com wrote:

>   From the turbo on back you do *not* want to coat or thermal-wrap the
>   exhaust. You want the exhaust to expell as much heat as possible to lower
>   the density and volume of exhuast gasses to be expelled, this reduces
>   backpressure and helps to decrease turbo lag and bring the boost up
>   faster. Do all your coating/wrapping before/at the turbo, turbine side
>   only. A Pro-Rally guy I know wrapped both the exhaust manifold and the
>   turbo and he says the performance improvement is noticable. Wrapping of
>   cast exhaust manifolds is NOT recommended though, due to the increased
>   possibility of cracking. I may look at the possibility of coating the SS
>   header for the Killer ur-Q Engine From Hell project.
>   -glen