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Re: Ceramic coating EM's - II

In a message dated 10/5/99 1:40:45 PM Central Daylight Time, 
gerard@poboxes.com writes:

> > maybe concurrent exhaust mods necessary.
>  Am thinking of doing that 3-inch downpipe story, but if I do then
>  I guess I'd coat that as well then. So in all coat the following:
>  manifold, turbine housing, downpipe and connecting flange. That'd
>  see a fair amount of cash. :) Wastegate? No.

Not sure the point, but good question given my basic ones.  Why do the 
manifold at all?  What expectations do you have?  In theory, you are 
increasing the exhaust velocity to the turbine, after that really isn't a 
heat v velocity problem, remember a turbine is a heat generator all it's own. 
 In practice, coating the inside of the EM didn't do a thing for 0-60 times 
measured, but I didn't expect it to.  Look, the longest runner to the turbo 
is maybe a foot, pretty optimal for a turbo application.   A 10% increase in 
power?  I should been able to measure that (tested stage II fwd autobox, no 
accel preload).  So I'm thinking 5% or less.  That's the case, even the DIY 
can hardly justify the time, better mods elsewhere in the system.  Where one 
sees big gains in CC, is with v6/v8 turbo cars that have a huge crossover 
pipe that can lose a lot of heat.  

So doing it for heat to the turbo, I suppose is valid theory, IME not 
measurable results.  Personally, I'd save the money and put a bypass valve in 
my 10vt car first.  

Do it for underhood temps.  Well, ok, I suppose.  Given that the highest heat 
under the hood is the turbo, and CC the EM moves the EM heat to the turbo, 
now what?  Measure the temps off the hot side of your turbo (CC'd or not), 
that thing cooks.  What you need, is someone with some BTDT measure on 
underhood temps.  If that's what you are going after, by the time you go all 
the way to the cat, a more effective mod would be some hood vents, ala Sport 
q, and every audi race car.

>  How about using a heat dispersing coating on the outside then?

Might help, might not see anything.  I tried heat dispersion coating on G60's 
and rotor hubs, and found no real measureable gain with or without.  Bad 

>  Do the downpipe then? That can be done DIY.
>  G.

Look, I'm all for good mods.  CC coatings have some advantages, but the 
location of the turbo on an audi really makes it a minimal gain.  My 
experience with coatings, is that porsche has a reason for CC in their turbo 
apps.  But, it's not the manifold the turbo or the downpipe.  IF they saw 
some gains elsewhere, then I'd bet they'd use it.  My own btdt tests really 
show little (and no measurable) gain in the areas you guys are proposing. 

CC is not bad.  I just question how "great".  That would depend on the 
definition and the intention.

My .02 arbitraged thru the peso
Scott Justusson