Re: The Rapp on exhaust

[PDQSHIP@aol.com]

>  Hmmmmmmmmmmm......... I guess you'll have to get "all nerdy" here to
>  convince me!
Ok ......
>
>  NASCAR cars are not turbo'd, so that's an apples n oranges comparison.
Exhaust is exhaust, Glen, turbo or no.......  It is an engine and we're
talking heat (delta-t's here), and were talking apples and more apples in a
smaller bushel.......
>
>  The Pro-Rally guys seem to like wrapping between the head and turbo -
>  makes sense to me, keep as much energy in the exhaust as possible to spin
>  the turbo and if something cracks or bakes, just replace it. ($$$ no
>  problem)
Again, I reiterate what I have said for months now......  Wrapping the exh
from the exh manifold to the tailpipe would be the "best" heat/energy
application.....  My concern is that, those of us who do not routinely tear
down our toys, or have 4ring sponsors that allow infinite parts replacement,
what is the most practical application for heat barrier/insulation......   So
the ProRally folks are right on the money (scuse the pun), but remember that
heat shield for energy to/at the turbo becomes a heat insulator when you shut
the car off...........     So you coke bearings, crack exh manifolds, and tax
the limited oil/cooling properties of your audi.....  The ProRally boys
prolly use brand new (if not oversized) radiators, larger oil coolers, and I
would guess some sort of Accusump arrangement, and how bout all those vents
in the hood....  All this is to bleed the heat from the turbo at idle or
off.....  We really don't have that luxury of these things on a stock
car..... However, I do not disagree with the theory, never have, I have
cautioned many times tho, the insulating of the turbo and manifold without
addressing what this action will cause........
>
>  Wrapping after the turbo would retain heat and therefore retain higher
>  pressure/volume. Cooling the exhaust as fast as possible after the turbo
>  reduces pressure and releives backpressure as the cooling gas is redcuced
>  in volume/pressure.
Nice idea, but in reality not putting the wrap on the exhaust with the idea
of a cooling pressure drop is heading in the wrong direction........  I have
yet to see that scoop or airdam on any turbo car.............  HINT:  Reduce
heat/reduce gas velocity, glen.......  And there is some speed, right at that
downpipe......
You have a major restriction at the downpipe/turbo pipe glen .........
  Think of your downpipe as a header Glen.......  Why would you wrap a header
one would ask........
>
>  So, please explain, why does retaining heat and high pressure/volume
>  after the turbo help performance? Go ahead, GET NERDY!!! (I got my pocket
>  protector ready)
A turbo car is no different than a normally aspirated car after the turbo,
glen.....  You still have to get exhaust gasses out
>  On my '73 RA IV 455HO 'Bird I too wrap from the manifolds to the
>  tailpipes, though the biggest effect I can feel is helping to keep the
>  interior a bit cooler!
So why did you do this, Glen?
>
>  How's the turbo availability lookin?
Got the CARB stuff late last week, hopin to have something this week, if
nothing else I will post a "to date" note.............
>
>  -glen
>
>