Interesting tidbit: I was at the Wiseco piston factory a couple of weeks
ago with the local Porsche club...the tour, incidentally, was really cool
as they do Formula 1 super-alloy metal forging-I now know what the Ferrari
F1 pedal box looks like...but they mentioned that since they do the pistons
for most of the Pro Stock race teams, they can figure out what size valves
each team uses and at what angle they run them in the heads (ie not the
angle of the valve seat grind, but the angle of the whole valve) based on
the valve reliefs cut in the pistons. Each of these teams are producing
almost the same horsepower, but they all get there with wildly different
size valves and valve angles, according to Wiseco.
Moral of the story: There is no one correct answer. Every engine is its
own package, and without serious flowbench/dyno time with your particular
set-up, you will never really know whether a 30 degree cut or 45 degree cut
is going to make any noticeable difference. It's great fun to plan, but
don't lose any sleep over it. Personally, I'd be more worried about
finding a knowledgeable and skilled engine builder who could do the work
correctly, at whatever the valve grind angles you (or the builder) choose.
Date: Thu, 5 Dec 2002 07:49:53 -0800
From: "Navarrette, Vance" <vance.navarrette@intel.com>
Subject: RE: 30 degree valve seats and 3 angle valve grid
Don:
-------------CUT-----------------------------
Don't know if this
would be a net gain or a net loss in performance.
Yes, a 3 angle valve job on a 30 degree seat would be
xx-30-yy. I don't know what would work best. I am sure everybody
has their favorite recipe.
If you are really worried about the durability, have the
machinist install hardened seats for the exhaust. The rest of the
car will turn into a pile of tiny rust chips long before the seat
wears out.
Cheers,
Vance
- ------------------------------
1974 Mimosa Yellow Triumph TR6
Cogito Ergo Zoom
(I think, therefore I go fast)
-------------cut-----------------------------------
William Whitmoyer
69 TR6
72 Fiat Spider
90 BMW iX
91 CRX Si
|