As a follow-on to the current discussion, I thought I'd post the results
of the teardowm of my Alfa race engine yesterday. For those unfamiliar
with Alfas of the 50s and 60s, they are DOHC, alloy block and head, wet
liners, hemi combustion chambers with relatively high compression ratios
and the -least- powerful engines for the sedans did about 60 HP/L or 1
BHP/cu in.at 6000 RPM (that was for the sedans!)
My engine did about 100 HP/L on the dyno in 1994 (yes, 5 years ago) -
157 HP at 7000 RPM, with typical shift points of 7500 and a rev limiter
at 7800.
When we built this engine, the only non Alfa factory parts were the
pistons, where we used high silicon J+E, for their low expansion. We
started with a stock 1600 cc engine, overbored, and did everything to it
- nitrided crank, shot-peened rods machined to exact tolerances,
balanced and blueprinted, modified the water and oil flow per factory
specs of the GTA days, ported the head, etc., etc.
We did breakin with dino oil and switched to Mobil 1 and Lally AW-1 (a
snake oil anti-wear additive developed for NASA). I changed the oil
typically every other race.
I ran the engine for five years. Never took it apart or even touched the
valves. We figure there is about 4500 miles of racing on it. It still
had over 165# compression and no visible oil burning. Oil pressure was
the same as after breakin.
Tear down showed pistons with minimal wear on the skirts and no blow-by
discoloration below the compression ring. There were no discernable
ridges on the bores of the liners. Valve seats look clean, but enough
carbon had built up on the #1 and #4 exhaust valves to leave a mark on
the piston crown! Main bearings looked fine, and only #4 rod was showing
serious wear. Several cam lobes showed scuffing.
Conclusion: use the best materials, blueprint and balance, use good oil
and run it hard!
Oh yes, warm them up gently!
While we could do rings and bearings and be safe, everything will be
measured and checked against specs. Then the engine will be magnafluxed,
blueprinted and reassembled with care.
Paul Glynn does most of the work, since I'm simply too busy anymore, but
it sure was nice to spend two days this weekend working on the car!
Jim
--
Jim Hayes Winchester, MA, USA
hayes@mediaone.net http://www.fotec.com/jim.htm
jeh@fotec.com http://www.fotec.com/
All generalizations, with the possible exception of this one, are false!
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