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RE: True definition of Knock
Carl,
Amen to the chamber/dome/dish shapes . Low / mid lift port flow vs cam C/L
displacement
Rod ratio and to infinity vs the Powertrain / Vehicle package and Vehicle
CD.
A Dyno is a USEFUL TOOL, however many folks put all the eggs in that basket
, without on the
RUN Backup Data. Dynos don't have slicks and steering wheel and aren't
accelerating the ACTUAL
Vehicle MASS , trying to punch a hole thru the atmosphere to get to the
other end. Or if you prefer
"Not up on Plane " as with a hull displacing water. We know how detonation
on BB / SC marine
application can literally UBBRELLA Inconel exhaust valves, even at low
thresholds/ intensities.
We can simulate and postulate, nothing beats the real world running.
With reference to KS,
Auto Manufacturers are focused on Lowering NOX levels, saving Engine
Components and trying
to "GO THE DISTANCE". No joke, Detonation is VERY Complex and mostly in a
state of FLUX.
They overshoot the spark to keep the engine off the belly pan.
Finally , I'd like to comment that we've seen differences between Dyno
pulls vs Track with respect
to a specific engine's detonation sensitivity. Both environments and
acquired data are of great value
as detonation appears to be the quickest way to trim about 15% power output
off the top , wack the
ring seal and knock the rod B.E. out of round on a diagonal + More.
[ Good numbers on that SC ENGINE ], and no hype, Cool.
Len
Thank you Len,
Finally someone with some real world experience explains it a little
better......no offense to anyone(please).....there are so many factors that
induce detonation and preignition.......fyi....the combustion chamber shape
and dome/dish shape drastically affects detonation as does high swirl vs rpm
and cyl filling height.....I have played with this extensively vs
compression ratio always trying to maintain as high a (static)compression
ratio as possible......I can go on forever about differing situations(cam
overlap,exhaust valve timing events, short turn entry angles vs rpm, etc
........all I can tell you is I have proven 1180 hp on pump gas with no
water injection.(yes, i have seen the claims of 1300+ on pump gas...been
there done that and more...works great on a dyno...doesn't live in the real
world)...intercooled/supercharged 8.3:1......but it took alot of effort in a
marine environment where it sits at 5600 rpm for very long times instead of
seconds as in a drag race or fun spurt......hth's
-Carl Summers
p.s. how about a 40' Hallett with twin 572's that went from Huntington to
Catalina in 16 minutes....takes longer to fly.....was alot of fun testing
though....hehehe
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