C.R. and Horsepower
I asked about power increases from raising the compression
ratio, and Roger Garnett replied:
> Well, you really ought to do some reading
Does reading this list count :^) ?
> You need to balance reliability, power, engine life, cost,
> economy, streetability vs trackability, etc. with your desires.
No arguments.
> (noteworthy comments regarding trade-offs deleted)
> It will benefit from those, as well as a hotter
> cam, better intake & exhaust manifolding, porting,
> headers, etc. (Overall flow is very important to
> performance) And, you need to guarantee valve
> clearance. And then, is your clutch, axles, wheels,
> etc. up for the additional power?
Aw gee, I was just hoping for some nice simple answer, but
since you bring up these points . . .
I'm putting in a rally spec cam, it has somewhere around
300 degrees of valve duration, and a higher than standard
lift (I think the spec is .454 inches, not certain). With
this I'm going from two to three HD6 SU carbs and I plan to
lighten the flywheel seven or eight pounds. I plan to do
the clay thing to see if I need any additional machining
to get sufficient valve clearance. I plan to polish the
ports and combustion chambers a bit and match the head to
the manifold. I'm not planning on doing any heavy-duty
porting for fear of messing things up.
My racing buddy urges me to shave the head, but as I
mentioned in my original message, I'm reluctant to make
modifications that can't be undone. HOWEVER, if taking
50 thou off the head would give me twenty additional HP,
I'd seriously consider it. If it only gives five, I'm not
as interested. I'm assuming the C.R. changes from about
eight to around ten or ten and a half. I'd like to avoid
the need to use avgas.
This car is used only for racing, but it's just vintage.
I have no illusions (delusions?) of taking the Lead Sled
out into the world of E-Production or anything like that.
-- Dave L. --
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