I don't know if this is a factor, but a friend of mine who works for Shelby
says that at a given displacement an engine will only make a certain amount
of torque. Thus, (according to him) the only way to get more horsepower out
of that spacific displacement is to increase the RPM (he did not elaborate
on bore and stroke configurations). Is there a point where strenthening the
components (and likely increasing mass) to sustain the higher RPM does not
allow the engine to reach that the intended RPM? I don't know.
Just another though that might have already been mentioned on the matter
is that a short sroke is said to be conducive to higher RPM. To obtain a
similar size displacement with a short stroke one would have to increase the
bore size. Increasing the bore size would allow the use of bigger valves,
which should help to increase RPM. Anyway, I don't want to get too far from
the discussion, but thought I would throw a few beans into this multi
vegatable soup (as it were). Tom Witt B9470101
----- Original Message -----
From: Bob Palmer <rpalmer@ucsd.edu>
To: 'Tiger News Group List (E-mail)' <tigers@autox.team.net>
Sent: Sunday, February 09, 2003 7:59 PM
Subject: RE: Desk top Dyno fun
> Frank,
>
> Consider this; why does any engine of a given displacement reach a point
> where it begins making less horsepower at higher rpm? The same reason, say
a
> 289 would make less horsepower at 6,500 rpm than at 5,000 rpm is the very
> same reason a 376 ci engine makes less horsepower at the same rpm (5,000)
as
> the 289. The specific reasons include, for example, the manifold vacuum is
> going to hell, which is indicative of volumetric efficiency, the result of
> turbulent flow which increases friction, inertia in stopping and starting
> the air mass, etc., etc. Even without valve float or any other extraneous
> reason, as you increase an engine's rpm past a certain optimum, horsepower
> starts to fall off. It's basically just a dynamic air flow problem; the
same
> induction, heads, cam, exhaust, etc. will peak at the same cfm regardless
of
> displacement or rpm.
>
> Bob Palmer
> rpalmer@ucsd.edu
> rpalmerbob@adelphia.net
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