[DeTomaso] Ford 392 rev limit?

[Boyd Casey]

I know I've been beating a dead horse as far as this post goes but I wanted
to clarify one thing. I never said nor meant to imply that you couldn't
have a Windsor engine ( or any other pushrod engine) that wasn't capable of
operating at high Rpm levels of 7,8 ,9k or greater IF it was built with the
proper components to achieve and maintain those rpm levels. In this
particular case Jeff Cobb was asking for advice on the RPM limit he could
run the engine he was asking about. The problem was and is that we don't
know the particulars of all the components that Corey just mentioned. We do
know the typical stroke for a 392 Windsor  so we can determine the average
piston speed for that build. Since there are published piston speed limits
for different levels of crank construction ( as posted by Dan Jones) we can
determine what a safe RPM limit should be based on the information we have
at hand. I would rather err on the side of safety ( of not giving advice
that may result in a blown engine) then assume the engine was built to a
higher standard ,especially when so many are not.
Boyd

On Saturday, September 7, 2013, Will Kooiman wrote:

> Corey,
>
> I think you pretty much nailed it.
>
> --
> Will
>
>
>
>
>
> On 9/7/13 1:33 AM, "Corey Price" <coreyjprice at gmail.com <javascript:;>>
> wrote:
>
> >I don't want to beat a dead horse.
> >
> >I thought that there are a lot of factors in determining the maximum safe
> >RPM of any engine, with some being:
> >
> >1.  Valve float.
> >2.  Rod bolt capacity and fatigue limit.  I understand the greatest load
> >on the rods is actually when the piston reverses direction and the piston
> >is pulled toward the crank, putting the rod in tension.  This is directly
> >related to the piston momentum (speed-related).
> >3.  Crank strength and toughness, meaning the fatigue limit and the
> >tensile strength at a given strain.  Most cast cranks have limited
> >toughness, which is why forged cranks are used for their increased
> >capacity to deform without breaking.  Again, this is related to the
> >piston momentum (speed-related).
> >4.  Piston capacity to resist the cyclical loading.
> >5.  Block strength and fatigue limit.
> >6.  Oiling system capacities and limitations.
> >7.  Cylinder wall strength.
> >
> >Did I forget anything?  Any of these could be the limiting factor as I
> >understand it.
> >
> >Corey
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