I don't remember years that these things happened, but I'll try my best
here. In the earlier days of motoring top piston speed was 2500ft/sec.
This is due soely to metalurgy and the technology in rods. When the ford
flathead(or nailhead I don't remember) came out it that era of cars was
able to mintain 3500ft/sec. This should have been late 50s/early 60s. I
didn't pay too much attention to the dates/times because my 63 Buick 215
was made after the 3500ft/sec cutoff line. The piston speed is the speed
at the middle of the stroke, since the speed is zero at TDC and BDC and
must accelerate everywhere in between. Off hand I don't remeber the
formula, but it is a function of RPM and stroke. With a little math
knowledge you should be able to find it, otherwise I can look the details
of this up over the weekend. In regards to your question, with increases
in engine technology the bar has probably been raised again but I think
the V8s, As, Bs, etc should stick with 3500ft/sec. This is of course for
stock rods; if you put is hi tech rods then this limit increases.
James Nazarian
'71 B roadster
'71 BGT ever so slowly turning into a V8
'63 Buick 215
"I sure wish I had a racer's budget, or are the racers just better at
explaining expenses to the wife?"
-Unknown
On Fri, 4 Aug 2000 BobMGT@aol.com wrote:
> In reading some old automotive magazines articles, the term "mph at 2500
> ft/sec piston velocity" came up several times. Is this supposed to the
> maximum safe crusing speed for a given engine? (This is given as 60 mph for
> the TD. ) If so, is it still a good rule-of-thumb for modern engines?
>
> Bob Donahue (Still stuck in the '50s)
> EMAIL - BOBMGT@AOL.COM
> 52 MGTD - under DIY restoration NEMGTR #11470
> 71 MGB - AMGBA #96-12029, NAMGBR #7-3336
>
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