Randall,
I have a cast 6 vane pump impeller, and I have no trouble in Phoenix. I
also have, as a Gift from Darryl Uprichard of Racetorations, a new milled
pump impeller. The cast al. is great, and the machined one will probably be
wonderful.
Gene
-----Original Message-----
From: triumphs-bounces+geneglenn=qwest.net@autox.team.net
[mailto:triumphs-bounces+geneglenn=qwest.net@autox.team.net] On Behalf Of
Randall
Sent: Tuesday, July 24, 2007 1:52 PM
To: 'Triumph Sports car discussion'
Subject: Re: [TR] Alloy Water Pump
> My conclusion from that conversation was that adding vanes does not
> necessarily improve water pump performance. Does anyone know
> if there is credible
> evidence that it improves cooling in this case?
Improving cooling is a different matter than improving water flow. The
evidence of increased water flow seems clear to me, several racers have
reported increased pressure readings inside the engine. Henry Frye reported
pegging a 35 psi gauge coming off the straight (but declined to mention his
tach reading at the moment).
Whether and how much that improves cooling is a different matter. However,
on the TRactor motor, there does appear to be a problem with insufficient
water movement around the #4 cylinder, which increased flow is bound to
help, IMO. I've heard from several people who are also experimenting with
restrictors fitted to the front water passages, for the same reason. (For
example, Mordy Dunst sells head gaskets with smaller holes for the front
water passages.) All this is under racing conditions though, so may or may
not be applicable to the street. Higher pressure inside the head will also,
at least in theory, reduce nucleate boiling near the limit, which can be
important for engines modified to produce twice (or more) as much power as
original.
It's not even clear to me that the real difference is 6 vanes vs 4 vanes.
The 6 vane pumps have more surface area on the vanes, and are finished all
over, while at least some 4 vane impellers have rough sand-cast surfaces.
The vanes are also curved on the 6-vane, straight on the 4-vane. Might be
that a 4 vane pump built to the same vane shape and size as the 6 would work
just as well. But until someone builds a pump like that, it's kind of a
moot point.
Randall
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