You can reduce cavitation in several ways, decrease RPM, increase the
pressure at the suction of the pump, or change the blade design. Most
modern centrifugal pumps have blades that curve smoothly back. Triumph
pumps have straight blades. A pump bypass from outlet to inlet can also
reduce cavitation.
-----Original Message-----
From: Gt6steve@aol.com [mailto:Gt6steve@aol.com]
Sent: Monday, July 22, 2002 12:04 PM
To: kaskas@earthlink.net
Cc: FOT@autox.team.net
Subject: Re: Triumph water pumps
Thanks Kas,
That's about what you told me a few years ago so I'm glad you reaffirmed.
All has been done on my engine as you stated and it worked well until
recently. Something's changed and I can't put my finger on what it is.
First thing I'm gonna try tonight is a different gauge!
Steve
<< I figure that 20 pounds is a good saftey pressure. You can't get hurt
with lots of block pressure. The thing to measure is the presure when
the engine is under load and revving in the higher ranges . The high
water pump revs is what causes the caviatation and loss of pressure. Do
this while driving or on the dyno ( I did all this on the engine dyno) as
the revs go up around the 5 grand mark the pressure just starts to slide
and goes down quickly nearing zero at about 65 to 7 g's.. I've seen the
normal block pressure go to zero from cavitation at around 5000 revs in
several engines. Most cases the pumps were made to cool at normal STREET
rpm which is under 3500 in most cases ( my view) but at racing revs they
are WAY too high fast. Probably about 3 water pump to 5 crank will get
the thing right. I don't remember the exact ratios and a lot is dependant
on the pulleys you can find. I remember using a 3" on the water pump and
the smallest I could find on the crank which was in the 1" plus range.
(These were Gilmer belt pulleys) These were of course in the "olden days"
so probably a lot more is available now. AND if you the drive with a
Gilmer belt you also pick up a nice piece of power @ high revs.
From: <Gt6steve@aol.com>
To: <FOT@autox.team.net>
Sent: Monday, July 22, 2002 9:06 AM
Subject: Triumph water pumps
> Greetings Amici,
> I spent the weekend playing around with the water pump on the GT6,
trying > different combinations of things in an effort to improve
cooling. I put a > pressure gauge on the block and ran it into the dash
with 1/8" copper line > thinking to monitor pressures. I was surprised
to find Zero pressure at idle > (with the rad cap off) and only saw 5-7
PSI when revved. Putting on the cap > the pressures came up to about 15
but that was with the temp coming up and > not a result of the pump. A
very trustworthy source on this list told me I > should see 20-25 PSI at
the drain plug for best results. (Right Kas?) > So the question, has
anyone played around with their pumps, have any idea of > the flow
rates? Does anybody measure pressures? I swear I measured 20 PSI > at
that fitting years back because I had to adjust the restrictor in the >
T-stat housing to get it up there. > I'm a bit stumped... > Steve Smith
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