[Fot] Nuerburgring Nordschleife 400 km race

[Kas Kastner]

The way that I did it was to install a very small crank pulley and a 3" 
water pump pulley for
Gilmer belts. I think that the crank pulley had to be steel though but only 
about 1.25" / 1.5" in diameter. (don't remember exactly the diameter other 
than it was the smallest I could find).
----- Original Message ----- 
From: "Bill Babcock" <Billb at bnj.com>
To: "MadMarx" <tr4racing at googlemail.com>
Cc: <fot at autox.team.net>
Sent: Thursday, October 02, 2008 11:21 AM
Subject: Re: [Fot] Nuerburgring Nordschleife 400 km race


> Certainly possible, but you'd have to run a huge pulley to reduce the
> pump RPM significantly. According to my crappy memory the one that
> comes in the typical thin-belt kit is about 10% bigger than standard.
> I tried to find an old pulley to measure but I don't seem to have one.
> I think most people look at reducing the pump RPM as a way to increase
> horsepower rather than limit cavitation.
>
> You should be able to see signs of cavitation on the pump blades. They
> should erode enough to show marks if you had serious cavitation. It
> would be nice if someone did a real impeller, with arched blades.
> Blades that curve away from the direction of rotation are much slower
> to cavitate. But even if you had gross cavitation in the pump you'd
> still see some pressure and flow, it just becomes unstable and noisy.
> I'd look elsewhere, like perhaps a suction hose collapsing, or too
> much pressure drop across your radiator, before I'd worry too much
> about pump rotation speed. Even if it is cavitation reducing the
> system flow, anything that decreases the suction pressure will make it
> worse.
>
> I eliminated a consistent high RPM cooling problem on Peyote with more
> hard aluminum piping, using flexible hose only for the joints.
>
> On Oct 2, 2008, at 7:05 AM, MadMarx wrote:
>
>> Henry,
>>
>> can you tell me the sizes of your crank and water pump pulleys?
>> I have the stock water pump with that sharp edged impeller. I really
>> suspect
>> the impeller to cavitating when turning longer at high revs. I hold
>> 6000 for
>> about 30-40 seconds in on go.
>>
>> Chris
>
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