Hi all,

I've currently got the large water pump pulley on my fresh 1310 motor.

http://minisport.com.au/mini-large-wate ... car-cooler

I've decided I'm going to take it off and put the standard pulley on.

My question is, has anyone in the past used this on a road car, and noticed a difference in temp under exact same conditions? Currently my car sits around 90 deg driving around, and if you sit in traffic it goes to 100deg+ (temp pretty accurate on my gauge (checked with a infra gun)

The coolant is new, and system is completely cleaned out ect. The pulley is the only thing I can think that is putting the temp up at this stage.

Cheers,
James

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I wish I had some sort of witty quote in my signature

A larger pulley will make the pump run slower so it is possible that's it.

The big pump pulley is only good on a racer IMO. For traffic I'd stick with a stock one.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Yes. I was trying to prevent cavitation at High rpm by using one but found that under 2000rpm it ran hotter. I believe it is only needed for race or hill climb engines running at high rpm. The pulley will have slightly less drag giving a slight HP increase. Kieth Calver has a bit of info on them.
http://www.calverst.com/articles/Coolin ... r_temp.htm

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AKA - GTOGREEN1969

Do you know which water pump you have? Is the car fully run in and tuned, it might be running a bit lean? I assume you have the fan on the right way..

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Yeah that seems to be same as what is happening. It is fine when on the highway but horrid in traffic.

Timmy - the car is actually a bit rich, definitely not lean. High flow water pump w/ bypass.

Fan is on the right way

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I wish I had some sort of witty quote in my signature

Sorry to hijack but rather than starting a new thread, what are the sizes of the 2 pulleys? My temps also increase, but only when sitting at the lights. Pump and radiator are new, 88? deg thermostat.

Cheers.

This oversize pulley is 4.750" diameter, stock one is 3.875". There is also a 4.2" pulley.

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AKA - GTOGREEN1969

I would be curious James to find out if the temp actually drops to close to the thermostat temperature with the change in pulley. They did apply a lot more clevers than it would appear to the coolant system design back in the day, so a pulley designed for another intent (racing homologation) will definitely have an effect. I would be keen to know if it was that much.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Yes I tend to agree Mick, and I'll be sure to update you on the results once it's changed.

Another thought too - it's not just the fact of pushing less water, but with the pulley being bigger, the fan would spin considerable slower - making the system even less effective.

I'm annoyed that I chucked it on without even thinking about it. But we'll see!

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I wish I had some sort of witty quote in my signature

With diameters above the big pulley will run about 20% slower.
So 20% less water and 20% less air, but, the slower the fan the less efficient it becomes !

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Find a job you love and you will never have to go to work !

Until you reach maximum efficiency around 2000rpm +20%.

Water pump is centrifugal, flow rate is not proportional to speed. Output curve is more hyperbolic than a straight line. So if slowed 20% flow will drop much more.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Hi All
The water pumps we have to day only just pass the test, BMC got it right in the day with there cast iron impellers, the tin ones we have today are not very efficient, one they are a open back pump, and the impellers are not pressed on far enough.
I have found them to be up to 3mm off the pump body I like to press them on to about .005 INS.
The water pump will reach it's maximum efficiency at about 5000 rpm and the water flow will increase proportionally to the pump RPM up to about 5000 RPM, water flow will increase above this but the efficiency starts to fall away.
The pressure in the block and head at maximum efficiency should be around 30 psi regardless of radiator cap pressure when the water is restricted by a thermostat or a restrictor plate, it is this pressure that stops a layer of gas bubbles from forming on the cylinder walls and around the combustion chambers.
On testing water pressure in the small bore motors with the tin type impellers on the dyno with no blanking sleeve as the dyno has it's own thermostat to regulate the temperature the pressure in the block was 12 PSI with the cooper S pump it was close to 20 PSI.
On the dyno I can not run a large dia water pulley while trying to run the motors in as they just over heat till the RPM gets up
to about 5k to 5.5 k and this is a problem with a lot of motors be it the 4 cyl fords or the v8 motors.
I know that the later A+ motors have a larger pulley on them but they would have changed something to counter act this I know they have blocked off some of the water holes in the A+ heads but I have not looked into it any further.
With these tin impellers they can start to get cavitation at low RPM so make sure the clearances are set right before you put them on.
Graham Russell

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"It's better to be not informed than ill-informed"

Thanks GR - Some very good stuff there. Not sure why Calver says 2000rpm against your own findings of 5000rpm.

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AKA - GTOGREEN1969