Club Cobra - Overheating at speed

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Overheating at speed - Water pump Pulley

Discussion Tools

06-13-2016 02:59 PM - permalink

joey4420

So after much learning and research, I have found that the original pulley that was ordered with my car from WCC is a 6 inch pulley for the water pump, the crank pulley is a 5 3/4. This basically means the water pump is being under driven by about 10 - 15 % depending on your calculations (I currently have a headache and don't trust my math).

So March (pulley manufacture) makes a 5 1/4 pulley for the 460 part # 1813 and from Summit Racing is $95. My local engine builder is going to check to see if he has a used one or a take off in his shop to save me even a few dollars. (I am very frugal, but I like things to be right and work properly).

I say all that to say if you are overheating at speed check your pulley size if it is a 6 inch it is called a performance pulley allowing for more horsepower.

06-13-2016 03:02 PM - permalink

joey4420

1000 word count sucks.

If the same size as your crank pulley it is stock sized.

If smaller than your crank pulley it is then overdriving your water pump allowing it to cool better and with our huge (thick) radiators more drive is better.

Either way I will report back on how it runs better hopefully this weekend, if all goes well.

06-13-2016 05:02 PM - permalink

BOBOCobra

5.25" March was still not enough for me. I had a custom one made to overdrive 20%. See picture below

06-13-2016 05:09 PM - permalink

BOBOCobra

But, if I may say that the pulley diameter should not have as much to do with overheating at ram air unless it is grossly oversized. If your spinning the engine at 3000 and the pulley is spinning 2700 you should be moving enough water to cool that engine. High heat at ram air usually means poor air flow through the radiator, collapsed hose, no water pump vane plate or plugged radiator core. Over-driving your WP (making the pulley smaller than crank) will be all the difference at idle.

06-13-2016 05:42 PM - permalink

joey4420

My issue comes at higher RPM and doesn't matter as much about speed. Speed does cause some issue, but I do have to run higher RPM's to get there. But if I am driving around in lower gears at higher RPM's I have same issue. Temp goes up.

Radiator has been flushed and cleaned (at a radiator shop), new metal flex hoses, Stewart performance high flow water pump with new backing plate, new Stewart 180 performance thermostat. My local engine guy has a 5.25 March waiting on the shelf for me to pick up tomorrow for $50, I only pay if it works. He is pretty sure it will since how my issues are. I drove all over the place SAT and it only got hot when I got spirited in my driving no matter the speed - I was still under 80

06-29-2016 07:58 AM - permalink

joey4420

Well thought the pulley would work, sadly it has helped but still having the same issues. I have also made a makeshift ram air duct around the nose opening to the radiator forcing all the air through the radiator that comes in. Looks like I may have a radiator issue.

06-30-2016 04:51 AM - permalink

Xack

You may need to address the fan and shrouding too. Your efforts to increase pump speed worked but only a fraction of your desired result. With Centrifugal Impellers increased pump speed will at some point cause cavitation and thus be a limit to flow. You may still have room to decrease pulley size to improve further.

06-30-2016 05:52 AM - permalink

joey4420

I currently have a 4000 CFM dual fan setup that is fully shrouding the radiator fins.

07-02-2016 04:55 PM - permalink

Xack

It sounds like it's probably not air flow... I'm assuming the fans pull the air in and not push it out the front. water level or air in the system, perhaps. With everything else being good, it does sound like water flow cavitation issue or flow leveling off well before RPMs max. This is all just a guess as I think about it. ???

07-03-2016 07:16 AM - permalink

joey4420

I appreciate any thoughts Xack. Tank is as full as it can be, no air in the system as I have bled it and even vacuum filled it once trying to make sure no air. Shouldn't be cavitating, at least if it is it has to be better than when I bought it and it didn't have a water pump backing plate. The reason I am now thinking radiator (oh and I also shrouded the nose of the car to ensure all air went through the radiator) yes fans pull air not push, after a hot run (keep in mind it only gets hot above 2500 rpm's) I checked the temps and the radiator from top to bottom was 205 degrees F (top) to 114 degrees F (Bottom). I an sadly 95% sure it just isn't flowing. What really sucks is I paid a radiator shop to test my radiator out of the car, then even said they would put a camera in it to check everything. Well I found out later the shop I went to doesn't have a very good reputation for quality work.

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