Radiator cap pressure

[Joe Gordon]

I have a Formula B car with a Lotus twin cam and am wondering what radiator cap pressure is recommended. Over the weekend I was racing and the water temps were hitting 220-235F. This seems high to me and currently the rad. cap is 13lbs. Any suggestions? Joe

[tzei]

You may want to put your Q also to Racing Technology forum.

[RTH]

13lbs is normal, does it lose any water (other than about normal 1/2pt expansion ) ? 80-90 deg C is normal at speed does it have a toothed water pump belt drive ? with a water pump pulley smaller that the crankshaft pulley, does it still have a thermostat ? is there great enough radiator area? what sort of ambient temp. is the car running in? Have you bled all the air out of the cooling system ? Is all the pipework unrestricted and of great enough diameter usually ID of about 32mm ? are you confident the head gasket is OK, checked cylinder compression pressures ? (usually soon pumps out water if there is a blow ) Good idea to use antifreeze or 'water wetter' in the coolant. Have you done a cooling system pressure leak test ? Is the radiator core clogged with rust etc ? Is the swirl pot above the height of the engine ?