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4th October 2020, 10:28
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#191 | |
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This is my second home
Rover75 and Mreg Corsa. Join Date: Nov 2006
Location: Sumweer onat mote o'dust (Sagin)
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Quote:
From my observations, the threshold for this effect with the original buff PRT was around 2000rpm. This stat is said to have the 'medium' spring rate. The Lotus forum suggested it's in the 1500-1750 range. It's seen when you suddenly increase the engine revs. I've observed it best (with the buff one) when travelling reasonably fast (but well below 2000rpm) in a high gear, then changing down while maintaining the same speed. This negates any effect of airflow rate through the radiator. So temperature variation is more about the 'hot & cold' coolant mix through the PRT. When the revs suddently increase, the pressure differential opens the relief valve. The effect is immediate and the temperaure dips and doesn't then rise at the rate you'd expect from increased burn rate. Obviously you need to have the diagnostic screen showing coolant temperature. From the spring compression rate I measured on the bench, LR's grey version wasn't any lower than the buff one ('medium' tension). I was hoping for the 'low' spring rate of the grey version to be very obvious using a digital weighing balance. It wasn't, so I asked the LR supplier for advice on the relief pressure. They didn't even know what I was talking about, so I returned their PRT unused. The black one I currently have fitted has never demonstrated any pressure effect at all. The Lotus SELOC site says this one has the 'high' relief pressure, which explains why I've not observed anything up to 4000rpm. I've never pushed it beyond that. I like the sound of the grey specifications, and would fit one if I can see the evidence, so do get back with this if you can. TC |
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