Porker:
I had a talk with one of the mechanics at Manthey yesterday, they said they consume so much of their water tanks, after 6 laps even their 14 liter setup is finished. I never thought it consumed that much. He couldn't really say what the difference in power is when the water is depleted, but he said it is substantial. Do you notice the same?

It depends how hot the post turbo/intercooler intake temperature gets maximum power is usually there up to about 50DegC the program has tables which will gradually reduce the boost and the timing and increase the fuelling per each incremental intake temperature increase this will keep the exhaust gas temperatures within spec and will keep the intake temps from going too high.

Have a look at the tables below these are for my 997 Mezger motor which was running VTG turbos at the time you can see how at 50.25DegC IAT it starts to reduce boost from 2000rpm upwards so at 5000 rpm boost is at 0.979980 of its programmed optimum so if that should be 1.5bar it would now be 1.47bar

If the ambient is 30DegC and there is no water spray left the intakes could easily rise to 45DegC above ambient ie 75DegC so on these tables at 6000rpm onwards the engine would get 0.914917 of optimal boost which if was on a GT2RS its 1.5bar would be reduced to 1.37bar.

Timing and feulling will have similar tables with of course everything interacting. The engine could lose 150+hp if the temps can't be controlled that would still mean 550hp which is a lot of horsepower and heat to manage.


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997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2018 McLaren 720S 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.