by roman » Mon Feb 05, 2007 9:12 pm
yes, david, the liquid intercooler is it, i was talking about the heat exchanger for it, or the pre rad, if you will. thats why i used this set up on my car as well.
it would be unwise, however, to underestimate the cooling recquirements. for 300 hp the air cooling need is roughly 40 kw. at a dt of 50 c° this means 13 l/min of coolant flow. i dont think you would want to heat up the cooling liquid to 90 c° though, so at dt of 10 c° its 65 l/min of coolant flow to get an in temp of 40 c° and an out temp of 50 c° (pre rad, that is). now if you imagine cooling 40 kw at an dt of 25 c° (ambient= 20 c°), it works out to 0.046 m2 of air at 100 km/h. the core then should be 2 x 0.046 = 0.9 m2 and due to pressure drop and inefficiencies probably 0.18 m2.
that is 20 x 90 cm at an average speed of 100 km/h. this also casts a light on the pumping requirements. no way to get this through the a/c radiator for example.
the above is for a steady 300 hp. on the track this will only be 200 hp on the average and for street driving, where you occasionally floor it, the pre rad becomes marginal.
by the way the buffering capability of 5 l at dt of 5 c°of coolant is roughly 2.4 seconds. it doesnt sound like much, but it will sure cut of the worst pikes in intake temp (the ones, you can hardly even measure, because they occure that fast).
