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Speedy Squirrel Speedy Squirrel is offline
Rocket Scientist
Join Date: Jun 2008
Location: Detroit
Posts: 882
The RUF CTR solution is great for a twin turbo layout, but it is hard to make that layout work for a single turbo. Plus, it requires those inlets in the upper rear fenders, which I think ruin one of the best parts of the vehicle, aesthetically.
Air-to-air intercooling is great for what the 935 was built for, which was endurance racing. The engineering of heat exchangers is a fairly precise engineering discipline, and has been for a long time. One important factor in engineering heat exchangers is the velocity of the cooling flow. During the age of the 935, the average speed around the La Sarthe was well over 120 MPH.
Many boosted high performance cars now use air-to-water, since their average daily driving speed is usually something less than 120 MPH. Air-to-water provides several advantages:

1. Compactness Water has 10 times more thermal capacity than air. This means that the charge air to water heat exchanger can be made much smaller. This can allow for improved flow paths to the engine (less pressure drop), and smaller manifold volume for the same amount of cooling (better throttle response, better packaging).

2. Performance Because the cooling fluid is water, the charge air heat exchanger and the cooling fluid radiator can be optimized for their respective task. For instance, the fluid radiator can have round passages, thin fins, high fin density, and preferential mounting. The charge air heat exchanger can have more passages and thinner walls. All of this can be exploited to reduce system size, and lower charge air temperature. I believe a well-engineered air-to-water system can easily outperform the SECAN air-to-air intercooler that was used on the GT2 EVO, and still fit entirely within the whale tail.

3. Efficiency In the old days, water pumps for air-to-water systems were either engine driven, or single speed electric driven pumps. With modern pump systems, either the speed, the on time, or both can be controlled electronically. Under high demand, coolant flow can be increased/optimized to handle the required cooling, without using up excessive power. Further, at low speeds, cooling can still be achieved, to a greater extent than air-to-air systems.

From what I know, I see no reason why an air-to-water system could not be developed for a 930 that could handle 500 600 HP, fit entirely within the whale tail, and out-perform the SECAN intercooler.
Old 02-28-2014, 02:00 AM
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