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Hey Paul,

Based on your book and our many discussions, it looks like the largest water radiator I can practically fit in front of the engine will be a pair (cross-counterflow)  of about 20x16” radiators, using a 45 degree mounting angle.  The plumbing is feasible in this configuration.

The stock RX8 radiator is 17.5x26x2”, with a core area of 14.5x25 = 362 sq inches of frontal area.  It is about 1.5” thick.  Total cooling volume is 543 cubic inches, but this is way too wide to fit.

The Neon radiators are 24.7x14.7x2”, with a core area of 23.5x11.7x1.5”.  This is 274 sq inches and 411 cubic total volume. They use a 1 3/8” fitting as does the RX8.  However they are still too wide.   If I cut 4-5 inches off one end of the neon radiator to make if fit, I would have about 20x11.7 frontal area of core.  This is 234 sq inches or 351 cubic inches.  Two of these would total 468 sq inches and 700 cubic inches.  The two of these together will be have more frontal and volume area compared to the stock radiator.

My questions are:
Will reducing the radiator size (each will have a volume of 64% of stock), plus having twice as long of a fluid path through 2 radiators, possibly present a significant resistance to water flow?

I assume we are still looking at intake ducts of about 15% of the frontal area, which in this case would be 35 square inches.  This would allow ducting for other  functions (air intake, cooling tube and oil radiators).  I have a couple of decent options for the oil coolers, and should be able to have larger areas and volume than stock.

Should we be using smaller main pulleys  to under drive the water pump and alternator  due to a target RPM of about 7,000?

Thanks,

Scott Gettings

Your core thicknesses are off. The Neon is only about 1 inch thick or less.
Some modern rads are 5/8th inch thick. The old rule of 600 cubic inches does not apply anymore.
The Kays and London wedge or even better S shaped diffusers are far more important.
The Kechemen and Weber will work if the duct is long enough. It is now more like 450 cubic
inches.

Which of these configurations are most like what you have in mind?
Mounting the rads back by the gear box is a good idea using the Kays & London wedge
looks like the best. The ducts can be quite thin alongside the engine. The prop can suck
some air out.


Paul Lamar


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