2-Blade 18" Steel Fan by Hendren Racing Engines--Multiple Colors
18" 2-Blade Steel Fan with 32 degrees pitch.
Dyno testing proves that it requires the least amount of power to drive the fan while also providing better cooling in most situations. It is best when used in conjunction with a fan shroud. Most applicable to dirt cars. It is suitable for use with all crate engines, including 602's, 603's, 604's and CT525's.
Frequently Asked Questions--answered by Hendren Racing Engines:
Q: What kind of gains were shown?
A: The gains and losses are in comparison to no fan at all and the 19" GM four blade fan, PN 405442, on our chassis dyno. So I'm talking rear wheel numbers, not crank numbers. The 19" GM fan, if 100% positively driven (meaning no belt slippage) will take away 20rwhp every time, vs no fan at all. An 18" four blade fan with 4 degree's less pitch, with no slippage, will gain you back 8-10rwhp (i.e. it only robs 8-10rwhp). The two blade 18" fan, same scenario with no slippage, will gain you back another 5rwhp. So essentially what you end up with is a loss of 5 horsepower at the rear wheels, vs no fan at all on a 604 crate engine. As a side note, a 15" four blade fan will also only take away 5rwhp vs no fan. But we had issues with cooling while trying to run it. So the 2 blade 18" did the job.
Q: Just out of curiosity, have these been tested at all with the 602 engines?
A: No I've never tested these specifically with the 602. But I can say with 100% accuracy that the results would be close to, or identical.
Q: Do you run this on your car?
A: On our own house car, we run this same blade all throughout the summer months. Of course we have a good fan shroud, which is suggested in any application. We found, and many customers found the same results......with a good shroud, the two blade will actually cool a bit better. We are only assuming that the better cooling is because the two blade allows more air to flow past the blades at higher RPM. It other words, you eliminate a "wall effect", for lack of better description.