OK Guys ... no takers on the last question. I'll try to be more specific.
The Powermaster site indicates that for circle track racing one would like a 1:1 pulley ratio; for drag racing a 2:1 ration and for the street a 3:1 ratio (where the alternator rpm = ratio*engine rpm)
Looks like the high continuous rpm of circle track racing allows a relatively low alternator rpm.
Now ... lots of varying philosophies about w/p pulley ratios. Underdriving by 20% or so can save some hp if you can tolerate a lessening of cooling. Probably not a really good idea for a GT40. I was thinking that a 5-6% overdrive might be worth trying.
That leaves the a/c compressor. Mine is a Sanden 508 (slightly large) and has a max sustained rpm of 6000. There fore one must underdrive this puppy just a little in order to stay within the design constraints.
The question comes down to how much to underdrive the a/c compressor? Looks like a 4" main pulley would give a max rpm of abt 7200 while maintaining a 6000 rpm rotational rate for the a/c compressor.
With that pulley, the a/c compressor will be turning about 2000 rpm at 70 mph with my G50/52. Sound reasonable?
I will check with Vintage Air tomorrow to see what they say and pass the info along.
Thanks,
The Powermaster site indicates that for circle track racing one would like a 1:1 pulley ratio; for drag racing a 2:1 ration and for the street a 3:1 ratio (where the alternator rpm = ratio*engine rpm)
Looks like the high continuous rpm of circle track racing allows a relatively low alternator rpm.
Now ... lots of varying philosophies about w/p pulley ratios. Underdriving by 20% or so can save some hp if you can tolerate a lessening of cooling. Probably not a really good idea for a GT40. I was thinking that a 5-6% overdrive might be worth trying.
That leaves the a/c compressor. Mine is a Sanden 508 (slightly large) and has a max sustained rpm of 6000. There fore one must underdrive this puppy just a little in order to stay within the design constraints.
The question comes down to how much to underdrive the a/c compressor? Looks like a 4" main pulley would give a max rpm of abt 7200 while maintaining a 6000 rpm rotational rate for the a/c compressor.
With that pulley, the a/c compressor will be turning about 2000 rpm at 70 mph with my G50/52. Sound reasonable?
I will check with Vintage Air tomorrow to see what they say and pass the info along.
Thanks,