Blower Overdrive for Altitude
I am running a Littlefield 6-71 with an Enderle Birdcatcher tuned and running great at Irvine Lake on pump gas. I would like my boat to run just as hard at Lake Tahoe as it does at Irvine Lake.
I would like to understand how much more I need to overdrive my blower to maintain the same performance.
My question is, is there a formula or ratio for calculating overdrive for an increase in altitude?
My current setup is:
Pulleys: Crank 61 teeth, Blower 55 teeth, 10.9% overdriven
Fuel Pump: 80-A
Main Jet: 118
Lynn at Littlefield Blowers suggested going to a 52 tooth blower pulley, which would put me at 17.3% OD. Jim at Enderle feels that I may need to overdrive the blower in the neighborhood of 25% and still lean it out with smaller jet and nozzle size.
Irvine Lake is at 791 feet elevation.
Lake Tahoe is at 6,224 feet elevation.
Thanks in advance,