8v-71 Blower drive ratio

[3408cat]

I'm trying to come up with some low dollar horsepower gains - pistons, turbo, and coolers are not within my budget). What I was wondering that instead of the normal advance the timing, big injector black smoke thing, what about more air and more fuel. Are there different blower drive ratios for 8v-71 engines ? Most truck 8v-71 are 318 hp. Can I set up my engine to have the right torque curve for a 4 spd manual trans and have 318 hp by changing injectors and blower speed ?  Thanks, Bill.

[luvrbus]

3408, there 3 or 4 different ratios for the blower drive along with different blowers if you like I can look it up for you.FWIW the A timing doesn't help much on a bus with a 4 speed     good luck

[3408cat]

Luvrbus, Is my thinking correct I have access to free junkyard 8v-71 engines. If I knew how to tell which ones are which by serial number or engine code I'm sure I can find the parts I need to change mine. Would you know where I could find any of that info ?

[Don Fairchild]

Bill;

There are three gears that were used in most of the V engines, a 38 tooth a 39 tooth and a forty tooth gear. The 40 tooth slowed the blower down 5% from the 38. The only one that will speed up the blower is the step up gear found on some 6 & 8 V 92 naturals.

Don

[luvrbus]

3408, here are the drive ratios I found so far for a 8v71

205:1
200:1
195:1
175:1 used on industrial N/A engines for operation above 10,000 ft

I will keep digging through the books and see how much each ratio changes the air box pressure and what blower produces the most pressure and air.
   


good luck

[3408cat]

Thanks guys for helping me with this one, Do you think I will gain as much as I'm thinking = 25 - 35 hp