Top Fuel Fuel Control

[butelja]

Just out of curiosity, does anyone have a general explanation of how the air/fuel ratio is controlled and tuned on the fuel injected supercharged engines used in top fuel and funny car drag racers?

 

[evelrod]

I watched the 50th Anniversary drags at Pomona yesterday and I saw a fuel injector line come loose on a dragster. It looked more like a fire hose to me. I think these 5000+ hp engines are WAAAAAAY beyond simple fuel ratio. Something like 5 gallons of nitromethane fuel in 5 seconds !!! Simply amazing.

Rod

 

Top fuelers burn 13 gallons (give or take a little) in the burnout, staging and 1/4 mile pass. The ratio is controlled by a meachincal fuel injection system on top of the blower. Nitromethane is 53% oxygen, which is the reason you can burn so much of it so quickly. The oxygen is it's only virtue, other than that it is a very poor racing fuel. It burns slow and is very prone to detonation.

Those 14-71 blowers make 40 psi of boost and to maintain that boost at 9600 rpm, it takes over 800 hp just to turn the blower.