what gear is better for drag racing, 3.73 or 3.42?

 

M6 or A4?...Generally A4s use 3.73s and M6s go with 4.10s...I used 3.42s in my 10 bolt for years, Put a Strange 12 bolt in last year with 3.73s....I'm an A4...Depends also on goals for the car, cam size, tire height, etc...

--Alan

 

Too many other factors.

Engine rpm range
Cam grind
Torque converter stall if an automatic transmission
Transmission gearing
Tire size
Vehicle weight

You need enough gear so that you cross the finish line at or just before your red line in high gear, not OD.

If you cross the finish line before you red line in high gear you need more gear so 3.73 would help. If you run out of rpm before you reach the finish line then less gear is needed and 3.42 would work.

 

My original diff had 3.27 gears with 26" tall tires and I was able to run high 11's at 117 mph. I'm now at 4.56 gears and 30" tall tires and I shift at 7000 rpm.

 

He said the better gear for drag racing. As you want to go thru the traps as close to your peak power in your 1:1 gear as possible it doesn't matter what trans you have. It's your power curve and redline that matter.
Generally speaking that means 4.10s but as posted above, peak power rpm and tire size are the main determining factors.

 

As Al stated, there is no answer to the way you have posed the question. My Camaro has 3.42's and my race car has 4.86's. Both trap mid 140's and both gears are "best" for each application. the variables are tire size and rpm range, in that case.

Rich

 

trap 140.... my god that is insane

 

Ya but fun. I have to try and keep it under 150 mph this year so I don't have to install a parachute.

 

I bet they came up with that 'chute requirement back in the days of drum brakes. I can easily stop in maybe half the run-off area at my local track, without the 'chute. I do have one on the race car though. I think a more reasonable speed would be 175 or so in this era of good brakes.

Rich

 

Yeah a lot of NHRA/IHRA rules are for equipment from the past. Like battery boxes in the world of sealed gel batterys.

 

Actually the rule states you need a parachute at 150 mph but don't need to use it. I saw an old Nova run 12 seconds with drum brakes that almost needed a parachute to stop.

My car still has the factory disk on the front. I have large ford drum on the rear. I don't like slowing down hard to take the first turn off but can easily make the second turn off.