titanjc

I was browsing the "11 second N/A Mustang" thread and was noticing the quarter-mile ET's and trap speeds of the various posters in the thread, and it got me thinking: Say your car is already a mild N/A setup (CAI / UDP / CMDP / Tune), and you go from the stock 3.31 or 3.55 gears to a 4.10 or 4.30 setup. Will your quarter-mile trap speed be affected?

shaun_beauchamp

Sure will.

When you look at NA cars in particular, you notice many are in the 13.20 range, but the trap speed varies from 103 to 112 MPH. Pushing you out of the hole faster gets you to the line quicker, but doesn't necessarily generate higher trap speeds. Your gains are typically seen on the 60' times, and thus you could theoretically run a slower trap with a better 1/4 mile time.

You see these things all over the place. Some guys run high 12s with trap speeds in the 120 range. That's wicked tire spin and poor 60' times from a powerful setup.

It's all about putting it to the ground and keeping the car in the power band. The whole setup is a package. Sometimes you gear up too much and end up shifting right before the line and lose a little.

I'm no pro or even experienced in drag, just good at math and read a ton. Use a gearing calculator, engine power, 60' time and vehicle weight and you can pretty much calculate the trap speed and time.

There's a science to it, no doubt, but I've been more of a desciple than a pioneer. I run 3.55s in a mildly modded NA car and I finish at the line below my 110 mph top in 3rd at near 13.20. Usually I see 13.19 @ 105.8.