I've heard that MPH is a better indicator of the power or speed of the car and ET is more of 60' and driver skill, am I right on this, or am I wrong on both? What does ET show as compared to the MPH for a 1/8 or 1/4 mi run?

 

your pretty much correct.

EXAMPLE- turbo supra with 600rwhp runs a 12.3 @ 129+mph. we can tell buy the mph that the power is there to prolly run low 11s/ high 10s. but by the ET and 60ft, you could conclude that there was probably some traction/launching/lag problems in there somewhere.

thats a good AND common example.




jon

 

MPH should remain the same if the car hooks hard and gets a low ET or if it gets wheel spin and gets a slower ET.

Mph shows how much HP the car has. After it gets through any traction problems and gets into high gear, it's a brute HP pull to the finish line. All the shifting should be done in the first 1/8 mile.

ET will show if there's any traction problems. The lower the 60' time, the quicker the car will run.

Both contribute to the end results though. If you change your shift points and the car makes more or less hp, the ET and MPH will change because of the change in the power curve.

HP can change from run to run from other variables. Even if you shift at the same rpm every time there are other things that will affect the run. The weight of the car gets lighter as you burn off fuel. The air changes (barometric pressure, humidity, temperature), they all can change how much HP an engine produces. You could get a head or tail wind which will change how much the engine has to work. The temperature of the engine can change how much HP it makes.

Proper tuning is done by watching how much mph the car makes in the 1/4 mile. Every run needs to be a s close to the last one so any changes can be seen. That's why they always say to do one change at a time and see what it does. If you change jets, timing and shift point and go down in mph, you won't know if anything helped or hindered the change.

 

Heh... I ran a slew of 12.8's @ 103 mph yesterday. Car is having some issues @ 6k - but wanted to particiapte in the racing @ SLP Day so I was short shifting @ 5k. Had to shift into 5th @ about the 1000' ft mark.

Boooo