grogan545

I have done a little research on how the big 3 auto mags do their testing.There are some differences which affect the acceleration times.
C & D Uses no rollout (Timer starts as soon as the car moves).This causes approx .3 sec diff(slower)across the board.They also correct for weather conditions to equalize times for similar cars tested under different weather conditions

Motor Trend uses a 12" rollout(similar to drag strip) and they also correct for weather conditions.

R & T uses a 12" rollout but does not correct for weather conditions.This method is the most like drag strip testing.Their times are about what you can expect if you do your own testing using a GT2 timer or equivilent.A few months ago R & T tested several of the acceleration timers.They were all fairlyaccurate when set up according to the instructions.

I think R & T will probably get the best times for the 550,less than 5 sec to 60 and about 13.4 sec and 106mph for the 1/4

Bimmer32

Can someone explain to me how two car's can reach 1/4 at the same time but one travels at a faster mph? I think it was explain somewhere, but I couldn't find it.

jet190rs

Like if car #1 is really light and takes off the line really well, and the car #2 is heavier but more powerful, so it has a slow start but actually catches up at the finish line? Car #2 would be travelling at a higher speed.

Bimmer32

Like if car #1 is really light and takes off the line really well, and the car #2 is heavier but more powerful, so it has a slow start but actually catches up at the finish line? Car #2 would be travelling at a higher speed.
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Thanks jet190rs. I didn't think about the rabbit and turtle race.

znod

Thanks grogan. Definitely useful info to me. Maybe you should switch to a 12" roll out. You 5.0 probably would have be 4.9X

cobradav

Glad you did this helps in comparos and sorting out differences. Thanks

doug_999

I've found that C&D with their weather and alt correction tends to come up with the fastest most consistent time.

grogan545

Your welcome guys.

Waiting for the mags to test the 550I to see if my preditions are close.Traction problems for the 550 may present a problem due to increased torque.Therefore the 0-60 time may not be much faster than the 545I.It is impossible to get best times without disabling ESP & traction controls.This could present a wheelspin problem on the 550 unless stickier tires are installed.

znod

Your welcome guys.

Waiting for the mags to test the 550I to see if my preditions are close.Traction problems for the 550 may present a problem due to increased torque.Therefore the 0-60 time may not be much faster than the 545I.It is impossible to get best times without disabling ESP & traction controls.This could present a wheelspin problem on the 550 unless stickier tires are installed.
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Right on--unless, for example, the testers let a lot of air out of the rears. And, of course, they will make several attempts and should learn to hook up reasonably pretty quickly.

On the issue of fastest times, I did some small-sample statistical tests implying the C&D's results are faster for 0 to sixty. My quarter mile tests did not show much. I am going to redo it all someday when I can increase my sample sizes significantly. Check my results out here (post #80).

grogan545

Thanks grogan. Definitely useful info to me. Maybe you should switch to a 12" roll out. You 5.0 probably would have be 4.9X
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You are correct about the switch to 12"rollout, but the drag strip #s were so close to the GT2 with the 10' rollout that I hesitate to change.Maybe I will reconsider so that our times will be directly comparable