Does RT effect ET?

[009crewchiefboss]

This may be a stupid question for me to ask but what the heck.
Proposing that it is a normal launch...no spinning etc...
009crewchief

[Tom 396]

No, it does not. Take care. Tom Worthington.

http://www.hotrodder.com/Tom396

[009crewchiefboss]

Here's the thought process:
Theoretically: a driver leaves at the exact same time on the tree
1) one pass the 60ft time is 1.435 with RT of .008
2) one pass the 60ft time is 1.440 with RT of .015
3) one pass the 60ft time is 1.438 with RT of .012
Maybe the real question I have here would be... does 60ft variance effect RT?
If a car can move to the 60ft beam variably quicker or slower, is there a relationship between that variation and RT. I've heard lots of guys say that there is a relationship with 60ft time and ET...even 330ft time and ET. I've even heard rules-of-thumb that .00x (60ft)=.0x(ET). I can understand this due to it correlating with the vehicle's rate of acceleration.
Wouldn't the same hold true on a much smaller scale in relation to 60ft and RT?
I am wondering if anyone has developed a rule-of-thumb based on 60ft time variance to use as a check-and-balance to estimate actual RT...as a more mathematical way determine the driver's reaction to the bulb.
In other words using the examples above:
The vehicle actually varied .010 in 60 ft time. Could one effectively say that if the 60 ft times stayed the exact same that :
1) the driver reaction was actually .002 red
2) the driver reaction was actually .005 green
3) the driver reaction was actually .002 green
Now I have a headache:sick:
Just wondering,
009crewchief

[383nova]

My 60' times are usually the same whether i'm .05 on the tree or .00 on it provided i barely bump the stage beam on the same time. If u jump in deep it will take away e.t. because the roll out is shortened leaving u less of a start to get rolling before the stage beam goes out starting ur e.t. Anderson's red oldsmobile is a half a tenth slower when he deep stages vs. regular staging.

[Tom 396]

Actually, I've heard a different theory on how the launch impacted reaction time. As in, if the tires initially spin, it actually decreases RT.

I can't testify to the accuracy of the theory, because I'm never going to be good enough to state "all other things are equal". However, the theory goes something to the effect that a wrinkled sidewall actually slows the car stopping the RT timer more than a sidewall that hasn't flexed (and hooked up perfectly).

Personally, I prefer to just stick to believing that RT does not impact 60' ET and that any impact that 60' ET has on RT is beyond my control anyhow. Take care. Tom Worthington.

http://www.hotrodder.com/Tom396

[staginglt]

Maybe the real question I have here would be... does 60ft variance effect RT?


Slightly, if the car is not set up properly and is being inconsistent in the 60', but it's not a 1:1 ratio by any means. If a 60' was off due to spinning or bogging, then it will certainly show up in R/T.

the theory goes something to the effect that a wrinkled sidewall actually slows the car stopping the RT timer more than a sidewall that hasn't flexed (and hooked up perfectly).


That very well might be the case with some big-tire, high horsepower cars. I've also heard of R/T's moving around depending on whether the car 'drives' out of the beams, or is picking the wheel up out of the beam. I never would've imagined that my car was picking them UP out of the lights, but Angela Macy caught it in this great pic. Note the Pre-Stage light is out, and the Stage light still has some glow in it.
http://s168.photobucket.com/albums/u194/AngelaMacy1967/2008%20Piedmont%20Pro%20Am/?action=view&current=100_4091.jpg

I ran 8.5x26" M/T's on my Duster for many years, w/ about 18psi. Typically, if it ever spun, about half of the 60' variance would show up in the R/T.

With my Volare, I've been *trying* to get it to react quicker. I switched to M/T Radials, which don't wrinkle anywhere near what a bias ply does, but surprisingly, there was little if any improvement in the car's rollout. When a Radial spins, it doesn't recover like a bias ply, so your 60' will suffer far, far great than your R/T. Even blowing them off instantly usually only kills my R/T by .02 tops.

So, as they often said in the early days of the internet, YMMV. (Your mileage may vary).

In terms of staging depth, I take tiny bumps from pre-stage to stage, and can continue bumping after lighting the stage beam to reduce R/T. Each bump in my car is about .010 to .015 in R/T, but I'll only lose .003 to .005 in 60' even taking 2 bumps. It's often a useful tradeoff.

[DCInc]

[QUOTE=staginglt] I never would've imagined that my car was picking them UP out of the lights, but Angela Macy caught it in this great pic. Note the Pre-Stage light is out, and the Stage light still has some glow in it.
http://s168.photobucket.com/albums/u194/AngelaMacy1967/2008%20Piedmont%20Pro%20Am/?action=view&current=100_4091.jpg

QUOTE]

Doesn't the picture actually prove the opposite...if the car was picking them up out of the beam with no forward movement, both lights would be out. Since the pre-stage is out and the stage is on that means the cars is moving forward while picking up the front wheels.

I have seen cars on video that actually put both pre-stage and stage out at the same time and basically no forward moovement in the car.

[staginglt]

The stage light is on, and the tire is off the ground. I consider that 'up' out of the beam, as opposed to the tire being on the ground for the first 7 inches and then driving into the wheelstand.

I think it's more likely to see the type of launch you described with transbrake or stick shift cars.

In any case, it's a really neat pic! :biggrin2:

[DCInc]

Gotcha - different thought process. I would want a footbrake car doing exactly what your picture shows..forward and up but not too "up"! :biggrin2:

What I described is defiently picking them up out of the beam. Both lights go out at almost the same time. In slow motion you can actually see the pre go out first but only by one or two frames. At 7 frames a second thats not much.