Not to derail the thread on shifting on time. Iwas wondering what is the most et you have loss due to early shift rather it be spin when usinf rpm to shift or a shift that was below rpm when using time.

I have a side thought that using both might be best . I have a rpm activated switch that is doing nothing. Seems I could wire it son the timer sent signal to rpm switch would either shift bacause at rpm or delay it till rpm reached and then shift. Guess that is clear as to how I think it would work.

I know some swear by rpm and cpl others time including one member who has won his share of races. SO both can work and both can cause issue so it seems.

The few runs I have gotten I have been on time. According to data recorder never exact same rpm which means more or less fall back. Then Most runs have had an issue of shake or spin, so that may mean nothing.

How much different from shift other thsn were or when planned. Why would using both not owrk rather more effective or not.

Fwiw, on my old car. @ 2550 lbs with a sbc400, car ran 6.2/6.3 so not real high hp. My experience in trying this was. I could get away with it in early spring/late fall. Shift on time in the summer in Georgia just knocks the wind out of it and car got terrible inconsistency. I would suggest sticking to rpm unless t-stop racing with a high hp combination.

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I have a side thought that using both might be best . I have a rpm activated switch that is doing nothing. Seems I could wire it so the timer sent signal to rpm switch would either shift because at rpm or delay it till rpm reached and then shift. Guess that is clear as to how I think it would work.

Consider installing an MSD 7730 Grid. Can do all of this and more.

If you shift to high gear just after trans brake release, you'll be around two and a half tenths slower, than shifting at your normal shift rpm..

Not wanting to shift early. Just wondering how much it threw et off if car shifted early because of spin if you were using rpm . If anyone has seen a difference when shifting on time and there was good amount of rpm gap

I know all car will be little different, weight, hp and combo in general. I was just curious.

Makremark. I know grid will do all of that, but if can do it for now with what is here. I could try and see how well it worked now instead of waiting on the MSD grids number on the want list to make it to the top. Right now it is down a little ways,

that's why I asked the question I thought time would be the same every time regardless of tire spin or not but looks like RPM is what everyone likes

I am curious if you can legally use time vs RPM to control the shift?

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Originally posted by NortonRacing:
I am curious if you can legally use time vs RPM to control the shift?

Not sure why you wouldn't be legal shifting on time. IIRC the rule books for the 2 *HRA's both indicate which categories are allowed to use automated shifters / shift controllers, but I am quite certain neither says anything about whether they can or can't be based on time, RPM, or anything else.

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Originally posted by wideopen231:
Not wanting to shift early. Just wondering how much it threw et off if car shifted early because of spin if you were using rpm . If anyone has seen a difference when shifting on time and there was good amount of rpm gap

Well if it spun you lost ET there (usually)and shifting early added insult to injury and made it worse.
If your converter is on the tight side it will hurt it even more.

What I had in mind was using time vs RPM, meaning if you didn't hit X rpm by Y time. In other words the shift time and RPM would be variable based on when you hit certain RPM.

Norton is asking about senario I mentioned where both have to happen for it to shift. I am about 100% sure there is nothing about it illegal. It is not a traction control thing like a slew rate sensor.