Kind of a swag question. Nobody can be certain what RT would be and then say x rpm changed it x amount. You do know what you should be and if you hit light or not. You also know or have very good idea if the rpm was right high or low.

Yes With 2 step and sle non of this should change. Guess some that do not use both or either of these will have better idea.

Let say how much do you think your rt change with 300 to 400 rpm change?

While most bracket racers run the two-step and/or sle. Quite a few seem to not be fan of sle. Some setups do not like two step and some guys don't for that matter.

This message has been edited. Last edited by: wideopen231,

Back when delay boxes were not allowed in Div 1

I used rpm mostly to adjust RT's off the bottom bulb....no blinder

The human element and maybe traction make it very inaccurate but I had a base setting....3200 rpm and adjusted up from there.

The rev limiter box I had did not go lower than 3200 or 3000 and had little dipswitches to adjust rpm....I don't recall who made that but it was a pita to adjust at night....could barely see it and needed something to move the switches like a pen or a little screwdriver.

Mid to low 9 second cars....2 different cars and I won with both...

One week was near red at 3200 and the next week couldn't hit the tree for chit.....ended up at 3600-3800 and won !

My old rule of thumb was if I have 2 RT's in a row that are somewhat close....I don't care what I did in the past....I adjust off that...

200-300 rpm higher was definitely gonna speed up your RT if the traction was ok....but not a lot....

OK, thanks.

Working with throttle position for rpm. Using stop and rpm varying some. The 200 to 300 comment is very helpful. Need to refine for closer numbers. Hoping to go to mention stop and be plus or minus x amount.Looks like need to aim for plus or minus about 150 or less w/o 2 step.

I agree with SCDIV1 on all of that. RPM does make a difference as does brake pressure when foot braking. And Tire pressure and water temperature. And seat time like we were talking about in another thread.
Ideally you would like everything the same every pass and only change one thing at a time. We do not always have time for that though.

As much as .030 anyhow. You certainly need to do all you can to tighten up the leave rpm in order to have consistent lights. We had a rev limiter problem on my son's car and it was almost not worthwhile competing or even trying to get data.

Bucky how much was rpm varying? Seems alot of react.

quote:

Originally posted by wideopen231:
Bucky how much was rpm varying? Seems alot of react.

4400 to 5800

quote:

Originally posted by Bucky:

quote:

Originally posted by wideopen231:
Bucky how much was rpm varying? Seems alot of react.

4400 to 5800

Ok that is lot more than I was having with the tension stop I have. Getting 200 to 400. 200 is probably not a problem but the 400 I can see be enough to make a noticeable difference if sitting up for less tan .010. Which in my case probably would be ahope like hell I hit it.LOL

I used to bump the rpm up or down a 100 RPM and thought it was worth about .010 when I was footbraking. I used a throttle cable to set the RPM so I know it was pretty accurate.

Car setup would make this vary IMO.

Hopefully with new off dealy allowing me to run sle/2step and control when it goes full thorottle while also limiting 2 step actually kicking in.. Getting rpm exactly same every shot will not be problem. Hope being key wors. LOL