Can somebody give me a starting point to slow my dragster (7.30 now) down to 8.90 Looking at time slips the car runs 4.40-4.50 in the 1/8

I'd like for the stop to come on 1/2 -1 second in....

I understand every car is different but just a place to start is all I'm asking for....

Why are you looking to go on the stop so late?

I suggest to start
4000 rpm cruise
On at .1
Shift at .5
Off in the 2.20-2.40 area

That is based on your 7.30. 4.40-4.50 is normally a good bit faster than 7.30

Come on .2 tenths out, cruise 4000-4500 and on for 2 seconds or so.

Biggest thing you need to take the time to get right is your cruise throttle setting. The RPM is not as critical, what you want is to not gain or lose any RPM while on the stop.

Hummm....apparently I'm going to have to shift on time instead of rpm. Seems weird to shift while on the stop. Won't the car speed up when it goes into high gear at a set rpm?

Thanks for the help....

quote:

Originally posted by imakehp:
Hummm....apparently I'm going to have to shift on time instead of rpm. Seems weird to shift while on the stop. Won't the car speed up when it goes into high gear at a set rpm?

Thanks for the help....

If your car is actually running in the 7.0-7.3 range it will be hard to get that car off the stop in first gear consistently. Getting it in high gear on the stop also helps control the cruise rpm.

What size motor and carb?

quote:

Originally posted by SP 124X:

quote:

Originally posted by imakehp:
Hummm....apparently I'm going to have to shift on time instead of rpm. Seems weird to shift while on the stop. Won't the car speed up when it goes into high gear at a set rpm?

Thanks for the help....

If your car is actually running in the 7.0-7.3 range it will be hard to get that car off the stop in first gear consistently. Getting it in high gear on the stop also helps control the cruise rpm.

Why would I lie about my et?
I just had a discussion here about my cars jacked up et vs mph vs 60' times.
I have put a new convertor in and new tires to hopefully get everything back in line. Or at least closer to normal. Whatever the fuc could be considered normal in this sport.
I'll set-up shift on time, shift it while on stop, 4000-4500 on-stop rpm and 2 seconds on stop for a start. Thanks for the pointers.
I've never liked t-stop racing but that's all thats available out west anymore. And damn little of that.

quote:

Originally posted by Mark Yeager:
What size motor and carb?

580 something and a single 1250. Actually I remember I bored the carb for bigger blades. Only reason I remember it is I just realized I have to do the same thing to the t-stop I have or it's going to block off some of carb venturi.
But I have to believe went from 1050 to 1250. I built this engine going on 10 years ago now. Hard to remember everything exactly. And my notes are scattered between my old shop and here.

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

Go on the stop very fast and also shift on time very fast

The sooner you go on the stop and shift get's your 60' slower and you get behind which is what you want....

If you use 4500-4600 cruise rpm thats good BUT

A big carb may be not work as well as a 1050 or 1150......won't come off the stop as well.....

My car went 7.50's wide open

I made some runs experimenting on T&T days and you'll need to do the same...

Plate stop or inline.....I ran them all.....Carb and injection....Gas an alcohol....

I don't have my logbooks handy but have tons of runs and stop info in them....

the question you have about shifting on time vs rpm. if you shift on rpm your stop rpm (while on the stop) will creep up 500 to 1000 rpm over the duration of the stop time. No good.

Shifting on time will allow the stop to lay at the chosen rpm and not creep. also as stated it is going to slow the 60 down. shifting on rpm will have a faster 60.

i personally dont like going on the the stop less than .20 . i have seen cars at .1 loop the tire and be in the beams when the stop starts on so i dont take the chance.

you should be fine with a 1250 carb but as stated 1050s and 1150s tend to stop better. definately no bigger than a 1250. as far as stop rpm that all depends on your carb. if you can get 4000 and it is clean, doesn't dip when it goes on and doesnt stumble when it comes off then that is good. some carbs like a little more rpm on the stop but you can play with that.

i rule of thumb it this
4000 = 2:1
4200 = 2.25:1
4400 = 2.5:1

i usually shift .5 behind my stop. so if on at .20 shift at .70. you can adjust the 60 by moving the shift point. that move typically is 2:1. meaning every .02 you move the shift up or down will move the 60 .01. i have played with all of this crap.

there are 1000 ways to throttle stop. just find what your car likes and do it. it doesn't have to be like everybody else. i will say that you can go out 1.0 or more to go on the stop but to kill the et you are going to have alot of time in. do it early in the run and your time will be much shorter. the more you are wide open the better.

ep-converters also have a lot to do with stop duration as well.

wow, lots of info !!

Thanks guys...

As said before pick a # for the stop to come on and a # to shift at, and tune from there it takes lots of runs to get a data base but when you do it gets easier to set up.

Just reprogrammed my Digital Delay box to shift on time rather then rpm. Set it at .5 after t-brake release for testing and it seemed to work correctly. But, man I'm telling you 1/2 a second is almost instantaneous. LOL
Funny I just changed convertor, tires and launch rpm to try and get my 60' times down. Even installed a wheelie bar so it wouldn't yank the front tires and redlight. Only spent a couple of grand just to neuter it all before I even got to run it.
Ain't racing a blast??
I don't care, I'm happy to have a couple of races coming up.

I've shifted as early as .2
Stop on at .02
Your shift time will effect your 60' time more than going on the stop time....a lot more

I've seen guys barely move and the stop goes on and shift very qucikly

Watch some NHRA S/C racing and look at the incrementals for time and speed

There's a lot of ways to go 8.90 but getting some separation and getting behind early in the run GENERALLY is a plus....

Average speed at the 1/8th is around 135......bigger speed guys are well over 140

Injected cars mostly go to a dead idle and have real slow 60's and a carb guy can do that too...
They usually shift after going back to wide open like making a normal run.....I never really tried that but ran my best speed ever going back to a near idle with a Terminator and shifting early....

My car 60'ed a best or 1.07's......for S/C I liked being in the 1.60 or sower range but usually was in the 1.50's......

You do what works.....and is consistent and predictable......I ran almost nothing but S/C for a lot of years......very little bracket racing...