throttl stop ratio?
 

Guy's kind o new to the stuff and have 2 dragsters for the kids. I'm having a hard time figuring out the throttl stop ratio's.
here's an example
Run number one have 2.00 in the timer and car runs a 9.321
Run number two we have 3.00 in the timer and the car runs a 9.488
we are on a 9.50 index. So I under stand that you divide the timer change by the et change and looks like this
1.0 Divided by .167 = 5.988 so would that be a 6 to one ratio?

Ace

Re: throttl stop ratio?
 

Yup. Im assuming your cruise rpm is fairly hi ?

Re: throttl stop ratio?
 

I've only ran the car once and I think its some where between 4200-4600 rpm's

Ace

Re: throttl stop ratio?
 

I think Billy hit on your possible problem.. try setting it at 4000.. and maybe have the first timer come on at .100 into the run.. then try your 2.00 and 3.00 runs..

Don't know where you have your first timer coming on, but that also makes a diffence..

Re: throttl stop ratio?
 

first timer comes on .030 in the run and the shift timer shifts 1.50 in the run. I also have a #1 stop thats air and has both primary and secondary plates. I'm a little comfused as how to read the number of turns on this. I think the less turns out will drop the rpms

Ace

Re: throttl stop ratio?
 

I like to bring the stop on at .100 like Charlie said , I tried to bring it on at .030 , granted I only tried it for one run but im pretty sure the car didnt get out of the beams before the stop came on. I recall feeling like I hit it good and looked up to see an .040 light so I put it back to .100 and was .003 red next hit. If you are running a dominator carb with an under carb stop I wouldnt drop rpm below 4200 ,IMHO. The farther you screw the knob out the lower the rpm will drop, its easy to set by taking the air out of the stop cylinder and put a spring to hold stop blades shut, then put it against the trans brake. Your rpm will be 150-200 rpm higher when your rolling down the track than when on the break, so if you want 4200 set it at 4000 on the brake

Re: throttl stop ratio?
 

Billy

Thanks for all the info. I just got done reading the tips on Biondo's web site and what you said. I'll change both cars and start over again. I wonder how much this would change the Crew-Chief prediction as well?

ace

Re: throttl stop ratio?
 

I dont know much about the Crew Chief , but I would assume if you change your setup, you will have to start over with the Crew Chief input if it gathers your ratio for you. I think that stuff is cool and may be helpful to me but i dont use any computer programs.

Re: throttle stop ratio?
 

Once you make all these changes, you will need to start another new database for sure so you can establish a new baseline. Making those kind of changes and adding the new runs to database you already have will really get you really lost (and frustrated), guaranteed. Start a new one and maybe rename the one you already have "Bad Runs". With your new database, if you get a run that doesn't make any sense, that's the database ("Bad Runs") you'll save it in for your records. That way, all your new "good" runs will make more sense allowing the program to give you more reliable predictions.
Good Luck!

-Don

Re: throttle stop ratio?
 

I know what your saying on the crew chief deal between good and bad runs. Biggest problem is that the weather changes so much in a short period of time its really hard ti figure your ratio. In colorado it will chaing 200-400 feet in just a matter of minutes. so its really hard to make a back to back run and get good data. Most of the poeple here have years ove experince and lots of racing under their belt

Ace