alky rail
 

Hi,this must be the most infomative forum on draggin so I'll ask the question here. We run a 89 s&w rail with glide,476 bbc,trans brake, in nova scotia [outlaw racin, only safety rules],runs 8.3 on pump gas. As the rules of draggin require you to up the stakes each year we have a enderly stack injection and big pistons going in. My wife likes the transbrake but my big concern is, can we still run the stutter box ??? [fuel volume] If not, is there anything I can hook up to the transbrake to limit throttle position in staging; either electrickly or mechanical,adustable and repeatable.I'm a tool and die maker so ideas as well as products are wellcome............check out the car on youtube,linda neal dragster....thanks....Pat

Pat;

Bob Szabo wrote a FANTASTIC book about mechanical injection.

www.racecarbook.com

The book even covers the topic you're asking about.

The answer is yes, you can use a 2-step... Getting the correct a/f ratio however will require some testing. More than likely you'll also want a electronically activated lean out to work in conjunction with the 2-step.

This will allow you to tune the a/f ratio when your foot is on the floor with the 2-step is activated.

The other thing you can do (probably more expensive), is to use a pneumatic cylinder in conjunction with the 2-step. The air cylinder will be used to control how far the butterflies open which again will allow you to adjust the a/f ratio at which you launch at.

Hope this helps....

nice link there One Bad... thanks

also, Pat, check out www.hre.com nice forum, lots of fi info, but you gotta join for a few bucks, but well worth it for the info

also check out www.kenlowe.com.au
he has a fi book, also well worth the price,

Use the air cylinder. that way you can set the RPM to exactly what you want...no 2 step is required...basically activate the brake and the cylinder vents pressure.. put you foot to the floor and because the cylinder lengthens your overall throttle cable the butterflys will only open a certain preset amount... Good luck

Dak is right.... The system he is refering to is called AutoStart. You push a button before you roll in and the pedal will go to the floor to an adjusted RPM. Roll in, set the transbrake, hold it to the floor and when you release the transbrake button the engine will deck automaticly. Don

Just because I'm curious...

When you use the pneumatic control and the air density changes, do you re-adjust the butterflies, or do you just allow the RPM to change?

I set the stop every morning ....warm the car up and then activate the brake and check to see what the convertor stalls at.. typically when you start using this system 1 turn the bolt in or out 1 turn is @ 200 rpm..

alky rail
 

Thank you gent's, this is great information. Who makes autostart ? Every time I google that name I get remote car starters and I don't think Tech would like that.......Pat

Shiftnoid makes a line of products for controlling throttle RPM at staging...

https://haconten.appieshost2.com/app...rs++++CATEGORY

Dedenbear also has their line (scroll down mid page):

http://www.dedenbear.com/thrtl_cat.htm

Just make sure you have a means to enrich the system at part throttle, or you'll be launching way lean.

Not sure about Autostart.

Since we run a Pro Mag 20, we're going with the MSD 8973 and a 2-step. So much easier than having all that air plumbing.

throttle stop
 

thank you,thats me sorted out...see you at the drags !