Blown Injected and a two step.....

Looking for options and opinions here:

What is the optimum two step for starting line RPM control and burn out limitations?

We are running a 509 cu in blown injected alcohol application with a clutch and a B&J. The ignition system is a Pro mag 44, points box and solenoid shut off.

I have looked at the MSD website and have seen their suggestion using a two step off a switch (such as the cluth pedal). I have also seen a Dedenbear air piston set up which is preset to length and controlled by either a clutch switch or a tranbrake button to maintain pedal length and throttle position.

Some would say just use the tach, an ear or ???? but I am looking for 'thoughtless' consistency. I have heard so many of the TAD TAFC and Pro Mod cars raise their launch RPM's to constency so how do you all do it?

My query also includes will there be a hydraulic issue using the two step rather than a mechanical limitation?

Any sugestions?

Thanks for your help, Scott

 

msd two step pluged into the points box and wired to work of the clutch pedal along with a fuel bleed(not nessacary) is all you need air cylinders and associated stuff over complicares a simple system

 

Thank you Bird for the info, I didn't much see more and with a limited mechanical engineering background I wonder if there are some unanswered possibilities. I have seen great responces in all of the other posts so maybe someone else can join in more a little enlightenment and spend a couple of moments here on this one.

I am not totally convinced that MSD has solved all problems in filling cylinders equally and then firing them arbitrarily; this must cause some hydraulic issues- even minute (are we also causing the coil some discomfort?).

Our project is using Brodix heads, Dart Big M with a moderate cam (.714/ .722 with 108 lobe separation); finally we are turning the 6-71 at 32% over with 36' of timimg. Although the 44 is very efficient and we really aren't under a load while staging I still see issues with the unburnt fuel being compressed in the cylinder without ignition.

Can someone offer a little more insight as to whether this practice of dropping cylinders is or is not a recipe for disaster?

I am also interested in the throttle stop such as the Dedenbear but if I can find the addition of a clutch pedal trigger and wire in a two step as a simple choice, well that is pretty simple math.

Again thanks again for the reply and to those who also read the post.

Scott

 

2 step

You have to do what makes you comfortable. no matter what anyone else is saying or doing. But you can take fuel away from the system if you like while you are on the 2 step.Mine has a jet can in it so I can change the amount returned. We used it when we flowed the system, so got a good idea what we wanted. to do. Don

 

I never heard ever of anyone having hydralic problems on the chip, without a fuel bleed, at worst you will cool your heads/cylinders a little, what does your 6/71 make at staging rpm? the 44 will have no issues with igniting the mix no matter how much you put in the cylinders
an alky nos fuel solanoid wired in with the two step will make a decent fuel bleed, the air ones can be a little slow to close sometimes depends on your batterie situation

like said by someone else its ultimatly up to you and what your comfertable with ,all i can say is what works for us and just about every other guy running serious pro mod ect the tad/tafc dont use them although maybe the do now its all about rules,

 

Depending on how much fuel your putting through it at WOT, you may or may no want a fuel bleed...if you have too much fuel in it, bye bye blower belt. Darren Mayer makes a complete setup, www.dmpeinc.com, he can help you out as he's fairly experienced with it on a blown motor. He also makes the clutch switch for the 2 Step.

Brandon Booher
NHRA TAD #34

 

Thank you to all for your help and interest. The DMPE site not only was helpful with the kit but also with several other interesting items.

Again, thank you all.

Scott