two step and roots?

Just curious. Who is using the two steps with the roots stuff? I have purchased a air throttle but I am curious is the two step any better???Pro's and cons?

 

I ran both system , and i prefer 2 step , simpler to install and works great
BAE with convertor

Claude

 

2 step

Outlaw 68 , I run a dedenbear air on / air off to hold the blades open enough to bring car to appox 5000rpm. I then 2 step it at anywhere between 3000 and 5000 rpm. Mike is right about backing up though, no throttle. Seems like it does the same thing as the pros do by bringing up the rpms manually. Hope this helps. I run a big chevy 14/71 hh with big duke heads. Jody Stroud TD 9325

 

Glad to hear that someone else could not get the air throttle to work satisfactory. I didn't like it at all. Went to a 3 step (burn out-starting line-Upper RPM) and I'm content

Blessings........Ron Clevenger.

 

That's weird you guys had troubles w/ light throttle I ran the Biondo unit that hooked to the arm on the blades, and the throttle cable pulled the Biondo solenoid down to open the blades. W/ no air, your pedal did nothing. You guys must've used it on the other side and not as part of the throttle cable???

 

Has anyone used a 2 step on a D PSI?

 

Mike is right about an air cylinder setup being "spooky". When we used an air cylinder, we has a 2 pole switch on on our data logger which also controlled the cylinder. That way the system was not active until thr first bulb was lit. Another note on this, it is also possible to use both an air cylinder and a 2 step together. This gives you exact control of starting line rpm, plus the throttle can be set only part way open and the throttle action can be controlled if desired.

 

Air Throttle

Mike and Ron,

I am interested in how you had your air throttle hooked up. Mine works great and I believe it to be incredibly safe. If you had a bad experience, I would like to know. I may want to look my set up over closer. I am all about safety.

I would be glad to share some pics of my set up for you to share your opinions on. You guys place really great posts and your opinions would be appreciated.

I also have some detailed set up instructions for mine and pics that I would share. Mine is really close to a clutch set up at the launch and the motor is not bouncing of a 2 step.

I have never tried a 2 step with our blown deals and don't know much about them.

Brad Hiatt

 

Note that the "spooky" problem only applies to cars with clutch, with trans. brake there is no problem.

 

Brad H., it was a Biondo unit. But I think most of them are the same...just different stickers. I installed it at the foot pedal. Never did like the feel of it from the beginning. Tried it a couple of outings with different adjustments (air pressure and bleed off rate) but it just didn't perform to my satisfaction. I only tried it because of a couple of intake explosion$ and I thought it was related to the blower, but it wasn't. It may be a generational thing. Just did not like the lack of control at all times.
We do race against competetors that use them with sucess, but I'll pass.

That's my story and I'm sticking to it

Blessings........Ron Clevenger.

 

I was worried about valve train failure and patches..etc etc. Seems it would be excessivly hard on the rods and mains. Remember I am a converted NOS guy, so I look at it like SPRAY ON THE TWO STEP... and Thats a NO NO...But I know I have heard some guys doing it. I just dont have the budget that the pro teams do and dont want to be tearing shit up...
I appreciate everyones input.

 

We use it with a C Rotor... Works Great! We run a Bruno Drive, and a AJ 481X. The car reacts quicker and more consistently with a 2 step, as its not effected as much by altitude and weather conditions.

 

ignition interupt hard on belts and cranks

I know of one racer who was breaking blower belts with an ignition interrupt for launch. When he stopped running the two step, he stopped breaking belts. And I saw another racer who cracked his crank through the counter weight. He ran ignition interrupt on the start. If you have a marginal crank and an old blower belt, it may be a problem. Although a lot of teams do run the two step with a blower successfully.
If you do run a throttle launch control with mechanical fuel injection, there are some interesting fuel delivery problems caused by the bypasses that may be initiated at part throttle. We have some diagrams in our FI book. Just keep in mind where the throttle is at launch and where the barrel valve spool is at that throttle setting. And see where the fuel is all going. It can get harry especially if you make a minor change to throttle position at launch.
Bob Szabo, author of Fuel Injection Racing Secrets and 5000 Horsepower on Methanol
www.racecarbook.com