I wasnt sure where to post this so I figured I would start here.

I am looking for a general description of what two steps are and how they work and what they are used for. I heard about them a few times but wasn't really sure what it was. Just trying to expand my knowledge a little. And please, no jokes about country dancing

 

Mostly for a launch control in my case. It enables you to preset the rpm that you wish to launch at while at the starting line of the drag strip. In a turbo application it can be used to spool the turbo faster by letting unburn fuel into the exhaust and burn there to create heat energy to spool the turbo. Most aftermarket 2 steps drop spark on random cylinders, and then alternate to the cylinders that did not previously fire in order to keep one cylinder from loading up with fuel.

 

To elaborate on that a little, a two step allows you to put the pedal down all the way. This puts you at WOT. The engine RPM is limited and adjusted by the two step device. It allows for consistant launches with both and automatic and especially a manual transmission.

Andrew

 

is there a way to put one on an 05 gto yet?

 

I am sure we could. I just need the layout of the PCM and we can configure our Two step too it maybe.

Rick

 

ooowwwwww i like the sound of that!

its basically acts as an engine limiter on the line from the sounds of it. and you set the limit point for best luanch. once you go green light, how do you turn it off???

Chris.

 

i have one on my mustang that is competly for fun and stupidity

how it is set up in the tune is that it has a few things to all have to come together for it to work

1st: under 1 MPH
2nd: clutch In/Neutral
3rd: gas has to be pushed atleast at/alittle past the RPM limit

 

so how do you launch with a 2-step in an automatic? is it anything like launching at higher RPM witha high stall converter?

 

just been thinking about this! World Rally Teams (ie WRC) use a smilier system to get about 1bar of boost on the startline! but i think they just use the max rpm as the launch rpm as they run 4WD with REALLY REALLY complex diffs!

i think they run in parale with the Anti-lag (i love that stuf) to get the turbos upto boost and keep them there!!!!

still another motorsport application

 

Yeah, mustangs have it easy, they can tune in a 2 step, v.s. the LS1 where you have to buy one.

 

Back in my travelling days before the wife and kid, I used to work for Prodrive with the Subaru Rally Team. For the Subaru Rally cars, the anti-lag system(ALS) is used on the start line with the launch control. The Pectel systems on the Subarus worked like this: Speed must be less than 1kph, ALS must be set to hard-cut, clutch in, 1st gear, handbrake up, throttle at WOT. All of those conditions had to be satisfied or the launch control wouldn't come on. During launch control, the ECU retards timing 40+ degrees and trims the fuel very rich. With the throttle fully open, the revs would be held at 4500 solely through timing retard and fuel trim. Cylinders weren't cut. The result was that the fuel ignited as the exhaust valve was opening, which basically turned the hot side of the turbo into a mini turbine engine. The car would hold over 1 bar of boost on the starting line!

The ALS system had full control of the throttle. With the ignition timing retarded so far, the ECU would have to open the throttle almost halfway to keep the engine idling. It would idle at 1200rpm and have the meanest lope of any engine I've ever heard outside of a V8. On the Group N cars which had a blow-off valve, when the ALS system was shut off, there would be a whoosh of air as the closing throttle would cause pressure to vent out of the BOV. There was a price though, as the ALS was very hard on turbos. The open class cars would have their turbo replaced every two rallies and the GroupN cars twice a season. Turbo failures during the rally were common. The turbo ran very hot as you can imagine. We had a power steering pipe burst and spray fluid on the hot turbo where it ignited and caused a fire, putting the car out of the rally.

The launch control on the Motec M800 we used on our naturally aspirated formula car was a little more straight forward. There was a table of speeds and rpms. Below 2mph, the maximum rpm was set to say 8000rpm. From 2-6 mph, the rpm was set to say 10,000. Then from 7 mph and up, it was redline. There were more points than that, but you get the picture. It worked great in our parking lot and we spent a few hours timing the car and dialing in the launch control. Then at competition, it rained and the wet ground meant our numbers were no longer correct. A better way probably would have been to use the traction control, where you could set an allowable percentge of slip between the front and rear wheels before the ECU started cutting cylinders, but we ran out of time to develop it and I had graduated by that point. Lot of fun though.

Al

 

ProdriveMS, you lucky git! lol i have allways wanted to work for a rally team

you have to love the way top flight rally cars do business. they really are like F1 cars for rallying. and they run in all weather conditions!

so the launch control is purly from knocking the timing back??? thats gots be on bad *** 2 step setup! i saw one pikes peak car that dumped the BOV air back into the echaust manifold. it worked really well as wasn't to hard on the turbo! then he turnd on the anti-lag and then there was NO lag at all!

i know what you mean about the temps they run at though. i read about a ford machanic that went to remove the exhaust from a car as it came in. the exhaust was sooo hot (car tuned off for a couple of min) it set his NOMEX glove on fire!!!!! now thats hot! the article went on to say the EGTS were about 1100#C!!! they had to run a special Ti exhaust. they also had to run a cermaic turbine blade to whitstand the heat!

im sure STS guys would have any spol problems running thoes temps! lol

i have no idea how F1 launch control works but the Renault guys have it down to an exsact art! lol i know the Racelogic traction control had a launch feture that is siad to work really well.

thanks Chris.

 

that spark launch system is very similar to the "timing slew" system MSD developed a couple years ago... it was promptly outlawed by the NHRA.. lol
MSD originally designed it for open shore boats... they jump across teh water, and the prop regularly comes out of the water.. when that happens, the engine can dangerously over rev even with limiters... so they added that slew control so that it can only accelerate the motor so fast...

but yea, if i had open choice on a launch design, it would involve a combo of wheel acceleration and accelerometors... i wouldnt use the front wheel, as they may be off the ground.. lol

 

i take it that the lil device wouldve been perfect for bracket racing?

 

On my m6 car I latch the 2 step to the clutch switch,ie push in clutch,activate 2 step,when you release the clutch it turns the 2 step off.
You test various rpm settings on the 2 step to find the best 60 ft.

 

What do you mean by timing slew system? Do you mean a table where it limits RPM per MPH (or knots? in the boats case)?

 

slew as in the change (delta) of RPM... basiclly letting the engine accelerate only so fast....
i did a google search for you and found this from hotrod mag:

http://www.hotrod.com/techarticles/g...ction_control/

i just skimmed it, but it sounds like they're explaining how it works.

the i THINK MSD box number is 7531... so if you search on that, you might find more info.

 

Al.. If you are who i think you are... its great to see you! Last time i saw you was when you stopped in to visit with the 2004 team before comp. I'm sure you heard of the unfortunate accident of the 2006 Car on the day of the competition?

Anyhow, talk to ya later

 

Yup, you have the right person. I keep meaning to stop up there and see how the car is comming- one day I'll make it over there. I didn't hear about the 2006 car. Sounds pretty serious- what happened? Send me a PM please.

Alin

 

That's not really traction control. Real traction control is more complicated than that, but you do have to use the MSD 7531 box.