2 step launch?

[zerodegreec]

is a 2 step used for launch control in WRC? From what I have found out they use a fuel overfeed setup for anti-lag. correct me if I am wrong (please) but for the anti-lag they use exhaust temps to detonate the fuel before the turbo and using the gas expansion to keep the turbo at full speed.

Could you not use a 2 step setup for your anti-lag as well? If you can keep your mass flow up with a 2 step by pulling spark, and overfeeding fuel you get the best of both worlds, full boost with limited engine RPM.

I am sure some of you will roll your eyes with my lack of knowledge, I'm trying to sort out the setup and reasons for the setups.

[zerodegreec]

over 200 views and nobody has info??? anyone know of a forum with Mechanics or technical info? :)

[Daniel]

What's a two step launch?

[SubaruNorway]

I yet to find anyone who will explain the ALS completly so good luck on that!

[OldF]

Maybe this link gives some answers.

http://www.kosunenracing.com/eals.html

[Nenukknak]

is a 2 step used for launch control in WRC? From what I have found out they use a fuel overfeed setup for anti-lag. correct me if I am wrong (please) but for the anti-lag they use exhaust temps to detonate the fuel before the turbo and using the gas expansion to keep the turbo at full speed.

Could you not use a 2 step setup for your anti-lag as well? If you can keep your mass flow up with a 2 step by pulling spark, and overfeeding fuel you get the best of both worlds, full boost with limited engine RPM.

I am sure some of you will roll your eyes with my lack of knowledge, I'm trying to sort out the setup and reasons for the setups.

Maybe if we'd know what the question was we could give an answer. "Full boost with limited engine RPM", that's the point of having ALS.

So what is your question?

[zerodegreec]

2 step is a method of rev limiting a engine that allows full mass flow through a engine by pulling spark randomly from the cylinders and basically dumping raw fuel through the engine. Its used in drag racing on some of the big cars. What they do is pull the spark and slightly pull some fuel. What this does in effect is keep the boost up at near max pressure but your engine output power is kept below the torque converters limit. Thus on a launch you get near full boost and instant response once you disengage the 2 step. (A 3-STEP also exists and this is used for burnout, then pre-launch and then the actual run.)

Now you can take a car and put in a rev limiter tune. When you put your foot to the floor it will limit the boost by pulling fuel and air. By doing this you get the RPM you desire, but your boost is low, your mass flow is slim to none and you still get major lag at the light.

So now please read the orig post and I hope you will know what I am asking. If not, sorry its not a new concept although its not well known.

The reason I am ultimatly asking is my cousin is going to be putting a 2-step control into his truck for next seasons drag season and we were trying to find out how we could make the most out of the technology. Trying to keep 800hp with over 1000fp/lbs of torque under control at launch is a challenge to say the least. Rally cars can do it, why cant we?

(800hp stroked hemi 6.2l 2003 ram pickup. Garret 75 squires turbo running 16psi boost.)

after next year with either a twin turbo OR replacing the turbo with a much larger one he should be into the 1000hp range without Nitro. :D

[zerodegreec]

thanks OldF Nice site. now if I could read the rest of it :p is it Finnish?

[Daniel]

Perhaps I'm missing something but WRC engines are not rev limited as such but are limited by the air restrictor on the inlet so it's a little bit different than a car with a rev limiter.

[SubaruNorway]

Perhaps I'm missing something but WRC engines are not rev limited as such but are limited by the air restrictor on the inlet so it's a little bit different than a car with a rev limiter.

Of course you have a rev limiter on a wrc engine or else you would blow it up.

[Daniel]

Of course you have a rev limiter on a wrc engine or else you would blow it up.

What I meant to say is that WRC engines are not rev limited by the FIA :) They are limited to whatever the manufacturer wants them to rev to.

[OldF]

Zerodegreec, use this http://translate.google.com/ web site to translate the text from Finnish to English.


There is rev limiting at launch.

http://www.kosunenracing.com/eals.html
Launch Control (HKS Pro and Power FC pro)
Decent ECU include traction control and a launch control for starting. Launch Control usually include also a traction control and ALS functions. Real traction control use wheel speed sensors to determine slip ratios of wheels. But the rules may say you can’t use wheel or axle speed sensors.
When the throttle is floored and the clutch is fully depressed, the launch limit is in effect and the engine will not pass the set rev limit. Antilag is used to built up at the 0.5 - 1.5 bar boost. The rapidfire machinegun and bang-bang sounds you could here damm far a away! Hopefully a racecar accelerate smoothly and as fast as possible, avoiding spinning of the wheels, ECU revlimiter protects engine failure due to overrevving. After the car is running at a certain speed, this stop work.
Why launch control? High power delivered by the engine to the gearbox and driven wheels cannot be easily managed even by the most experienced drivers. MoTeC does TC by using the gear speed, driven wheel speed and known ratios. There is a table of speeds and rpms to set. Easy and simple. Beware! You may get few hours timing the car and dialing in the launch control.
Example starting
revs set to 5800:

5800 rpm - start
5900 rpm - 10 km/h
6100 rpm - 20 km/h
6200 rpm - 30 km/h


Here’s another link where they tell about building the Mitsubishi Colt rally sprint car.

http://www.kosunenracing.com/ebuild.html# (http://www.kosunenracing.com/ebuild.html)

The video “Dyno ALS (antilag) testing” didn’t start, at lest not on my computer but at the bottom of the site is a video and I think the dyno run in the video is the ALS testing.

[Nenukknak]

Now you can take a car and put in a rev limiter tune. When you put your foot to the floor it will limit the boost by pulling fuel and air. By doing this you get the RPM you desire, but your boost is low, your mass flow is slim to none and you still get major lag at the light.


Yeah but this is were the ALS comes into play. The ALS makes sure you have high boost, while the engine is near idling, i.e. provides little to no power.

So I guess, ALS is the question to your answer. :s

[Zico]

Yep, ALS wasnt designed soley for launch control, calling ALS part of a 2 step launch control is a bit misguided, the fact that its there merely helps although its certainly possible that they have utilised ALS to control/feed in the boost gently off the start line.

ALS is a complex system, this is how it works.

Firstly, boost is controlled very acurately by using 2 fuel injectors as air valves, these feed the boost/atmospheric pressure to the waste gate actuator, allowing minute and very fast acting boost control.
Secondly, the normal method of controlling engine idle via an idle control valve, that bypasses the throttle butterfly is dispensed with, the static idle is set in the old fashioned way by a locked off bypass screw.
Thirdly, where the idle control valve used to be, a new valve is fitted that has a solenoid controlled valve (looks like an engine inlet valve internally) that can open/close the throttle butterfly bypass orifice very qickly.
Forthly, a miriam turbo shaft is used to withstand the massive increase in turbo temperature generated by ALS.
Fifth, there is no dump valve used on an ALS equipped engine, the whole point of ALS is to keep boosting the engine, even on closed throttle.
The way it works is that when you come off the throttle, for example braking hard into a corner, the throttle butterfly closes as per normal, once the boost drops to a certain level, the ECU starts to pulse the Throttle butterfly bypass valve, this has the same effect as you constantly stabbing the throttle on and off very quickly, this means that the engine is being driven by the ECU as though it wants to accelerate again, however this oscilation of the throttle bypass valve is happening so fast, it has the effect of allowing the turbo to stay spinning yet produces no additional torque to drive the car forward. The ignition timing is also controlled during this off throttle period to again reduce torque yet maintain boost pressure.
The effect of all this is that massive heat is generated in the turbo exhaust side, which ignites all the excess fuel, there is no deliberate overfuelling going on to explode the turbo impellar area.
The most modern of ALS systems on the current world rally cars are far more efficient than a few years ago. The turbo used in ALS equipped rally cars is smaller than you would see on a race car for two reasons. the first is that the FIA has a mandatory 34mm turbo inlet restrictor that limits air flow into the turbo, this means that it is pointless useing a large inlet turbine unit as the inlet could not flow any more air, secondly the lag would increase due to the inertia of the larger impeller.



Slightly Off topic- How well could an ALS system controlled by traction control sensors work for launches?... or is this the system you were thinking off?