Turbonator SMEC codebase

[ShelGame]

Sounds nice! So, with the spark cut, it will keep the RPMs in a narrower range while the limiter is active right? Any possibility of a "soft touch" or similar style limiter in the future that cuts spark to alternating cylinders instead of turning them all off or on? I don't know enough to know if something like that would be possible with our ecu's, but it would be nice if it could be done.

Well, since our cars use a distributor, you can't really control which cylinder will get cut. It will just cut the coil feed until the rpm drops, then restore the feed, etc. I really have no idea how hard or soft it will be. But, the fuel cut rev limiter can't control the rpm to within 2000rpm (at least not when loaded up on the converter while staging an auto car). Which is far from what should be possible. It certianly is no good for drag launches. I can control my right foot more accurately than that. I'm hoping to see only a ~200rpm band with the spark cut. I may have to add in some sort of ramp sensing or PID logic, though, to really get it to hold accurate rpm. Hopefully this is at least a big improvement.

[Tony Hanna]

Well, since our cars use a distributor, you can't really control which cylinder will get cut. It will just cut the coil feed until the rpm drops, then restore the feed, etc. I really have no idea how hard or soft it will be. But, the fuel cut rev limiter can't control the rpm to within 2000rpm (at least not when loaded up on the converter while staging an auto car). Which is far from what should be possible. It certianly is no good for drag launches. I can control my right foot more accurately than that. I'm hoping to see only a ~200rpm band with the spark cut. I may have to add in some sort of ramp sensing or PID logic, though, to really get it to hold accurate rpm. Hopefully this is at least a big improvement.

I'm pretty sure the aftermarket boxes can do the alternating cylinder limiter even with a distributer type ignition. I'm not sure how they accomplish it though. If I had to guess I'd say it's timed somehow so that it cuts the power just long enough to kill 2 cylinders, and then at a different time in the next cycle so it fires those two and cuts the other two. However it works, they claim that the cylinders that don't fire on one cycle will fire on the next to eliminate plug fouling, backfires, etc... Supposedly it makes for a very smooth, very precise limiter.

Though if you're expecting a 200 rpm band from just the spark cut, it sounds like it should be precise enough to make an alternating cylinder limiter not worth bothering with.

[zin]

Well, since our cars use a distributor, you can't really control which cylinder will get cut.

From what I recall, a MSD doesn't cut a specific cylinder as such, it just randomly cuts on and off to keep it from being an "all or nothing" kind of limit. If the coil could be cycled on and off (PWM perhaps?), that should produce a "softish touch" limiter. What do you think?

Mike

[ShelGame]

From what I recall, a MSD doesn't cut a specific cylinder as such, it just randomly cuts on and off to keep it from being an "all or nothing" kind of limit. If the coil could be cycled on and off (PWM perhaps?), that should produce a "softish touch" limiter. What do you think?

Mike

That's how it works - the coil get scycled on and off at specified RPM limits. But, it's also that limit-based system that's part of the problem. The engines momentum keeps the revs going up well past the setpoint. Also, I think the fuel cut probably allows a 1-2 cycle delay in cutting combustion. Where a spark cut should be immediate. I'm going to try it tonight. We'll see...

[Tony Hanna]

That's how it works - the coil get scycled on and off at specified RPM limits. But, it's also that limit-based system that's part of the problem. The engines momentum keeps the revs going up well past the setpoint. Also, I think the fuel cut probably allows a 1-2 cycle delay in cutting combustion. Where a spark cut should be immediate. I'm going to try it tonight. We'll see...

I think what Mike was getting at is that instead of completely turning the coil off at the high setpoint and back on at the low setpoint, the MSD boxes will fire the coil at random intervals when the RPM are between the two setpoints so that instead of the limiter being either "full on" or "full off" you're actually getting cylinders firing at random intervals in the space between the setpoints. If I'm thinking right, this would act to hold the RPM in a tight range without the "surging" that's present with an all or nothing type limiter.

I'd think a setup like that would help with the momentum problem as well since it would act to maintain the set RPM by firing occasionally instead of letting it drop below the low setpoint and going immediately to all cylinders firing (which causes it to go back to full power and immediately trys to drive the RPM past the high setpoint).

[ShelGame]

I think what Mike was getting at is that instead of completely turning the coil off at the high setpoint and back on at the low setpoint, the MSD boxes will fire the coil at random intervals when the RPM are between the two setpoints so that instead of the limiter being either "full on" or "full off" you're actually getting cylinders firing at random intervals in the space between the setpoints. If I'm thinking right, this would act to hold the RPM in a tight range without the "surging" that's present with an all or nothing type limiter.

I'd think a setup like that would help with the momentum problem as well since it would act to maintain the set RPM by firing occasionally instead of letting it drop below the low setpoint and going immediately to all cylinders firing (which causes it to go back to full power and immediately trys to drive the RPM past the high setpoint).

Well, that's certainly feasible. You'd want to detect a rising or dropping RPM, though, and only pulse the coil when the RPM is dropping. If you pulse it when it's still rising, then it would only serve to reduce the resonsiveness.

I tried it last night. All I can say is that the spark cut definitely kills the engine quickly. I couldn't get the car to start because I had the polarity wrong on the coil cut code. I fixed that but ran out of time. The car is loaded up for Indy now, so I won't get to try it out until next week sometime.

I guess I have time to work on 'softening' the limiter...

[Tony Hanna]

I'm really interested to see what you find out.

[zin]

Thanks for clarifying Tony, that's what I was trying to get at.

Mike

[Tony Hanna]

Thanks for clarifying Tony, that's what I was trying to get at.

Mike

Cool. I hoped I was thinking right.

[1966 dart wagon]

I was wondering if there would be a way to wire up a type of clutch switch that would tell the computer that the clutch is in, enabling you to have antilag/2step from a roll if you wanted? I know honda's with AEM EMS do this, i though it would be a cool thing if it was possible.

[ShelGame]

I think the clutch switch is alreayd wired in to the same input as the P/N switch on the auto cars, isn't it?

Anti-lag already works from a roll, anyway. It works during staging OR anytime you go WOT. Say you're cruising down the freeway, not in boost, and you go WOT to pass - anti-lag kicks in.

What good would the 2-step be in a situation like that?

[GLHNSLHT2]

I've got a clutch switch wired up to my system that allows the 2 step to activate. I only want it to activate when the clutch is in. I used a spring loaded door hing from Homie Depot and a brake light switch to get it to be adjustable so that it activates right after the clutch starts to disengage. Why would you want anti-lag or the 2 step to activate at anytime you go WOT only? I don't want anti-lag activating when I'm trying to pass a car. I want the timing cranked up and the car to rocket around the car I'm passing.

[ShelGame]

I've got a clutch switch wired up to my system that allows the 2 step to activate. I only want it to activate when the clutch is in. I used a spring loaded door hing from Homie Depot and a brake light switch to get it to be adjustable so that it activates right after the clutch starts to disengage. Why would you want anti-lag or the 2 step to activate at anytime you go WOT only? I don't want anti-lag activating when I'm trying to pass a car. I want the timing cranked up and the car to rocket around the car I'm passing.

It doesn't go at WOT only. Actually, the 2-step doesn't go at WOT at all. Only anti-lag. Both work while staging.

I guess it really depends on how big the turbo is on whether or not you'd be better off using anti-lag at speed. I think if you have a really big turbo, you'd be better off with it on. With a Mitsu, I doubt you'd notice the difference either way.

But still, why would you ever want the 2-step working at speed? What would the purpose be of limiting the rpm while shifting gears? If it's something guys really want, I can figure out a way to add it in. I just don't see the purpose.

[Tony Hanna]

But still, why would you ever want the 2-step working at speed? What would the purpose be of limiting the rpm while shifting gears? If it's something guys really want, I can figure out a way to add it in. I just don't see the purpose.

Rob,
Take a look at the "no lift shift" feature the new Cobalt SS TC is available with. I'm not sure exactly how it works, but supposedly it interrupts the power for a fraction of a second as the clutch pedal is pressed to allow for easier powershifting without the extra stress on parts. Maybe he's wanting to use the 2-step for something similar?

[GLHNSLHT2]

yea I tried using it like that. You've got to have the clutch swith adjusted just right so that you don't cut power before the clutch is disengaged or let the rpms jump another couple hundred rpm between shifts. I haven't had enough track time to try it with or without to see if it's hurting or helping. I can shift damn fast and the seat of my pants feels like I lose time with the no-lift shift vs. not using it. But the Cobalt comes with it, you can get it for SRT4's too.

What would be sweet is a staging limiter with an on off, anti lag with on or off, and a no lift limiter with on or off. All 3 activated through the clutch switch. A staging limiter because I have to set my launch rpm at 2750 but now it's probably gotta be like 2200, Anti-lag for well anti lag, and a no lift limiter set at whatever my shift point is. That what I can heel and Toe downshift and not have to deal with turning the current 2 step off to do so.

[Tony Hanna]

yea I tried using it like that. You've got to have the clutch swith adjusted just right so that you don't cut power before the clutch is disengaged or let the rpms jump another couple hundred rpm between shifts. I haven't had enough track time to try it with or without to see if it's hurting or helping. I can shift damn fast and the seat of my pants feels like I lose time with the no-lift shift vs. not using it. But the Cobalt comes with it, you can get it for SRT4's too.

What would be sweet is a staging limiter with an on off, anti lag with on or off, and a no lift limiter with on or off. All 3 activated through the clutch switch. A staging limiter because I have to set my launch rpm at 2750 but now it's probably gotta be like 2200, Anti-lag for well anti lag, and a no lift limiter set at whatever my shift point is. That what I can heel and Toe downshift and not have to deal with turning the current 2 step off to do so.

I think (and hopefully Rob will correct me if I'm wrong) that the big issue isn't the code for things like that as much as the limited number of physical inputs and outputs that are available to use.
What do we have, AC switch, cruise control switch, brake light switch, and park/neutral switch for inputs?

Then you've got to look at whether or not the extra code you want to run is ok beside the inputs primary function. For example, on a car with functional AC, you wouldn't want to use the AC switch for 2 stage boost control because you'd also be running the AC either on high or low boost (depending on switch polarity). Along the same lines, you wouldn't want to use the set or resume switches on a car with functional cruise. That cuts your options even farther.

[GLHNSLHT2]

could they all use the same input? It's been a while since I've looked at how they are activated. I know I'm using 2 inputs right now, one for the 2 step, and one for the high/low boost (which doesn't work ) but I can't remember which ones I'm using.

[Tony Hanna]

could they all use the same input? It's been a while since I've looked at how they are activated. I know I'm using 2 inputs right now, one for the 2 step, and one for the high/low boost (which doesn't work ) but I can't remember which ones I'm using.

I'm not really sure to be honest. I would guess that it would work, but I haven't tried it. Rob would be the one to give a definite answer, or somebody that's tried to run more than one extra feature off of the same input.

[ShelGame]

You could run all of the optional code off the same input, if you wanted. But then, they'd all be on at the same time.

[GLHNSLHT2]

well is there a problem with them all being on at the same time if they're all activated only when the clutch is depressed?