Power Grid timing curve on blown Hemi Pro Mod, shifted, 2 disk clutch

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Marco Maurischat, Sep 13, 2017.

  1. Marco Maurischat

    Marco Maurischat New Member

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    Hi, run a Blown Pro Mod in Europe. Still running a 2 disk clutch. so fare we trying to run the clutch as"hart" as possible and look it up as sonn as possible don´t really use it as a tuning tool. Try to tune the engine with the Grid only. Starting at 0.10 sec. taking timing out with a soft curve to pass the shake zone. Usually degree by degree up to 10 or 15 up to track conditions and that smooth back in . Usually have full timing back shortly after 1 shift. I heard from other guys that they taking timing out really abrupt up to 15° ( up to track conditions) after clutch locked up and full back in after clutch locked up in second gear without "drawing" a curve at the Power Grid and even not ramping timing smooth up and back in as we do. They try to fine tune more with clutch weight.
    We are still struggling from time to time with spin or shake like most are faced with but not sure jet if we are on the right page with how we are doing it so fare.
    Any advice would be great, thanks Marco
     
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  2. Mike Canter

    Mike Canter Top Dragster

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  3. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    Marco,

    I'm sure you will get a bunch of different answers on this because there are a number of different theories on timing curves.

    I don't think there's one 'right' way other than what works best with the rest of your combination and the way you are trying to run the car. Gearing, fuel system and fuel management, car set up all come into play, and the timing curve is trying to get the most out of the combination of those elements.

    Also, I think too often we focus too much on the "number," that is how much timing we have out at a given time, without remembering it is relative to what we are pulling from. Pulling 10 degrees from a combo that has a 165 degree head and already at 800 degrees by 30' is going to be a lot different from a 135 degree head that is only 700 degrees. Camshaft profile, heads etc., also come into play because it affects where the engine makes torque. A lot of the technology out there today is aimed at making upper rpm power, so even though it may be a more powerful engine, it may make less torque at 7500 than what you ran 4-5 years ago. This all goes back to the 'relative' aspect of it, especially if someone tells you 'well I take 15 out at .4.' Same concept can be applied to leanout jets, but that's another discussion.

    Now here's my theory on ramps. The shorter the wheelbase, the more important it is to ramp the power out (with the exception of at the initial hit). I think if you knock too much power out too quick, you run the risk of setting the front end down and getting the car flat footed, unloading the rear and/or sticking the tire, driving over it into weak shake. Now it doesn't have to be a huge ramp, but any slope is better than a "step" straight down.

    I think throwing all the power back in in a flat step up is problematic for several reasons. If you are at a stop sign on a wet road, are you going to stomp the pedal to the floor or are you going to ease back in. Same concept with what we are doing with the aggressive ratios we try to run these days. Every blown alcohol combination generally has a range from 1.5 to 2.0 that, depending on the track conditions, you are not going to knock the tire off no matter how much power you throw at it. Obviously with an all-in step, you have to be on the other side of that line. I think this all-in step leaves some on the table, because a ramp could have been started much earlier, gradually putting power in where you had power out. Often times you will have an earlier point to get the power in this way vs just shoving it all back in at 'x' seconds.

    Another thing that we see with these big swings in timing to get it through the shake zone is even with a ramp, it will flare the clutch or converter when you ramp it in. If it doesn't it usually will try to hike the front end up.

    All of this said, I have heard of some pretty fast cars in Pro Mod and Top Alcohol having step timing maps instead of ramps. These are just my opinions based on my years of power management. If anyone wants some further help, shoot me an email at will.hanna@insidetopalcohol.com.
     
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  4. TOL

    TOL Active Member

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    Will, would like to explore this topic a bit, with you and with others.

    What are your thoughts about totally locking up the clutch at the hit (smoothly of course) , and then managing (shaping) the drive line torque at all times thereafter with pure engine torque management controls?

    Basically, take the clutch/converter shear voodoo out of the equation, and then just use engine controls to map the torque to the rear axle and tires.

    Turn the clutch into a simple on/off "switch", and then use controls to handle the rest of the considerations.

    The locked up clutch would have to have sufficient torque shear capacity of course, for the worst of the worst possible conditions, say max torque in least gear.

    Plausible or not?......

    Thx.
     
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  5. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    Something has to give to get the car going. Either the clutch/converter or the tire. If you run a real tight converter or a lot of base, you will see minimal flare of the motor, and it will lay over and 'angle' up to the shift more so than a looser set up that will 'flash' to a certain rpm, then kind of flat line over to the lock up/coupling point where it ramps to the shift.
    I don't know that you could achieve total lock up, but there are certainly teams that are trying to get real close to that. That's why some TAFC teams are leaving north of 8000 now to get that plate load from the counterweight up (along with boost/inertia).

    Running a lot of ratio and having a good amount of clutch, I prefer the motor get a little ahead of the clutch/converter early so it's slipping there, and not just trying to spin the tire. Don't get me wrong, I love a 'controlled' spin as much as anyone, but the more static or with a tighter pump/stator combo, you have less of a buffer there and any miscalculation will result in it smoking the tires at the hit or very early.

    There's plenty of times I have a great idea on paper and the car just wants something else.
     
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  6. turbo69camaro

    turbo69camaro Member

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    I am doing this on a turbo pro mod car 3 speed in the 1/8 4 speed in the 1/4 have a good timing program for low gear. lock up the clutch 1.5 into the run all the timing is in about the same time. I use the grid to pull 5 timing out at the 2 nd gear change and ramp it back in in .5 Clutch is locked up 1 to 1 after 2 nd gear i can make 6 runs with .015 wear 3 disk AFT 10'' run very little base 5191 disks bronze floaters TMT coated flywheel /donuts
     
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  7. rb0804

    rb0804 Member

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    1.5s into the run is pretty late. So the clutch breaks apart on the 1-2 and is locked solid on the 2-3? I'd like to see a graph if you have one that is not too super secret and you are able to share. I'm thinking Walt is talking about catching the engine at .5s like a pro stock car. I use 1.8s lockup as a good go down the track goal. At 1.2s the car is pretty quick and still pretty consistent. Anything less than that and it seems that I have problems with tire shake.


    Walt I sent you an email some time ago about the 477 combo you were asking about. Haven't heard back from you yet.
     
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  8. TOL

    TOL Active Member

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    Thanks everyone for your thoughts. Rob, you were reading my mind. Couple and lock early, and then use the ECU to torque shape. Got your email about the 477. Will catch up offline shortly. Good night all.
     
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  9. TOL

    TOL Active Member

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    W
    Is this with foot release or an automated release mechanism? Thanks.
     
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  10. turbo69camaro

    turbo69camaro Member

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    clutch is locked up on 1-2 shift on a good track we can lock up the clutch in low gear in .7
     
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  11. turbo69camaro

    turbo69camaro Member

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    LOL foot and manually pulling levers no gizmo's
     
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  12. comp altered 632

    comp altered 632 New Member

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    Are you timing the points on the run from the driveshaft starting to move or clutch switch release ( launch on power grid) ?
     
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  13. comp altered 632

    comp altered 632 New Member

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    When taking timing out i take it out without ramp .but start putting / ramping it back in instantly with no time delay .this makes for a relatively long ramp back in.does this make sense
     
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