Slow 60' Looking for suggestions

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by TADHemiracer, Apr 17, 2017.

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  1. TADHemiracer

    TADHemiracer Member

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    I am running a 285" dragster with a 526 hemi with AJ fuel heads, 14-71 roots, 3 disk 10" Crower pedal clutch 3 spd Lenco CS1 1.98 low and a 4.88 gear with 34.5 Hoosiers. So far it has only ran a 4.205 but same run did 178 mph in the 1/8. It is slow out of the hole but comes on in the big end. 60's between 1.018 and up. Last run was 4.38 with a 1.018 60'. Pulling 10 degrees out at the hit, ramping back in at .9 seconds. Any suggestions as to what I might try to help the 60' numbers? Data shows DS/wheel spin until about .50 then a dip where it couples. Max G's during the wheelspin until the dip. Took an additional 2* out, so 11* out and the 60" was even slower. Should I increase the wheel spin at the hit? I want to keep the 4.88 gear and the trans gearing but trying to fix the down low time with the timing. Any suggestions?
     
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  2. TADHemiracer

    TADHemiracer Member

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    Launching at 2500 rpm on a two step. Wheel stands 40+' every time, wheelie bar at 3". I could launch at higher rpm but trying not to shock the tires too hard. Fat tune-up, not even 1/2 plug burn. Any suggestions appreciated.
     
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  3. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    There's a number of factors at play with what you mentioned. Beadlock or liner? Air pressure?

    2500 rpm on a two step is way, way low for a clutch car. I mean that's just off idle.

    You are probably going to have to come up with a timing curve to make it work leaving around 5000.

    Honestly depending on the track, you may have a hard time getting that much ratio to hook up. I don't know what you have on the clutch for base/counter, but I would just put a 4.29 in it and be done. If you have the clutch light now, you may be able to put more clutch on it with the taller rear gear.

    A car like that should 60' .950 no problem, with a 4.29 and that 1.98 low.
     
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  4. TADHemiracer

    TADHemiracer Member

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    Beadlocks, 5.75 to 6.00 air pressure, DS .25= 1959, .50=2512, .75=3255, 1.00=3405 ran 4.38 ET 1.018 60'. I know something is out of whack because this dragster is capable of much more than I am seeing. May need to raise the launch rpm as Will suggested and put some timing back in at the hit to raise the DS and hopefullly it will continue the 3.0 G's it does at the hit a little longer into the launch. The G's drop at about .5 into the run down into the 2's while the tires are spinning but dip when the clutch couples and goes 1 to 1.
     
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  5. jody stroud

    jody stroud ZOMBIE Top Dragster

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    That 1.98 low gear is a lot. Like Will said, try a 4.30 and I'd try a taller first gear. Say a 1.50 something or so. Leave at a higher rpm also.
     
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  6. JustinatAce

    JustinatAce Member

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    To really put it in perspective, you need some high speed video. You have to remember the car takes time to react and trip the timer as well, so if you are zeroing the run on your data logger at the first bump in driveshaft, typically when you're looking at a .5 second number, if you correlate to a higher frame rate video in the same way, you'll see that by .5 second from the first move of the tire, your car hasn't gone as far as you would in a normal footstep.

    You have a ton of gear, so other than the initial shock of the tire at the hit, you're probably pretty well glued to the track, especially consistently carrying the front end. If you're climbing the ring gear, it's aggressive, but not in the right place for low ETs. You're restricted to how fast the engine can accelerate itself and the entire driveline, especially with the wind knocked out of it from the timing dip. You've essentially got your dragster locked up like a pro stock car and letting the clutch hit the motor at idle and half it's power if that makes sense. Taller rear gear, even a 4.56 would show you a difference, more launch RPM, more motor and maybe back off some clutch to let it slip. If the driveline is aggressively chasing after the motor, you'll be quicker than if it's locked as you see in your g-meter. G-meters and time slips are two things that will usually give you more consistent, and potentially less misleading, feedback than even DS RPM.
     
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  7. Bob Meyer

    Bob Meyer Comp Eliminator

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    Old Minnesota barnyard logic...............
    Q. What's the definition of a wheelstand ?
    A. back wheels aren't going fast enough !

    First motion of car needs to be forward.......NOT Down !!


    Bob Meyer
    Meyer Race Cars / San Diego
    2015 Our 50th Anniversary
     
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  8. TADHemiracer

    TADHemiracer Member

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    The years of experience a racer can draw on to find a solution to a problem is exactly WHY I posted this issue on ITA..... Every suggestion made sense to me and every one of those suggestions has been put on the "to try" list. Thanks, guys.
     
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  9. TAFC 5 81

    TAFC 5 81 Member

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    The gear and trans ratios that have been recommended should help the engine burn some more fuel (and make some more power).
     
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  10. sammy christian

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    leave in second gear if you plan to keep the 4.88.
    you will be hard pressed to find any dragster outside of TAD with more than a 4.30 rear and a 1.80 low gear, even that is too much typically.
     
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  11. turbo69camaro

    turbo69camaro Member

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    Wow...... Do you have a data logger if so how fast the the clutch lock up in low ? like will said you need to be at 5000 plus for clutch and fuel system to be happy
     
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  12. TADHemiracer

    TADHemiracer Member

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    From what I see, the clutch locks up in low gear right before the 1-2 shift at about .87 seconds, then after the 1-2 shift, the clutch slips again until 1.53 seconds, then it is locked up again. It appears to me now, after reading all of the replies and suggestions, that A. I have way too much timing taken out, B. I should leave at a much higher launch rpm and C. I should have asked for suggestions on this site a long time ago. We are planning on renting the local track to so some testing and help shorten the learning curve. The weather forecasts is not looking good but when the testing does take place, I will post the results. I am expecting to see big changes in the performance, 60' AND ET. Stay tuned.
     
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  13. WIDEOPEN231

    WIDEOPEN231 Member

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    As stated get those gears out of it. Not only are they killing any chance of getting out of hole,top end rpm will be ungodly .
    In our old funny car with 526 and 14-71 we had 1.88 with 4.30 gear leaving at 6500 to 7000 (depending on track) and .92 to .98 60' times running 5.90 to 6.0 et.

    Working with TA/D team that's also running old peterbuilt style blower and 509" Old's motor. Having other issues . Understand low cash flow you do what you have to do,but roots blower is hard way to play now days.
     
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  14. turbo69camaro

    turbo69camaro Member

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    How much base and counter weight are on the clutch now ? raising the launch rpms will put you in left field clutch wise if nothing gets changed
     
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  15. TADHemiracer

    TADHemiracer Member

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    I realize that if I put the timing back in it to get on the tire that the clutch will react differently than it is right now. As far as base and counterweight, I pretty much have that concept down. I need to make a few passes with enough DS (wheel speed) and make the changes accordingly. I think that more launch rpm (like 5,000 instead of 2,500), more timing in it at launch (like 4 degrees out at the hit versus 9 to 11 degrees out), making the timing curve fit the HP requirement to keep the tires happy should result in better 60' and ET. Last weekend's plan of renting the local track for testing was cancelled because of the rain chances (95%). As it turned out, it did not rain a drop but I still lost the testing. I do have the track rented for this coming Sunday for testing. Stay tuned.
     
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