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Thread: Put the slicks on

  1. #1
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    Put the slicks on

    I did 3 runs at a crappy track but was hooking up better each time. This is my last run, I don't know what any of this means:

    60' 2.492 @ 48.99mph
    330 5.488 @ 73.39mph
    1/8 8.524 @ 82.32mph

    This is with 3.42 gears.

    Now here is the kicker! The guys there told me that on the last run I got the tires off the ground 1.5 to 1.75"!!!! I never expected that!!

    I had to stop because my heater core sprung a leak and was running out on the track. I wasn't actually racing anyone, just seeing what it can do. A very small crowd.
    I think I need to get some taller gears, and well since it's almost summer, bypass the heater core.
    I was testing the slicks at home in the drive and have 17psi driver, 16 passenger.
    I still can't believe I got air.
    Tony

    1955 Bel Air Sport Coupe

  2. #2
    Registered Member chevynut's Avatar
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    Don't know how accurate this is.....

    http://www.wallaceracing.com/et-hp-mph-8th.php

    "Your Flywheel HP is 287 computed from your vehicle weight of 3600 pounds and ET of 8.52 seconds."
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


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    Registered Member chasracer's Avatar
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    I guess you're kidding about not knowing what any of it means but for right now, working on the 60 foot would be good if you want the car to get quicker. Remove whatever weight that you can, possibly move up the timing a bit and see how it improves. I am a little worried about the different pressures in the slicks - that's something that we tend to stay away from. It might work okay at this slower speed but as things get quicker having one tire pressure higher than the other will tend to "drive" the car to the lower pressure side. Also if you look at your 330 to 660 speed, that was half the distance of the run, yet it only picked up 9 miles per hour in that distance. Horsepower is being limited by something. Have fun!
    Remember the "13"


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    I can't believe you left hard enough to pull the wheels off the ground, yet ran a 2.492 60'. Got any video?
    Dave, from the old neighborhood in Jersey!

  5. #5
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    OK, accuracy is out the window here. The track still doesn't have any electronics, I was using a cell phone app that goes by GPS. I know times would be a lot different with different gears, a lot different I hope. 3.42's aren't made for racing and a calculator without factoring in gears, I think is useless. No, no video. I'm just going by what they told me. As far as the different air pressures, I had the air low and did a little burn out in my driveway. It was all on the sides nothing in the middle so I kept adding air. The one side got a good patch and the other side caught up with another pound. I don't want to lower the one so I guess I'll raise the other. Maybe I could use more air in both? In the driveway I can hang out the door, give it a little throttle and see them wrinkle. That's just going a little more than off idle. For the first time it seems like I can actually feel the caltracs working.
    Tony

    1955 Bel Air Sport Coupe

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    Quote Originally Posted by chasracer View Post
    I guess you're kidding about not knowing what any of it means but for right now, working on the 60 foot would be good if you want the car to get quicker. Remove whatever weight that you can, possibly move up the timing a bit and see how it improves. I am a little worried about the different pressures in the slicks - that's something that we tend to stay away from. It might work okay at this slower speed but as things get quicker having one tire pressure higher than the other will tend to "drive" the car to the lower pressure side. Also if you look at your 330 to 660 speed, that was half the distance of the run, yet it only picked up 9 miles per hour in that distance. Horsepower is being limited by something. Have fun!
    No, I'm not kidding about not knowing what the numbers mean. I've been to drags maybe two times in my life and never was around a car or driver. A complete newbie. Well except for my first visit to this track back a couple months with street tires, that was about useless.
    Tony

    1955 Bel Air Sport Coupe

  7. #7
    Registered Member chevynut's Avatar
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    Quote Originally Posted by 55 Tony View Post
    a calculator without factoring in gears, I think is useless.
    You don't need to know the gears or anything else about the car to calculate horsepower. All you need is weight, distance and time to get the average horsepower produced. One horsepower is 550 ft-lb/second. I would think a GPS phone app would be pretty accurate over 1/8 mile, maybe not as good over 60 feet. Doesn't your app give you horsepower?
    56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension


    Other vehicles:

    56 Chevy 2-door BelAir sedan
    56 Chevy 210 4-door sedan
    57 Chevy 210 4-door sedan
    1962 327/340HP Corvette
    1961 Willys CJ3B Jeep
    2001 Porsche Boxster S
    2003 Chevy Silverado 2500 HD Duramax
    2019 GMC Sierra Denali Duramax

  8. #8
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    Quote Originally Posted by chevynut View Post
    You don't need to know the gears or anything else about the car to calculate horsepower. All you need is weight, distance and time to get the average horsepower produced. One horsepower is 550 ft-lb/second. I would think a GPS phone app would be pretty accurate over 1/8 mile, maybe not as good over 60 feet. Doesn't your app give you horsepower?
    That doesn't make sense. Why do people racing have tall gears and for economy short gears? Maybe that calculating works for HP at the wheels, not the motor? Or HP USED, not available. I see the calculators everywhere, but it just doesn't make sense. And not that it's a giant number, but a TH400 takes what 25 HP just to run? Also on a dyno they go up to red line where normally is your peak power. Hell I was paying attention to the car and the track and honestly didn't feel it shift, but I'm right at the point where I'm just hitting 3rd close to the finish line. Taller gears are needed. I don't know what to say about the calculators? HP being used makes the most sense to me.
    Tony

    1955 Bel Air Sport Coupe

  9. #9
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    "Taller" gears means less rpm at a given speed, not more. You want "shorter" gears, which are higher numerical.

    For formulas like this, it's not horsepower at the flywheel, or "horsepower used" , it's horsepower applied. Because that's what's known. Any implication of horsepower at the flywheel is an assumption of the drivetrain efficiency, including tire spin, converter slippage, power loss in the transmission and rear axle, etc.

  10. #10
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    Gearing is more about torque multiplication, not horsepower anyway. If you pick a dedicated drag gear like a 4:11, unless you trailer it, it won't be much fun to drive to the track or anywhere else without buzzing that BBC at 4000RPM plus just going down the highway. Tire diameter is one factor, and determine what speed, and redline engine speed will be when you trip the lights. You wouldn't want to hit redline in high gear before you even get there. A G-force meter app, or similar can calculate horsepower, 0-60, 1/4 mile times, etc. You are also pushing a big shoebox into the wind. I would look at torque converters, not knowing what you have now, or how much traction you have,.
    Last edited by 55 Rescue Dog; 03-18-2018 at 01:17 PM.

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