ET Vs. MPH

Discussion in 'The Bench' started by cjeboyle, Apr 16, 2018 at 2:52 PM.

  1. cjeboyle

    cjeboyle Gold Level Contributor

    Let's say 2 different cars both run 12.5 seconds in the 1/4 mile but car A crosses the line at 106 mph and car B crosses the line at 115 mph.
    What would cause the difference?
    Cliff
     
  2. hugger

    hugger Well-Known Member

    Horsepower and torque, torque because car b probably spun like sob
     
  3. 1972Mach1

    1972Mach1 Just some guy.....

    Gear ratio, chassis set-up, tire hook-up, "torquey" engine vs a high rpm engine, light car vs heavy car etc. Lots of variables, but for the most part the expected mph usually doesn't change by more than 5 mph or so one way or the other for a given 1/4 mile e.t. unless the car in question has a LOT of power and a crappy chassis set-up.
     
  4. BQUICK

    BQUICK Well-Known Member

    I was running 12.80s at 107 with 2.56 gears. Switch to 3.90 gears and run 12.50s at 109. Not much mph difference but lots of ET.
     
  5. cjeboyle

    cjeboyle Gold Level Contributor

    So which is a the better run? and why?
    Thanks
    Cliff
     
  6. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    The race is over so its a moot point. However the car with the faster speed is quicker. In your scenario the two cars cross the line at the same time. The faster trap speed indicates that car had to catch up to the lower speed car. If the race was longer the faster speed car would be pulling away...
     
    johnriv67 likes this.
  7. 1972Mach1

    1972Mach1 Just some guy.....

    You would want the one with the higher trap speed, if you're asking which car is potentially "better". The higher trap speed car would most likely have more power but probably is either spinning on take off or geared too high for optimum quarter mile performance, so it has more potential.
     
    Last edited: Apr 17, 2018 at 8:31 AM
    Harlockssx likes this.
  8. jay3000

    jay3000 Well-Known Member

    For winning a race, it's reaction time plus ET. That's what determines who crosses the line first. The MPH doesn't matter
     
  9. TexasT

    TexasT Texas, where are you from

    I would like to put in for the car that hooks and runs the 12.50 and the lower mph. In a drag race or street race the participant/competitor that gets there first is the winner no matter how fast they are travelling at any part of the track/course.
    if I can get the participant in the other lane to get rattled when I jump em out of the hole and hit is nitrous too soon and spin or put too much throttle into it and spin and I can get to the other end ahead of em . Yep, I win.

    mph is a function of hp and if you can't get that power down it is worthless. Spinning ain't winning.

    lots of ways to get the power down. Converter in am auto trans car, rear gears and tire height make a difference. Chassis setup with adjustable arms, moving the mounting points, different bushings and springs. Lots goes into getting the power down.
     
  10. hugger

    hugger Well-Known Member

    I had 70 Skylark street/strip car years ago that I street raced ALOT, it only ran 7.40's at 87 so by no means was it a beast, but back in 2003 to 05 it was a contender against 95% of the stuff out riding around, I out ran TRAINLOADS of LS powered Fbodies, Vettes, 03/04 cobras etc most if not all ran faster mph to the stripe but from a first gear roll I would eat their lunch once we would get up to 120 or so they would pull back up on me but I would be tached out so the race was over
     
  11. Dr. Evil

    Dr. Evil Silver Level contributor

    I can tell you car b is a lot of fun on the street.
    My 96 Vette ran bottom 12s at 116 mph. That thing was a blast on the street with the manual trans. Never got it to 60' better than 1.85 though.
     
  12. pbr400

    pbr400 68GS400

  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I think GENERALLY, trap speed can give you an idea of what ET the car can run.

    95 MPH or so, high 14's
    98 MPH or so, high 13's
    103 MPH or so, high 12's
    106 MPH or so, mid 12's
    110 MPH or so, low 12's
    112 MPH or so, high 11's
    115 MPH or so, mid 11's
    118 MPH or so, low 11's
    121 MPH or so, high 10's

    I'm sure there are lots of exceptions to these GENERALIZATIONS. If you spin a lot, the ET suffers, but the MPH can increase a bit over it would normally be.
     
    Brian Albrecht and 1972Mach1 like this.
  14. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

  15. cjeboyle

    cjeboyle Gold Level Contributor

    It sounds to me like car A with the lower MPH is then getting more out of the car or closer to full potential while car B with the higher trap speed is leaving something on the table. Is this a correct assumption?
    Cliff
     
    gs66 likes this.
  16. 1972Mach1

    1972Mach1 Just some guy.....

    Yes, exactly as I stated in post #7 ;) .....
     
    cjeboyle likes this.
  17. Ken Mild

    Ken Mild King of 18 Year Resto's

    I have 3:08 gears but cross the line at 108+mph with like 2.1 60ft time (non-posi). One example is I raced a guy and I crossed at 12.90 and he crossed just after me at 13.11 but at over 110mph. He was running 4:56 gears and a hi-po dual quad 409. My guess would be that if I was runni9ng something other than the stoch converter and 3:08 non posi, I would be in at least mid to low 12's.
     
  18. Gary Bohannon

    Gary Bohannon Well-Known Member

    108 as follows:

    1.71 60 ft
    7.75 1/8 mi
    88 mph
    12.27 1/4 mi
    108 mph

    This is with great traction, 3.73 to 3.42 rear gear, well built 3200 to 3500 stall converter, etc.
     

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