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Power to weight ratios > Turbo equivilency nonsense

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  • Power to weight ratios > Turbo equivilency nonsense

    This is my latest letter to the SEB (I write one or two a month):

    Add weight to boosted XP cars or better: measure the horsepower

    The minimum weights in XP are absolutely out of whack at the moment, specifically for forced induction engines. The current "1.4" multiplier forces competitive XP drivers looking for the best power-to-weight ratio into the smallest, highest boost level motors they can afford to build, in order to get the lowest minimum weight and best power-to-weight ratios. This means: A MORE EXPENSIVE and LESS reliable engine is going to be the norm.

    Rumor has it that the extremely out of date, "1.4" displacement multiplier for forced induction "engine equivalency" is getting a look by the PAC (thank you!) and might go up to a more reasonable 2.2 factor. That's a good start, but its still behind the times.

    Please look at this historic racing article to better explain where the magic "1.4 number" came from - the CAN-AM series in the 1970s. It was a farce then, and its a bigger farce now, almost 35 years later: http://www.classicandperformancecar....tor_sport.html

    As we saw in Formula 1 and IMSA GTP in the 1980s, and even the SCCA's own Trans Am series in the 1990s, boosted engines kept getting smaller and the boost levels kept going up, to the point where there were 1.5L engines making 1500-1800 horsepower. This was all to be able to exploit loopholes in class rules to be able to run the lightest minimum weight and the most horsepower. Its not brain surgery - if you can do that, you greatly increase your chances of winning.

    In GTP the lightest car on the grid had the highest power level. Ditto the Audis in Trans Am. Guess which cars won the most races back then? It was a blowout for the turbo cars, until turbos were completely kicked out of each series.

    What did these "turbo equivalency" rules from decades ago teach us? You can't base a car's weight on displacement when it comes to boosted engines, and that when it comes to boosted engines, money is almost the only thing that limits horsepower. Also - you can almost never have turbo and non-turbo cars in the same class, unless you can make everyone have the same horsepower number.

    The end goal of all this "equivalency trickery" is to really get equal power to weight ratios among all cars in a class, no matter what motive power is underhood. Multipliers do a terrible job of this, as boosted cars can make more power the more boost pressure you run, the stronger you make the block, the more exotic the fuels become (see the current trends with using ethanol and methanol in turbo cars), etc. This allows people with the resources to build a car with a much better "power to weight ratio" if they are willing to build their car around the smallest displacement, least reliable, highest boost power plant possible. Sure, some can say that "this doesn't apply to autocrossing" but they would be fooling themselves. Power to weight ratios are nearly everything in any form of racing.

    The advances in turbocharging and other internal combustion advances have made weight to displacement rules in general simply out of date. Modern road racing classes (outside of the SCCA) are being built around actual measured power to weight ratios. These classes make (all racers beforehand and the the top finishing) racers prove the power level of the motor with a simple, portable chassis dynamometer, and then they weigh the cars. Two measurements, then its simple math from there. Give the XP class a power to weight ratio and measure both numbers on the top 3rd of the cars at Nationals. Hell, do this for ALL of the classes. Its done in NASA and it damn well works. No more 1970s-era trickery needed.

    If this class were power to weight based, then racers could chose how they wanted to build their motors. They could build a lower stressed, larger displacement, naturally aspirated engine that didn't have to be pushed to the extremes to make the same power as a micro-engine with a power adder pushing 30+ psi of boost pressure. Or they could build a smaller displacement engine that revved to 10,000 rpm, or go boost crazy - whatever they wanted, so long as they stayed under their power to weight ratio. It would no longer benefit racers to build smaller boosted engines. It would give racers lower cost options to make the same ultimate power numbers, and not be saddled with hundreds of extra pounds of ballast.

    Right now, with the old/broken XP min weight rules, if you are building anything other than a tiny boosted motor for this class you are going to get loaded with lots of extra weight. And you will lose to the lightest car in the class - which for 3 years has been a 1770 pound, carbon fiber, 1.6L boosted Lotus. That is getting a bit boring.

    Thank you,

    Terry Fair - Owner, Vorshlag Motorsports
    fair@vorshlag.com - www.vorshlag.com
    SEB Letter Tracking Number #3167
    Terry Fair - www.vorshlag.com
    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

  • #2
    Re: Power to weight ratios > Turbo equivilency nonsense

    Originally posted by Fair! View Post
    This is my latest letter to the SEB (I write one or two a month):


    SEB Letter Tracking Number #3167
    I would suggest adding to your line about the advances of turbocharging, "advances in turbocharging as well as engine management..."

    Comment


    • #3
      Re: Power to weight ratios > Turbo equivilency nonsense

      Iain

      '01 Honda S2000 - extra crispy
      '05 Honda CR-V EX AWD - alphabet soup family truckster
      Always looking for a co-drive...

      "We don't stop playing because we grow old, we grow old because we stop playing." - George Bernard Shaw

      Comment


      • #4
        Re: Power to weight ratios > Turbo equivilency nonsense

        Terry Fair,
        Your letter has been reviewed by the Prepared committee, and tabled for further review. After additional research, the committee will send a recommendation to the SEB. Your letter details are below:

        Letter #3167
        Whatever this means...
        Terry Fair - www.vorshlag.com
        2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
        EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

        Comment


        • #5
          Re: Power to weight ratios > Turbo equivilency nonsense

          It was brought up at the meeting but someone has to go research it now and come back to the group with a recommendation. Then they either review it further or shoot you down.

          Brian
          Brian Hanchey
          AST Suspension - USA

          Comment


          • #6
            Re: Power to weight ratios > Turbo equivilency nonsense

            Originally posted by hancheyb View Post
            It was brought up at the meeting but someone has to go research it now and come back to the group with a recommendation. Then they either review it further or shoot you down.
            Brian
            My take was:

            1. Thanks for sending something in
            2. it was too long for us to read / understand
            3. SuckIt! We know who you are
            4. Have a nice day

            Comment


            • #7
              Re: Power to weight ratios > Turbo equivilency nonsense

              Originally posted by John in Houston View Post
              My take was:

              1. Thanks for sending something in
              2. it was too long for us to read / understand
              3. SuckIt! We know who you are
              4. Have a nice day
              I think they have an auto-responder for my letters that's pretty much just that, yea.
              Terry Fair - www.vorshlag.com
              2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
              EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

              Comment


              • #8
                Re: Power to weight ratios > Turbo equivilency nonsense

                I've had some private PMs from this thread here on Vorshlag - haven't pushed this on any other forums. Some people had modified versions of the existing displacement-to-weight formula, to help balance out the NA vs FI cars. That helps, and I agree that we need to discourage FI in XP, but I hate all SCCA "weight-to-displacement" formulas in general.

                I'd rather see measured power and measured weight to make a simple power-to-weight formula. Tweak that number to balance out FWD, AWD, rear engined, and maybe even DOT R's vs Slicks. That takes out SO many variables with respect to FI, engine prep, etc. Power-to-weight numbers are so simple to understand and they don't rely on old, broken "1.4" multipliers or static displacement adders.

                Again, this is just for XP, but if it works there... there's a lot of other SCCA Prepared, SMod and Modified classes that are using old-and-busted displacement-to-weight formulas.
                Terry Fair - www.vorshlag.com
                2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
                EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

                Comment

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