AMA Checks Power-to-Weight Ratio on Pro Daytona SportBikes – A&R Checks the Math

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AMA Pro Road Racing officials dyno tested the 10 motorcycles that qualified for Friday’s Superpole session at Barber Motorsports Park, in an effort to maintain a more competitive balance among the hodgepodge of bikes competing in the series. In their study, they found that the bikes range in power-to-weight ratios from 2.65lbs/hp to 3.14lbs/hp, with a .28lbs/hp gap between first and second ranked bikes. What is interesting about the report from the AMA is that they never named which bikes were making how much horsepower, thus leaving it a mystery who had the supreme power-to-weight advantage. Never fear, math and common sense are here. We crunched the numbers to figure out what the likely results are in this report. Our conclusions may astound you, and/or confirm your suspcions about the series, and maybe AMA road racing as a whole.

For those of you that might not watch the AMA Pro Daytona SportBikes series, here’s a quick primer on its format:

  • Eligible Bikes: Yamaha YZF-R6, Suzuki GSX-R600, Honda CBR600RR, Kawasaki Ninja ZX-6R, Buell 1125R, Aprilia RSV1000R, Ducati 848, Triumph Daytona 675
  • Minimum Weights:  365lbs (4 cyl.), 375lbs (3 cyl.), &  385lbs (2 cyl.)
  • Single spec fuel and tires (Sunoco 260GTX and Dunlop SportMax GPA Front (120/70ZR-17) and Rear (190/55ZR-17) respectively)
  • 1st place- Jamie Hacking (Kawasaki ZX-6r – no wins), 2nd place – Danny Eslick (Buell 1125R – 3 wins), 3rd place – Martin Cardenas (Suzuki GSX-R600 – 3 wins)

Minus the four-cylinders 600cc bikes, this group represents the bastard children of road racing, and the AMA has devised a clever formula to try (or to at least give the appearance of trying) and create a level playing field for these very different bikes to compete upon. The results of that effort however, have not gone without criticism, especially when it comes to the Buell 1125R’s inclusion in the series.

If it wasn’t for a needlessly disastrous race at Daytona (Buell started with two bikes in the Top-5, and with one on poll), Buell would be walking away from this series with a huge lead, which shouldn’t surprise anyone considering it has a substantial displacement advantage over the bulk of the competition (a criticism that’s occurred more than once in post-race interviews with riders). Adding more fuel to the fire is the fact that Buell is an official partner with the AMA (no other manufacturer is listed on the AMA website as a partner to the organization), and the fact that the Buell 1125R received a considerable number of special dispensations from the AMA to race in this series (more on that later). 

With only 20lbs separating the fat from the lean in the Pro Daytona series, the fact that there is a .48lbs/hp difference in the field means a huge difference in power output. To put it in perspective, if we held all the bikes’ weight at a constant 375lbs, that would mean the field is comprised of bikes ranging from 119hp t0 142hp (a 33hp difference). In that same scenario, the difference between the 1st ranked bike (142hp) and 2nd ranked bike (127) would be nearly 15hp.

Before we start talking horsepower, we would be remiss if we didn’t disclaim the fact that we are dealing with real-world, rear-wheel horsepower. Not the mythical factory numbers which are almost always crankshaft estimates with RAM-air included into the figure. That being said, let’s get down to it.

Using some basic intuition on race bike preparation, we can expect to see at least a 10% power gain in the Pro Daytona SportBike series bikes considering the class rules allow for the following: an increase in the motor’s compression, machining of the bike’s valve seats, cam timing adjustments, fuel-management computers (Power Commanders), and full-exhaust systems. Knowing this, we can take the following information, and begin to make educated guesses about power and weight.

Based on reported dyno figures for various bikes, and the presumption that all the bikes will weigh the class minimum, what we know so far is the following:

Bikes Weight HP – 3.14 Ratio HP – 2.65 Ratio Stock HP Stock HP-to-Race Weight
Yamaha R6 365 116.24 137.74 104 3.51
Suzuki GSX600R 365 116.24 137.74 104 3.51
Honda CBR600RR 365 116.24 137.74 105 3.48
Kawasaki ZX-6R 365 116.24 137.74 107 3.41
Triumph Daytona 675 375 119.43 141.51 106 3.54
Aprilia RSV1000R 385 122.61 145.28 114 3.38
Ducati 848 385 122.61 145.28 116 3.32
Buell 1125R 385 122.61 145.28 130 2.96

With a stock Buell 1125R making around 130hp at the rear-wheel, it isn’t too much of a stretch to imagine the bike making another 15hp with the modifications allowed in the Pro Daytona SportBike class. Also, it would seem unlikely that with the given provisions the Buell would only improve on its power-to-weight ratio by .03lbs/hp. This would seem to confirm the fact then that the Buell 1125R is the top power-to-weight ratio bike in the class. A potent factor to be sure, but consider further the fact that the Buell has been given special dispensations to make the following modifications: magnesium rims, a larger airbox, front forks, connecting rods, and a converted chain drive, and it is easy to see why the little bike that shouldn’t, is becoming the little engine that can, with better suspension and less rotating mass than its competitors.

Knowing the controversy that has surrounded the Buell’s perceived unfair advantage, we cannot help but think that the AMA’s non-disclosure of power and ranking for the tested bike might not have had something to do with the fact the scales have been so greatly tipped into the favor of a series partner. We will concede of course the point that teams probably don’t want their technical specifications to be released to competitors, and the AMA’s desire to heed those wishes, but doesn’t that just seem to convenient of an excuse, especially given this situation?

*Editor’s note: While the article refers to power-to-weight ratio, it is important to note that the numbers expressing this ratio are in fact representative of weight/power, thus lower numbers indicate a better ratio, and theoretically “better” racing motorcycle package.