Speed isn't all just about horsepower........

Since I mentioned the 200 mph class in the siver state classic-I've had a bunch of emails arguing for different car / engine combinations. I've also heard from many drag racers as well. Let me break this down for everyone-once and for all. # 1. Drag racers-shut up on this subject. My Ford pickup which has a stock 195 hp 302 V8 and the aerodynamics of a UPS truck can run 120 mph on the freeway pretty easily, even with camper-style mirrors and the tailgate up. ( I know, I got a ticket and the cop said the Radar read 122 mph ) However-A Ford Lightning Pickup with a 380 hp supercharged 5.4 liter V8 has a top speed of  "only" 139 mph according to Car & Driver magazine. That's right-even though the Lighning has double the horsepower-it's only 17 mph faster on a top-end run. Road and Track did an article a few years ago when a reader asked the same question about BMW's. If a 230 hp 328I can go 133 mph, how come a 300 hp 335I can only go 147mph ? 70 hp is only worth 14 mph in speed? Yes. R&T broke it down with the help of BMW engineers. They showed that it only took something like 55 hp to push a 3-series 60 mph. It only took like 90 hp to push it 100 mph. Then wind resistance kicked in-to go 120 it took like 155 hp. The remaining 75 hp was needed to get from 120-133 mph! It took another 70 hp to get the 335I from 133-147. That's why I told the drag racers to shut up. A car that runs 12.40's in the 1/4 is only going about 105 through the traps. A car that runs 11.80's is only going 120. And one that runs 10.90's is only going about 130. As you can see by R&T's report-Aerodynamics do not come into play until about 120 mph. The power difference in the BMW's was not as pronounced as with the trucks-because -duh- a BMW 3 series slices through the wind a lot easier than a Ford truck. But as a general rule- for every 10 mph over 120, you need like 50 more hp! So there's my prediction right on the button-if you need 200 hp to go 120, you'll need 600 hp to go 200. But power and aerodynamics aren't the only factors. There's also weight and un-sprung weight. All other factors being equal- whether drag racing or Superspeedway-a 3,000 lb car with a 300 hp engine will run just as fast as a 4,000 lb car with a 400 hp engine-in theory. I say in theory-because yes; they both have a power to weight ratio of 10 lbs per hp. However-two 2012 rice rockets- both weighing about 3,000 lbs-a Subaru WRX ( 305 hp ) and the Nissan 370Z ( 332 hp ) are both quicker in the 1/4 and have a higher top speed than the fearsome, legendary 450 hp, 3980 lb LS6 Chevelle!! Check Road tests from Hot Rod, Car&Driver, or Motor Trend if you want. How is that possible, if they both have power to weight ratios of roughly 10 lbs per hp? Un-sprung weight. The jap sports cars have light, free-revving engines with lightwieght cranks, rods, pistons and flywheels, as well as light OHC valvetrains with roller cams. How much heavier, and harder to get up to speed quickly is that stuff on an OHV, flat-tappet cammed 454 Chevy? The Jap cars have light, easy turning transmissions-either stick or automatic-they require a lot less hp to turn than an M22 4-speed or TH400. The jap cars have aluminum driveshafts, forged aluminum control arms on the suspension, lightweight rear axles, carbon-fiber brake rotors and light aluminum wheels. A lot easier to get moving quickly and keep moving than the cast-iron suspension, rear end, drums and rotors and heavy steel wheels on the Mighty Chevelle. That's how-the Z-car and the WRX could go just as fast or faster with actually slightly less power to weight advantage. The unsprung weight was managed much better. That's how my brother's 3,731 lb '69 GTO with it's 381 hp 400, blew the doors off his buddy's 550 hp, 5,700 lb Viper-engined SRT-10 Dodge Ram Pickup. You have to look at many different factors-like power loss throught the drivetrain-that's why many Ford Racers run C4 automatics instead of C6s, and why many GM guys run TH350's instead of TH400's, or 200R4's instead of 700R4's. Those 20 inch wheels that you think are so cool-looking? Their a LOT heavier than the 15 or 16 inch wheels they replaced! And that's pure, unsprung weight, that takes additional power to get moving and keep moving. I hope this clears things up-Speed isn't just about raw power. Mastermind