Yesterday I took my Pagoda to a dyno. Results were 230 rear wheel hp DIN at about 4750 rpm and 285 ft.lb of torque at about 3800 rpm. That's about 275 to 280 hp DIN and 345 ft.lb at the crankshaft. Regarding Hp, that's about right, as compared to the 300hp version of the M117 560 motor I am not using the tri-Y exhaust manifold system (was not clearing the Pagoda chassis rails) which have been measured to yield an additional 15hp over the euro log set-up I have. My engine is also 9:1 CR instead of 10:1 CR. However, torque seems to be slightly over the 336 ft.lb of the 300 hp version. Peak power and torque on my engine are also reached at respectively 250 and 200 rpm below the 300hp version (5000 and 4000) indicating that my camshafts may be a tad bit advanced. I should be able to get my max figures at 5000 and 4000 rpm by retarding my camshafts by 3 to 4 degrees with offset woodruff keys, gaining a few more hp in the process. In any case, that's not bad compared to the 230hp the engine started its life with in a 560SL, and considering that the long block has stayed absolutely stock. My target when I started the build was 275 hp, so I'm good, and there there is room for a bit of improvement acting on the camshafts timing.
We also measured maximum speed on the dyno: 150 mph in 4th gear at 6000 rpm and 180 mph in 5th gear. However, in real life it may be different, taking the car's aerodynamics and weight into consideration. I went on an online calculator using an estimated 17.3 square feet as a frontal area (with hard top) and 0.42 cd. Result was still over 170 mph. I guess the car would be able to reach a good 160 to 165 mph on a long straight, flat, with no wind.
We also weighed the car with a fancy system of four scales, one under each wheel, communicating with a computer. Result was 1340 kg with a full tank, without hard top, but with soft top, spare wheel, jack, tools etc., corresponding to the definition of curb weight. 53% on the front, 47% on the rear. This is 20 kg lighter than the factory figure for a 280SL. Not bad, considering that I have power steering and a 5 speed transmission. Factory figure is with no options. So I would say my car is 30 to 35 kg lighter than a stock 280SL with comparable equipment, with better weight distribution compared to the stock 56/44.
In any case, this is giving me an estimated ratio of 209 hp per ton. Online calculators says the car should be able to run 0 to 60 mph in 4.81s. This is theoretical as I doubt my 205mm wide tires would provide enough grip for that.
I spent a bit of time on the net to see how my car would compare with some other cars of the era. Below are a few:
1962 Mercedes 300 SL gullwing: 215 bhp, 1329 kg, 162bhp/ton, 160 mph
1973 Porsche Carrera 2.7 RS: 207 bhp, 1075 kg, 192 bhp/ton, 149 mph
1962 Ferrari 250 GTO: 296 bhp, 950 kg, 311 bhp/ton, 158 mph
1969 Ferrari 265 Daytona: 347 bhp, 1200 kg, 289 bhp/ton, 170 mph
1967 Iso Grifo 300GL: 295 bhp, 1450 kg, 204 bhp/ton, 143 mph
1971 Jaguar E Type V12: 272 bhp, 1500 kg, 181 bhp/ton, 142 mph
1972 Maserati Ghibli SS: 330 bhp, 1350 kg, 244 bhp/ton 160 mph
1967 Lamborghini Miura P400: 350 bhp, 1293 kg, 271 bhp/ton, 172mph
1969 Lamborghini Espada SII: 350 bhp, 1700 kg, 206 bhp/ton, 155mph
Note that power figures for these supercars of the 60s and 70s were often optimistic for marketing purposes. Putting them on a dyno today may yield very different figures, especially for the ones that are difficult to tune due to many carburetors, dual ignition distributors, valve clearance etc. In comparison, adjustments on my car are very simple and very stable, so there is no power loss in between two services.
