I should have said something about repeatability, you are right about that but it had slipped my mind when I wrote my post. I did find a better picture Harry Miller’s dyno and it is a water brake type. (On the photo that was posted you can’t see the water brake only the test bed)
I am mainly interested in race bikes, in that sport the range of dynos used in engine development goes from the eddy current dynos of factory teams in Japan to some guy in Denmark hopping up his moped testing the results on a dyno he build using a rotor out of a ten horse electric motor (He use the rotor like the drum on a dynojet, check him out on U-tube). The amount of BS I have heard over the years about horsepower numbers has taught me to take what I told with a grain of salt.
Consider this the Coventry Climax FPE “Godiva”, this 2.5 liter DOHC 90 degree steel cross plane crank V8 engine was built in 1954 for Formula One. Coventry Climax had technical problems adapting the engine to fuel injection however the FPE initially showed 240 bhp using Weber carburetors, but the press at the time reported the rumored fuel-injected Mercedes 2.5L GP engine is quoted as producing more than 300 bhp, and a corporate decision was made not to release FPE in light of the lack of proper fuel injection, leaving the Kieft F1 project, as well as other prospective users, HWM and Connaught, high and dry.
There were reports to the effect that the engine was not run because of fears about the rumored power of other 2.5L GP engines, but shortly after 2.5 era of formula one ended, John Cooper brought a race-winning, works Maserati F1 engine he had on loan into Coventry Climax, where it produced 225 bhp running on the same dynamometer upon which the FPE had made 264 bhp after some development. The FPE never ran in a car.
Or the Honda NR500 (500cc) a race bike that millions yen were spent on than was slower that a stock TZ350 (90 Honda horses vs. 65 Yamaha horses). The TZ350 raced in a lower class (350cc GP) the Honda raced against 500cc Yamaha and Suzuki.
Something to remember is that the problem with race engine development it is rare that you get a chance to compare a competing engine.
The reason I wrote my first post is people are quoting numbers without giving any meaning or context to them. I hope both Harold Bettes and Mike LeFevers give their options’ about this thread.
Maybe my dream of a hundred horsepower single cylinder motorcycle is not stupid if the Burton Brown head works.
WELL, yes, there is lots of "smoke" about engine bhp numbers. ALWAYS has been, ALWAYS will be.
As a "student" of engine design history, I am well aware of the FPE. I consider Walter Hassan and Harry Mundy to be some of the great I/C engine minds of the 20th century. Their track record speaks for itself.
Depending on the type of racing, getting a look at a "competitor's stuff" is not that hard, except for "pinnacle" formulas. I'll remind everyone that before Toyota moved up to the Cup Series, they bought (through a team) one each of all their competitor's engines. Took them apart, and then went to Nascar with a "proposal" for "their" engine design. A bit on the "tricky" side, but also
smart. They knew what they were up against.
Don't think that good engineers don't work on track performance backwards to determine engine bhp numbers, because we do. It's just math . . . . .
Fordboy