That's plenty cool Jim. With the subjects of power measurement and HP at the forefront, this thread seems like a reasonable place to solicit input on the HP potential of a naturally aspirated Norton engine. I'm not at all hung up on HP, just trying to reconcile historical hearsay with reality.
On various forums and in Norton folklore I've seen reference made to Norton engines (750s?) developing ~ 80 hp, which in at least some of the cases has been attributed to CR Axtell and various racing engines he developed (and I'm sure many around the world have perhaps reported similar results). I've never seen any concrete reference or substantiation of this result, i.e., never seen similar data/results posted by modern builders, nor have I ever got clarity as to whether the 80 HP referred to engine HP, real wheel HP (rwhp), or the size of the engine that developed such power. From the airflow numbers I've seen quoted on this forum, IMHO it seems unlikely that 80 rwhp could be obtained. So I'm wondering if the 80 hp is an old wives tale, data from a large displacement engine or what.
I suspect my comments above will result in a deluge of input from all quarters on this subject, which I welcome. I'm especially looking forward to input from the veteran racers that have built and tested designs for decades both here in the states and abroad, and who may know more about the genesis of the 80 hp number.
And yes, we are all aware that no 2 dynos give the same result and that a dyno is not a road or a track. That said they are still a useful measurement system, especially if you use the same dyno consistently, and with enough dyno results should do a decent job of bracketing the performance possible from the design.
If people have specific comments on this subject, in the interest of demystifying rather than further mystifying the subject, would you please state the engine size you are talking about and whether HP is rear wheel or crankshaft.
To start the conversation off, Jim just posted 65 hp @ 6000 rpm for a 750 racing engine (in this case it's neither crankshaft or rwhp, but something in between - countershaft HP?, and since the engine can rev another 1000-1500 rpm more, we don't know what its max output would be. Also on this forum Mike Hamilton in NZ shared his results from a well prepared 850 engine that developed 65 rwhp at ~ 6500 rpm. Confronted with these 2 examples, I can't for the life of me imagine how one would increase the HP of a well prepared engine an additional 23% to achieve 80 HP. I know more HP can be had from this engine but suspect the gains will be more incremental (5-10%) rather than monumental.
