[RobMcQuarie]

Interesting post Steve. For a lot of guys, the numbers are all important-whether it's dyno numbers or flow numbers. For them, it's always the size that matters, not necessarily the actual performance. (They are the ones that dream of dipping into water when using the urinal).
We dyno most of our engine builds, primarily to performa a proper break-in, determine optimum total timing, tune carburation, set & check valve train, etc. We look at the dyno numbers in relation to what we expected to see, and what we have gotten from other similar combinations.

Our dyno numbers -as well as flow bench numbers- have typically been lower than many of the ones I see passed around. As an engine builder, it sometimes puts me on a bit of the defensive when talking to a customer. I tell them what sort of HP numbers we will expect to see in a certain combination, and they then see advertised numbers that are significantly higher, for similar and often cheaper quoted prices. Sometimes I even question myself as to if we are doing somthing wrong when I see big results from some other well known engine builders. But, then I talk to a few shops around the country that I highly respect, and they are getting similar results, and I feel better again.

True, two builders can take two very similar engine builds with very similar parts and come up with different results, but if the machine work and assembly are both of high caliber, both are decently tuned, the differences will not be that significant. That is not to say you can't find an easy 40-60hp on the dyno. I've seen that when a customer's carb was ill matched to the engine, or when they didn't set up their ignition properly. I always have a say in final carb selection and we set up the distributors on our engines in order to try and avoid those inconsistancies.

Yes, there are a lot of small details and little tricks that can be performed on one specific engine build that will set it apart from another engine using the same parts. Many are for durability and quality. But, the ones done to increase HP, typically only result in small, incrimental power improvements-which is all important in competative racing classes where the racers all fall into a specific power level. But the importance is significantly less for the average street engine.

I tell my customers that the dyno numbers are for general reference, and are not a measure of the "success or failure" of the engine. The proof is in the product as they say. There is SO MUCH MORE to an engine than dyno numbers. The quality, parts combination, and attention to detail are the most important things in my book.