[snowman]

This info was obtained from some of the most experienced gurus of the industry. Its very close to being right, a whole lot closer than most other info out there for the amateur. Its not "easy" as several things have to happen to make it true, but a good guide to get to first base. After that, the last couple of percent, is for the pros who have the money and their life to dedicate to the solutions. For old engines like the 356/912 its a fact as they have been beat to death and then some. You arn't allowed to design a new engine, only work with what you have.

The referances you cited are very interesting. A good analogy is stepped waveguide design for broad band operaiton. Also, since an engine is a Pulsed System and sort of periodic you can apply very advanced theory to broaden the response over a larger rpm range, just like you can with microwaves. Just got to love those fourier series.

I am not an automotive engineer, but I haven't seen anything published using advanced broadband theory, only attempts at flat responses and absolutely nothing about giving up more after the peak to help enhance the peak. Some small ammount of ripple in the response would certainly broaden it considerably, without giving up anything significant. I would suggest any automotive engineer that really wants to opitmize the tuning read up on everything a Dr. Ralph Levy has patented and written on broadband filters and wave guides, especially the periodic waveguide structures. Make sure the electrical equivalents are correct, and possibly generate some new models using distributed elements as they will likely be needed. You will need at least a masters level of math, some background in pulsed periodic systems like radar and a whole lot of time. I am absolutely certain that much better results can be obtained over much wider rpm ranges using this theory than simple ones used in the papers refered to. I would suspect that somewhere, especially in the big auto companies, that this may have been done, Probably based on acustic theory that is more directly applicable than electrical. On the other hand some of this theory is very advanced, even for the microwave industry, and may not have been looked at yet.