[olddog]

Now we are talking big dollars. We kind of started out with a question of 4.125 verse a 4.25 stroke. It pretty much costs the same to do either. If you want to spin high, say 9000 or 10000 rpm, the price tag goes up exponentially. Doing it with an FE will cost more than a lot of other engine families, that is for sure.

Personally I would be hesitant to spin 4"+ stroke FEs much past 6K rpm. It's not because I do not think it can be done, rather it is because it costs a lot of money, and when it fails, all the money is gone. For me it is like setting $10K on a roulette wheel. I derive no pleasure from the thrill of gambling (in my mind loosing my money). However I pass no judgement on those who do. Those who build and run these engines, I admire.