[drag79stang]

Originally posted by MiracleMax:
Sir, This could turn into a lengthy discussion, so I'm going to do two things, at least for now. I'll make a couple of comments and then I will suggest areas for your further thought. Then, if you want/need to discuss the matter further, just let me know. Much has been written/practiced about the benefits of square, over-square and under-square engines. Actually, each has advantages and disadvantages depending upon application, method of aspiration and fuel type. Simply stated, piston motion approaching and leaving TDC {as you are obviously aware} changes the conditions observed during "constant volume combustion" at TDC. Your reference to combustion rate, based on fuel type, is valid...if no other changes are made that affect net cylinder pressure {mechanical compression ratio, spark timing, valve timing, etc.}. While currently available unleaded premium fuel has a quicker flame rate than a "racing" fuel, an engine's tendency toward detonation would increase {all else being equal} as a function of rod length increase. However, and here is an area for your thought process, I suggest to you that a quick flame rate can be advantageous in optimizing IMEP or "net" positive torque. Do you not have an opportunity to delay spark timing, as flame travel increases, and correspondingly reduce negative torque? The fact a "long rod" engine's piston is also leaving TDC {under positive torque conditions} slower than an engine of "short rod"? Perhaps this is an opportunity that could lead to a benefit for street engines of increased connecting rod length. Of course, as in the case of most "absolute" situations, there are other parts that govern the whole. Bottom line is I suggest you stay focused {as it appears you are} on factors that affect net cylinder pressure as a function of crank angle, working toward minimizing pre-TDC combustion pressure and maximizing post-TDC pressure. I hope this provides some clarification for you. But if it doesn't, my offer still stands. Jim McFarland

Hey Dirt I knew I wasn't entirely off base with the L vs. S rod thing on a street motor. I guess it depends on how you digest the information. This is the reponse I got to a question regarding the matter.

The site is http://www.n2performance.com/

I'm sure EVERYONE has seen/heard it a couple hundred times by now, but my 351W (Eagle stroker kit), 418 made 572.6 HP @ 6400 and 517 ft lb. tq. @ 5200, carbureted. Plenty reliable motor. I'd stroke the 351!