Ok, well thought I don't care for the "Tuner" scene and the Fast and Furious stuff I believe that if you don't learn from every aspect your not mastering your art. So recently I've been reading various information from the "Tuner" world. These guys know there stuff I'll say that, they seem to indulge more into engine techniques and building than the V8 guys tend to go into. I've never seen this kinda information in the small block world.
This is the information:
"A commonly known, but often forgotten fact is that the internal geometry of an engine can affect the engine's power delivery. Bore size, stroke and rod length all have a profound effect on an engine's power-delivery characteristics. An area of tuning just now being exploited by import engine builders is altering of the rod length to stroke ratio. The bigger the stroke-to-rod-length ratio (commonly referred to as the "rod ratio"), the more dwell time the piston has around TDC. This accomplishes several things. Since the piston is near TDC longer, the combustion event has a longer time to impinge upon the piston, allowing a better transfer of force to the piston, which slightly improves the engine's thermal efficiency. The longer dwell time also gives more time to fill the cylinders at bottom dead center on the intake stroke and more time to scavenge the cylinder during overlap. Since the piston is accelerated more gradually away from TDC, there is less mechanical stress on the crank, rods, pistons and cylinder walls. Reduced rod angularity at the point of highest cylinder pressure, also reduces mechanical stress, as the piston has less side load, and therefore rubs on the side of the bore less...Higher rod ratios result in less velocity in the intake ports; there is a lower demand for the ports to flow as well, as there is more time available to fill and scavenge the cylinder. Conversely, this can also mean stagnant flow at low rpm, which is not good for low-end power production, either...The bore-to-stroke ratio of an engine can also affect the engine's power characteristics. Over-square engines, ones that have a bigger bore than stroke, have lower piston speeds and less internal stress at high rpm due to lower inertial loads. There is also more time to fill the cylinders because of the lower piston speed. Engines with longer strokes and smaller bores, called under-square, have more internal stress due to faster piston acceleration and higher piston speeds. This accelerates wear and can induce seal-killing ring flutter...Under-square engines have higher torque and low-end power producing intake port velocities to ensure more complete cylinder filling at low rpm. Many import engines, most notably Hondas, are under-square. High-performance motorcycles (with a few notable exceptions like the torquey Supertwin racing class bikes) and purpose-built racing engines like the ones found in Indy and F-1 are over-square to improve cylinder filling at high rpm and reduce piston speed."
- Mike Kojima http://www.sportcompactcarweb.com/tech/ ... index.html
So, the Doc your a genious let's just get that out there. However, the 198 has the highest rod ratio. So, wouldn't make more sense to go with the shorter stroke with these nice new rods being made? Next the 170 is still better yet (than the 225), so does that necessarily make it the race engine of the group? If you boost any of the stock engines or "long rod" what would be the best combo with the information given above? Last I hope this was helpful even if it was a lot of info. Wes
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(Duh)