Originally Posted by Scott Fisher
Finally, the general difference. As you increase stroke, you increase torque. As you increase bore, you increase RPM. The RR and LL engines are torquier, and the NSR/LS is a more revvy (yeah I know that isn't a real word) top speed engine. The simple reason is as follows. Shorter stroke, the piston has to travel a shorter distance to complete a cycle. This makes it rev easier.
Hey Scott, how is going.
I am sure you can easy explain that is why 14.04 stroke engines revving higher then 14.25 (it is only .21 mm or 1.4% difference in stroke). The bore diameter is 0.06mm or 0.43% difference. How RPMS or torque change with this small difference? I am not interested data from web sites, just your filling. I haven’t seen any of 14.25 mm engines faster infield then 14.04 mm.
If we assume that ports lay outs are the same, the exhaust difference will be about 1 degree (14.25-157.7/14.04-158.8), so dwelt time of combustion pressure is about absolutely the same-means with all differences mentioned before-no real difference in performance.
Just for references, go to my web site (
www.palmarisracing.com) and in downloads you will find timing calculating software. I am sure it will be very helpful to figure out which engine perform and where is curve can be expected.
Best regards
Edward