From the evidence I've seen, rod length/ratio has a very little effect on torque/power. It's responsible for maybe 1-2%. Engine displacement is by far the biggest factor in torque production. A decent engine makes 100Nm per litre. Cheap production engines make a little less and high performance engines make a little more than 100Nm per litre.
@@tiitsaul9036 it's more than 1-2% on some engines, I think a M30 is a perfect engine to test it out on, one with 135mm rod and then one with a 144mm rod, the 9mm is enough to get some real world info from
@@Grooty79it's very hard to do a proper test. Longer rod demands for a different piston design. It's hard to isolate rod length. "Garage4age" has done a really good rod test. He swapped longer to a longer block. Everything else remained the same, pistons, crank, head, oil and so on.
@@tiitsaul9036 it's easy to do but requires some custom parts, the small engines his playing with are to small in size to show a measurable gain and they have very good flowing heads, the test could be done on M30 as it's 3.5 litres and going as large of a difference in rod length will show the characteristics best , I know that there's a benefit as I've been playing with rod length on many different engines my whole life, going longer rod is only beneficial until piston height gets too short and ring seal gets compromised hence why I'm happy building engines with a short rod or a long rod depending on block height and piston availability, the 130mm rod and 84mm stroke 2.9 is the same rod ratio of 1.54 as a 347 ford sbf Windsor 🤔🤔🤔 I like long rod combos and like to get into the 1.7 RR range, the maximum effort 2.9 has a RR of 1.64 and yes it does make more power than the head flow suggests it should
