tundra2000

My b20b4 has a r/s ratio of 1.54 and i heard 1.75 is perfect, so is their a way i can get my r/s ratio close to that?

chris164935

Yeah, by changing the length of your rods, the length of your stroke, or both. Basically, to get your rod/stroke ratio closer to 1.75, you'll need longer rods, a shorter stroke, or a combination of the two. In any case, you will require custom pistons.
You only really need a 1.75:1 rod/stroke ratio if you are planning to rev the dog **** out of the motor. For reference, bike engines run close to that rod/stroke ratio.

chris164935

Quick searching on Google found this: B17A1 motor from '92-'93 Integra GS-R has a stroke of 81.4mm. Running that crank with your B20B4's rod's would net you a 1.68:1 rod stroke. Of course, with the B20A4's pistons, this would drastically lower your compression ratio, so custom pistons would most likely be needed, depending on your goal(s). This, of course, assumes that the B17A1's crank would fit in your B20B4's block...

Gunmetal_B20_Hatch

iTrader: (9)

Perfect R/S ratio is just a myth... Dont worry about it.

Red_Army

a b16 has the closest to it that i know of in honda world. :p.

JeffBro

There are tons of people who have proven that the rod ratio on the ls/b20 crank can handle rpms. It's been talked to death on this forum. It more important to think about the other key points in building reliable motors. Things like the pistons, rod bolts, the machine work, time put into planning and building the motor. There is an excellent build thread on the allmotor forum