wesaysoracing

Does the rod to stroke ratio have as much of an effect on two strokes as it does on four strokes? playing around with dirt cars , i have found that if the ratio is 1.6 or greater the engine is easier to drive and pulls better off the corner and down the straights, i know this is comparing apples to oranges, but still would a two stroker with a long rod ratio have a better disposition than a short ratio one?

BadAzzMaxx

I am no exspert by any means, But if you are talking about longer or shorter strokes, As a general rule a long stroke will have better toque than a short stroke, The longer stroke will swing a bigger prop and shorter will give faster and more rpm.

wesaysoracing

not asking about stroke but the stroke to rod ratio (6.250 rod length , 3.50 stroke = 1.78 rod to stroke ratio)

kenhiraihnl

FWIW, here's the features of my DA50 engine:

Features Desert Aircraft, auto advance, electronic ignition. Walbro Carburetor, Exclusive Desert Aircraft designed cylinders, pistons, and crankshaft. CNC milled, 7075 aluminum alloy crankcase. Low vibration. Most torque in its class. Long rod to stroke ratio. Aerobatic power curve. DA engines are designed using the latest tools and techniques, including 3D CAD and Stereo Lithography.

pe reivers

Two stroke engines have by virtue of their construction a longer rod ratio that multicylinder four strokes. This makes the piston linger in BDC less, and adds to the port area availability.
Long rods tend to shift best torque to lower rpm, whilst not increasing best torque. In many larger engines a desirable feature, if a large prop needs to be driven without reduction gear.

fujiman

My Feedback: (133)

also effects piston speed. as the longer rod will allow the piston to remain around tdc for a longer time. makes the eng. torquier at a lower rpm to mid range. Smokey Unick of chevy racing days covered the subject really well in his CHEVY RACING book. also effects side loading of the rod, as the angle is less in the cranks rotation. depending on the eng. app. a short rod or a long rod can be used to change the personality, if you will, of an eng. According to Smokey any eng. can benefit from a longer rod, and he says to go with the longest rod that will fit within the pist., to crank package or what will fit within the cyl. length.

av8tor1977

My Feedback: (6)

Also interesting thing about high rod length ratios, is the fact that engines with them tend to be less detonation prone, though this is not much of a problem with our smaller bore engines.

AV8TOR