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B-maniac
02-14-2008 18:17:09
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Re: 2 cylinder fans in reply to mlpankey, 02-14-2008 17:07:56
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Cars and tractors and their individual requirements are on complete different ends of the chart. The more cylinders you have for a given displacement, the more valves you have and the more port volume you have and also the shorter stroke you have. This is all condusive to more horsepower, ,BUT , the engine must turn a lot more rpm to get to this peak power and torque. For every 25% decrease in rpm the power and torque decreases conciderably and therefore requires more gear ratio choices and more shifting to keep the engine in its power band. This is a perfect description of a multi-cylinder car or racing engine , NOT a tractor engine that must, or at least should , maintain most of it's advertised power and torque over at least 4 to 500 rpm drop from peak. I would love , just for grins , for some of you dyno owners to do a test sometime on bone stock 2cyl JD , 4cyl Farmall and 6cyl Oliver antique tractors from approx. the same model years with opprox. the same engine displacement , for max hp. and then lug them down to 70% of max rpm and finally 50% of max rpm and record the hp. figures at each rpm. This would be more representative of actual field work for which they were designed. I believe the old 2 cyl JD's figures will speak for themselves. Long stroke has the leverage and the volumetric effeciency at lower rpm that you won't get with 4's , 6's , etc. Why do you think that everyone (inc. Deere) went to T/A's , over/under hyd. shift , multi-power , Power-shift and all the other names they gave it?? They were all on higher rpm , narrow power band "screamer" engines that didn't have the power band width to lug through a tough spot without down shifting. Our 830 Case (4cyl long stroke low rpm , 1800 max. would pull 4-16's at constant depth in plow gear whereas the neighbors 4010 (approx same hp) would have to lift or shift down in the tough spots to keep up. The Case would lug down to 1400rpm and still have most of it's torque to pull on through. The 4010 would drop 600 rpm in the same spots and had very little steam left. Not knocking any brands , I'm just saying there is no good substitute for a wide low rpm torque and horsepower band for a farm tractor and JD rode the gravey train for many years until even they gave in to the multi-cylinder marketing frenzie. Even they found it more economical to add gears and power shift etc to 6's rather than redesign a long stroke 2 cyl. transverse crank engine without the inherent limitations of the traditional design. The 40hp "screamers" of today couldn't hold a candle to a 40hp "G" hooked to heave field equipment for a days work. Just my opinion , no response required.
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