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Boney

Engine power, New vs Old

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Boney
As I am new to tractors this question comes to me. I have seen new tractors that are around 15hp yet they dont have the attachements that some of the older 8-10hp motors have. Also some of these 15hp tractors dont seem to be able to do much more if any more then the 8-10hp older tractors in regards to towing capacity. Why is it that the 8-10 hp tractor can plow, rototil, cut grass,ect. and I hear of new tractors with 15 hp boging down due to wet grass ? With all the hp of the new ones i would think they would fly throught wet grass. Is the Tourque that much different from old to new tractors ? Sorry for the winded question. If anyone understands what I am asking please feel free to add ANY comments.

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Dutch
Horsepower is a rating that is subject to who measures it and how it is measured. In other words, one engine may be more powerful than another engine with the same HP rating. Horsepower measures how fast work can be done. Torque measures how much work can be done. Torque can be multiplied (gears), horsepower cannot. Therefore, an engine with higher horsepower may not be as powerful as another engine with less horsepower with higher torque. To really understand this, look at power curve charts. Where the horsepower curve intersects the torque curve is where the maximum useable power is. Some engines develop horsepower far above that intersection. Bottom line is...... horsepower is cheap to produce and to the average consumer horsepower is what sells (so do wide tires). If a 25hp engine bogs down in wet grass, it is because it ran out of torque. Don't get me wrong, horsepower is not worthless. I use 10-12hp tractors for jobs that require brute force but not speed (plowing, grading, pulling, slow mowing tall grass, etc.). But, I use an 18hp tractor when high speed is needed (vacuuming, fast mowing lawn grass, etc.). Higher horsepower with high torque is the ideal. I guess the guys who run pulling tractors do their tricks to have both.

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DaveM
It's the same reason why my dad's 190 hp cummins diesel can out tow my 345 hp Hemi. He has around 450 lbs-ft. of torque to my 375 lbs.-ft. DaveM

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Dutch
quote:
Originally posted by DaveM
It's the same reason why my dad's 190 hp cummins diesel can out tow my 345 hp Hemi. He has around 450 lbs-ft. of torque to my 375 lbs.-ft.
Perfect example. Your dad's Cummins probably develops that 190hp at around 2100RPM and the torque probably peaks at around 1500RPM, and he probably has an 8-20 speed transmission/rear combination to keep the engine in that narrow (600RPM) range.

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KenK
I had a 42" snowblower on my 410 allis with a 15hp ohv engine installed.I had to go in granny low and still have to clutch it to get through.So I pulled the blower off and mounted it on my B-112 with stock 12hp.I could run in the same conditions in 2nd gear with the variable all the way forword.There is such a long stroke in these old cast iron engines that they walk all over the newer models.

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Boney
KenK "long stroke" are you refering to the travel of the piston here ?

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KenK
Yes sir. The rod is much longer in the old engine.This is where the added torque is coming from.

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MPH
Used to call that lugging power in farm tractors. MPH

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Dadsy98
Those "old cast iron" long strokin' engines make me smile! just love it when the folks down the road with a 25hp rider complain about the tall grass. I have cut their grass with my K341 in third gear and smoking all the way. Steve

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JimV
This has been a great subject. I try and explain it to people I run into all the time. They are amazed why thier shiny new tractors can't do a fraction of what all my old cast iron one lungers do. I tell them it is all low end torque. the same reason my 10.hp. farmall cub can run a sickle mower all day with no trouble.

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Terry9
Snowblowing this past winter with some of the accumulations we got convinced me that my old (1968) cast iron Briggs had torque up the ying-yang. Such a great sound to hear the governor kick in and the engine just surge as you dig into the 2 foot pile the snowplow driver just left for you. But, people like shiny plastic tractors with BIG engines. Must be the MTV baby boomers.

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simplejim
Dutch,i think the cummins that DaveM was refering to was the smaller b series that they put in the dodge pickups. if so it should have a four,five or six speed.

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andy gartner
Smokers fellas! I'm learning so fast, my shoes fell off! Thanks! Harley's might be another example. Lower HP, good torque. My STOCK 883 had enough torque in any gear, but low, measured REAR WHEEL HP. The 900 Ninja, plenty of RW HP but only at 8700 RPM to 10,500 RPM. A

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Tacey
Properly designed and executed 'belt & pulley' transfer of that HP and torque make a big difference in performance where the rubber meets the grass/pavement/dirt, also. My little 11 HP Briggs single continually amazes me with its brute strength. Tacey

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Dutch
quote:
Originally posted by simplejim
Dutch,i think the cummins that DaveM was refering to was the smaller b series that they put in the dodge pickups. if so it should have a four,five or six speed.
Jim, thanks for setting me straight. After years of messing with larger equipment, I just assumed............ I realize now that most of the 190s I was thinking of were probably scrapped years ago. Every once in a while I get shocked at my age. This was one of those times. I feel like an old man.

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Allis_B12
"Long stroke" on the old cast-iron engines is a very true statement. I pulled the head on my 300424 today to clean the carbon buildup. Then, I spun the flywheel slowly to see the piston and valves work in slow motion. The engine truly has a long stroke.

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Charlieson
Those old briggs and kohler's have big piston's too. My 3212 and 3416's do work that none of the newer tractors could ever do. I have an old model 70 cub with a 7 hp kohler and I never failed to be amazed at what she could do. I pushed snow with all of through 3 and 4 foot drifts. Piled the snow as high as the blade would lift up. I also plow the garden and tow a big cart that most of the time is full of rocks. I have mowed grass as high as the front of the tractor and My sovereigns just keep on chugging. Wife keeps after me to get a 'new' tractor saying that I wouldnt have to work on it as much. She doesnt realize that a lot of the time that I am just piddling because it is a labor of 'love'!!!

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dogboy
Thanks again guys, now i understand how my 20 yr old benz turbo diesel- rated at 67 hp, could beat many muscle cars, or the 13 yr old gas 6cyl rated at 157 hp moves the way it does.

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simplejim
Dutch dont feel old or you're gonna me me feel old too. my first ride in a semi was a late 60's GMC cabover daycab with the old non turbo 220. course i gotta admit the truck was old then.

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MPH
The truck was old in the late 60's??Hhmmmmmmmmmmmmmm.kids nowadays.MPH

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simplejim
no MPH.lol the truck was a 60's but my first ride in it was in it was in the early 80's. next truck i was in was i a 1978 international transtar. it had a 290 cummins turbo motor...seemed like that 290 had twice the power of the old 220.

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patrician12
short stroke engines need high rpm to develope what I would say equal power as a long stroke motor.My guess on the on this situation is that while engine power and torque curves have changed dramatically is it possible that gear ratios and weight have not been changed by the manufacturer?Don't forget also our A/Cs have heavy frames and 2 cast iron gearboxes to give them alot of weight.My 912 and 916 rarely need chains to plow snow.My other tractors just spin the wheels.Another thought,these new aluminum trans axles are of generic manufacture and not exactly what was made years ago. One transaxle can fit many many makes our A/Cs are not like this.A 350 Chevy engine in a Camaro is fast but can't pull.The same motor in a Chevy tow truck can push and pull 3 or 4 cars.Get the idea,gear ratios.

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