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What Does Horsepower Get You?

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AHS

Let’s just ask @Greentored about torque!! Wouldn’t I love to have his 14hp in my tractor for snow blowing!! 💪😀

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R Scheer

I don't know what horsepower gets you people, but it gets me a big smile on my face!

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sqrlgtr

“What does horsepower get you?” a little over 3 pages so far hehehe:laughing-rofl::laughing-rofl: .....

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Greentored
On 10/17/2020 at 7:03 AM, AHS said:

Let’s just ask @Greentored about torque!! Wouldn’t I love to have his 14hp in my tractor for snow blowing!! 💪😀

That would be an awesome test! 

Right now I have nothing to compare it to- the only stock 14hp I've ever worked with is backed up by a hydro. There is certainly a noticeable difference between that and my 12hp hydro.

 

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oilwell1415
On 10/16/2020 at 4:15 PM, ebinmaine said:

So does that indicate that a 10 horse older iron Kohler engine FEELS LIKE it has more torque than a modern 12.5 because it is using the torque multiplication of the heavy flywheel in a similar manner to dividing gears?

 

I do certainly realize I'm splitting hairs here but I'm just curious...

 

The flywheel does not multiply torque, it just stores energy.  There are a lot of moving parts here.  Torque is primarily driven by one thing and one thing only: displacement.  The more air you move per engine cycle the more torque you will make.  Horsepower is similar, except it's how much air you can move per hour instead of how much per engine cycle.  That's why a 150cc engine can make just as much power as a 300cc engine, but only makes half the torque and has to spin twice as fast.  Obviously it's not really that simple.  The old K241 was 390cc.  There were two different 12.5 HP engines used, one was 476cc and the other 398cc.  The 390 and 398 should be pretty close on torque, but the 476 should have a significant advantage.  So why would the older engine feel more torquey?  The flywheel can create that illusion for a short time, but over more than a second or two there has to be more to it.  Two possibilities come to mind off hand.  The first is how the governors are setup.  Some are able to add throttle even at idle to maintain the desired idle speed and others aren't.  I don't know how these are setup, but it's something to consider.  The second thing is the cam timing.  In the early 70s car manufacturers started retarding the camshafts in their engines to reduce emissions.  Ford typically retarded their cams by 8 degrees.  This killed low end torque.  Simply installing the cam straight up can be worth 20-30 hp and 50-60 ft-lbs of torque with no other changes.  It would not surprise me if modern lawn tractor engines are the same way.  And just like the compression ratio, the intake valve closing point will change things more at part throttle than it will at full throttle.

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clueless

I had a 1969 Z/28 with the high revving 302, a muncie 4sp and a 373 rear. Neighbor down the street had a 71 SS396 Nova same 4sp and a 355 rear. The HP to weight ratio was just about the same but the Nova's torque to weight was higher (big block). Both of these cars would run the quarter almost the exact same time if everything hooked up right, that high revving 302 could be a ***** (but fun) off the line. The Z usually owned the first 3/4 of the run, but after that if it was a big block you were racing you were looking in your mirror cuse it was coming. My Z was fast off the line sometimes taking it to 7000 rpm before shifting, but at the 3/4 mark in 4th gear and gas pedal on the mat you were done, still gaining speed but not much. When I'd drive the Nova it was still pulling at the 3/4 mark, you could feel the difference, you still had a little G force pushing on you in the seat. I was always told that was because of the larger torque. Don't get me started on the torque of a 502 big block I got to drive a few years ago:o.

Damn I miss those days:(.

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AHS
20 hours ago, clueless said:

I had a 1969 Z/28 with the high revving 302, a muncie 4sp and a 373 rear. Neighbor down the street had a 71 SS396 Nova same 4sp and a 355 rear. The HP to weight ratio was just about the same but the Nova's torque to weight was higher (big block). Both of these cars would run the quarter almost the exact same time if everything hooked up right, that high revving 302 could be a ***** (but fun) off the line. The Z usually owned the first 3/4 of the run, but after that if it was a big block you were racing you were looking in your mirror cuse it was coming. My Z was fast off the line sometimes taking it to 7000 rpm before shifting, but at the 3/4 mark in 4th gear and gas pedal on the mat you were done, still gaining speed but not much. When I'd drive the Nova it was still pulling at the 3/4 mark, you could feel the difference, you still had a little G force pushing on you in the seat. I was always told that was because of the larger torque. Don't get me started on the torque of a 502 big block I got to drive a few years ago:o.

Damn I miss those days:(.

A 302 running at 7000rpms, that must be a sound you’ll never forget!! 😀💪👍

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ebinmaine
30 minutes ago, AHS said:

A 302 running at 7000rpms, that must be a sound you’ll never forget!! 😀💪👍

Imagine every thunderstorm that ever existed put into the same place at the same time....

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clueless
2 hours ago, AHS said:

A 302 running at 7000rpms, that must be a sound you’ll never forget!! 😀💪👍

Especially with the headers uncapped. Back in the day I owned and raced a few muscle cars but that factory built 302 when tuned right was a blast to drive and a monster for the first 3/4 of the 1/4 mile. It could easily stall a 4000rpm and keeping the rear end connected even in 3rd gear was a challenge but still the best 14 seconds of my life. I my have told this before, a few years ago I ran into my brother's 2nd x wife, her new husband bought a 2010 corvette with the LT1 engine and a 6 speed auto, the thing was pushing well over 430 hp. She new I was a car guy and ask me if want to take it for a drive, hell ya :handgestures-thumbupright: I drove it a few miles to the county road were we use to street race in the early 70's at the end of a small bridge to two large pine trees, both still there, is exactly 1/4 mile so I ask her can I do it , she said sure :handgestures-thumbupright:. So with the traction control on I stood on it, well that thing was fast I'm sure when we reached the pines it took use less than 13 seconds and that's with the AC and radio on and one hand on the steering wheel. While is was fun it was nothing like driving the Z down the 1/4 mile, like I said best 14 second, a few time in the 13's in my life. 

Sorry didn't mean to hijack this post, just doing some reminiscing :auto-layrubber:

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tom2p


one friend has an original DZ302 

 

he showed it for years and then later raced it at the strip 

 

although the car ran impressive times with the initial read end ratios - 3:73 or 4:10 or 4:11 or whatever - that car *really* came alive when he went to lower ratio - 4:88 rear end (or it might have even been lower)

 

I gotta look for some pics of the car 

 

it was painted 'flip-flop' pearl purple with a lot of chrome - chrome plated suspension pieces etc ... factory chambered exhaust was also chrome plated 

 

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tom2p
On 10/19/2020 at 9:40 AM, oilwell1415 said:

 

The flywheel does not multiply torque, it just stores energy.  There are a lot of moving parts here.  Torque is primarily driven by one thing and one thing only: displacement.  The more air you move per engine cycle the more torque you will make.  Horsepower is similar, except it's how much air you can move per hour instead of how much per engine cycle.  That's why a 150cc engine can make just as much power as a 300cc engine, but only makes half the torque and has to spin twice as fast.  Obviously it's not really that simple.  The old K241 was 390cc.  There were two different 12.5 HP engines used, one was 476cc and the other 398cc.  The 390 and 398 should be pretty close on torque, but the 476 should have a significant advantage.  So why would the older engine feel more torquey?  The flywheel can create that illusion for a short time, but over more than a second or two there has to be more to it.  Two possibilities come to mind off hand.  The first is how the governors are setup.  Some are able to add throttle even at idle to maintain the desired idle speed and others aren't.  I don't know how these are setup, but it's something to consider.  The second thing is the cam timing.  In the early 70s car manufacturers started retarding the camshafts in their engines to reduce emissions.  Ford typically retarded their cams by 8 degrees.  This killed low end torque.  Simply installing the cam straight up can be worth 20-30 hp and 50-60 ft-lbs of torque with no other changes.  It would not surprise me if modern lawn tractor engines are the same way.  And just like the compression ratio, the intake valve closing point will change things more at part throttle than it will at full throttle.


when I think flywheel - I think of some of my old dirt bikes that had no flywheel ... basically just a 17mm nut ... instant revs !

 

those small bore high revving 2 stoke bikes were blast to ride - if you knew how to stretch that throttle cable ... no low end  lol

 

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AHS

Very good explanation @tom2p  toque=PLA 

P= Brake mean effective pressure (Bmep) the pressure pushing down on the piston

L= length of the stroke

A= size of the bore

LA= D= displacement

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