Why such the torque rise?

# Robin said:

I think it’s because the 41% torque rise is measured from rated speed back to peak torque.
The old engine had a much higher rated speed of 2100rpm and it’s not fuelling hard up there so on paper it’s measures a 41% torque rise back to peak torque.
In reality driving it at 1900 you wouldn’t feel that

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Cowabunga said:

You actually would. Because at 1900 you would still be producing rated power with still a very significant torque backup/rise below that, down to typically 1200 or 1300 revs, working against the engine being overwhelmed by the increasing load working against it. However, as others have mentioned, it is rather critical that the torque lowers gradually below this, so that the engine doesn’t just give up and die at fast idle. The problem here, of course, is that torque falls from where maximum torque is produced, rather than rises, so no matter what the engine is, there is torque lowering rather than rising down there. In changeable conditions it is always advisable to use as low revs as possible for good fuel economy but to run it at least 200rpm above where maximum torque is produced so that it does have some torque reserve [rise] left to cope with overloads.

Some engines typify this behaviour and the previously mentioned Ford Force engines, advertised as “Short Stroke - High Torque” really did underperform and had only around 5 to 10% torque rise if I remember correctly and had very poor ‘start-off’ torque, so they mostly suddenly died if lugged down past a certain point. On the other hand some performed way better than their official figures suggested, like my old JD2140 which on paper lacked specific maximum torque and produced it at a high, for the time 1500revs. However it produced maximum power at 2500rpm and I could never fault its performance right down to 1200rpm. Except the poor start-off torque would manifest itself sometimes on a paddle type mixer wagon where a lump could indeed stall it dead from around 2200 rpm. On a slight tangent, when this happened, the JD PTO system would disengage itself just as the engine stalled and the compression kick-back would actually have the engine running backwards until I could jump off the loader tractor and stall it. It never ran at high revs in reverse but it did actually suck in air from the exhaust and exhaust into the air cleaner. Never did it the slightest harm and it is still running perfectly today with over 12,000 hours on it with zero mechanical failures.

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Cowabunga said:

You actually would. Because at 1900 you would still be producing rated power with still a very significant torque backup/rise below that, down to typically 1200 or 1300 revs, working against the engine being overwhelmed by the increasing load working against it. However, as others have mentioned, it is rather critical that the torque lowers gradually below this, so that the engine doesn’t just give up and die at fast idle. The problem here, of course, is that torque falls from where maximum torque is produced, rather than rises, so no matter what the engine is, there is torque lowering rather than rising down there. In changeable conditions it is always advisable to use as low revs as possible for good fuel economy but to run it at least 200rpm above where maximum torque is produced so that it does have some torque reserve [rise] left to cope with overloads.

Some engines typify this behaviour and the previously mentioned Ford Force engines, advertised as “Short Stroke - High Torque” really did underperform and had only around 5 to 10% torque rise if I remember correctly and had very poor ‘start-off’ torque, so they mostly suddenly died if lugged down past a certain point. On the other hand some performed way better than their official figures suggested, like my old JD2140 which on paper lacked specific maximum torque and produced it at a high, for the time 1500revs. However it produced maximum power at 2500rpm and I could never fault its performance right down to 1200rpm. Except the poor start-off torque would manifest itself sometimes on a paddle type mixer wagon where a lump could indeed stall it dead from around 2200 rpm. On a slight tangent, when this happened, the JD PTO system would disengage itself just as the engine stalled and the compression kick-back would actually have the engine running backwards until I could jump off the loader tractor and stall it. It never ran at high revs in reverse but it did actually suck in air from the exhaust and exhaust into the air cleaner. Never did it the slightest harm and it is still running perfectly today with over 12,000 hours on it with zero mechanical failures.

Click to expand...

Cowabunga said:

You actually would. Because at 1900 you would still be producing rated power with still a very significant torque backup/rise below that, down to typically 1200 or 1300 revs, working against the engine being overwhelmed by the increasing load working against it. However, as others have mentioned, it is rather critical that the torque lowers gradually below this, so that the engine doesn’t just give up and die at fast idle. The problem here, of course, is that torque falls from where maximum torque is produced, rather than rises, so no matter what the engine is, there is torque lowering rather than rising down there. In changeable conditions it is always advisable to use as low revs as possible for good fuel economy but to run it at least 200rpm above where maximum torque is produced so that it does have some torque reserve [rise] left to cope with overloads.

Some engines typify this behaviour and the previously mentioned Ford Force engines, advertised as “Short Stroke - High Torque” really did underperform and had only around 5 to 10% torque rise if I remember correctly and had very poor ‘start-off’ torque, so they mostly suddenly died if lugged down past a certain point. On the other hand some performed way better than their official figures suggested, like my old JD2140 which on paper lacked specific maximum torque and produced it at a high, for the time 1500revs. However it produced maximum power at 2500rpm and I could never fault its performance right down to 1200rpm. Except the poor start-off torque would manifest itself sometimes on a paddle type mixer wagon where a lump could indeed stall it dead from around 2200 rpm. On a slight tangent, when this happened, the JD PTO system would disengage itself just as the engine stalled and the compression kick-back would actually have the engine running backwards until I could jump off the loader tractor and stall it. It never ran at high revs in reverse but it did actually suck in air from the exhaust and exhaust into the air cleaner. Never did it the slightest harm and it is still running perfectly today with over 12,000 hours on it with zero mechanical failures.

Click to expand...

Deerefarmer said:

Know a fellow who ran a keenan with a 7610 ford, wad of hay caused it run backwards one day, trashed the hydraulic pump iirc

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