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426/670T engine torque

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
Printed Date: 26 Feb 2024 at 8:31am
Software Version: Web Wiz Forums 11.10 -

Topic: 426/670T engine torque
Posted By: Northern Hoser
Subject: 426/670T engine torque
Date Posted: 23 Sep 2022 at 9:52am
Sort of a random thought as I was working through this on another machine; does anyone know the actual engine torque rating on the 426?

Working the horsepower formula backwards gives a 158hp engine at 2300 rpm around 360lbs of torque, but that's only the torque it produces at that particular rpm


Posted By: DrAllis
Date Posted: 23 Sep 2022 at 10:58am
Depends which HP rating the engine is sold as. I've got the specs at home and I think a 670-HI at 220 HP/2400 RPM has a peak torque of 440 ft lbs at 1700 RPM. The 158 version would be less.  1700 RPM seems to be their "peak" RPM on all their engines, by design.

Posted By: DrAllis
Date Posted: 23 Sep 2022 at 7:07pm
Update:  670-T/ 3500 engine rated at 158 flywheel HP @ 2300 RPM makes 410 ft lbs torque at 1400 RPM.   The 670-HI/ 3750 engine rated at 220 flywheel HP @ 2400 RPM peak torques at 488 ft lbs at 1700 RPM.

Posted By: Charlie175
Date Posted: 23 Sep 2022 at 7:31pm
How does that compare to an IH 414 or JD 404?


'48 B, '51 CA, '56 WD45 '61 D17, '63 D12, '65 D10 , '68 One-Ninety XTD

Posted By: DrAllis
Date Posted: 23 Sep 2022 at 7:36pm
Well, a Deere "404" was never known for big low end torque numbers. Now, the Deere 466 is another matter.

Posted By: Northern Hoser
Date Posted: 24 Sep 2022 at 10:16am
Very interesting, thanks for looking it up.


Posted By: AllisFreak MN
Date Posted: 24 Sep 2022 at 11:21am
Does the torque rating drop at pto speed or stay the same? Just curious.

'49 A-C WD, '51 A-C WD, '63 A-C D17 Series III, 1968 A-C One-Seventy, '82 A-C 6060, '75 A-C 7040, A-C #3 sickle mower, 2 A-C 701 wagons, '78 Gleaner M2

Posted By: steve(ill)
Date Posted: 24 Sep 2022 at 4:20pm
depends on the ratio of engine speed to pto speed..

As DOC said, a given motor may make max HP at 2400 RPM, but max TORQUE at 1700.

if your motor has a max rpm of 1800... then the max torque might be at 1400 rpm.

PTO speed of 540 is RATED at a given Engine speed... normally not at HIGH IDLE.

you CALCULATE HP by measuring  TORQUE and RPM...

HP = TORQUE x RPM / 5252  

most engines ( tractors ) will have a flat torque curve between 1200 - 1800 rpm with the "max" just a little higher somewhere in that range... HP will be higher as speed increases due to the formual... if TORQUE is basically constant and RPM keeps increasing, then the "calculated" HP keeps going up.

Like them all, but love the "B"s.

Posted By: steve(ill)
Date Posted: 24 Sep 2022 at 4:24pm
A "generic " curve might look something like this... The idea of a tractor is, as you PULL DOWN and load it ( 1400 - 1700) you get the MAX PULL --- TORQUE..

Like them all, but love the "B"s.

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