Jump to content

GM Torque

nick mcintire
 Share

Recommended Posts

nick mcintire Enthusiast

nick mcintire

Posted
Posted

How does GM figure Torque?  At the flywheel or the rear axle.

The sierra 1500 with 6.2 engine has 460 lbs of torque, which has the 3.23 rear axle.

How many lbs of torque does the 6.2 engine with the Max Tow Package have which has the 3.42 rear axle.

Gangly Senior Enthusiast

Gangly

Posted
Posted

GM uses an engine dynometer to gather engine HP and TQ.  However, GM is very conservative with their numbers and the engines will usually outperform the measured and calculated test results in the real world.  The LT1 from the mid 90's to the LS motors that ran through the late 2000's were notorious for being under rated and outperforming their factory numbers.

  • 2 weeks later...
Transient Senior Enthusiast

Transient

Posted
Posted

GM, and most of not all other manufacturers utilize SAE testing to determine the hotelier and torque ratings of its engines. As others have said, it's at the flywheel and not the rear axle. As another person said, GM has been known to understate the numbers. That could be because they went with the lowest numbers achieved at time of testing. I use to have a supercharged Cobalt SS (engine code LSJ). GM said that engine produced 205hp/200tq. I dynoed the car and it was a little more than that. I actuality got it into the 130 MPH Club on the Bonneville Salt Flats in showroom stock condition with an average speed of 131mph by running 4th gear all the way to ten limiter (which was 134mph at 6,500 rpm).

 

Sent from my SM-N960U using Tapatalk

 

 

 

 

  • Like 1
swathdiver Senior Enthusiast

swathdiver

Posted
Posted
On 3/11/2021 at 11:18 PM, nick mcintire said:

How does GM figure Torque?  At the flywheel or the rear axle.

The sierra 1500 with 6.2 engine has 460 lbs of torque, which has the 3.23 rear axle.

How many lbs of torque does the 6.2 engine with the Max Tow Package have which has the 3.42 rear axle.

You can figure this out with a formula on an excel spreadsheet.  

 

My truck puts down about 689 foot pounds of torque at 2000 rpms in 6th gear.  A 6.2 with 3.73 gears in my generation puts down about 980 ft lbs in 6th at 2000 rpms.

Transient Senior Enthusiast

Transient

Posted
Posted
You can figure this out with a formula on an excel spreadsheet.  
 
My truck puts down about 689 foot pounds of torque at 2000 rpms in 6th gear.  A 6.2 with 3.73 gears in my generation puts down about 980 ft lbs in 6th at 2000 rpms.
I can't find a calculator that considers rear axle gearing, but I did find these formulas.

Torque = (Horsepower * 5252) / RPM
Horsepower = (Torque * RPM) / 5252
RPM = (Horsepower * 5252) / Torque


Sent from my SM-N960U using Tapatalk

aliveguy5 Enthusiast

aliveguy5

Posted
Posted

I think I get what you are asking for... How do you calculate the torque multiplication that the gearing and gears will give you. I don't have this answer either but I'd be very interested as I feel the 6.2 is even beefier than what they say as well. 

redwngr Senior Enthusiast

redwngr

Posted
Posted (edited)

When going through a gearset, (transmission, differential etc) the ratio of the torque in/out is the opposite of the ratio of the speed in/out.  Both are calculated by the number of teeth in the gearsets -- but are sometimes expressed as the ratio of in/out speeds instead.

 

 

So, if the output speed is lower, the output torque will be higher. (in 1st gear, the output torque is higher than in second gear)

If the output speed is higher (as in an overdrive gear) the output torque will be lower.

 

Every time power goes thru a gearset, some of the power is lost (converted to heat and noise). 

Since gearsets don't have 'slip' the power loss is be observed as a reduction in torque. (if there is torque measuring sensors on the input and output sides of the gearset)

 

HP out = HP in x efficiency

torque out = torque in x speed  ratio x efficiency

speed out = speed in x gear ratio 

 

Edited by redwngr
  • Thanks 1
swathdiver Senior Enthusiast

swathdiver

Posted
Posted
3 hours ago, aliveguy5 said:

I think I get what you are asking for... How do you calculate the torque multiplication that the gearing and gears will give you. I don't have this answer either but I'd be very interested as I feel the 6.2 is even beefier than what they say as well. 

You multiply the final drive ratio in the given gear with the known torque value at the desired RPMS.

 

An LC9 makes 302 ft lbs of torque at 2000 rpms.  The final drive ratio of the truck (gear ratio multiplied by axle ratio) is simply multiplied by the torque value.

 

6L80 6th gear ratio is .667 and the axle ratio is 3.42 which results in a final drive ratio of 2.28.  So we multiply 2.28 by 302 and get 689.

Gangly Senior Enthusiast

Gangly

Posted
Posted (edited)
3 hours ago, redwngr said:

When going through a gearset, (transmission, differential etc) the ratio of the torque in/out is the opposite of the ratio of the speed in/out.  Both are calculated by the number of teeth in the gearsets -- but are sometimes expressed as the ratio of in/out speeds instead.

 

 

So, if the output speed is lower, the output torque will be higher. (in 1st gear, the output torque is higher than in second gear)

If the output speed is higher (as in an overdrive gear) the output torque will be lower.

 

Every time power goes thru a gearset, some of the power is lost (converted to heat and noise). 

Since gearsets don't have 'slip' the power loss is be observed as a reduction in torque. (if there is torque measuring sensors on the input and output sides of the gearset)

 

HP out = HP in x efficiency

torque out = torque in x speed  ratio x efficiency

speed out = speed in x gear ratio 

 

Your efficiency comes down to frictional losses, as described above as heat and noise, as well as the energy required to maintain rotation of said mass.  

 

Also, the ratio is calculated by the number of teeth on the gear set as mentioned above, but more specifically the ratio of the circumferences (circular pitch) of the matching teeth gearsets.  Its a small difference, but important.

 

Very accurate and great answer!

Edited by Gangly

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.6k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,993
    Total Members
    8,960
    Most Online
    President Roberto
    Newest Member
    President Roberto
    Joined

  • Who's Online   2 Members, 0 Anonymous, 198 Guests (See full list)

  • Latest Articles

  • Posts

    • bwiese
      upgrading speakers on 2026 std cab WT...

      By bwiese · Posted

      I don't wanna do major surgery/upgrades, behind-the-dash work, add amps, change radio etc. on my '26 std cab WT. On the WT, it has the base 7" IOR infotainment setup, and only two speakers (doors). Since I listen to classical, looked around for speakers that do well and dug thru reviews. Two-way speakers were found to be better than 3-way. So I've ordered a pair of  Infinity Reference REF-9632IX 2 way speakers.  [These may  or may not have been discontinued / succeeded by the 3-way ...9633 ones.]    These speakers are lauded for 3 ohm and 94db sensitivity spec so they'll work well for ordinary base car radios without amps and offer better performance (quality,  strength) than  default base paper-cone speakers. They'll be installed in a few days and I'll let y'all know what I think. Bill W San Jose      
    • RyanbabZ71
      RyanbabZ71's 2019 High Country

      By RyanbabZ71 · Posted

      Thanks!   Changed out the rear shocks today to Bilstein 5100s.  So far feel much better. The stock Rancho were wore out.  Lots of heavy hauling (2 moves, home renovations, etc).  Next up is new BFG tires Monday.  Cant wait the current tires have little to no wet traction and are super loud (hum)    
    • Snowcamo
      No high speed fans...

      By Snowcamo · Posted

      Ok, I got the all the codes. What do you all think would be a place to start?
    • Chuck FB
      Correct way to service 2024 l8t allison trans?

      By Chuck FB · Posted

      How about I just point to the factory pans stand pipe little drain plug and claim its a pan with a real drain plug !. I just couldn't swallow the fact that a Dorman pan which at this point is probably the only pan out there that fits the gas version truck cost that much up here in Canada so I decided initially anyway to skip it and see what I thought of pulling the pan method and down the road if I felt inclined enough then I would either install a drain plug kit in the factory pan if there is enough room for it, or have a bung welded onto it, or put an aftermarket pan on. The thing is if the pan is not pulled then the magnets in the pan can't be inspected and cleaned or if wanting to change out the filter. However of course it certainly would make the job easier to be able to drop the oil first before having to handle the pan if dropping the pan that go around was the goal.    I knew a guy locally that was doing custom field spraying years ago with a pickup pulling a ground driven sprayer, I believe it was a GM pickup with an automatic trans. He had a drain plug in his pan and would drop the oil out of it once a week and top it back up through the dipstick tube to keep refreshing a portion of the oil often and that made the transmission last far longer than had he done nothing. Soft fields pulling 500 gallons of water at the start of each mixed up sprayer tank batch and in low range sucking along. I imagine he got some tips from other custom sprayer outfits doing the same thing at the time and learning from their blown up tranny mistakes. Transmissions then had no lock up converter so would cook the crap out of the fluid slipping that much and it would not have been synthetic fluid either. 
    • KARNUT
      Gas Prices

      By KARNUT · Posted

      3.39 Kroger’s in Montgomery Texas. 

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...