[z28guy30]

I was reading the following the attached article below from HotRod magazine, and it left me completely befuddled about what they are talking about. Are they saying that an engine that produces 100 lb/ft of torque will produce 410 lb/ft of rear wheel torque with 4:73 gears? lol I am either reading something wrong, or they have lost their flipping minds.

[TSloper]

They are correct

[Mikey LikesIt]

They are correct

[z28guy30]

Originally Posted by TSloper

They are correct

What am I reading wrong then? I read it like a car that only produces 100 lb/ft at the engine will produce 410 to the rear wheels with 4:10 gears which is entirely bogus. If your engine only produces 100 lb/ft you are going to experience frictional loss through the driveline and your rwhp is going to be around 13% less than at the flywheel.

If that was the case the LT1 would produce 1865 lb/ft of torque to the wheels simply by swapping 2:73's for 4:10's. lmao (455x4.10=1865)

[ender2664]

Originally Posted by z28guy30

What am I reading wrong then? I read it like a car that only produces 100 lb/ft at the engine will produce 410 to the rear wheels with 4:10 gears which is entirely bogus. If your engine only produces 100 lb/ft you are going to experience frictional loss through the driveline and your rwhp is going to be around 13% less than at the flywheel.

If that was the case the LT1 would produce 1865 lb/ft of torque to the wheels simply by swapping 2:73's for 4:10's. lmao (455x4.10=1865)

Torque is effected by gearing.

[tcal780]

Originally Posted by z28guy30

If your engine only produces 100 lb/ft you are going to experience frictional loss through the driveline and your rwhp is going to be around 13% less than at the flywheel.

You are correct here, talking about HP, however, torque is multiplied by the gearing.

[z28guy30]

Originally Posted by tcal780

You are correct here, talking about HP, however, torque is multiplied by the gearing.

What am I missing then? The 2016 Camaro SS produces 455 lb/ft of torque at the engine. In the dyno graph below a bone stock 2016 Camaro SS produced 400, 402, and 405 lb/ft to the rear wheels.

The 2016 Camaro SS (automatic) has a differential gear ratio of 2:73.

2:73 x 455 = 1242 lb/ft of torque to the wheels. <--- According to the article.

[TSloper]

The dyno knows what the effective drivetrain ratio is and divides accordingly.

[Zeke.Malvo]

Originally Posted by TSloper

The dyno knows what the effective drivetrain ratio is and divides accordingly.

No it does not know the effective ratio. a DynoJet works backwards, it reads hp and calculates tq (or not at all if you don't hook up the tachometer, and it'll print hp based on mph).

[z28guy30]

Originally Posted by Zeke.Malvo

No it does not know the effective ratio. a DynoJet works backwards, it reads hp and calculates tq (or not at all if you don't hook up the tachometer, and it'll print hp based on mph).

That I am aware of since the dynojet is an inertia type dyno which output is measure by the speed of the drums compared to a load type dyno like the mustang dyno's.

I am just having a hard time grasping the concept of if actual torque to the wheels is around 1242 lb/ft on our cars why does the dynamometer give you a different reading?

[Zeke.Malvo]

Originally Posted by z28guy30

What am I missing then? The 2016 Camaro SS produces 455 lb/ft of torque at the engine. In the dyno graph below a bone stock 2016 Camaro SS produced 400, 402, and 405 lb/ft to the rear wheels.

The 2016 Camaro SS (automatic) has a differential gear ratio of 2:73.

2:73 x 455 = 1242 lb/ft of torque to the wheels. <--- According to the article.

That's exactly what you would do. Torque is multiplied through the gears. Say with stock gearing, you barely chirp the tires in 2nd, but with better gearing you blow the tires off. The engine didn't make more power, but more torque was now available at the wheels.

That's why a high revving low displacement engine can do fine with proper gearing.

[z28guy30]

Originally Posted by Zeke.Malvo

That's exactly what you would do. Torque is multiplied through the gears. Say with stock gearing, you barely chirp the tires in 2nd, but with better gearing you blow the tires off. The engine didn't make more power, but more torque was now available at the wheels.

That's why a high revving low displacement engine can do fine with proper gearing.

Can you explain why the rear wheel torque results are lower instead of being much higher due to torque multiplication on the dyno graph then?

[Zeke.Malvo]

Originally Posted by z28guy30

That I am aware of since the dynojet is an inertia type dyno which output is measure by the speed of the drums compared to a load type dyno like the mustang dyno's.

I am just having a hard time grasping the concept of if actual torque to the wheels is around 1242 lb/ft on our cars why does the dynamometer give you a different reading?

Because the dynometer doesn't read torque at all, just calculates it based off of horsepower and RPM.

[ender2664]

Originally Posted by Zeke.Malvo

Because the dynometer doesn't read torque at all, just calculates it based off of horsepower and RPM.

Isn't it the inverse?