How does a Dyno Really Work?

[RustyRatRod]

True to measure an engines work potential you got to give it a job first and see how it does, aka dyno, quarter mile, hauling a trailer etc.. But you can't measure torque without given it a job either, free revs won't tell you the torque.

Well of course not. The dyno has to measure the torque. Then it tell you HP based on THAT.

 

[273]

I get that. Not what I'm talking about.

What I'm trying to get through is, a dyno cannot measure HP. PERIOD. End of discussion. It MUST have a torque spec in order to "figure" HP. Torque is the DIRECT measurement and THEN the dyno "figures" HP based on torque.

Now, if you're talking about a horse pulling weight X amount of distance then that's a horse of a different color. That IS a direct measurement of HP, but a dyno cannot do THAT. It MUST see torque FIRST.

I get what your saying dyno doesn't measure hp directly, only rpm and torque (which is power) which you have to calculate hp, but don't understand why that's a big deal, you know how many things can't be measured directly? But we still know about them and how them works, we calculate watts by reading volts and amps.

 

[RustyRatRod]

I get what your saying dyno doesn't measure hp directly, only rpm and torque (which is power) which you have to calculate hp, but don't understand why that's a big deal, you know how many things can't be measured directly? But we still know about it and how it works, we calculate watts by reading volts and amps.

It's not a big deal to me. I'm just making the factual point that torque is the only thing they dyno takes a direct measurement on.

 

[273]

It's not a big deal to me. I'm just making the factual point that torque is the only thing they dyno takes a direct measurement on.

Sir, You are correct on that factual point

 

[273]

67Dart273 claims it's a myth cause it can only be calculated and many have also implied the cause it's calculated that it's of lesser importance. I know you/others don't overly care it's a pet peeve of mine and since it's the bases of performance it's shouldn't be misunderstood as it is.

Performance = power to weight, since most of the cars were talking are similar weight it comes down to power and how well you apply it. (Job)

Power = some kind combination of rpm and torque, mainly based on hp (top end), tq/cid (efficiency) and displacement. (How you go about getting that Job done)

Don't know why some insist on a hp vs torque dynamic, shouldn't be at that controversial,
Hp is tq and rpm no "VS". You could argue which way to make X HP, RPM vs TQ which I think people kind of mean when they say hp vs tq.

 

[RustyRatRod]

I think maybe what he was trying to say was that a dyno does not measure HP. It measures torque and uses that to estimate HP. But I don't know for sure. .....and I'm no expert. I am probably wrong about everything I've said here. lol

 

[273]

I think maybe what he was trying to say was that a dyno does not measure HP. It measures torque and uses that to estimate HP.

Could be his point.

But I don't know for sure. .....and I'm no expert. I am probably wrong about everything I've said here. lol

I don't think your wrong, I know you understand all this ****, I just think we just looking at it from slightly different angles, I agreed with 99% of what you said

 

[Newbomb Turk]

It's not a big deal to me. I'm just making the factual point that torque is the only thing they dyno takes a direct measurement on.

It takes a direct measurement of torque. And about as many other things you may want to measure. Then the world known formula of T*RPM/5252 come in. Simple as that.

Look at the math. Until you have RPM in the equation torque means nothing. In fact, until the crank starts turning you have 0 torque. Torque plus RPM makes power. Without RPM you have nothing. Nothing to even measure.

Arguing that horsepower doesn’t exist is even further from reality than saying building a big power engine doesn’t need a better block. It makes no sense.

If you want to take it further, look at a dyno graph. Once the engine gets past peak torque, the horsepower keeps going up. It goes up until it runs out of it, hits valve train issues or something like that.

So I’m expected to believe that less torque makes more power and it’s non existent? That little detail right there should prove that horsepower (albeit it’s calculated) is real. The torque is less (above peak torque) but the power goes up. Horsepower is calculated but it’s real, and it matters.

 

[273]

If you want to take it further, look at a dyno graph. Once the engine gets past peak torque, the horsepower keeps going up. It goes up until it runs out of it, hits valve train issues or something like that.

That's a great point.

 

[Frank Mopar]

I can do it with my iPhone.

 

[MopaR&D]

Load cell in a torque strap or mount is soo 20th century, nowadays we have accelerometers and GPS...

Or just go to a test and tune at your local drag strip.

 

[273]

Load cell in a torque strap or mount is soo 20th century, nowadays we have accelerometers and GPS...

Or just go to a test and tune at your local drag strip.

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