Torque equals HP at 5252 RPM... is this always true?

[Ilmater]

Isn't there some way of measuring torque and HP where they're actually MEASURED separately, and they aren't always equal at 5,252 RPM?

Edit: The reason I ask is that the 2006 Infiniti G35 has two separate power ratings:

AT - 280 hp, 270 lb-ft torque
MT - 298 hp, 260 lb-ft torque

I can't imagine how torque can be less on a basically identical car and engine with 18 more hp.

 

[MikeMike]

Originally posted by: Ilmater
Isn't there some way of measuring torque and HP where they're actually MEASURED separately, and they aren't always equal at 5,252 RPM?

no matter what you do, the formula for HP IS.

HP = (RPM* TRQ)/5252

so, unless your math is funky, it must be equal

 

[WiseOldDude]

you clearly don't understand the difference, so why do you care? Is this for some shallow reason such as bragging rights?

 

[Ilmater]

Originally posted by: MIKEMIKE

Originally posted by: Ilmater
Isn't there some way of measuring torque and HP where they're actually MEASURED separately, and they aren't always equal at 5,252 RPM?

no matter what you do, the formula for HP IS.

HP = (RPM* TRQ)/5252

so, unless your math is funky, it must be equal

Doesn't a dyno measure them separately, or does it just use the formula as well? I thought maybe real-world dynamics would make the formula not exactly perfect.

 

[MikeMike]

Originally posted by: Ilmater

Originally posted by: MIKEMIKE

Originally posted by: Ilmater
Isn't there some way of measuring torque and HP where they're actually MEASURED separately, and they aren't always equal at 5,252 RPM?

no matter what you do, the formula for HP IS.

HP = (RPM* TRQ)/5252

so, unless your math is funky, it must be equal

Doesn't a dyno measure them separately, or does it just use the formula as well? I thought maybe real-world dynamics would make the formula not exactly perfect.

uh, HP is a function of Trq, HP is not a true measurement, Trq is.

 

[Ilmater]

Originally posted by: WiseOldDude
you clearly don't understand the difference, so why do you care? Is this for some shallow reason such as bragging rights?

No, just curious how the G35's ratings could be what they are. I don't think that's shallow.

 

[Vic]

is this always true?

Yes, with imperial horsepower (metric hp, it's 5180).

Power = torque * angular speed

1 hp = 33,000 lb-ft/min

edit:

I can't imagine how torque can be less on a basically identical car and engine with 18 more hp.

Torque is work, power is work over time. The engine with less torque but more power is able to output that lesser amount of work faster. Make sense?

Suppose you have 2 engines, both with the same torque output, but one engine is able to make that torque at a higher rpm. Thus, that engine has more power because it is able to do the same amount of work but in shorter periods of time (i.e. faster).

 

[Ilmater]

Originally posted by: MIKEMIKE
uh, HP is a function of Trq, HP is not a true measurement, Trq is.

If that's the case, then how can the G35 pull 10 less lb-ft of torque at the same RPM (4800), but pull MORE hp (18 more) at a higher RPM (6400 vs. 6200)??

 

[mwmorph]

auto has a torquire engine but torque converters cannot handle higher rpms. The Manual probably has a less torquey engine but the redline is raised since manuals with a clutch can handle much higher rpms.

Either that or the manual has a larger exhaust manifold, downpipe or cat back exhaust. A larger exhaust will improve power top end but take off the maximum torque. For example, Hot Rod mag had an article. They made a big block (454?) and ttested ti with among other things, 2 exhaust manifolds. The smaller diameter runner manifold created higher torque in the midrange and thus higher peak torque while the larger diameter runner one sustained higher torque in the high end and thus created more horsepower at the expense of max torque, and low end torque.

this makes sense.

237lb ft at 6200rpm =280hp
244lb/ft at 6400rpm=298hp

it probably has different exhausts thus able to carry higher torque at the high end.

 

[MikeMike]

Originally posted by: Ilmater

Originally posted by: MIKEMIKE
uh, HP is a function of Trq, HP is not a true measurement, Trq is.

If that's the case, then how can the G35 pull 10 less lb-ft of torque at the same RPM (4800), but pull MORE hp (18 more) at a higher RPM (6400 vs. 6200)??

give me the numbers....

because as you increase RPM, and Trq stays similar...

for example...

100 trq at 4000 rpm only gives you 76 hp

but 90 trq at 6000 rpm gives you 102...

i dont get what you are trying to say.

 

[MikeMike]

Originally posted by: mwmorph
auto has a torquire engine but torque converters cannot handle higher rpms. The Manual probably has a less torquey engine but the redline is raised since manuals with a clutch can handle much higher rpms.

Either that or the manual has a larger exhaust manifold, downpipe or cat back exhaust. A larger exhaust will improve power top end but take off the maximum torque. For example, Hot Rod mag had an article. They made a big block (454?) and ttested ti with among other things, 2 exhaust manifolds. The smaller diameter runner manifold created higher torque in the midrange and thus higher peak torque while the larger diameter runner one sustainer higher torque in the high end and thuscreated more horsepower at the expense of max torque, and low end torque.

or it has a trq limiter.

 

[Vic]

Originally posted by: Ilmater

Originally posted by: MIKEMIKE
uh, HP is a function of Trq, HP is not a true measurement, Trq is.

If that's the case, then how can the G35 pull 10 less lb-ft of torque at the same RPM (4800), but pull MORE hp (18 more) at a higher RPM (6400 vs. 6200)??

Because the engine that makes the higher torque output at 4800 rpm cannot maintain that output at 6400 rpm.

 

[giantpinkbunnyhead]

I never really stopped to think about it... but a dyno chart on a buddy of mine's Ranger suggests this is true:

Clicky

 

[Ilmater]

Originally posted by: MIKEMIKE
give me the numbers....

Torque:
AT - 270 lb-ft @ 4800 RPM
MT - 260 lb-ft @ 4800 RPM

Horsepower:
AT - 280 @ 6200
MT - 298 @ 6400

 

[randay]

lol. no.

edit: @ question in OP, not title.

 

[Ilmater]

Originally posted by: Vic
Torque is work, power is work over time. The engine with less torque but more power is able to output that lesser amount of work faster. Make sense?

Suppose you have 2 engines, both with the same torque output, but one engine is able to make that torque at a higher rpm. Thus, that engine has more power because it is able to do the same amount of work but in shorter periods of time (i.e. faster).

Yeah, but in this case, the peak torque for the two setups (and again, these are the same engines) is at the same RPMs.

 

[randay]

Originally posted by: Ilmater

Originally posted by: Vic
Torque is work, power is work over time. The engine with less torque but more power is able to output that lesser amount of work faster. Make sense?

Suppose you have 2 engines, both with the same torque output, but one engine is able to make that torque at a higher rpm. Thus, that engine has more power because it is able to do the same amount of work but in shorter periods of time (i.e. faster).

Yeah, but in this case, the peak torque for the two setups (and again, these are the same engines) is at the same RPMs.

I can't believe this... I am actually going to try and explain this...

AT stands for automatic transmission
MT stands for manual transmission

Without caring at all about the actual numbers, assuming the exact same engines, you can figure that they have measured the HP and torque at the wheels(tires). Therefore the difference is because of transmission gear ratios. Simple as that.

 

[mwmorph]

Originally posted by: randay

Originally posted by: Ilmater

Originally posted by: Vic
Torque is work, power is work over time. The engine with less torque but more power is able to output that lesser amount of work faster. Make sense?

Suppose you have 2 engines, both with the same torque output, but one engine is able to make that torque at a higher rpm. Thus, that engine has more power because it is able to do the same amount of work but in shorter periods of time (i.e. faster).

Yeah, but in this case, the peak torque for the two setups (and again, these are the same engines) is at the same RPMs.

I can't believe this... I am actually going to try and explain this...

AT stands for automatic transmission
MT stands for manual transmission

Without caring at all about the actual numbers, assuming the exact same engines, you can figure that they have measured the HP and torque at the wheels(tires). Therefore the difference is because of transmission gear ratios. Simple as that.

torque is measured at an engine bench not at the wheels.

 

[randay]

sure it is, thats why every time you want to dyno your car, you have to remove your engine. :roll:

 

[Ilmater]

Originally posted by: mwmorph

Originally posted by: randay
I can't believe this... I am actually going to try and explain this...

AT stands for automatic transmission
MT stands for manual transmission

Without caring at all about the actual numbers, assuming the exact same engines, you can figure that they have measured the HP and torque at the wheels(tires). Therefore the difference is because of transmission gear ratios. Simple as that.

torque is measured at an engine bench not at the wheels.

Exactly. Nobody really measures at the wheels. Plus, if this is the case, why don't the thousand other MT cars out there have different measurements for their AT and MT setups?

Also, I know what AT and MT stand for, thanks.

 

[Ilmater]

Originally posted by: randay
sure it is, thats why every time you want to dyno your car, you have to remove your engine. :roll:

Um... car manufacturers NEVER publish engine ratings on a dyno that I know of. I believe ALL of them measure their engines on a bench.

 

[MikeMike]

Originally posted by: randay
sure it is, thats why every time you want to dyno your car, you have to remove your engine. :roll:

SAE ratings are done on a bench, ratings for modified/unmodified cars that ppl just want rated, are done on a wheel dyno.

 

[randay]

Originally posted by: Ilmater

Originally posted by: randay
sure it is, thats why every time you want to dyno your car, you have to remove your engine. :roll:

Um... car manufacturers NEVER publish engine ratings on a dyno that I know of. I believe ALL of them measure their engines on a bench.

The specs you give prove otherwise.

 

[MikeMike]

Originally posted by: randay

Originally posted by: Ilmater

Originally posted by: randay
sure it is, thats why every time you want to dyno your car, you have to remove your engine. :roll:

Um... car manufacturers NEVER publish engine ratings on a dyno that I know of. I believe ALL of them measure their engines on a bench.

The specs you give prove otherwise.

you are a dumbass.

leave all car threads, now.

 

[randay]

Here is your answer: They arent the exact same engine.

If you take the time to look at the specs on infinitis website

AT: DOHC, 4 valves per cylinder with microfinished camshafts. Continuously Variable Valve Timing Control System (CVTCS) for intake valves.


MT: DOHC, 4 valves per cylinder with microfinished camshafts. Continuously Variable Valve Timing Control System (CVTCS) for intake valves and eCVTCS for exhaust valves.

edit: smilie attack