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

[Vic]

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.

That doesn't matter. The peak torque for each engine might be at the same rpm, and a different number, but the engine with the lower peak torque is able to make more hp because it maintains that torque output at a higher rpm.

Originally posted by: 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

Using hp = (tq*rpm)/5252, the MT is still making 245 lb-ft at 6400 rpm, while the AT peaks at 237 lb-ft at 6200 rpm (and likely falls off even more before 6400 rpm).

Given otherwise identical engines, this is a tuning issue and has nothing with the transmissons themselves. Manufacturers ALWAYS advertise bhp (brake horsepower), which is measured at the flywheel on a bench dyno, NEVER whp (wheel horsepower).

 

[OS]

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.

The obvious answer is the torque curve/output for one engine must drop off faster than the other after peak.

The MT version of the VQ has a cam phasing sprocket on both the intake and exhaust cam. The AT version of the VQ has a cam phasing sprocket on the intake cam only.

The tuning of the MT version is obviously that peak torque is slightly sacrificed in order to maintain the flat output for higher rpms.

 

[Ilmater]

Originally posted by: 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

Hmmmm... well, I guess that's right, but it seems weird that a system for timing of the exhaust valves would decrease torque and increase hp.

 

[foghorn67]

OMG. HP is a calculation. Torque is a measurement. Get this into your heads. Formula includes both of them intersecting at 5252 rpms.
Nobody claims they dropped off at the said rpm. they intersect there.

 

[Nebor]

There are plenty of good explanations in this thread, but Ilmater doesn't want to believe any of them.

 

[Ilmater]

Originally posted by: Nebor
There are plenty of good explanations in this thread, but Ilmater doesn't want to believe any of them.

No, the only correct explanation is that the eCVTCS system manages to maintain its torque at higher RPM, while lowering the actual peak torque output. It just seems weird that a system related to a exhaust timing would decrease peak torque output at all.

All explanations related to the inefficiencies of the automatic transmission are incorrect.

 

[ElFenix]

Originally posted by: Ilmater
No, the only correct explanation is that the eCVTCS system manages to maintain its torque at higher RPM, while lowering the actual peak torque output. It just seems weird that a system related to a exhaust timing would decrease peak torque output at all.

why wouldn't it? exhaust backpressure is a key factor in power/torque produced by an engine. obviously the right answer is that some sort of tuning was done to give MT drivers a bit more of a thrill (they can hold the gear longer, so the increase in power is useful), while the AT drivers can use the torque more, most likely.

 

[randay]

Originally posted by: Ilmater

Originally posted by: Nebor
There are plenty of good explanations in this thread, but Ilmater doesn't want to believe any of them.

No, the only correct explanation is that the eCVTCS system manages to maintain its torque at higher RPM, while lowering the actual peak torque output. It just seems weird that a system related to a exhaust timing would decrease peak torque output at all.

All explanations related to the inefficiencies of the automatic transmission are incorrect.

yes that was incorrect. I was only going off the premise of having 2 exact engines but different output. not reading whole posts 4tl.

but even with that out of the way, it seems like you still need help to grasp the whole horsepower formula thing?

 

[Vic]

Originally posted by: Ilmater

Originally posted by: Nebor
There are plenty of good explanations in this thread, but Ilmater doesn't want to believe any of them.

No, the only correct explanation is that the eCVTCS system manages to maintain its torque at higher RPM, while lowering the actual peak torque output. It just seems weird that a system related to a exhaust timing would decrease peak torque output at all.

All explanations related to the inefficiencies of the automatic transmission are incorrect.

It's not wierd, it's normal. A more free-flowing exhaust reduces backpressure and the scavenging effect, often below ideal. This has the effect of reducing torque and power at lower rpms, but by allowing the engine to breathe easier and rev higher, it gains power on the top-end. It's actually a less powerful engine that is capable of revving higher, thus making more power (but only at the higher revs).

 

[Eli]

:thumbsup: to Vic and a few others posts.

Can't believe it took so long to get things cleared up.

 

[Zenmervolt]

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)??

Simple, less torque fall-off. The probable answer is that the automatic engine is tuned slightly different to make more torque at a lower RPM to offset the effect of the automatic transmission.

The engine in the automatic-equipped car suffers a more severe falloff in torque as engine speed increases, which means less high-RPM horsepower.

ZV

 

[Eos]

Feh.

Try 525 hp at 1400 rpm and 2250 ft lb of torque at 1200 rpm.

Shove it, Infiniti boy.

 

[alkemyst]

always true, unless you have a Type R sticker on your ride.

Stating torque and one rpm and HP at another, then trying to figure out why a car with two different trannys aren't equal is borderline retarded though.

For any *engine* HP = Torque @ 5252. You can have two back to back engines off an assembly line, they can be off a few points at that same mark.

In the AT vs MT battle...it's usually ECU tuning along with other differences under the hood. Plus AT's have a larger HP loss overall.

I really don't know the point of this thread, unless it's based off total car n00bhood.

Å

 

[Ophir]

Originally posted by: eos
Feh.

Try 525 hp at 1400 rpm and 2250 ft lb of torque at 1200 rpm.

Shove it, Infiniti boy.

That's nice and all, but does it have VTEC?

 

[Eos]

Originally posted by: Ophir

Originally posted by: eos
Feh.

Try 525 hp at 1400 rpm and 2250 ft lb of torque at 1200 rpm.

Shove it, Infiniti boy.

That's nice and all, but does it have VTEC?

You don't need it. Always gets 6 mph.

 

[Pacfanweb]

Originally posted by: 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.

There's the answer right there. The engines are simply tuned differently.
Might even have different exhaust.

Camaros back in the day used to have the same engine as Vettes, but they'd always have less power because of more restrictive exhausts. But they were identical internally.

This is no mystery at all.

 

[Ophir]

Originally posted by: eos

Originally posted by: Ophir

Originally posted by: eos
Feh.

Try 525 hp at 1400 rpm and 2250 ft lb of torque at 1200 rpm.

Shove it, Infiniti boy.

That's nice and all, but does it have VTEC?

You don't need it. Always gets 6 mph.

There's your problem. Slap on a Type R sticker and you'll top 10mph.