deciphering power of a Caravan and an Echo

[CL8]

99 Dodge caravan power
118 kW , 158 HP @ 4,850 rpm; 203 ft lb , 275 Nm @ 3,250 rpm

2003 Toyota Echo Power
SAE and 80 kW , 108 HP @ 6,000 rpm; 105 ft lb , 143 Nm @ 4,200 rpm

I need help reading these numbers and how the two compare.
My Toyota Echo has a tachometer that runs @ about 2000 Rpms,
60-70 idling
My caravan has no tachometer, would the Rpms be about the same or higher at the same speeds since it's a six cylinder?
And what does NM stand for? I know HP is horse power.
Also what is the KW?

Thanks, Cl8

[vgames33]

NM = Newton Meters
KW = Kilowatts

They're metric units for power and torque. I know .746 KW= 1 HP, but I'm not sure about NM to FT-LBS.

[CL8]

Thanks
vgames33

[MagicRat]

Torque is a measurement of force. HP is a measurement of actual work being performed, that is, force applied over a certain distance.

In real-world terms though, it's tough to compare the two without looking at other factors, such as the vehicle weight, transmission efficiency and gearing.

For comparing acceleration, you want to look at torque and HP per pound of vehicle.

If your van weighs 3800 LB, then it has ~24lbs/hp.
If the Echo weighs 2400 lbs, it has ~22.2 lbs/hp.... so the Echo may seem to have a power-to-weight advantage.

However, the van produces more torque at lower RPM,s so, with an automatic transmission, the engine does not need to rev as high to produce maximum acceleration. Therefore, the van will accelerate faster than the Echo, until the Echo's engine revs get quite high.

Generally, engines that produce maximum power and torque at lower revs are better suited for heavier vehicles, utility vehicles and automatic transmissions.
Engines that produce max power and torque at higher revs, like the Echo are more suited for lighter vehicles, manual transmissions and vehicles that are designed for a sporty 'fun-to-drive' feel.

[curtis73]

1 hp = .746 kW
1 lb-ft torque = 1.356 N-M

HP = (TQ x RPM)/5250
TQ = (HP x 5250)/RPM

1 hp = 1.014 DINhp (metric hp). Most European makes advertise DINhp in Europe and "regular" hp here in the states, but some don't. But considering they are nearly identical, it won't make a real difference in the calculations.

[CL8]

Great explanation MagicRat,

So basically the echo has to work harder to accelerate
because it has a smaller engine.??..

And would that mean the Caravan would be running on lower RPMs
at the same speed as the Echo?

Thanks for the formulas curtis.

[MagicRat]

Originally Posted by CL8

So basically the echo has to work harder to accelerate
because it has a smaller engine.??..

And would that mean the Caravan would be running on lower RPMs
at the same speed as the Echo?

"work harder" is not the best description. It's more accurate to say 'rev higher', which the Echo would have to do.

And the Caravan would run at lower RPM's to achieve the same power output (not necessarily 'speed') as the Echo.

[shorod]

Keep in mind that there is a transaxle between the engine crankshaft and the wheels. The gear ratios in the transaxle will determine engine speed to engine speed and one would hope they are matched to the engine HP and torque curves. Your final drive ratios are not likely to be 1:1 for each of the vehicles in question when in overdrive.

-Rod