I'm curious why is that the E55, and mostly ALL cars out there in the market have just as much tq as hp or more tq then hp...at least that seems to be the case with mb...but for the m5...it lacks so much tq ?

Is it due to engine design ? if so whats the diffs ?

 

Torque is effected by a few things. the size of the piston and overall size of the engine in terms of volume. and the main thing that effects torque is the piston travel distance. In higher torque cars the piston travels further than say in the high revving BMW M motors the pistons dont travel as far. (just a interesting pice of information the BMW M3 motor at its redline has the same G forces on the pistons as a formula 1 car.) One of the reasons most cars have about equal hp/tq numbers is cost to produce an engine, a high revving BMW type motor will cost a lot to produce. And usually most car companies only make a few motors spread them over the different chassis they use. Personally i prefer a motor with more TQ than HP for the street since the TQ is available at lower RPM and usually drops off in the upper RPM range, But if i am on a race track i would want a car with more HP than TQ since i would be near the engines red line the whole time and able to take full advantage of the cars power. Hence a BMW M's engine is better for the track where you really never stop the car, and AMGs are good for the drag strips and driving off the track due to the high TQ and ability to get the car moving quickly.

 

Ok, I test drove the new M5 today and found it very lacking for street use. I would never be able to drive this everyday as I could with the 55K engine. IM sorry, but for me the M5 is not the car. I dont track my cars, nor do I plan to.

FYI, I prefer more torque than HP. I hope the new 6.3 liter V8 does not dissapoint my addiction to vast amounts of torque.

 

I think its just a coincidence that the Tq and Hp figures are nearly the same - they aren't in SI units. eg the E55 is 350kW and 700 Nm.
TQ and power (Hp) are mathematically related and I understand Tq is measure and Hp is derived (and rpm related).

Maybe that helps.

 

you sum it up perfect in the info i wanted to know ! great post man !! brilliant mate..spectaculer! haha

 

This needs a little clarification. The distance the piston travels (stroke) has the same effect on torque as the size (diameter) of the piston. Two engines of the same size, one with a large bore and one with a long stroke, will make the same amount of torque if their volumetric efficiencies are the same. The long-stroke version has the advantage of a longer moment acting on the crank axis. The bigger-bore version has the advantage of more piston area for the expanding gasses to act upon. Either way, if they're properly tuned, their output will be the same.

 

Isn't the equation Torque x RPM = Horsepower?

 

there are units and other constants to consider for eg

power (watts) = Torque (Nm) x Angular Speed (rad/s)

to convert rpm to rad/s

Rad/s = RPM x 2 x pi / 60

 

HP = (Torque x RPM) / 5252

Torque and HP will always be equal at 5252 RPMs.

 

A lot of countries don't use hp and torque (lbf) so it actually means not much in terms of physics but its purely the units used.

eg If you use Kw and Nm, Torque and power will be equal at 9550rpm which is pointless to everyone.

So i guess that the answer to the first post is read OzE55's post.

 

I think physics says combine some measure of torque with speed and time the result is horsepower.
Both hp and torque are related... but torque gets the car moving.

 

Horsepower sells cars and torque wins races.

FYI, the Ferrari 360 Modena produces around 275 lb-ft of torque. That explains why the older Corvette C5 Z06 would eat it in a straight line.

 

Torque is the force itself.
Horsepower is the rate at which that force is applied correct?

 

Horsepower is the engine's ability to sustain engine torque at high engine speeds (rpms). The more torque you have at higher engine speeds, the harder your car will pull at higher car speeds. The longer your car can keep producing torque in terms of engine rpms, will also give you greater horsepower. DO NOT for one second think that if an engine produces 516lbft/700NM (55V8K) that car is actually putting down that much torque to the wheels. Engine torque is multiplied by the gear ratio (of whatever gear your car is in) multiplied again by the final drive minus power losses. The M5 has high ratios and low engine torque but together when multiplied, the combined result equals if not betters the E55's high torque and low ratios (ie longer gears) That is why both cars punch ahead with similar ferocity, but the M5 has an advantage, in that its engine can consistently keep producing torque at high rpms and the subsequent high gearing makes the best use of multiplication effect =-->end result? harder pulling at high speeds.


Torque in terms of engine measurement, is the total force by which the explosion in the cylinders forces down the crankshaft twisting it. Obviously, if an engine revs at 500rpms, it is producing some torque, give some more gas, the engine spins faster (ie revs increase) normally more torque is produced, until a point of efficiency is reached, after which torque drops. The horsepower is just an indication of the engine's ability to produce and sustain torque at high engine speeds. Diesels can have 1000lb ft of torque at 2000rpms, but afte accelerating past 1 st gear, if none of that torque is available at high engine speeds (rpms), the end result is pretty pathetic, no? = low horsepower rating = slow pulling at higher speeds because there is no sufficient torque at the top end for the gears to make best use of.