Standing start punch. Horsepower or Torque?

If you want a vehicle that has a good amount of 'get up and go' from a standing stop, what figure is more important, horsepower or torque?

Generally torque. More torque will get you off the line faster, usually at the cost of higher speed. Horsepower includes torque in its equation, but you can have a high horsepower number without having a high torque. A good example of this would be a car like the Honda S2000. Because it can rev upwards of 9000 rpm it has "good" horse power numbers, somewhere around 240hp I believe, but since it gets most of that power due to the high rpm it is not very good off the line. The Nissan 300Z fell into this catagory too. Even though it had similar hp numbers to a camaro of the day, the camaro would dust it off the line.

Hello Orion,

Torque will get you moving, horsepower will keep you moving.

Tom

People tend to BUY Horsepower, but we actually DRIVE torque.

A decent example... back in 1995 I drove a then new Powerstroke F-250 5 speed as part of an oil test.

If I was on a 2 lane, and wanted to get around a slower car... just put foot down, count to 5 and that sucker started MOVING! No rpm to speak of, it was doing it with Turbocharged TORQUE!

In 2001, we had a Dodge Stratus as a renter in Vegas. It would go, but not until it was wound up pretty good. No torque without revs.

Too much torque right away will just get you tire smoke.... but I would much rather have low rev torque over high rev.

Absolutely torque.

Torque smokes the tires and pulls the loads. HP is all that the advertisers talk about though.

Example:
At one point I had a 250HP Volvo and a 135HP electric car. Both weighed about the same. The 135HP electric was quicker from 0-60... by almost a full second. The reason: 100% of the electric's torque comes at zero RPM. The Volvo had the HP advantage, and even more torque - but that torque didn't come in until the car was moving a brisk clip. By that time the electric was just a pair of taillights. /ubbthreads/images/graemlins/smile.gif

So... not only is torque the important one here - but WHERE the torque comes in is just as important for getting off the line.

Gotta love electric motors for torque. I used to race some RC, and I had an electric touring car. Some of the guys I would hang out with had gas (Nitromethanol.) My car would top out at about 45mph and they could hit 60+. The big difference was that I could get to 45mph in about 40 feet, it took them over a 150 or so feet to get to 45 and almost 400 to hit thier top speed. Needless to say on most tracks I smoked them because I was faster out of the corners and even in the straights, they could not make up the distance.

Being a basher mostly now, I like gas for the longer run times, the sound of the engine and the more realistic feel, but in a race or rock crawl, electric motors toast the gas powered stuff.

Torque is for get up and go, start out power.

HP gives ou better top speeds, like punching the gas at 100 mph, to gain speed there, it takes HP.

Interesting. Okay, let's say [for example] I have two cars. Same make and model but with different engine options.

#1. 130 hp @ 6,000 rpm; 125 lb.-ft. @ 4,200 rpm

#2. 170 hp @ 7,600 rpm; 127 lb.-ft. @ 4,400 rpm

The torque of the two vehicles is pretty similar. The horsepower differs. So these two cars will have similar acceloration, but #2 will have better performance when on the highway, such as going up hills?

If all else is the same (weight, aerodynamics) then I believe your assumption is correct.

[ QUOTE ]
Orion said:
Interesting. Okay, let's say [for example] I have two cars. Same make and model but with different engine options.

#1. 130 hp @ 6,000 rpm; 125 lb.-ft. @ 4,200 rpm

#2. 170 hp @ 7,600 rpm; 127 lb.-ft. @ 4,400 rpm

The torque of the two vehicles is pretty similar. The horsepower differs. So these two cars will have similar acceloration, but #2 will have better performance when on the highway, such as going up hills?

[/ QUOTE ]

From my limited knowledge:
Depends on the transmission. Usually a manufacturer will install a transmission with shorter gears in #2 to take advantage of the undersquare (I assume) engine. So, #2 may be quicker to 60 as well as have better highway acceleration due to the shorter gears. If the transmission for #1 were put in #2, then #2 may actually be slower to 60 and have worse highway acceleration. If the transmission for #2 were put in #1, then #1 may be faster to 60, but will be screaming on the highway and get really bad mileage.

Someone please correct me on this...

Aloha
Brian

[ QUOTE ]
Orion said:
Interesting. Okay, let's say [for example] I have two cars. Same make and model but with different engine options.

#1. 130 hp @ 6,000 rpm; 125 lb.-ft. @ 4,200 rpm

#2. 170 hp @ 7,600 rpm; 127 lb.-ft. @ 4,400 rpm

The torque of the two vehicles is pretty similar. The horsepower differs. So these two cars will have similar acceloration, but #2 will have better performance when on the highway, such as going up hills?

[/ QUOTE ]

What you really need to look at is the hp and torque curves, not just a single static max point. Nissans tend to have peaky curves which advertise at higher maximums while hondas tend to have flatter curves which provide more useful torque and hp over a greater range. The higher the hp, the higher the top end speed in general.

Very very true about the torque curve!

A 700 Cubic inch MOUNTAIN MOTER makes like 800lbs of torque. But it makes no less than 350lbs ANYWHERE in the curve! INSTANT throttle response!

An extreme example to be sure. But a nice linear torque curve is more driveable than a peaky one.

[ QUOTE ]
unnerv said:
Gotta love electric motors for torque. I used to race some RC, and I had an electric touring car. Some of the guys I would hang out with had gas (Nitromethanol.) My car would top out at about 45mph and they could hit 60+. The big difference was that I could get to 45mph in about 40 feet, it took them over a 150 or so feet to get to 45 and almost 400 to hit thier top speed. Needless to say on most tracks I smoked them because I was faster out of the corners and even in the straights, they could not make up the distance.

Being a basher mostly now, I like gas for the longer run times, the sound of the engine and the more realistic feel, but in a race or rock crawl, electric motors toast the gas powered stuff.

[/ QUOTE ]

I went to a model airplane show last weekend. The last time was over 10 years ago, I was amazed at the Lithium Polymer battery model airplanes that were capable of doing 200 MPH and the acrobatics they could do just as good as the gasoline powered ones. I saw a model B-17 made out of solid styrofoam doing barrel rolls and inverted loops.

kinda off topic but it is cool as hell a mazda 1.3 litter moter can prudice like 300 hp in the new rx8,s if i recall.to me that is way coolnow i doubt it pruduces lots of torque and it dont realy pruduce lots of hp to a very high rpm

The RX8 uses the Wenkel Rotary Engine which has a couple of more thousand RPM capability than standard engines. All it really does is allow you to go faster more quickly when you are already going fast. Oh the Wenkel engine was developed in the 1920 and 30's in Germany. So still no great technological leap just improvement on materials, tolerances, balancing and manufacturing to make a really hot engine.

Torque, but only if the torque curve is decent. Electric cars are the BEST in this regard.

My Saab doesn't look THAT great on paper, good but not great--but it's a blast to drive--because the torque curve is very, very flat--but still not as flat as a electric.

I wouldn't count the rotary out just yet - if some fraction of the resources went towards rotaries that go towards continuously refining the piston engine, there might be some amazing improvements on the horizon.

Rotaries are always in balance* - much like electric motors - yeilding inherent mechanical advantage.

* - the primary moving part is always in balance. The valves and other supporting mechanical subsystems may not be.

Lada Niva anyone? Out dragging boy Racer's hot hatches away from the traffic lights? You bet!

Stick the sucker in low range 2nd gear, and put the foot down. Okay...you have now got a maximum speed of about 40mph in 5th...but wow...it gets there fast! Is pretty quick off the mark anyway, low geared (3650rpm at 62mph) even in high range. Accelerates pretty quick, just struggles over about 50 in that regard thanks to brick-wall aerodynamics!

So, you've got a pretty quick off the mark 4WD, despite only having a 75bhp 1.7 litre engine, torque by the handbook is 133Nm at 3200 rpm...someone can convert that to real units I'm sure. Is a very falt torque curve though, which is why it works. With that fan though, boy things get noisy over 3500 rpm!

[ QUOTE ]
Orion said:
If you want a vehicle that has a good amount of 'get up and go' from a standing stop, what figure is more important, horsepower or torque?

[/ QUOTE ]
Can I use this example for a vehicle unrelated to automobiles? Take a look at something like a bicycle versus running full out. In this case running alone would be the horsepower. Bicycling would be torque. Wouldn't the bicycle have more get up and go because of the large number of gearing, which allows for torque? /ubbthreads/images/graemlins/confused.gif

Torque is good...

You can't really compare an electric motor to a gasoline engine; an electric motor's torque is greatest at 0 RPM, while a gas powered engine's torque peak can be variable.

--dan