Torque and horsepower

[BryanPD]

ano po ang mas nakakaapekto sa performance ng car, torque o power?

2 cars, A and B. both cars same specs (weight, gear ratio, size, drag coeff... basta lahat na).. except car A has greater power but lesser torque, car B has lesser power but greater torque.

[BlueBimmer]

high torque - faster acceleration from full stop
high hp - may be slower from full stop but will pull away at higher speeds

[niky]

In general. Yun na yun.

Horsepower really isn't anything more than a calculation of torque versus engine speed.

Basically, when you say "high power, low torque", all you're really saying is that the engine produces more torque at high rpms than low rpms... and when you say "low power, high torque", it's producing more torque at low rpms than high rpms.

What's really important to the driver is the amount of torque available at all points along the rpm range.

For daily driving, more low range torque is better, because, like BB says, you have faster acceleration from a full stop.

For racing, you don't use low rpms. You use primarily high rpms, so a car with more high end horsepower (in other words, a torque curve shifted towards higher rpms) will allow you to accelerate faster at higher speeds.

[kinyo]

What if Car A have diesel engine and Car B have gasoline engine but both have same max Hp and max torque?

Obviously, they have different torque/hp curves to reflect their engine characteristics.

So assuming other things equal (losses, drag, weight, etc),

1. Who will reach 100kph first?
2. Who will reach 1km first?
3. Who will reach 10km first?
4. Who will reach 100km first?

My answer: Car A (diesel) on all counts because it would out-accelerate Car B during first few seconds and its initial lead distance would be maintained by the time they both reach their equal top speeds (remember, same max Hp, same losses, same drag, same weight, same etc).

Whaddya think?

edit: Let me just add equally skilled drivers, say Niky.

[mbeige]

That depends on the powerband and the driver's good use of this. Powerband is a different dimension to consider. The diesels can be slow off the line unless you have turbochargers (just like in the BMW 530d with one small and one large to compensate for lag)...

[rion]

you need HP for top speed.

you need torque for quick 0-100 acceleration.

bottom-line: you need best of both.

but if I had to choose best of one for everyday driving, I vote torque.

but torque band should be best at low rpm. para hindi pansin yung sound fx at the same time the acceleration is awesome. meaning, low profile, yet fast...

[blue1108]

hello mga pips, hope this helps

[blue1108]

regarding car performance, both torque and hp affect it although more in adverse or vice versa effect. cars with good torque will usually take off faster from a standing start. those with higher hp but low torque will need longer roads to build up speed. engine size and transmission also play a big factor.

good example will be the 1600 civics and corollas from the 90's, the rollas would usually pull stronger during the lower rpm range but then the civic will catch up once the rpm's start to build up.

main reason is that rolla engine blocks have longer strokes for better lower rpm torque but they have lower rev limits and compression ratios, limiting power production in the higher rpm range. i have a friend who had the head of his corolla shaved to give the engine a higher compression ratio then a full free flow exhaust allowed to engine to rev a lot higher. if you happen to be drag racing in libis aound year 2000, this is the flat black corolla that could smoke civics.

civic engine blocks on the other hand have shorter strokes, it needs to rev high in order to produce power but generally lack torque in the lower rpm range. good thing hondas are generally lighter kya hindi kailangan ng big torque sa low rpm. and mas efficient din ang transmission ng honda kaya konti lng ang power loss from the engine to the wheel.

big engines are another story. they do not need to be revved high bcoz they already develop good torque and power even from low rpms. this is due to the sheer volume of air and fuel that combusts in the chamber with each cycle of the engine. ang pinaglalaruan na lng nila ay yng transmission and gearing in order to effectively transfer the power to the wheels and carry the weight of the vehicle.

newer engines though are totally different. almost all new engines now have valve timing technology and advanced ecu's of some sort to manage power production, output and fuel efficiency. usually displacement and rev limit n lng ang responsible sa final output ng engine.

hope this helps mga pips.

[pup2]

Nalilito pa din talaga ako dito. Ang impression ko kasi sa torque from when I was in HS ay 'lifting power'. At the time, I just projected it as 'pulling' power pagdating sa engines. Noon, ang mga diesel ay mabagal umarangkada pero malakas bumatak at ang dahilan ko noon ay dahil low HP, high torque. Doon ko din napapaliwanag na pag mas mataas ng malaki ang torque ay mas mahirap pigilan ang pag-arangkada.

Kaso ngayon, ang mga diesel ay malaki na ang binilis sa arangkada. Ano ba ang nangyari? Baka naman kasi HP ang tumaas sa diesel RELATIVE sa torque? Kasi dati nang mataas ang torque ng mga diesel di ba? Pero mabagal sila umarangkada noon?

[alwayz_yummy]

mag bigay na tayo ng real world examples:

2.0 focus: gas at diesel..(di pala pwede--matic ang gas, manual ang diesel!) iba pa:

1.6L gas matrix-manual(meron nito) at 1.5Lcrdi matrix......

1.4L getz-manual vs 1.5crdi-vgt getz

eto pa: kia carens 2.0gas vs 2.0crdi-vgt-->parehong semi-auto lang mga yan..

more torque * low rpm-->advantage on everyday and emergency situations...

[blue1108]

yup, malaki n tlga improvement ng mga diesel engines.

the main reason why old diesel engined vehicles were slow was their weight. their engines used to be made exclusively from iron to tolerate the stronger but slower combustion of diesel. unfortunately they're also a lot heavier than gas engines. tpos yng mga vehicles n gumagamit ng diesel engines noon usually have reinforced bodies kya medyo mabigat cla. (for towing, transport, etc...) kya mabagal cla umarangkada.

diesel fuel also burns a lot slower. dun galing yng pulling power ng diesel engines. the slow burn allows the engine to generate more power per revolution than gas engines.

but if installed in lighter vehicles, they do have the capability to push the vehicles to good speeds. (used to make the wheels of our adventure squeal: just don't tell my dad) the nissan safari is a good example.

newer diesel engines are lighter na. plus diesel fuels these days have improved combustion and burn cleaner. konti n lng and they will combust as well as gasoline na din. allowing diesel engines to rev higher and maybe match the revolutions gas engines are capable of

[niky]

What if Car A have diesel engine and Car B have gasoline engine but both have same max Hp and max torque?

Obviously, they have different torque/hp curves to reflect their engine characteristics.

So assuming other things equal (losses, drag, weight, etc),

1. Who will reach 100kph first?
2. Who will reach 1km first?
3. Who will reach 10km first?
4. Who will reach 100km first?

My answer: Car A (diesel) on all counts because it would out-accelerate Car B during first few seconds and its initial lead distance would be maintained by the time they both reach their equal top speeds (remember, same max Hp, same losses, same drag, same weight, same etc).

Whaddya think?

edit: Let me just add equally skilled drivers, say Niky.

If they have identical HP and Torque, and identical gearing, Car B will win.

Why?

Because Car A makes torque and horsepower over a shorter range than Car B. Car A enters the next gear much earlier than Car B, who can delay the time-wasting shift much longer. Car A will have a longer reach through the gears, and will be able to reach 100 km/h at a much lower gear than Car B, and will be able to hit top speed in fewer gearshifts than B.

Of course, both cars are turbocharged. Because a naturally aspirated gasoline engine cannot have the same horsepower and torque as a turbocharged diesel engine.

A turbocharged diesel engine with more torque but the same horsepower as a gasoline engine also has similar problems. They're often as fast as gas engines with the same power (which is contentious, because turbocharged engines almost always make more power than the manufacturer claims), but if you wring out the gasoline engine, you can get better acceleration due to rpm limitations for the diesel. Basically, making between 200-250 hp is great, but if you only make it over 1000 rpm in a diesel, whereas with a gasoline engine, you can make it over a span of 2000-3000 rpms, you can only put that power down for a shorter amount of time in-gear.

But this all depends on gearing, the car, etcetera. There is no direct one-on-one comparison between gas and diesel. The only manufacturer I know that makes performance diesels and gas engines in the same mold, BMW, has a turbodiesel 3.0 that makes 286hp and 580 Nm of torque and a 3.0 gasoline turbo engine that makes 306hp and 400 Nm of torque.

The gasoline version, mind you, is mapped to make less power than it can, not for reasons of engine longevity, but in order not to be faster than the new M3.

Still, the gasoline car can hit 60 mph in 5.8 seconds, as opposed to the diesel's 6.1. (official figures). Torque is great off-the-line, but in racing, you're almost never below the powerband.

[rayban7g]

...What's really important to the driver is the amount of torque available at all points along the rpm range.

+1

One example of this is the 2L Civic FD, torque starts from 2.5k-3k all the way 5.5k rpm (if I'm not mistaken or up to 6k rpm pa nga ata, giving it a range!), you can still feel the pull of the improved K20.

Most rally cars are like this too, though for racing application only, a governed max. of 300hp, but torque depends on every racing team's tuning, ranging from 520nm to an axle-breaking 600+nm (yup, like Loeb's Xsara). Availability of torque starts from a low 2.5k rpm up to a redline of 7.5-8k rpm, (i.e. Subaru) ....now that's a LOT of torque, geesh!

[GroundEffex]

Kinda off topic pero what's the difference between PS and HP sa measurement ng power ng auto?

[niky]

A tiny bit... 1 PS is 0.98 hp or so.

Many manufacturers misquote PS as horsepower, but the difference is not insignificant.

[pup2]

Kinda off topic pero what's the difference between PS and HP sa measurement ng power ng auto?

Parang nabasa ko before minimal lang yata. Parang less than 10%.

[rion]

indeed, gearing factor talaga. and average drivers like me tend to fail and lose momentum most of the time in 3rd gear in agressive driving mode from a standing start. and I just hate short 1st gear in diesels.

so your ride may be a speed beast. but can you really tame the beast?

HP-PS or PS-HP converter:click here

[pup2]

So basically, mas mabagal nga sa arangkada ang diesel pero mas malakas ang batak?

[hominid]

When it comes to FC kaya? With gas u need to rev a little to move, sa diesel no need. Considering all factors to be the same?

[niky]

*pup2: Yup.

*hominid: It's not how much or how little you rev. Diesel contains more energy per liter than gasoline.

For comparable diesel and gas engines, the diesel engine will drink less fuel than the gasoline engine if both are held at a steady 2000 rpms.