peak horsepower? low or high?

**take1bar** · April 9th, 2007 11:22 PM

A peak horsepower at low rpm or peak horsepower at high rpm. ie 252hp * 4800 rpm, 250 hp * 6000 rpm. Which one will deliver authoritative power? Vehicle displacement is a not a question here for all other factors being equal, a larger engine displacement is therefore more powerful than a smaller one. The grey area is the peak horsepower

**OTEP** · April 9th, 2007 11:40 PM

Still lots of factors to consider like gear ratios and axle ratios.

Consider also how lineary the power is delivered. Peak power is just that - the peak. How it got there is also an important story. Was it delivered in a linear fashion like those big muscle car engines or did it just explode into action when the turbocharger kicked in like on some rice rockets?

I'd still prefer having power at lower rpms because that's where I do most of my driving. Also less stressful on the engine unlike those 10,000rpm sewing machine engines on some sportscars.

**redorange** · April 9th, 2007 11:56 PM

Originally Posted by take1bar

A peak horsepower at low rpm or peak horsepower at high rpm. ie 252hp * 4800 rpm, 250 hp * 6000 rpm. Which one will deliver authoritative power? Vehicle displacement is a not a question here for all other factors being equal, a larger engine displacement is therefore more powerful than a smaller one. The grey area is the peak horsepower

What do you mean by authoritative power? What type of scenerio are you requiring the power?

Peak horsepower isn't as important as the horsepower curve of the engine. Because peak horsepower is just that, the peak of the horsepower and power will start to drop off beyond that optimum rpm of the engine. The best would be an engine with good low rpm torque and mid to high rpm horsepower curve.

**Si 06** · April 10th, 2007 12:05 AM

Originally Posted by redorange

What do you mean by authoritative power? What type of scenerio are you requiring the power?

Peak horsepower isn't as important as the horsepower curve of the engine. Because peak horsepower is just that, the peak of the horsepower and power will start to drop off beyond that optimum rpm of the engine. The best would be an engine with good low rpm torque and mid to high rpm horsepower curve.

+1 ako dyan sa peak wala nang sipa #'s na lang sila.

**the_wildthing** · April 10th, 2007 12:18 AM

250hp at 4750 tapos hanggang kailan? Baka naman hanggang 5000 lang ang RPM.

I agree with the previous posters. The entire curve must be reviewed. It could be peaking early, but then drops dramatically after that. Or it could be peaking late, but reaches 80% at low RPMs.

**take1bar** · April 10th, 2007 12:45 AM

i ask the question for this maximum horsepower is always an integral part of marketing ads by car manufacturer. if u go to vehicle specification you will notice the likes of 140 hp * 6300 rpm, 128 hp * 4300 rpm and sometimes the said vehicle belongs to the same category of displacement 1.8/2.5/3.0 but have difference only on peak horsepower high and low rpm. What difference will it make if the vehicle maximum/peak horsepower can be reached at a higher rpm as compared to the vehicle peak horsepower which can be reached at lower rpm example a 1.6 with 128 hp * 4300 rpm AND 1.6 140 HP * 6300 rpm ... thanks.

**redorange** · April 10th, 2007 01:31 AM

Originally Posted by take1bar

i ask the question for this maximum horsepower is always an integral part of marketing ads by car manufacturer. if u go to vehicle specification you will notice the likes of 140 hp * 6300 rpm, 128 hp * 4300 rpm and sometimes the said vehicle belongs to the same category of displacement 1.8/2.5/3.0 but have difference only on peak horsepower high and low rpm. What difference will it make if the vehicle maximum/peak horsepower can be reached at a higher rpm as compared to the vehicle peak horsepower which can be reached at lower rpm example a 1.6 with 128 hp * 4300 rpm AND 1.6 140 HP * 6300 rpm ... thanks.

It all depends on what type of vehicle you will use the engine and what the purpose of the vehicle would be. For a daily driver, horsepower and torque in the midrange would be better than one that requires you to rev to 10K rpm. Typical cars now have a power curve that builds to it's peak at around 4k-6k rpm. Again for regular street use horsepower is less of a factor than torque. Because torque is what you need to move the car in stop and go traffic. What good is having 200hp*7500rpm and only 115lb-ft*5500rpm, you would have to rev the engine just to get it to move the car. If you just want to run the car for top speed then you want high rpm horsepower peak so that your car doesn't run out of steam with the increase in revs. But if you have a truck and you use it to haul stuff or even off road then you want low rpm torque and low to mid rpm horsepower peak, because that's where it would be of more use for the purpose of the vehicle.

Most vehicle ads just mention the horsepower and don't mention the rpm since most buyers get hypnotized by the horsepower numbers without considering how that power was attained. Hence, you have people that buy the S2000 and complain that they have to rev the engine to get any sort of torque from the motor to drive around town.

**///MPower** · April 10th, 2007 03:33 AM

To be honest, it doesn't really matter. Power is power.

However, you need to understand that engine displacement is very important. The bigger an engine, the greater the torque. The greater the torque, the lower the RPM's one needs to attain any given amount of power.

This is why American cars are generally low-revving, but still able to put out massive amounts of power, whereas a comparatively tiny engine like the B16B can still manage output a remarkable amount of power. A GM Vortec HO 6000 with 6.0L will produce 345 horses 5400 rpms, whereas a BMW M3 Engine at only 3.2L produces an almost equal 333hp at 8000rpm.

Keep in mind, it's still not accurate to say that the larger engine (which will have more torque than a smaller one) is always better. One must consider space and weight, as the larger an engine, the less nimble a car is going to be.

Next, saying that one prefers power at lower RPM's for normal driving is silly. As said by redorange, power gives you the top speed, so power is not a factor during normal driving. Secondly, saying you like it at low RPMs because it gives less strain on the engine is irrelevant. Different engines are capable of different things. The Ford Model T had a max of 20hp at 1600 RPMs, so are engines today put through more strain? Hardly.

**mbeige** · April 10th, 2007 04:28 AM

It all depends on what the car and the engine was built for. If you have a diesel engine, peak power at a high RPM isn't all that great unless it is meant for highway driving or acceleration, but a huge oil tanker diesel engine can have peak power at what, 250rpm?

You also need to understand how the engine works, your question is just on paper and not in the real world.

Basically, put it this way. Horsepower is used in the marketing business to attract consumers to their product. Heck, the Ariel Atom has what, 300hp only but costs $40k I think. But that thing has a power to weight ratio greater or equal to a Ferrari Enzo! Too many other factors to consider...

**OTEP** · April 10th, 2007 01:39 PM

Higher rpms do put more strain on an engine. It's hardly rocket science. That's why there's a redline. However, if the engines have been designed for such operation, they will most likely be reinforced/hardened/designed to take such punishment.

If you used more pedestrian internals on say a Honda S2k engine, you'd probably blow it up in one lap.