One of the most discussed topics on the S2000 capabilities always gets around to the subject of power - specifically torque. Here's my thoughts on the subject. We do have torque! We have more than any other production engine I'm aware of. It's just at a different place. It's where most engines never go - it's above 6000 rpm.

In an internal combustion engine, power is made by controlled explosions. Every engine makes power out of fuel. The 8.0L engine processes an explosive mixture at a given RPM at a greater rate than our mere 2.0L. That baby can just suck more air than our peanut whistle! However, when that large kluge can spin no faster (large mass). our little sewing machine begins to purr. At some rpm range our 2.0L engine will process the same amount of explosives as that kluge did when it ran out of steam. At that point, we have similar "power". I know, there's more to it than this, but the basics are here. Understanding this, the issue becomes efficiency of the engine and rate at which it can process explosives (fuel/air).

One point that this makes crystal clear is that our engine, along with every small displacement engine that develops mega-power at high rpm, will NEVER produce massive amounts of torque/power until it running at a rate at which it can process the needed amount of fuel - high rpm! Ever watch one of those CART cars leave the pits? Notice how they heat the tires? Hi rev, spin the tires, bog to below most efficient rpm, head for the track, reach their power band (at about 9k rpm) and really start to go. These are multi-thousand dollar engines that are made to produce as much power as possible in the largest part of the rpm spectrum possible. Even they (really, especially they) develop their "power" at high rpm! Not even money can change the laws of physics!

Some adjustments and tweaks can be made to the torque/power curve of any engine. It's always at the cost of equivalent power loss somewhere else in the engines performance curve. A better fix is to increase the efficiency or fuel handling capability - for example: compression ratio, valve timing or forced induction. In our S, Honda has already conquered the first two. Some on this forum are experiencing the third (Comptech in my case).

It's not about getting more power. That will take big bucks and redesign steps. It's about using the power we already have. It's there, we just need to know how to take advantage of it. It makes more sense to change the gearing of our S to allow us to get into the sweet range of VTEC in 1st gear without a major bog and WITHOUT having to start a fire in our wheel wells!

Sorry, I had to get that out of my system!

 

Of course, since you have an SC, it's even less of an issue

 

you just spend a lot of time telling us what we all know already.....

 

[QUOTE]Originally posted by Matt
[B]you just spend a lot of time telling us what we all know already.....

 

Note: my first post here, so please bear with me if I goof...

[QUOTE]Originally posted by Garyj
One of the most discussed topics on the S2000 capabilities always gets around to the subject of power - specifically torque. Here's my thoughts on the subject. We do have torque! We have more than any other production engine I'm aware of.

Although I do agree that "torque" is more often misunderstood than the reverse, respectfully, I cannot fully agree with what you wrote.

First, if we are talking torque at the engine, the S2K's 153 ft-lb is high for a 2.0L, but low for a performance car. To it's credit, it is the highest specific torque (torque/displacement) that I know of. Though nowhere near as dominant as its hp/L. There are a fair number of 70+ lb-ft/L engines out there.

But in reality, it is the force or torque at the road wheel that matters. And frankly, hp is just as good a measure. Since hp=force*velocity, for a given road velocity, hp tells you how well you will accelerate as would torque, or force.

So, the 240hp S2K has the accel of any 240hp car. But there are plenty of other production cars that make more hp and more torque where it counts, at the wheel. Any with more than 240 hp. But I do agree the 153 lb-ft is misleading. IF, and its a big IF, you do drive it where it makes that power, ie at high rpm.

I've looked at the torque (/power) curve of the S2K. Below 5000 rpm, it has about the same torque as any DOHC 2L engine (<135 lb-ft). So, at low-to-mid rpm, it'll behave like, say, a Ford Focus. This is just physics, not an aspersion. But through a combo of the huge rpm and, secondarily, increased torque at higher rpm, it is in the Boxster S / M-roadster league when driven enthusiastically (just a gear change away).

So, yes, for those who are unwilling to shift or drive at high rpm, the lack of torque is evident. Let them whine. Be amused by their lack of understanding of both physics and auto enthusiasm. This car is made for people who live to drive hard, love revs, and know what the stick to their right (okay, left for some out there) is.

 

[QUOTE]Originally posted by Garyj
[B]

Whenever the "torque" issue comes up, someone either says Turbo or SC.

 

What matters is torque at the wheels, and you get change that through gearing. So while the s2000 might only make 135 lbs/ft at low rpms, you also can go to 9000 rpms, so you can run a much lower gear to reach the same speed as a lower revving engine. If you think the engine feels weak below a certain rpms, that is an issue of the torque curve not being flat. If the peak hp and torque stayed the same but the torque curve was perfectly flat, the car would pull equally hard at all rpms. Horsepower means nothing as far as what you feel. You feel the torque. High horsepower and low torque numbers generally tell you that you have a high revving engine. It doesn't necessarily mean that you have a peaky engine. All that matters is the area under the torque curve in the powerband that you drive in. In fact making more torque down low can be just as fast and torque up high as long as you still have the same usable powerband. That is why peak HP numbers can be deceiving. An engine that has a nice flat torque curve can have a lower HP number than a car with almost no torque except right at the peak, yet the engine with the lower HP number would be considerably faster.

The torque curve is all that matters. The peak HP and TQ numbers are both derived from this. Neither number really gives you much information about the rest of the. HP is usually a little better indicator of performance since it takes the engine rpms into account, but you still aren't getting much information on how the engine really behaves.

 

[QUOTE]Originally posted by FCGuy
But in reality, it is the force or torque at the road wheel that matters.

 

I argue that torque and hp are synonymous if you state the rpms. The problem is that most folk just go around quoting "peak hp". HP at your current rpm is what counts. I agree with your comment that wheel torque at a given rpm indicates your accel. But the hp at that very same rpm equally tells your accel. Just look at the eqn: hp = force * velocity = torque/whl radius*velocity.

Put another way: show me a torque vs rpm curve and I'll show you the hp vs rpm curve. If you know one, you know the other and they give you the exact same info.


Even at low rpms the s2000 is faster than your average 135 lb/ft car. Why? Because of the gearing. Low gearing multiplies the torque at the wheels. You can run lower gears in the first place because of the high redline. That's why the torque number is misleading: because it is only measured at the crank.


Here, I do not agree. Well, not fully. I do agree that the high redline of the S2K allows them to use higher ratio gears which means greater torque multiplication. But a necessary outcome of that is this: if you are at the same rpm, and in that higher ratio'd gear of the S2K, you are going at a slower speed (rpm/gear ratio). You have the same power at the engine(same torque*same rpm), same power at the wheel (if the same losses). You argue that it results in greater torque at the wheel thus greater accel. I agree. But that is because you are going slower! (accel = force/mass = power/vel/mass).

If you are going the same road speed, but you are purposefully keeping the R's down (maybe you don't like the sound ), then you have to be in a higher gear and you've lost that gearing advantage!

I'm sure I could make this clearer

The advantage comes from having more revs, not from the gearing. If it was just gearing, any 135 lb-ft (or 153 lb-ft) 4-banger car could get same accel of the S2K. They can't. It's because the S2K revs to 9000 and hp=torque*rpm.

Put another way: shift your S2K at 6000 rpm, even with its higher gearing, and you'll see accel like that Focus. I think some damned-fool reviewer actually did this.

 

[QUOTE]
I argue that torque and hp are synonymous if you state the rpms.