lobuxracer

iTrader: (2)

The smaller engine is also operating near peak torque more often than the domestic counterpart which also means it is working closer to peak efficiency at any given time, because peak torque and peak efficiency are coincident. Stationary generators are prime examples of this, which also begs the question why don't the hybrids all run their engines at peak torque (and subsequently, peak efficiency?) Because Americans are conditioned to believe running engines at "high" rpm is bad. Really, it's conditioning, it's not based in fundamental thermodynamic physics.

CK6Speed

iTrader: (1)

I like reading your posts. Very insightful For me, I never really cared about HP this, torque that. As long as the bottom line performance was acceptable I'd call it good I also love high reving engines. I just love the screaming sound of it

lobuxracer

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I was stoked when I got my 500 Interceptor in '84 to go production racing with the AFM at Sears Point. It had a 13,000 rpm redline. I bounced it off the rev-limter more times than I'd like to remember...

mmarshall

There is a reason why many Americans don't like high RPM. Peak torque and peak efficiency are true to some extent, but high RPM=more piston travel up-and-down, more camshaft actions opening and closing the valves (especially with the secondary ones in VTEC engines coming into play at high RPM's), more crankshaft motion on the main bearings, and more wear on the belts and pulleys driving the power steering, A/C compressor, water pump, etc.... when these devices are not electrically-driven.

Unless the revs are so low that the engine is lugging badly or straining (some people actually drive like this ) , in general, more revs mean more engine wear. That is why Castrol emphasizes the quality of their engine oil so much in ads.....the heat and wear that comes with high-revving engines, and the necessity for a good oil like Castrol that will maintain its viscosity and deal with it.

lobuxracer

iTrader: (2)

I don't buy that marketing crap for a second, especially from Castrol. I despise Syntec and it's variants for personal reasons. There is so much marketing and so little real differentiation between motor oils it isn't even funny. The more I learn about oil, the more the commercials irritate me.

Despite the completely unfounded fear that these "high revving" engines will wear out sooner, we are surrounded by empirical evidence that it just isn't true. There are plenty of small engines with 100, 200, and even 300k miles on them that run just fine and will continue to do so with normal maintenance. Toyota and Honda have built reputations for reliability despite building smaller engines that are rev-happy and not making big torque at low rpm.

You comment about lugging an engine does remind me of the first Hyundai I rode in. It was 1981. I was in a small town in the middle of Korea going downtown in a taxicab. The driver mercilessly lugged the poor thing and it rattled and pinged like nobody's business. I have often wondered about the ultimate service life on that particular engine.

mmarshall

It is more than just marketing. If you look at most of the professional racing teams, whether NHRA, NASCAR, or F1, (and remember, these are people whose very livelihood depends on how well their engines hold up under extreme stress) you will find that the majority of them run one of three brands of oil in their machines.....Castrol, Valvoline, or Penzoil (Havoline used to be popular but you don't see it much anymore).

Coincidence? I don't think so. While, as you point out, there are many brands of oil that meet auto manufacturer's warranty or SAE standards (currently, I believe, SM-grade), those three have an especially good reputation, whether petroleum or synthetic.

ff_

I'll bet they use oil from the mfg that sponsors their race team.

mmarshall

When their engines are at stake, racing teams are not going to use junk oil no matter how much of it the factory supplies free....you can bet the rent money on that. Even if the manufacturer gives you a whole new engine, that does you no good if you lose a race because your oil got too hot and cooked.

IS_Mine

I think you are taking things out of context but I can respect that, being Asian myself... however I don't take those *names* as bad.. I guess because everyone gets called a name no matter what color you are.

But as another poster said. Compare JapANESE cars with domestic counterparts 3.5 vs 3.5 and so on and you'll see we put down more horses and maybe just as much or more torque.

We don't have big block V8s like the domestic crowd but we're getting there. I don't know if I'll wait around long enough for it to happen though.

lobuxracer

iTrader: (2)

You'd be amazed how many of those big name sponsors on the outside have Red Line on the inside. Mobil 1 is about the only oil sponsor who actually have the product in the engine.

Like Richard Petty said many years ago, "Hey Richard, do you really run STP in your car?"

"Sure do, got a can bolted right under the driver's seat..."

Threxx

This rule always holds true: HP = TQ*RPM/5252

Your horsepower and your torque will always be an equal number at 5252 rpm.
Therefore if you have a motor that's rated at 200 horsepower, but that rating is assigned at some lofty 7600rpm or whatnot - then you have to assume, generally speaking, that the power curve is going to look like a fairly steep hill going up unless it's turbocharged... as certain turbo designs can be setup to basically primarily flatten out the power curve rather than focus on peak power. My A4 is an example of this. The motor makes 200hp and 206tq... doesn't sound that impressive for a turbocharged 2.0 until you consider it also manages to achieve that 'peak' torque rating all the way from 1800 rpm all the way until redline. The engineers probably could have used a different turbo setup and made the 2.0T output 250+ horsepower very reliably in stock form, but then it'd have an annoying lag and lack of power at low rpm until the turbo spooled up at high rpm. It also probably wouldn't have gotten as good of gas mileage due to negative boost at cruising rpm.

Also as a general rule of thumb, motors with a low displacement per cylinder tend to be capable and benefit from higher RPMs due to their lower rotating mass.

And lastly, as a rule of thumb, cam profiles can typically only serve one specific purpose. They're either setup for optimum power at high rpm, low rpm, or both.
With stuff like variable valve timing engineers can try to compensate for this by using two cam profiles, but most small displacement high RPM motors have more to benefit by keeping both cam profiles biased toward mid to high rpm power.

So... with that said, yes many japanese import cars and many economy cars in general seem to be engineered to sacrifice low rpm power to generate more high rpm power and I think until geometric supplemental turbos start becoming more mainstream, or marketing departments stop trying to wow people with peak power numbers at the expense of a power curve that's nice to have when daily driving and not just at the race track... we won't see much change with that.

CK6Speed

iTrader: (1)

This may be true. Yes, engine wear may be greater, but who cares when the engine is designed and built to do such a thing and the engine still last to 300K miles? How long do we really need the engine to last before a rebuild? 500K, a million miles? I say anything that last to 200K is good.

mmarshall

Even with engines, like many diesels, that can't reach 5252 RPM? Some diesels are redlined at 3000 or below.

Threxx

Yep, even with diesels. If you were to put a diesel motor on an engine dyno and manage to get it up to 5252rpm without killing it, hp and tq would be exactly equal, though probably very weak on both fronts.

edit: to clarify, equation holds true at *any* RPM - from 1 rpm to an infinite rpm because that is literally how horsepower is defined. You can actually tell all that you need to know just by looking at the horsepower OR the torque line on a dynograph - one can always be derived from the other by following the equation.
Doesn't matter if it's an electric motor, diesel motor, or even your legs pedaling on a bicycle. It's an actual definition of physics.

lobuxracer

iTrader: (2)

^^ exactly correct. Horsepower is mathematically derived from torque on an engine brake dyno, and torque is mathematically derived from acceleration on an inertial dyno.