Is Power (rwkw) Figure Everything? Why Are People So Hung Up On Kw Figures

[Rolls]

EDIT: I just re-read what you wrote and you said "possibly", so I don't think they actually do You got me really excited then because that was one thing I didn't know about.

Yeah my bad they don't, however a few high end audis do have them on their V8 engines

[r33_racer]

Horses for courses. All the points made were moot about silly engine configurations and all that crap. Different racing styles/cars/sports require different torque/power/rpm setups.

Unfortunately there is no such thing as the perfect engine. So you just have to use what you have and try to make it the best you can in the real world. If you know much about racing, the kind that people on our level do, you aim for torque, not peak horsepower, especially in turbo cars like we all drive/race. In circuit stuff generally the guy with the most usuable average power does the best. Then its different for drag racing and so on.

But to the real point of this topic, E-wangs would be my response! People like to have big HP figures for the sake of E-wang comparisons.

[RBceffy25]

PS.. variable length intake runners ??

I am pretty sure there were three versions of the heads on the CA18DET all with different runner design. I think most Aussie models have the two runners per cylinder heads and manifolds while I think the poms got the big port single runner CA's. I think there was also a version with three runners per cylinder.

Another example is the 3RZ-FE in my HiLux which has two runners per cylinder.

One runner will be longer and thinner internally to maintain/increase flow velocity, while the other runner will be short and fat for minimal restriction at high RPM.

Take notice of all engines you view and you will be surprised at how long this idea has been in use and how many makes and models use this.

Edit: Also have a look at the manifold on the Toyota 1G-GE/GEU/GTE/GZE, just to mention another.

Edited October 26, 2010 by RBceffy25

[The Dan]

With all due respect to everyone in this thread, what is wrong with wanting a shit load of hp?

Some ppl like to go fast around a race circuit.

Some ppl like to go fast in a straight line.

Some ppl like to go fast sideways.

Some ppl like to go fast in circles.

Others like to make a lot of hp and have not much care for going fast around corners. What is wrong with that? They are no less of a fanatic than you or I. Why is it E-wang or Dyno queen when referring to these ppl? Each person gets something different out of their car. Who are we to judge how they enjoy it?

At any rate, who cares about hp or torque just enjoy your damn car!!

[Rolls]

At any rate, who cares about hp or torque just enjoy your damn car!!

It is still interesting to discuss it.

[r33_racer]

There isnt anything wrong with having alot of horsepower. However this whole topic has become about peoples opinions on the matter and it is a public forum....

Eitherway, its all good.

[The Dan]

It is still interesting to discuss it.

absolutely

There isnt anything wrong with having alot of horsepower. However this whole topic has become about peoples opinions on the matter and it is a public forum....

Eitherway, its all good.

Yeah man, I'm just saying coz I hear it too often. I think the point I was trying to make was that it doesn't matter about hp or torque....at the end of the day if you enjoy how the car feels to you, then the number it makes on paper doesn't mean anything.

As for racing etc, yes it is more important to have the right setup for whatever event you take part in but for the general consumer I think the most important thing is how it feels to drive

[jarrod83]

Rolls pretty much hit the nail on the head with this arguement, i think alot of people dont understand the fact that if you had a car that can rev twice as much as another car, and had the first cars torque curve stretched over its rpm, that the second car could be geared (2:1 reduction ratio) so it had twice the torque at the wheels than the first car, also note that with its new gearing.. what hasnt changed versus its rpm?? its power output.

Both curves are pretty closely related and can both be used to interept a cars performance. All the people that are aiming for flat torque curves are still aiming for maximum average power, just looking at it from a different, less descriptive perspective, as the power curve displays the rate of work being done to move your car forward, ie your torque curve can start dropping off long before your power curve and long before its time to change to the next gear.

[Crans]

Anything is better than 0rwkw isn't it Jarod

[Lonewolf1983]

I am pretty sure there were three versions of the heads on the CA18DET all with different runner design. I think most Aussie models have the two runners per cylinder heads and manifolds while I think the poms got the big port single runner CA's. I think there was also a version with three runners per cylinder.

Another example is the 3RZ-FE in my HiLux which has two runners per cylinder.

One runner will be longer and thinner internally to maintain/increase flow velocity, while the other runner will be short and fat for minimal restriction at high RPM.

Take notice of all engines you view and you will be surprised at how long this idea has been in use and how many makes and models use this.

Edit: Also have a look at the manifold on the Toyota 1G-GE/GEU/GTE/GZE, just to mention another.

Theres a bit of a difference between engines with multiple runners per port, which are designed to keep velocity up whilst still maintaining flow, and those with variable length runners.

You will find that in a boosted application, variable intake runners are usually not bothered with, as the forced air stops the resonance and harmonics that you get in a N/A application. There is some pretty cool physics involved!

With regards to the other discussion, you can make extra torque by gearing, but not extra power

[RBceffy25]

Had another look at the Lux.... I was wrong about that one.....

http://www.bezman.com/haru4703-img600x450-...396dsc00006.jpg

http://www.bezman.com/ca18inlets.jpg

Edited October 27, 2010 by RBceffy25

[ARTZ]

With regards to the other discussion, you can make extra torque by gearing, but not extra power

so lower diff gears for eg, would show as extra torque on a dyno graph??

[Rolls]

so lower diff gears for eg, would show as extra torque on a dyno graph??

Total tractive effort at the wheels yes, but an engine dyno shows corrected and calculated engine torque so that won't change. This is why you see diesel engines with really short gearing or 20 gears as you can make up for lack of torque by gearing, and they need all the tractive torque possible with their heavy loads, as mentioned you can't make up lack of power though. As always trying to picture this and understand what is going on is really complicated and confusing, took me a year or so to get my head around it.

Great article about it here http://autospeed.com/cms/title_Power-versu...48/article.html

Edited October 27, 2010 by Rolls

[ARTZ]

so because dynos are really only showing tractive effort and there alot of variables here making these figures somewhat misleading..Would probably explain why people are mainly hung up on power figures, cause few wheel dynos can actually give acurate readings..and even fewer people actually get their engine dynoed...

I used to have a v8 commy, my mate had a n/a13b mazda, driving in either of these you soon learn the difference between power and torque...well so i thought ..

Edited October 27, 2010 by Arthur T3

[zebra]

As always trying to picture this and understand what is going on is really complicated and confusing, took me a year or so to get my head around it.

Hahah Yeah, its a pain in the neck

[DCIEVE]

To add to the discussion a bit of a comparison. Obvisouly only torque is multiplied with the speed reduction so wheel power = engine power - drivetrain losses (but not considered here).

power 400 kW

wheel speed 1000 rpm

engine speed 6000 rpm

engine torque 637 Nm

wheel torque 3820 Nm

power 300 kW

wheel speed 1000 rpm

engine speed 4500 rpm

engine torque 637 Nm

wheel torque 2865 Nm

power 400 kW

wheel speed 1000 rpm

engine speed 4500 rpm

engine torque 849 Nm

wheel torque 3820 Nm

[Birds]

To the people raging over "horsepower sells cars, torque wins races", quit hating on the saying...it's supposed to be ironic, not literal. It's just an old marketing adage poking fun at the very idea that average consumers care more about the big end figures than the more technical, not as widely understood unit actually responsible for delivering results - and ignore the fact that the two are actually related.

Also, what's with people quoting peak torque at low RPM?!? It seems to be the latest craze for marketing material given the swinging popularity towards turbo diesel engines etc. over the past few years. It does not tell a useful story about performance though, particularly with factors like turbo lag. You really need to see the rest of the engine specifications to make it worthwhile. It's about as useful as someone telling you their peak power...neglecting to mention they have a nice laggy T51 bolted on to a small displacement engine!

[PM-R33]

I'm a bit confused by your last statement? Having peak torque come on early as possible is a great thing and in a petrol engine is harder to do (compared to a diesel) and definetely should be highlighted as a good selling point.

[Birds]

All it says is that torque starts to die off after an early point in the rev range...even if it's not a rapid decline. It can suggest something about what type of engine it might be (low down torque diesel etc.), but the way people use it these days...is as if it's a performance benchmark in the daily driver and sports car...

[PM-R33]

Hmmm I dont think I really agree; let's discuss

Can we use the N54 BMW engine as an example due to it being modern, award winning and something similar to what we own (with it being a 3.0L TT straight 6) and the fact I can relate well to it in this discussion

I have the sales brochure here with the BMW engine dyno graph.

Peak torque of 400Nm arrives at 1300rpm (sorry I said 1200rpm in previous posts, it was ment to be 1300rpm) and holds flat of 400Nm until around 5200rpm and then starts to drop off to 280Nm at 7000rpm.

Power is a peak of 225kw at 7000rpm.

Now to me that seems like a shitload of torque throughout the revrange for a turbo car and hence why every one (including my dad that has driven one) says you can bearly feel the turbos coming on and it just feels like a V8 down low, but keeps pulling to 7000 without dropping off like a V8 normally would.

So to me I don't really see why BMW mentioning the low RPM torque figure is a bad thing. Considering most consumers would assume a twin turbo 6 to have lag, mentioning this low down torque makes people go "Oh wow, thats quite a lot at 1300RPM for a turbo engine".

See kind of what I mean?

Edited October 27, 2010 by PM-R33