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Old 05-11-2001, 10:44 PM   #1
Bob J.
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Post What is truly the best type of Powerband?

The other day I was doing some thinking as I was reading some other message boards and came across a thread that was criticizing the Honda S2000. One of their obviously biggest gripes was that the cars powerband was set too high to be considered useable around town and in traffic. That got me thinking though, Why in the heck would you want gobs of low end power and torque around town when all its going to get you is worse gas mileage and a quicker way to rear end the guy in front of you in traffic. Wouldn't the most truly optimal powerband be located high up in the RPM range so that in the low RPM's you could still get good gas mileage around town, but when you reached those beloved country roads you could truly open the car up and get into those higher RPM's and thus the Power. Just thought I would bring this up and see what peoples opinion was on the issue. BTW I consider this Subaru related because I find that there are also many people on this board who praise Subaru's low end grunt and torque but seem to dislike high RPM Horsepower and I hope that a topic like this could truly explain to me why this is. Please don't turn this into a War guys, only intelligent responses please.
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[This message has been edited by Bob J. (edited May 11, 2001).]
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Old 05-11-2001, 11:09 PM   #2
Jonathan
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Actually I find that with my Subarus powerband being really "high" that in order to make use of the cars power, the car is geared way to low for comfortable and quiet "cruising".

An engine that produces a lot of lowend torque, can be geared much taller. This is how your typical 5+ Liter American cast-iron V8 can return fuel economy numbers between 17(city) and 25 (highway), while in many situations out-performing our Subarus.

These American "Tanks" (Muscle cars and SUV, etc...) typically are running ~1700 RPM at highway speeds, where are 2.5 Liter Subarus are running TWICE at fast (~ 2700 - 3100 RPM). This means that are Subarus are NOT twice as fuel efficient, although they have nearly two-thirds the horsepower and half the displacement.
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Old 05-11-2001, 11:17 PM   #3
Patrick Olsen
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Last I checked there was no direct relationship between good low end grunt and poor gas mileage. Actually, I would venture to say that the opposite would be true - if I'm driving a car with no low end grunt, I'm going to have to "put my foot into it" more, and therefore my mileage would suffer. (I haven't really thought that through at all, so don't crucify me or read to much into that statement).

This is one of those things that comes down to personal preference, plain and simple. I've run my buddy's S2000 through its paces, and it's a sweet car, no doubt about it. However, I could never own one because I like torque. No, let me rephrase that, I love torque. The high powerband of the S2000 just doesn't do it for me. To me, the car feels slow. Another friend of mine has an Integra GSR, and it, too, felt slow to me. It sure is cool to wind the hell out of an engine like that, it sounds sweet, but when I rev the engine I want it to push me back in the seat.

Sure, that top end power is nice for when I hit the back roads and want to tear it up, but how much time do I spend doing that relative to the amount of time I spend doing "normal" driving?

I do like the Subaru's performance because of the pretty broad torque band. I personally would not be driving a Subaru if instead of a 165hp @ 5500rpm, 162ft-lb @ 4200rpm 2.5L it had a 165hp @ 6800rpm, 130ft-lb @ 5750rpm 2.0L. It's just my personal taste in performance.

Of course, it is possible to have both low end grunt and top end power - just slap a centrifugal supercharger onto a small block V8.

Pat Olsen
'97 Legacy 2.5GT sedan
'89 Mustang GT convertible, blown and intercooled
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Old 05-11-2001, 11:26 PM   #4
Nordstone
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This is an extremely complicated question. I think the best answer is, it depends on what your needs/opinions are with regards to performance. For starters(my professors would kill me if they saw this sentence), AWD reduces gas mileage. It costs more mpg to run 4 wheels than it does to run 2. There are benefits that you derive from AWD, however. If you live in snow country, you might find it invaluable. I live in Minneapolis and I've owned and driven a two wheel drive sports car in the snow. It's horrible! I had more fun and was safer in my RS last winter than I could have been in just about any car. So, for me it's great. I had to store my MR2 in the winters but look forward to driving my RS in the snow.

The RS actually has good torque for a four cylinder engine. Compare 166 ft pounds to Hondas or other four cylinders with the same hp.

There are additional performance benefits derived from AWD as I'm sure others will attest.
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Old 05-11-2001, 11:31 PM   #5
MiXer
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I think you just need to drive a car with high low-end torque/power and then you'll know. It's absolutely much more fun for the street.

It's also very useful for track use... much easier to power out of corner exits into the straights.

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Old 05-11-2001, 11:40 PM   #6
Digital_Boy
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Ideally, the best powerband is peak torque from idle to redline. This is what Honda's VTEC, Mitsubishi's MIVEC, BMW's VANOS, Porsche's VarioCam and Subaru's variable valve systems try to accomplish to some degree.

The ideal torque curve is a square wave, in other words. Straight up from idle, max torque until redline.

There are a couple of technologies that may bring this VERY close to reality. Aura Corporation has a camless, electromagnetic system to open and close poppet valves. (i.e. the type of valves used in modern internal combustion engines) This system, if it can be perfected and made affordable and small enough, could revolutionize engine tuning. Basically, you could program in ANY lift, duration and overlap from idle to redline.

I've heard that F1 is already employing something nearly the same as Aura's product, called a Moog Drive, or something similar. It too is an electromagnetic valve actuation system. It too will revolutionize the automotive industry.

Another key benefit, with the loss of the camshaft(s) and valvesprings, you also can then rev the engine into the stratosphere. The bottom ends on most modern production cars are more than capable of spinning up to 10K RPM or better all day long. It's the valvetrain that's the weak link.

It would also give the Honda boys one less thing to brag about, since a V8 Chevy would have a better "VTEC" than the Honda. Or a Sube 2.5!


[This message has been edited by Digital_Boy (edited May 11, 2001).]
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Old 05-12-2001, 12:37 AM   #7
Sanguine
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Digital_Boy has it exactly right. The perfect torque curve isn't curved at all. Unfortunately, no current engine design is able to produce this. Often times, the key is not the power curve itself, but how well the gearbox suits the power curve.

The s2000 has more than adequate power, and can certainly "push you back into the seat". You just can't expect it to do so when you're in 6th gear at 65MPH. You need to put the car in a gear where the car can put the power to the wheels. Sure you have to rev the snot out of it to get to the power, but for me, working the gearbox is half the fun of driving.

I don't hear Schumacher complaining about the lack of low-end torque in his F1 car...
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Old 05-12-2001, 12:47 AM   #8
Digital_Boy
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Actually, I just had a thought hit me...

There *IS* one type of vehicle on the road that exhibits this kind of torque curve. Electric vehicles. A DC motor has instantaneous torque, and LOTS of it. The Saturn/GM Impact drive motors can make 1200 lb/ft of torque from the word go. The batteries that power said motors, however, are somewhat less than stellar for energy density and longevity.

If fuel cells or batteries can achieve similar energy densities to gasoline, then I'd switch to electric in a millisecond. The advantages would be HUGE. Drivetrain layout would be easy. Mount a motor on each wheel hub, run a power and ground cable and BAM! AWD. Torque, as noted, would not be a problem. 4 100HP electric motors would give the car F1 like acceleration. Traction control and ABS become VERY precise and greatly simplified. Hell, you can even use regenerative braking to help repower the car.
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Old 05-12-2001, 03:55 AM   #9
AKGC8
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Yea like sanguine was saying, S2000's have plenty of pull. The only time they really don't have that much pull is up to about 5000rpms(so assuming you don't rev and drop the clutch, that would be from 0 to about 20 mph). After that you just have to keep in the proper gear and you'll have about 240hp at your disposal all day long.

High rpm cars are really good in the sense that you can make good use of gearing. With the S2000 you can get to 60 in only one shift. So you're making much better use of the lower gears where you aren't gearing your power down as much.
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Old 05-12-2001, 04:36 AM   #10
tonytiger
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Talking

Digital: Did I read correct: Subaru is using variable valve timing or planning? That'd be interresting If you integrate the torque curve from idle rpm to peak rpm you get the "power" rate, which can be fairly compared with other engines. The cam system seems pretty non-high-tech. Didin't know that the high rpm is limited by the valves, now I know. Audi has built a car which hasn't got a gears at all. It has only one cone shaped wheel that changes the ratio to wheels. If you rev it to peak rpm and drop the clutch (? dunno if it has one) you could use the high rpm all the up. Considering that air drag reduces the acceleration (until it drops to zero), it can be counted to use the optimal rpm which might give raised top speed compared to normal geared car. Tell me if I thoght wrong. Maybe forgot to mention something. I think mostly in finnish and have to translate it to english --> some thoughts might be lost.
The regenarative braking would be great. It saves nature since nowadays the gasoline burnt to produce energy goes straight to the air when braking. Quicly thinking the braking system, which we have now, could be replaced by magnetic brakes that stores the energy to a battery. What would we do with the battery energy is another guestion and the magnetic brakes costs a LoT.
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Old 05-12-2001, 11:26 AM   #11
Digital_Boy
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tonytiger,

Yes, Subaru has a variable lift/phasing camshaft system. It's not available in the North American market, but I believe Europe gets it.

And the transmission you're referring to with the dual cones is a CVX (Continously Variable Transmission). That too would rock the house, especially with our cars.

Honda licensed the technology from the European (Dutch, IIRC) company that has, presumably, the best CVX design on the market. Of note, this company, whose name eludes me, built a few prototype Formula 1 CVX's, the same design, but built to take 800 lb/ft of torque (whatever that may be in kW), and put it in a Lola chassis with a Renault pnuematic valved V10. Against an identically prepped car (same engine/chassis, but with the paddle shifted 6 speed), the CVX car was a consistent 2 seconds faster. Unfortunately, FIA changed the rules and banned automatic or semiautomatic transmissions before the CVX ever ran a race.

Honda's Civic HF (I believe) has a CVX, and the Justy also had a CVX, but the units they use can't take much more than maybe 120 or so lb/ft of torque before things start breaking inside.

So, unless someone invents a miracle battery or fuel cell that's cheap enough to put in a car, I'd settle for a boxer 4 with infinitely variable valve timing (electronic valve actuation) and infinitely variable gear ratios (a beefy 500 lb/ft capable CVX) and AWD.
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Old 05-12-2001, 02:31 PM   #12
Hucker
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Any 2-stroke dirtbike has the best powerband. Car owners could only dream of having a top end hit like that....
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Old 05-12-2001, 02:40 PM   #13
WRXwannbe
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<IMG SRC="http://lobu20.tripod.com/NoBreak.gif" border=0>

yeee
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Old 05-12-2001, 06:57 PM   #14
Patrick Olsen
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Like I said, for me, personally, the S2000 felt slow. And yes, I ran it to redline a number of times. That vaunted VTEC kick that everyone always talks about with the GSR, ITR, and S2000? Never felt it. Sweet chassis, and revvin' to 9 grand is damn cool, but it has no torque, and to me that makes it feel slow.

Quote:
I don't hear Schumacher complaining about the lack of low-end torque in his F1 car...
Well, maybe that's because he's driving a race car that weighs a bit more than half what your car weighs and makes about 5 times as much power. For him "low end" is 13,000rpm (? - I'm just guessing) and he's still probably putting twice as much torque (and four times as much power) as we are to the ground. Plus, he speaks German, so even if he complained about a lack of low end torque I wouldn't understand a word he said!

Pat
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Old 05-12-2001, 07:18 PM   #15
Gethin
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Nice and flat is best

I'm getting there slowly! MoTec next or Possum Link!

WRX v3 MY97
http://www.hongian.demon.co.uk/pictures/dyno2.gif
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Old 05-12-2001, 08:02 PM   #16
Digital_Boy
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Gethin,

Motec is my weapon of choice (M48 Pro, specifically) in the horsepower wars. The Link is handy, and very convenient as far as installation goes, but unless they've recently pulled a rabbit out their a$$, I doubt it can match the Motec.
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