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#11 Re: Thoughts on high RPM
Datopower Posted on: 2002/11/18 19:55
Hey guys,

Um OK about this whole torque thiung ... based on the correct scientific principles behind what torque is....perhaps i should put an example to my earlier comment....

Torque is good for towing...

Lets get a heavy old boat eh ? Now lets try and tow that boat with say our mighty lil A12 and a big ol say... HQ Holden.

If knowone knows what an HQ Holden is... swap this car for a big ol' truck, the principle is still the same...

Now the Holden is like a heavy ol' tank...struggles to get up to 120Km/h (without a trailer) but produces a heck of a lot more torque than the dato.

The Holden just 'clunks' itself into gear and crawls away witht the big boat behind it...

The lil' dato sweats away with it's trailer (probably burning out a few tires at the same time) hahahha....(i can just see it now)
But would have no trouble getting to 120km/h...(without a trailer)

I guess the key to remember... Torque is a Force of a car yeah ?

Make sense ???

Cheers




#12 Re: Thoughts on high RPM
minipearl Posted on: 2002/11/18 22:16
I do not fully understand what you all are talking about, but it seems to me that my son is just being difficult.


#13 Re: Thoughts on high RPM
dimlight65 Posted on: 2002/11/18 22:20
D'oh! Called out by my own mother! How do you like that!


#14 Re: Thoughts on high RPM
danielblues Posted on: 2002/11/18 22:45
The best info I found on this subject was The physics of Racing Series.

Based on that, on the remote year of 1997 I made a small java applet that mesured the mitty datto acceleration, it's now available on our Tech Section
(Enjoy)

I'm more of a horsepower guy, I love an engine that revvs really well more than a good kick in the back that fades fast.

daniel


#15 Re: Thoughts on high RPM
1200rallycar Posted on: 2002/11/19 4:11
that things pretty good, i was planning on making a program like that one day, pretty much already done it from a uni assignment, but it was never going to have that many variables

i like it!!!


#16 Re: Thoughts on high RPM
ddgonzal Posted on: 2002/11/19 8:44
Quote:
Okay, so what if the torque doesn't double when they double the rev's? If you rev the engine twice as many times, the torque is applied twice as many times.
I don't know offhand how the math works out ... but it sounds right in spirit.

The main point of the original post was that the same size engine revving can give better performance -- if engineered properly.

The point about a "torquey engine" is that a bigger lower-revving engine can push your car just as fast as a smaller higher-revving engine. It's just a generalization.

So somebody saying "my engine makes 125 hp" doesn't tell very much about the peformance it will give. Don't be misled by advertisements, etc.


#17 Re: Thoughts on high RPM
ddgonzal Posted on: 2002/11/19 9:17
Going along with L18_B110's comment about engine life, Wright says F1 engine parts are designed to last about 2x the number of race laps! The 1986 BMW qualifying turbo engines only lasted a few laps at ~1200 bhp from a 1.5 liter engine! Of course, they only needed a few laps to qualify in top spot.

The point of the original posting was just interesting information on ultra-high rpm engines. The same principles apply to A-series engines though with far less importance. Reduced friction is a concern even in 10,000 rpm engines. Don't all the serious A-series racing engines have windage trays?

Then Dimlight had to go bashing horsepower ratings

Yes, a lot of generalization followed, but that's not necessarily bad ...
Quote:
"With extra torque, you just go faster"

Sorry for not qualifying this. I meant that if you put a bigger engine in -- generally -- you can drive the car the same way as before and it "goes faster" from both the perception of the driver and the stopwatch.

Compare that to putting the same size engine in, only a high-revving, idle-loping version. If you drive the same way (shifting at the same low RPM as the old motor) -- generally -- the increased potential of the modified engine isn't being taken full advantage of. So you adjust, keeping the engine up in its new powerband. Sometimes you even run out of revs before the end of the track, or need to shift sooner at certain corners ... hence gearing is more critical with a higher revving smaller engine. This is a generalization, but is it a myth?

Quote:
"A high revving engine cost big bucks. A high torque engine can be very inexpensive."
Yes, another generalization. But isn't it generally true? Sure there are always exceptions. I was thinking of a 10,000 rpm motor (sometimes seen on the street) compared to a much bigger, but completely stock engine.

Quote:
"horsepower sells cars, torque wins races" or alternately "you buy horsepower but you drive torque."
I wouldn't agree with the last necessarily, but haven't advertised horsepower figures influenced some people to buy a slower car because "it has more advertised hp"? I mean, which one of us faced with buying a new car wouldn't be tempted to choose the "205hp" engine over the "210hp" engine if they were the same cost? But that HP figure doesn't tell which car is faster in any specific situation.


#18 Re: Thoughts on high RPM
phunkdoktaspok Posted on: 2002/11/19 9:41
So is it true or not with the old saying
"Torques Cheap Lets Race!"?


#19 Re: Thoughts on high RPM
1200rallycar Posted on: 2002/11/19 11:17
personally i always look at 0-100 and 1/4 mile times to judge cars against each other, because the clock doesnt lie, but this also includes power to weight ratio and drivetrain efficieny, co-efficient of drag, blah, blah, blah

only downfall, its bloody difficult to measure handling with a stopwatch without other variables clouding results

when i look at motors i will first look at hp i admit but if i decide to reaserch something genuinlly (you know what i mean) its the times i look at, most cars also have braking times included in specs these days too which is good

ddzagonals talk reminded me of somewhere i heard that with high budget race cars for qualifying they wind the turbos up to some rediculous figure like 35 or 40 psi and as soon as qualifyings over they just toss the turbos out, but for racing a more reliable figure like 15-20psi is used, just thought that was interesting


#20 Re: Thoughts on high RPM
simmodat1200 Posted on: 2002/11/19 11:50
ahhh my 2 cents.
Lets take a look at a couple of the bad things torque does, BENDING & SNAPPING, power will do this too, but is less likely as power delivery is more progressive.
Its all well and good to have 600 nm of torque at 2500rpm, but did anyone consider what drivetrain sacrifiices have to be made, let alone what it does to the chassis of our little dattos. Take gearboxes for example, full of numerous breakables. Any significantly abrupt change in the turning moment (torque) can cause breakeage in the driveline anywhere. So to remedy this u buy stonger heavier parts with more angular momentum, giving less acceleratory response than would be achievable with power. To put the "power" (torque) down u have to get wider tyres which dont handle in the wet and before u know it your car becomes a train, only capable of running the quarter mile. Cars were built with steering wheels, made to go around corners. Torque and power are equally important, but what is more important is the delivery of this power. F1 cars for example, have an relatively short range of useful power compared to their total RPM range, however this delivery is smooth and allows easier throttle control, and due to the physical size of the engine and its lateral weight distribution the car still remains competitive.
Power suits its application, remember, first u get the money, then u get the power, then u get the women.



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