ah but what if you change the final drive ratio to the rear axle.. now that changes your acceleration doest it..? why cos input RPM to the rear gearbox axle is higher, output is lower.. hence producing more torque.. hence producing more power, so accelerate faster.

remember, dyno shows results in power, but all it does is measuring force acting on a drum at known RPM.. at the end you can say torque and power have linear relation ship..

This post has been edited by ar188: Sep 17 2014, 10:37 PM

one more thing, the assumption is F=m X a only linear when in one gear.. but what if 0-100 you need 3 gear ratios.. (2gear changes)
or if you have 4 gear ratio, with 3 gear changes. at the end the 0-100 times are all different when you take into account what happens in the gearbox.



sorry no linear relationships to be found.. only exponential.. and affected by multiple ratios in a gearbox.. as chart above.

This post has been edited by ar188: Sep 17 2014, 10:43 PM

woi headache liao i read all those rocket science formulas.....

ktm always launch 1 cylinder bikes..
they 1 cyllinder bike fan kua

anyone own a duke 390 here?

giler nih.............mat rempit genius tahap ini gaban

i'll nvr look down on mat rempit anymore!!!

MCB YOU PIPUL SATAY ME NOW I CANNOT SLEEP KEEP THINKING OF RC390

If you change the final drive ratio, you changed the rpm & torque produced. But power only affects the acceleration at higher vehicle speeds because at high vehicle speeds the aerodynamic drag is pushing the vehicle back.

Dyno shows results in power & torque, check back the charts.

Refer to the equation I posted before, torque and power isn't the only parameter, you have to factor in rpm.

If you want to see the effects of torque and power, you have to set the other parameters to be the same:

Checking the effects of different torque values:
1) Both vehicle A & B have same weight, same horsepower, same aerodynamic drag (same shape). Vehicle A has double the torque than Vehicle B.
Results: Vehicle A will accelerate faster to top speed than Vehicle B but both will have the same top speed.

Checking the effects of different horsepower values:
2) Both vehicle A & B have same weight, same torque, same aerodynamic drag (same shape). Vehicle A has double the horsepower than vehicle B.
Results: Vehicle A will have higher top speed than Vehicle B, in addition, vehicle A will accelerate faster than vehicle B because vehicle A have higher rpm (check back the power to torque equations, with the same torque value, higher power means rpm must be higher). This is simply because when the vehicle A have higher rpm, it can hold on to the gear longer than vehicle B. When vehicle A is still on gear number 2, vehicle B already shifted to third gear and have to accelerate with lower torque even at the same speed as vehicle A.

ah but you are giving the example of 2 same vehicle with double the torque and same horsepower and example 2, double horsepower, same torque..
might as well compare, proton with porsche..can conclude with certainty which one will sure win the acceleration test.
why dont you say 10% difference in torque and horse power, but different gearing/gearbox which will affect the outcome differently.

as i said, in a conventional ICE, max power comes at 6-7k rpm , at 3-4k rpm max torque level, you dont get full power., hence you wont get full acceleration.
if you got a gearbox that lets you rev to max power sooner, and stay there.. then if both cars with same horsepower+torque, the one with the gearing advantage to let you do so will accelerate faster.

This post has been edited by ar188: Sep 18 2014, 10:24 AM

oi2 ini thread moto lah bkn engineering yada2

When comparing the effects of certain parameter/variable. All other variables must be controlled or made constant. This is standard practices. If you try to claim the effects of the parameters without doing that, those scientists/engineers would laugh at you man.

Gearing/gearbox doesn't affect the outcome at all. Gearing ratios are calculated from the given engine's power and torque chart. The one that would affect the outcome is the difference in torque and power chart between engines. There are optimal gearing ratios for every car, if you're talking about adjustable gearing ratios to fight on drag strips, sorry but that's for racing purposes and doesn't apply to production cars.

Every naturally aspirated Internal Combustion Engine have the characteristics as you said. But you need to understand that the peak torque range is affected by:
1) Camshaft timing & lift
2) Shape of the combustion chamber
3) The design of cylinder heads (number of valves and position)
4) Shape of the intake manifold/plenum
5) Shape of the exhaust manifold/plenum
6) Length of intake manifold
7) Length of exhaust manifold
8) Length, dimension, and equipments installed on exhaust (4-2-1, s-flow or straight mufflers etc)

There are many factors that determine the torque curves, for example the shape of the combustion chamber, valves, intake manifold exhaust etc etc affects the speed of the intake gas going into the cylinder. Different configurations affects different volumetric efficiency of the engine at different rpm because the ideal engine must have different configurations for different rpm for optimal engine performance at every rpm. This is the reason why manufacturers introduced variable valve timing and lift technologies. Here's some additional info for you, there will be a choke point at which if the speed of the intake gas is higher than the speed of sound, the total volume of the gas that are able to go into the combustion chamber will be dramatically lowered with the added speed.

Did you noticed that normal cars have max torque at lower rpm range to help with drivability while high performance naturally aspirated cars have max torque at really high rpms?

That's just naturally aspirated cars What about forced-induction cars? Turbocharged cars are totally different, take for example a Toyota Supra with twin sequential turbochargers. 90% of the max torque (325 lb ft) of the 2JZ-GTE engine is available from 1300rpm onwards.

You said that max power rpm must be higher than max torque rpm, but why the chart above indicates the max torque rpm is the same with max power rpm, is this blasphemy? No, sorry just great engineering.

Sorry man haha, engineers tak bleh tahan kalo tak defend balik fakta.

This post has been edited by terradrive: Sep 18 2014, 01:18 PM

K/TARD engineers at work

err.. you calculate the cars real world performance, taking into account all the drive train components until the rubber hits the tarmac..
so engine alone doesnt tell the whole picture.. you need to take into account gearbox, drive ratios, component losses.. wheel size etc..

3 same cars same engine /weight, with 3 different gearbox (say 4speed auto vs 5speed manual vs CVT) gonna give 3 different real world results.

look at the torque curve la.. thats like few % higher at the higher rpm.. effectively quite flat torque table..
but why dont you dare say max torque is higher than max power in this case.. at most also nearing same rpm range..

Sure, but as I said, as in previous post I'm explaining the different effects of the torque and horsepower. When comparing things everything else must be the same.

Remember even graphics's card reviewers would use exactly the same computer to benchmark many different graphic cards. If one system using AMD FX6300 + GTX 780 Ti compared to Intel 4670K + AMD R9 290X. The results of the benchmark cannot be compared because the computer systems used were different.

Talking about different gearbox would be another matter when we are discussing about torque and horsepowers.
If you want to talk about gearbox then the all others have to be constant to evaluate the pro and cons of different gearboxes.

I put out the chart just to remind you that different engine designs give different power/torque charts...

In the end just refer back to the most basic, paling basic punya 3 equations I posted before.

OI O!!! KALAU NAK DEBAT BUKAK TERED SENDIRI LA
DAH JAUH MENYIMPANG NI, MOHON KEMBALI KE PANGKAL JALAN

Ok soli soli i stop now.

nak kasih balik pangkal jalan.

Lampu motor KTM ni banyak hodoh cam beruk man.

I got 1 ktm rempit friend , he got duku 390 with abs , rempit all the way , cilok like bawak 125

AGREE