Power to weight ratio for technic supercars

[MSc Shobaki]

Remember this as well:

Each time you gear up or down, the speed will either increase or decrease resulting in opposite effect on the torque. Higher gear= Lower torque

But most importantly, you also need to consider efficiency as well where each stage of gearing results in 95% of the actual torque (power)/speed in that stage's output.

E.g. A motor connected to a 3:1 gearbox with input speed at 180 rpm. Basic math would give an output speed of 60 rpm, however due to power loss in the gearing, the actual output speed would be around 57 rpm. This efficiency should be considered at every down/up-gear stage as it will affect the total output in both speed and torque and the latter in power.

[Epic Technic]

I have worked out that my radical has 2.8 HP / Ton . So a bit less than your P1 Leocorno.

[LeocornoProductions]

Wait how many motors is it powered by, and how much does it weigh. And I can then see if that is correct.

[Epic Technic]

Wait how many motors is it powered by, and how much does it weigh. And I can then see if that is correct.

Well it has 4 L motors for power but it is powered at around 7.5 volts so less power... and it weighs 2.5 kg

Edited February 16, 2015 by Epic Technic

[LeocornoProductions]

I'm not sure how much torque an L motor produces at 7.5V, but at 9V your radical produces:

*0.013hp

*181.6N.cm of torque

= 5.2hp per ton

congrats

[Epic Technic]

I'm not sure how much torque an L motor produces at 7.5V, but at 9V your radical produces:

*0.013hp

*181.6N.cm of torque

= 5.2hp per ton

congrats

But it's not at nine volts sadly... :(

[LeocornoProductions]

Even with 7.5 I think it would still be higher than my Huracan.

[Captainowie]

Yea. I agree Captain, just because the Lego Supercar don't have a motor, theoretically you could still calculate the theoretical Horse Power of the little grey engine block.

You could, but it doesn't make for a very useful comparison metric - especially if you're comparing it to a model that has actual motors. For example, to get twice the power, you double the number of little grey engine blocks, and you add maybe a tenth of a percent of weight. But for a model with motors, if you double the number of PF motors, you increase the weight by maybe 10 percent.

(very rough, order-of-magnitude estimations)

Owen.

[Boxerlego]

Hi

I see you have many questions, but I will anwser the questions directed towards me. First, people like me like to compare other motorized mocs and the power to weight ratio figures can help me and other people compare them, maybe racing them would be proper, but their aren't many people eligible to race mocs, due to providing instructions etc. In the real supercar world, it's a buzz about power to weight ratios, because supercars always racing each other and such. But the best example is the bugatti veyron supersport vs koenigsegg agera r. At first it was difficult to compare these cars because no one knew what the koenigsegg was capable of speedwise (well now we know that it can do 186mph in 14.53 seconds and 200mph in under 18 seconds), but the koenigsegg has a power to weight ratio of 794hp per ton and the veyron has just over 600hp per ton. Power to weight ratio is useful for comparing modern, cars because comparing 2 cars from different decades is innacurate with power to weight ratios. The mclaren f1 has a power to weight ratio better than the original veyron, yet the veyron destroyed it in a race. Power to weight ratio comparisons are often 60% right for whether 1 car is faster than another overall. But power to weight ratios are 100% useful for comparing modern cars acceleration. Let me give you a statement I have just come up with, a supercar with a power to weight ratio from 300-420 horsepower per ton will have an acceleration to 60 mph from 3-4 seconds, a modern supercar with more than that will accelerate almost as quickly as a hypercar e.g. Lamborghini aventador, ferrari f12, Mclaren 650s, Lamborghini Huracan, ferrar 458 speciale, noble m600. A modern hypercar with a power to weight ratio over 500hp per ton will do 60mph in under 3 seconds and 100mph in under 6 seconds, and a modern hypercar with over 650hp per ton will be significantly faster than than the 2005 bugatti veyron in terms of acceleration, and a modern hypercar with over 700hp per ton will accelerate faster than a bugatti veyron supersport.

Second, the lego technic power functions website shows how much rpm and torque each motor makes, and there was this online calculator which used rpm and torque to workout horsepower and watts, thus I used the formula for working out power to weight ratio for cars. And applied all of this for working out technic power to weight ratio. Does this anwser your questions?

Very good explanation and examples too. It is interesting how the veyron was able to come out on top even though is hp per ton was not as much as the koenigsegg. I have no idea why but what was the key factor for the veyron to come out on top, was it be because of a smaller tire size or a better gear shift pattern or maybe the engine was running better that day.

Yes that answered my questions but I got one more question. Would hp per ton be the best from of measurement on the LEGO level?

You could, but it doesn't make for a very useful comparison metric - especially if you're comparing it to a model that has actual motors. For example, to get twice the power, you double the number of little grey engine blocks, and you add maybe a tenth of a percent of weight. But for a model with motors, if you double the number of PF motors, you increase the weight by maybe 10 percent.

(very rough, order-of-magnitude estimations)

Owen.

I see what your saying, very interesting. I guess that being said the same should applied with LPE to PF motors as well.

[LeocornoProductions]

The Veyron comes out on top because it has lots of torque to make up for its weight, not to mention its quick shifting dual clutch gearbox. Torque is important because it makes the horsepower more effective by letting the power outburst have a longer duration. You can have a car with lots of power, but if it doesn't have the torque than it will lack in acceleration at high speeds. That's why the Porsche 918 can accelerate faster than previous koenigseggs; eventhough it has 887hp and weighs almost 100kg more than an aventador, it has the same amount of torque as an agera r, which means it can keep on the power for a same rate longer than an old supercharged koenigsegg would. But why the p1 is significantly faster than a 918 at high speed is because the 918's electric motors turn off at a certain speed and around 40% of the torque is lost and it's only rwd with the 620hp naturally aspirated engine. How the Veyron catches upto the p1 at high speed: We all know the p1, 918 and laferrari are famous for accelerating quicker than a Veyron, the p1's acceleration starts to cool down at over 190mph because at a certain speed as well it's electric motors deactivate. But also the Veyron can keep it's acceleration rate for longer because it has the torque to hang on to the power, also to reach certain speeds you need a certain amount of torque depending on the weight. How this is ideal for technic? If you're comparing 2 technic supercars, then power to weight ratio can help compare them without racing them.

[Epic Technic]

Actually the reason the Koenigsegg one:1 doesn't come to the top top speed wise is because Koenigsegg doesn't have a massive testing track with a multiple kilometer long straight. But who knows the Koenigsegg Regera might do. Rumored to have around 600 electric HP and who knows how many gas HP.

Going back to Lego the Power to weight ratio is a good comparison but not always the defining factor in real. For example: the Audi RS 6 (the newer C7 with the twinturbo v8) and the Mercedes E63 AMG. The Merc has better specs but on the track the RS 6 is way faster, it is all in the tiptronic gearbox and the Quattro drive system.

[nerdsforprez]

I haven't read the entire post, so I hope this has not already been addressed, but in terms of LPEpower's engine's (Alex's) they are pretty powerful. High RPMs and high torque. If you take a look @ Philo's page http://www.philohome.com/motors/motorcomp.htm he/she describes torque as the stopping power needed to stop the output shaft of the motor. I have tried to stop the little i3 I bought from Alex and although certianly doable it took some pain tolerance. It burned my skin

I have also used the engine for several models and it appears to break through friction, gravity, pretty well. In the Unimog video, although it did not twist axles, it certianly popped the gears out from eachother no problem.

[nerdsforprez]

As with MSc Shobaki's comments.... couldn't agree more. With my unimog above I had roughly 35:1 gearing. Ridiculously inefficient.... and I am sure that it ate up alot of my power. However, the LPE was still powerful enough to wreck through my gears

[DrJB]

If you take a look @ Philo's page ... he/she

Philo is a 'He', at least from the picture on the top-left corner of his page

[LeocornoProductions]

The regera will have 700 electric horses and will probably have the one:1 engine, hybrid le mans format. And yes the drivetrain and traction plays a huge factor. That pneumatic engine is really powerful, I need to get my hands one.

[Epic Technic]

The regera will have 700 electric horses and will probably have the one:1 engine, hybrid le mans format.

Actually not 700 E-HP but only 690 E-HP, IKR so sad ;)

By Hybrid Le Mans / FIA WEC format what do you mean, there are multiple different designs.

[Epic Technic]

The current vehicle that I'm building is expected to have a power to weight ratio of 4.5 HP/ton

[LeocornoProductions]

Cool can't wait. And I meant that it has the hybrid layout found in most le mans cars, where the combustion engine sends power to the rear wheels and the electric motors power is distributed to the front wheels. The hybrid le mans car that doesn't follow this layout is the new gtr lmp1 car which has the reverse of that layout.

[Epic Technic]

Cool can't wait. And I meant that it has the hybrid layout found in most le mans cars, where the combustion engine sends power to the rear wheels and the electric motors power is distributed to the front wheels. The hybrid le mans car that doesn't follow this layout is the new gtr lmp1 car which has the reverse of that layout.

Ah, I was thinking of kers

[Epic Technic]

Well the car without any the body work now weighs 500g. So right now it has 7.4 HP/ton.

Edited February 22, 2015 by Epic Technic

[__________________________]

I think efficiency is equally important to power and weight. We saw supercars with okay theoretical power to weight ratio, yet they could hardly crawl.

Of course, loss of efficiency is usually due to detailed gearboxes, like what Sheepo does Is there a way to measure power which reaches the wheels?

[LeocornoProductions]

There is but not for technic vehicles :\