Power of the 1750TB in different modes - Page 2 - Alfa Romeo Forum
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Originally Posted by 147Alfaguy View Post
I’m wondering if anyone knows or can tell me where to find the actual max power figures for the 1750Turbo engine of a Giulietta Veloce in each of its three modes.
Squadra Tuning knows for D and N mode:

Euro 5:
https://www.squadra-tuning.nl/chiptu...tta/qv-235-pk/

Euro 6:
https://www.squadra-tuning.nl/chiptu...lietta/qv-tct/
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Originally Posted by Iron Wizard View Post
I think - might be wrong - that more torque gives faster acceleration and more power gives more top end speed.
A technical answer to the question of, “What makes acceleration: torque or horsepower?”, is torque.

But torque at the wheels—not at the engine.

And becauase acceleration is torque at the wheels, the real answer is horsepower, because horsepower encompasses not only the engine’s torque but the total torque that gets delivered to the wheels.

So more WHP = faster acceleration.
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My hypothesis about the extra puff down low and in the mid-range but not up top appears to hold true too. Thanks for taking the time to find and post the graphical data, hdvp.
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You need work to get something done. And that source of work in our case is engine power, measured in kW or HP. That power gets out of the engine via rotating shaft. Calculating power of a rotating shaft is quite easy if you have the speed (RPM) and torque. You just need right units and you multiply them. And that is a tricky bit for (especially turbocharged) car engines. You have a lot of torque at low RPM, so your power (multiplication of the two) is not as big. As RPMs rise, torque drops slightly, but as RPMs rise faster power goes up. At some point torque starts to drop faster and your power decreases even as RPMs rise. So the max power in N and D mode could be the same, as at that (max power) RPM, torque output in both modes is the same. But at low RPM torque output in D mode is higher, therefore power output at low RPMs is higher, therefore you accelerate faster.

Tricky thing when comparing diesel and petrol cars is the gearbox. Gearbox is a device that can change RPMs and torque, but only so that their multiplication stays the same (so in reality power stays the same). That is why it is really important that your gearbox is calculated properly. If you have two cars that drive with the same speed and have the same size tires, those tires rotate at the same speed. When you accelerate you add torque to them. If you multiply added torque with rotating speed of tires you get power, which should be the same (if there are no losses in transmission) as the power that your engine is capable to give out at the RMP that the engine is currently running on.
So who will accelerate faster, 170HP diesel or 170HP petrol? The one that has better calculated gearbox and a driver that knows how to use it.

I hope I helped clarify something and not add more confusion.
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So who will accelerate faster, 170HP diesel or 170HP petrol? The one that has better calculated gearbox and a driver that knows how to use it.
In that case (if weight, grip and aerodynamic is same, and unless gearbox is calculated in a not normal way) then acceleration 0-1000 m will be pretty much the same.
Give one car 30 whp more and it wil be faster.
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What about going up a incline? I gather the car with more torque? The same as having a car full? I'm trying to understand torque & HP. Difficult task ha!
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What about going up a incline? I gather the car with more torque? The same as having a car full? I'm trying to understand torque & HP. Difficult task ha!
Same...
You are overthinking this...
In the car with less torque at a given rpm you simple shift down, for adding more hp to the wheels.
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What about going up a incline? I gather the car with more torque? The same as having a car full? I'm trying to understand torque & HP. Difficult task ha!
You always need power. But if you have a car driving (it does not matter if they go up or down or on level surface), when you add torque to their wheels you add power, that is why you accelerate.
But lets say that you have two different cars (but with the same mass, to make it simpler) racing and accelerating at 50km/h. One has 200HP and the other one only 190HP. Lets also assume that they both achieve peak power at 5500RPM. Additionally lets say that manufacturer quotes that car with 200HP has higher max torque that the other one. So given that both vales are higher for 200HP car, you would assume that it would accelerate faster. Well in real life it might not be so. The car with 190HP might have engine speed of 5500RPM at exactly 50km/h and is therefore transmitting 190HP (minus some losses) to the wheels. 200HP car might have an engine speed of 4000RPM at 50km/h. But at 4000RPM the engine is not producing 200HP, but only 150HP. So there are only 150HP (minus losses) available at the wheels. In such scenario, car with lower max power will accelerate faster.
If you want to get to the torque, you always have to think about torque on the wheels. Max torque on the engine output is completely irrelevant parameter. Much more important is the torque curve, max power and gearbox ratios. Only with this 3 parameters you are able to compare cars (you also have to consider mass, losses - those are higher if you have 4WD, and at higher speeds aerodynamics)
In the scenario above, wheels of both cars were turning with the same speed (if they were the same size). So if Power=Rotational speed x Torque, and rotational speed is the same, more power equals more torque. But that does not mean that car which accelerated faster (and therefore had more torque on the wheels) automatically had higher max torque quoted by the manufacturer. It just had better gearbox ratio for the above scenario. That is why more and more cars have higher numbers of gears. In that way you can drive at any given car speed closer to 5500RPM and therefore always be able to transmit close to max power to the wheels.
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The car with 190HP might have engine speed of 5500RPM at exactly 50km/h and is therefore transmitting 190HP (minus some losses) to the wheels. 200HP car might have an engine speed of 4000RPM at 50km/h. But at 4000RPM the engine is not producing 200HP, but only 150HP. So there are only 150HP (minus losses) available at the wheels. In such scenario, car with lower max power will accelerate faster.
A very complicated explanation that doesn't make sense at all.

No - the 200 HP car will accelerate faster since it's at 4000 rpm and not maxed out.
The 190 HP car is at 5500 rpm, already at max power, and will need to downshift.

If all else is identical, then the car with most whp will accelerate the fastest 0-1000 meter, no matter what.

In-gear acceleration (eg 60-120 in 4 gear) is where things could be different and torque play it's role.
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You are right that the second car will have to upshift (not downshift) soon, but at that moment when it is at 5500RPM it will produce more whp. That was the point. If we look at the longer time period, think will of course change and probably the 200HP car will get the advantage (as it has more engine power).
What I wanted to demonstrate is that quoted max torque from engine does not mean most torque/power on the wheels at all times. Because that is what people sometimes think. If I failed to do so and I just added to confusion I apologize.
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Yes a typo - upshift pf course.

Simply use the gearbox to convert engine torque to most whp at any time.
Higher torque at a given rpm is just "nice" to keep rpms and gearshifts down.

My son have a modded Citroen C2 VTS with [email protected] rpm / [email protected] rpm
Curb weight 1080 kg (7,7 kg/hp)

Wife have a Giulietta MA 1.4 170 TCT with [email protected] / [email protected]
Curb weight 1355kg (7,9 kg/hp)


Weight to power are pretty much even but have a look at the differences in torque..!
They are neck to neck in acceleration, however the C2 VTS does nothing below 4500 Rpm and you have to drive it like a maniac

When driving 60 km/h side by side the Gulietta will easily fly away in 4th gear if the C2 was not in 2nd gear since lack of torque at low rpm
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Of course, that is why torque curve is so important. Citroen is not turbocharged and has 4 valves per cylinder, therefore has torque curve that is gradually increasing and reaches max at 5500RPM (quite high RPM). This means, low torque coupled with low RPM gives you very small amount of power. Hence "it does nothing bellow 4500RPM". Giulietta on the other hand has a turbocharger which gives it high torque at low RPM. High torque coupled with low RPM gives you medium power and it is actually quite OK to drive.
So Giulietta is not faster due to torque being 90Nm higher, it is faster because it has much better torque curve (a lot of torque available through whole RPM range). As you cannot have an engine with low max torque and great torque curve and a lot of power at the same time (without insane RPM range), max torque figure in technical specification is not really necessary. It just confuses people. It would be much better if instead of max torque you would be provided with torque curve. Or maybe this would confuse non-technical people even more. I do not know, but I would like to have it.
Usually when people say to me that max torque is really important I ask them if I should instead of QV with 340Nm buy a 150hp diesel with 350Nm, as apparently it will be at least as fast if not slightly faster. Then they get confused.
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And so, you just confirmed my point. Anyway, I went way off topic already, so will leave it here.
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