QUOTE(Dezs @ May 17 2022, 06:18 PM)
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Dayum that thing was 850kgs only lmao..
My existing 1.5 already a manual la unker... In the sense of factoring in transmissions, CVT clearly is the winner, Almari 1.0 CVT gets to 25km/l at 80kph from a fren who drives one and maintains barely 2k rpm at 100kph. Thing is to get the closest transmission comparison as well in this case dual clutch and manuals are said to have comparable efficiencies, leaving it to the downsized tebu vs bigger NA. Its like asking if i tebu my same 1.5 now, would it maintain its efficiency vs 1.5 NA, but with boost power available on demand, or the addition of that tebu will cost me fuel right off the bat?
But to properly frame my query "Which engine can produce the most HP for the least amount of fuel", which then begs the question if it should be a 2L NA 6 speed for highway cruise?
Or 1.5 tebu in the form of ketam CVT? But it comes in a fat ass package sucking out precious efficiency in size/weight. It is impressive though at 17km/l for 100kph if not wrong. Thats with 350kg extra weight.
One of the best matches unker met before was 1.2 tebu Vento, also bragging 25km/l ability at 80kph, heavier than milotin, but a 6 speed DSG giving it the low rpm advantage to cruise. But well, its out of market now.
Unker am guessing maybe a 1.3 tebu or 1.4 tebu with a 6-speed might be the sweet spot to get stupid all round economy + milotin bully power at the same time. But we come back to the age old question, if looking at pure economy at best RPM, forcing air through the forced induction pathway or just going 1.8L N/A with CVT a better choice?
The big problem is that 1.8/2L NAs come packaged with big fat asses, unker kenot brain, so they lose out any efficiency gained from better rpm. Mazda cx-3 look small with 2L, but the fugger is as heavy/fat as ketam niama. So hard to put a bit bigger engine into milotin size meh?
Put it this way, there is not 1 size fit all.
CVT good a variable speed by reducing the empty load during shifting, but loose out at constant speed due to CVT belt slip. If dead dead 80km/h on same car, same engine, minor weight different due to different transmission -> MT/AT/DCT vs CVT, CVT will be less efficient, even though no more than 2-3% with modern CVT. So overall CVT still save in combined usage city + highway.
Then engine most efficient rpm is not constant. We have
high rev low load,
high rev high load,
low rev low load,
low rev high load scenario.
I haven't seen enough research on their effect to fuel economy, but direct injection engine has different valve timing and injection pattern for each scenario. For low rpm low load, direct injection use stratified (that's the S is TSFI or TSI) combustion which burn extra lean, higher than standard 14.7:1 ratio, so fuel is closer to explosion rather than smooth combustion. But they can control so precise that it happens at the middle of cylinder away from cylinder wall.
The on high load, I think you more expert than me in this, it burn rich that inject extra fuel.
Here I want to introduce the idea -> Highway constant cruising rpm is determine by gear ratio and wheel circumference, ideally. No matter how powerful the engine, at the same ratio, same wheel circumference, it has to be the same rpm. What differs a big engine vs a small engine is the load, bigger engine running at lower load relative to max potential capacity. Ultimately it is the throttle opening the amount of air that flow through that matters, not the rpm alone, that's how TCR, GT3 racing put air restrictor to make everyone running at more or less same power capacity.
In real life, bigger engine allow the car maker to put a higher over drive ratio than small engine to let it run at even lower rpm.
Downsize turbo vs NA of equivalent power. A 1.5L turbo allow it idle more efficient than a 1.5L NA (due to reduce pumping loss), it also idle more efficient than bigger capacity engine due to smaller contact surface area of the piston to cylinder wall. But that's all the efficiency benefit ends. Downsize turbo + Direct Injection is super efficient at low rpm low load situation, it is basically a hack for city traffic jam driving. Highway, if you light enough on the throttle, keep it at low rpm low load, it is for sure more efficient than NA with same max power. That's 1.5L turbo vs 2.5L-2.8L NA, not 2.0L. vs 2.0L is still a fair play, depends on driving condition, no clear winner. On high rpm high load, it simply drink 2x fuel like a 2.5L-2.8L NA engine depend on the boost, if boost pressure is 2 bar it is 2x the volume = 3L, as simple as that.
Weight play bigger role in a lot of speed variation, then highway constant speed cruising it is more on aerodynamic drag. It is very hard to judge in theory, we know certain feature is more efficient, but overall package just get from real world test. Want most efficient all rounder, need multiple cars for city, highway, personal drive, or carry load.
All in all technology has done wonders, my 2 tonnes PHEV with turbo ICE on 750km long highway journey, depleted charge and drive like regular hybrid still manage 15km/l driving legal 110km/h most of the time (short 15-20min 160km/h to pass a crowded section). That's with 3 passengers + luggages. If push 180-200km/h+, I have seen 5-6km/l, you see it is the effect when the turbo is in max boost.