Perhaps I'm a little paranoid, but I do wonder how small capacity engines are able to produce similar amounts of power and improved efficiency for a similar cost when compared to their larger-engined counterparts.
I'm no engineer, but surely there has to be a compromise somewhere?
The addition of a turbo (not the same high output units as in the Subaru WRXs of this world) makea HUGE difference as regards overall power and torque, as well as delivery of that power at lower revs. The engines are also lighter.
On the downside, they are more complex, though this is less of an issue for most cars as they aren't high performance (over 200hp), and even those are far more reliable than they used to be when turbos first became really popular on hot hatches in the 1980s.
As such, the will cost more to build (more parts) and are likely to be less reliable than normally aspirated equivalents, but it does depend on the make, model of engine and when it was built. Most problem engines are well known and are shown in detail in the Car-by-car reviews sections for each vehicle.
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Perhaps I'm a little paranoid, but I do wonder how small capacity engines are able to produce similar amounts of power and improved efficiency for a similar cost when compared to their larger-engined counterparts.
I'm no engineer, but surely there has to be a compromise somewhere?
On the downside, they are more complex, though this is less of an issue for most cars as they aren't high performance (over 200hp), and even those are far more reliable than they used to be when turbos first became really popular on hot hatches in the 1980s.
I guess the complexity is what I was getting at but didn't really explain.
Take the 1.0 140 Ecoboost for example. Let's say a normal 1.0 engine produces about 75hp, so the turbo has to produce about the same. This seems a lot for a car that has to cater to all manner of buyers. As cars seemingly move to smaller capacities with similar or greater power outputs, is the reliance on a turbo or supercharger asking too much?
Personally, I like the route that Mazda have taken; larger capacity engines made as efficient as possible.
Edited by Bicycle_Repair_Man on 04/06/2018 at 17:29
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Perhaps I'm a little paranoid, but I do wonder how small capacity engines are able to produce similar amounts of power and improved efficiency for a similar cost when compared to their larger-engined counterparts.
I'm no engineer, but surely there has to be a compromise somewhere?
On the downside, they are more complex, though this is less of an issue for most cars as they aren't high performance (over 200hp), and even those are far more reliable than they used to be when turbos first became really popular on hot hatches in the 1980s.
I guess the complexity is what I was getting at but didn't really explain.
Take the 1.0 140 Ecoboost for example. Let's say a normal 1.0 engine produces about 75hp, so the turbo has to produce about the same. This seems a lot for a car that has to cater to all manner of buyers. As cars seemingly move to smaller capacities with similar or greater power outputs, is the reliance on a turbo or supercharger asking too much?
Personally, I like the route that Mazda have taken; larger capacity engines made as efficient as possible.
To be fair, 140hp from a 1.0T is at the very top of the range - most provide about 110hp, although most 1.0 N/As prodcue around the 70hp level at most, more like 65 average. Manatee's comments are true, so the combination of lower weight, better thermal efficiency and forced air induction produces on average a gain of 60-75%. The VAG 1.4 (now 1.5) TSi has a lower stressed 122 (1.4) / 130 (1.5) hp version and a higher stressed (but not that high) 140 (older models) / 150 hp version.
What often makes a large difference is general weight saving and aerodynamic efficiency as well as the power and torque that can be developed by the engine. The Mazda3 is a larger car than the Golf 1.4TSi 122 but roughly matches its 0-60 time because Mazda have really gone to town on weight saving (including with the engine itself) and it is a more sleek shape than the VW, but its easily beaten on mid-range grunt in normal driving so is a less relaxed driving experience, especially if you need (or want) to overtake a lot. Pootling around is probably about the same for both.
The new HCCI engine from Mazda due in the mk4 Mazda3 and other models next year or so will take this weight saving even further but I think they are adding some kind of supercharging (part time?) to the engine. I suspect, assuming it all works without problems, this will be the most (within reason) that (sort-of) non-turbo engines will be able to achieve as regards the trade off between performance and economy. Even Mazda admit its a stop-gap until they go fully electric, though they do have a hybrid coming within the next 3 years as well.
What may be of benefit (I can't confirm this) is that the HCCI engine may not need a GPF (gasolene particle filter) that many newly designed turbo-petrols will to meet new emissions regs, similarly to Mazda's diesel engines don't need AdBlue to meet the current ones. If so, this will be a selling point given the problems with DPFs and repeated short trips from cold.
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Perhaps I'm a little paranoid, but I do wonder how small capacity engines are able to produce similar amounts of power and improved efficiency for a similar cost when compared to their larger-engined counterparts.
I'm no engineer, but surely there has to be a compromise somewhere?
On the downside, they are more complex, though this is less of an issue for most cars as they aren't high performance (over 200hp), and even those are far more reliable than they used to be when turbos first became really popular on hot hatches in the 1980s.
I guess the complexity is what I was getting at but didn't really explain.
Take the 1.0 140 Ecoboost for example. Let's say a normal 1.0 engine produces about 75hp, so the turbo has to produce about the same. This seems a lot for a car that has to cater to all manner of buyers. As cars seemingly move to smaller capacities with similar or greater power outputs, is the reliance on a turbo or supercharger asking too much?
Personally, I like the route that Mazda have taken; larger capacity engines made as efficient as possible.
I personnally go for the smallest and most powerful engines available. Surely a large engine is going to take longer to warm up and I suspect many people wouldn't even get their large engines warm in normal driving. For me, the sooner it warms up, the sooner I can drive it properly and enjoy it. I can't quite understand why somebody would want a large engine.
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You choose your engine cpecs to be suitable for the type of driving it needs to do. Forgetting whether a car has a turbo, a larger engined one (assuming its not tuned to be a high performance model) will be lower stressed at motorway speeds than a small one, but consequently a small car with a small engine will be fine; a large car with an undersized engine (power/torque wise) will probably use more fuel, be less relaxing to drive and won't last as long than one with a a more powerful/larger engine that can easily cope with everything that's thrown at it.
Yes, a 1.0 N/A petrol engine in a city car will be the best combo for 1 person doing short trips to the shops; on the other hand, a rep doing lots of motorway mileage will prefer a 2.0 TD for both ease of use/overtaking and mpg - a 2.0 N/A petrol would be similar fine except for the mpg; a 1.4 T petrol would be better on usage than both but in the middle on mpg. Horses for courses.
As the turbo petrol designs really mature, they'll take over from probably all bar the micro and city cars across the board, until fully electric really starts to eat into their market in 10-15 years or so (at least).
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They have turbos (generally, some have had superchargers), so by compressing the charge they can transform more fuel and air into energy for a given swept volume.
They're more thermally efficient with fewer and smaller parts. They warm up very quickly (assisted in some cases by having low volumes of coolant and more than one cooling circuit) and other efficiency tricks.
The 1.2TSI 105 in our Roomster (now superseded) is very impressive in use, although early reliability was poor. I believe ours has the revised toothed chain so I'm hoping it will last a while.
The naturally aspirated 1.5 in my MX-5 produces almost exactly the same BHP per litre - but it needs 7000rpm rather than 5000 to do it. Different compromises.
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When I was working and doing 30K miles per annum I always had a diesel. My own so I claimed the HMRC mileage. Good way of doing it. However because of the mileage and differing types of road I always had at least a 1.9/2.2 litre diesel. Now retired I tow a caravan regularly and for long distances so I am still with diesel. My Volvo XC60 returns 30mpg towing and averages 42mpg around normal motoring. I will eventually become too old to continue towing a caravan then I will get a nice little petrol car. probably a 1.0 or so. My daughters Ford have been good with the 1.0 Ecoboost but also VAG have some nice TSi units. The power generated by the new small engines is remarkable. Been in a few and always impressed by the amount of power if you need it. Anyway by the time we on this forum are in our dotage there wont be any internal combustion engines around at all.
Cheers Concrete
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To be fair, 140hp from a 1.0T is at the very top of the range - most provide about 110hp, although most 1.0 N/As prodcue around the 70hp level at most, more like 65 average. Manatee's comments are true, so the combination of lower weight, better thermal efficiency and forced air induction produces on average a gain of 60-75%. The VAG 1.4 (now 1.5) TSi has a lower stressed 122 (1.4) / 130 (1.5) hp version and a higher stressed (but not that high) 140 (older models) / 150 hp version.
We have the 1.0 Ti 110 and the 1.4 TSi 150 (had the 140 previously) and all drive great. There is no need to rev them or give them large doses of throttle to get god performance, they just get on with it. Did try a 1.2 TSi 90PS in a Polo and we found it poor but the 1.0 TSi 95 PS in a Fabia was absolutely fine
What often makes a large difference is general weight saving and aerodynamic efficiency as well as the power and torque that can be developed by the engine. The Mazda3 is a larger car than the Golf 1.4TSi 122 but roughly matches its 0-60 time because Mazda have really gone to town on weight saving (including with the engine itself) and it is a more sleek shape than the VW, but its easily beaten on mid-range grunt in normal driving so is a less relaxed driving experience, especially if you need (or want) to overtake a lot. Pootling around is probably about the same for both.
That sums up why modern Turbo's are great to drive but 0-60 times are largely irrelevant in the real world. We tried the Mazda 3 with the 120 hp 2.0 litre egine and the 6 with the 145 hp 2 litre engine. Both felt fine in town but once out on the open road and when changing lane on motorways both were lacking in the extreme unless you dropped afew gears and revved them hard.
The new HCCI engine from Mazda due in the mk4 Mazda3 and other models next year or so will take this weight saving even further but I think they are adding some kind of supercharging (part time?) to the engine.
From what I have read Mazda may well just be wasting thier time The 2 litre 180 hp engine uses supercharging and gives only 230 nm or torque. That is well under the 250 nm that the VAG 1.4 TSi produces. Combine that with the combination of park and compression ignition and it becomes very complicated which is well out of step with Mazda's simple N/A path of recent years. Basically it appears to offer nothing over a much simple turbo only engine of their competitors, unless of course the real word mpg is staggering which having had supercharged engines in the past I find difficult to believe.
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