Smaller engines + forced induction
Discussion
That we see most manufacturers doing now, how far can it be taken?
In 20 years time will the engine be the size of a modern turbo, compression ratio still 10:1 but with intake manifold pressure at 5000x, giving compression of 50,000:5,000 (?), 100,000 RPM red line, and electrically operated forced induction?
Electrically forced induction gets rid of turbo lag and enables high compression.
Small CC engine cuts on friction, reciprocal weight, vibration, weight.
If materials could be made/found that are strong enough to withstand phenomenal intake pressure and compression ratios, would this be achievable, and would the end result be desirable? (from a torque/bhp/the other benefits as above point of view)
In 20 years time will the engine be the size of a modern turbo, compression ratio still 10:1 but with intake manifold pressure at 5000x, giving compression of 50,000:5,000 (?), 100,000 RPM red line, and electrically operated forced induction?
Electrically forced induction gets rid of turbo lag and enables high compression.
Small CC engine cuts on friction, reciprocal weight, vibration, weight.
If materials could be made/found that are strong enough to withstand phenomenal intake pressure and compression ratios, would this be achievable, and would the end result be desirable? (from a torque/bhp/the other benefits as above point of view)
fwaggie said:
That we see most manufacturers doing now, how far can it be taken?
In 20 years time will the engine be the size of a modern turbo, compression ratio still 10:1 but with intake manifold pressure at 5000x, giving compression of 50,000:5,000 (?), 100,000 RPM red line, and electrically operated forced induction?
Electrically forced induction gets rid of turbo lag and enables high compression.
Small CC engine cuts on friction, reciprocal weight, vibration, weight.
If materials could be made/found that are strong enough to withstand phenomenal intake pressure and compression ratios, would this be achievable, and would the end result be desirable? (from a torque/bhp/the other benefits as above point of view)
No, I don't think so. To get the power you have to intercool so you loose efficiency eventually.In 20 years time will the engine be the size of a modern turbo, compression ratio still 10:1 but with intake manifold pressure at 5000x, giving compression of 50,000:5,000 (?), 100,000 RPM red line, and electrically operated forced induction?
Electrically forced induction gets rid of turbo lag and enables high compression.
Small CC engine cuts on friction, reciprocal weight, vibration, weight.
If materials could be made/found that are strong enough to withstand phenomenal intake pressure and compression ratios, would this be achievable, and would the end result be desirable? (from a torque/bhp/the other benefits as above point of view)
Cheers
Christ, no. The quicker it spins, the harder it gets. High-speed engines are an absolute nightmare to lubricate, keep cool, make tractable at lower speeds, make reliable.. The trend is actually somewhat opposite to that. Yes, the engines are getting smaller, but not higher speed - using a turbo also has the handy advantage of giving you an increase in power without needing an expensively high-RPM design.
Even without the government-led efficiency motive, I think manufacturers would still have started to move towards dropping engine capacities as much as they could while still making up the shortfall with forced induction. But it's not going to get quite to the stages you mentioned
Even without the government-led efficiency motive, I think manufacturers would still have started to move towards dropping engine capacities as much as they could while still making up the shortfall with forced induction. But it's not going to get quite to the stages you mentioned
McSam said:
Christ, no. The quicker it spins, the harder it gets. High-speed engines are an absolute nightmare to lubricate, keep cool, make tractable at lower speeds, make reliable.. The trend is actually somewhat opposite to that. Yes, the engines are getting smaller, but not higher speed - using a turbo also has the handy advantage of giving you an increase in power without needing an expensively high-RPM design.
Even without the government-led efficiency motive, I think manufacturers would still have started to move towards dropping engine capacities as much as they could while still making up the shortfall with forced induction. But it's not going to get quite to the stages you mentioned
I wasn't thinking of an engine that powers a vehicle in the traditional sense, a very small engine at high RPM would have a tiny reciprocal weight so would need to run at a very high RPM tickover.Even without the government-led efficiency motive, I think manufacturers would still have started to move towards dropping engine capacities as much as they could while still making up the shortfall with forced induction. But it's not going to get quite to the stages you mentioned
Probably narrow powerband? So utilize it through a CVT?
What I know about engine design could be written on a postage stamp, borrowed from the Borrowers, and I'm just thinking out loud
For each doubling of intake pressure, you're feeding in twice as much air, so for the same output, can half the CC of the engine (roughly)?
But small engines don't like working at low RPM, and RPM * torque = BHP, so if you can design a high RPM engine with a torque output at high RPM, it should equal decent amount of power.
At least from the evidence I can see from model car/plane engines and the 800CC MotoGP engines that produce 230 odd BHP and rev to 20,000RPM.
I might not know much about the design of modern engines, or which way it's going to go, but it interests me and I'm curious about which way the manufacturers are going to go, smaller, bigger, more or less cylinders, multiple or very intelligent active turbos, supercharged, rotary.
It'll be sad if the engine just ends up as a hyper efficient single RPM unit purely to charge the battery, I'm sure there's a lot of fun to be had with different designs for conventional engines.
fwaggie said:
In 20 years time will the engine be the size of a modern turbo, compression ratio still 10:1 but with intake manifold pressure at 5000x, giving compression of 50,000:5,000 (?), 100,000 RPM red line, and electrically operated forced induction?
Sincerely doubt it. Why on earth would you want an engine with 100,000 rpm red line? And how much power would it make? Or, how little torque would it make?The future of super efficiency as I see it is hybrid systems using hydrogen fuel cells or turbines and 'mechanical capacitors'. get the engine running at full chat and then use energy storage systems to control torque delivered to the drive line. Much higher efficiency, much highly improved driveability.
Although I would say that, it would make me a very in demand professional.
In probably 20 years, just about everycar made with have an electric "traction" system. What provides the power for that system remains firmly open. I see IC engines being designed more and more towards single speed power generation devices, as limiting the operating rpm band also allows the most optimisation for economy. (suddenly it also reduces costs, as things like varriable cam timing, or intake systems are not needed anymore, and getting cost out of the IC engine will be critical to making future cars viable (because the hybrid bits take up so much £££).
As you get towards a power system that runs at only one operating point (WOT) then suddenly downsizing actually makes less sense, because a downsized engine is only more efficient at part load, and for a hybrid, you wouldn't want to start the engine without using it's full capacity.
So, i can see simple, 2,3 and 4 cylinder, bio-fuelled ultra simple lightweight engines of between 600cc and 1200cc being the future for a lot of cars. Larger more conventional engines, will be the preserve of "performance cars" where the engine is required to top up the hybrid systems burst performance (i.e. you can go fast for longer than just the batteries energy would allow)
Once the traction system has become fully electric, then it actually leaves an easy path to development, and even subsequent updgrade / replacement, or the power generation system. Imagine having a power "module" that is demountable, with the choice between purely battery storage for local trips, charged off a domestic solar array etc, or being able to lease/hire and higher power range extended "power pack" for longer M-way use etc
(the benefits of electric traction are just too numerous for it not to become the defacto std for future cars (i.e. pure E mode for creep/ low speed, re-gen braking, active torque controlled dynamics (multiple motors etc), simplified transmission, flexible system packaging into the body, and many more advantages)
As you get towards a power system that runs at only one operating point (WOT) then suddenly downsizing actually makes less sense, because a downsized engine is only more efficient at part load, and for a hybrid, you wouldn't want to start the engine without using it's full capacity.
So, i can see simple, 2,3 and 4 cylinder, bio-fuelled ultra simple lightweight engines of between 600cc and 1200cc being the future for a lot of cars. Larger more conventional engines, will be the preserve of "performance cars" where the engine is required to top up the hybrid systems burst performance (i.e. you can go fast for longer than just the batteries energy would allow)
Once the traction system has become fully electric, then it actually leaves an easy path to development, and even subsequent updgrade / replacement, or the power generation system. Imagine having a power "module" that is demountable, with the choice between purely battery storage for local trips, charged off a domestic solar array etc, or being able to lease/hire and higher power range extended "power pack" for longer M-way use etc
(the benefits of electric traction are just too numerous for it not to become the defacto std for future cars (i.e. pure E mode for creep/ low speed, re-gen braking, active torque controlled dynamics (multiple motors etc), simplified transmission, flexible system packaging into the body, and many more advantages)
Nick3point2 said:
Sincerely doubt it. Why on earth would you want an engine with 100,000 rpm red line? And how much power would it make? Or, how little torque would it make?
The future of super efficiency as I see it is hybrid systems using hydrogen fuel cells or turbines and 'mechanical capacitors'. get the engine running at full chat and then use energy storage systems to control torque delivered to the drive line. Much higher efficiency, much highly improved driveability.
Although I would say that, it would make me a very in demand professional.
This could work, other than the bold bit which is a load of rubbish. Or an ICE/turbine operating at peak efficiency to top up the batteries on an electric car.The future of super efficiency as I see it is hybrid systems using hydrogen fuel cells or turbines and 'mechanical capacitors'. get the engine running at full chat and then use energy storage systems to control torque delivered to the drive line. Much higher efficiency, much highly improved driveability.
Although I would say that, it would make me a very in demand professional.
Trains and big boats have been series hybrids for years.
fwaggie said:
Good point.
Is there any way to utilise that? Superheated air?
It's hot, so it's expanded a lot, so has low oxygen level, so doesn't sound that useful.
Mini steam engine hybrid Is there any way to utilise that? Superheated air?
It's hot, so it's expanded a lot, so has low oxygen level, so doesn't sound that useful.
Seriously though, anything hot should be able to be converted to forward motion one way or another, I suppose it then just comes down to efficiency vs. cost.
Rovinghawk said:
fwaggie said:
It's hot, so it's expanded a lot, so has low oxygen level.
20.9% oxygen, same as usual, surely?RH
Cold air is more dense, there's more of it in any size of fixed volume (i.e. a cylinder).
As there's more air, there must also be more oxygen.
If the airs very hot, the reverse is true and there's less oxygen.
Max_Torque said:
a downsized engine is only more efficient at part load
Is there an "ideal" engine size with respect to efficiency?And is that just down to the current design or some physical limitations that have nothing to do with design?
And why does reducing it's size (or increasing it) make it less efficient?
Max_Torque said:
(the benefits of electric traction are just too numerous for it not to become the defacto std for future cars (i.e. pure E mode for creep/ low speed, re-gen braking, active torque controlled dynamics (multiple motors etc), simplified transmission, flexible system packaging into the body, and many more advantages)
Yep, agree with all that.Eliminating all gearboxes (apart from a simple reduction box in each motor), diffs, axles, transfer boxes should save a shed load of weight.
A pity that everything's in place now apart from battery technology for a decent range out of the battery.
As an aside, does anyone else think that most current engine improvements wouldn't have come about if the emission regulations hadn't been bought in?
It seems to me that IC engines hadn't come all that far really until these emission regs came in in the states & EU, and so the manufacturers were forced to develop new technologies (DFI) and refine old ones (turbo+super charging), and it's almost an aside that power per litre has been increasing.
Max Torque, great post !
I like the idea of the range extender, I think the problems are that you need to have the motor, the range extender engine, fuel tank, the batteries and all the control gubbins so it gets a bit weighty but I think it will be the way to go, engines with no connection to the wheels that just starts up when needed.
I like the idea of small motors connected to or in all wheels, small range extender engine with regenerative braking, I guess the packaging could be very different as the engine can be anywhere and doesnt need a gearbox as its just for generation of electricity, it can be a much lighter duty unit as it doesnt have to shift the weight of a car and would run at constant RPM and never really be put under the loads that a traditional engine is.
I think it is all quite exciting really.
I like the idea of the range extender, I think the problems are that you need to have the motor, the range extender engine, fuel tank, the batteries and all the control gubbins so it gets a bit weighty but I think it will be the way to go, engines with no connection to the wheels that just starts up when needed.
I like the idea of small motors connected to or in all wheels, small range extender engine with regenerative braking, I guess the packaging could be very different as the engine can be anywhere and doesnt need a gearbox as its just for generation of electricity, it can be a much lighter duty unit as it doesnt have to shift the weight of a car and would run at constant RPM and never really be put under the loads that a traditional engine is.
I think it is all quite exciting really.
The engine size for ultimate efficiency is F'ing massive! Basically an engines efficiency comes down to 2 things, it's expansion ratio, and the ratio of combustion chamber surface area to volume.
Now the expansion ratio is really just a question of how much loading the engine can stand in terms of compression ratio, and is fairly size independant, but the surface are to volume ratio gets more favourable the large the combustion chamber gets.
Hence large marine engines and large stationary generating engines get much higher overall thermal efficiency than normal car engines.
It's a common misconception that electric motors don't require multispeed transmissions in traction applications. Yes, you can manage with a single (or twin speed) transmission. But vehicle performance and system efficiency is massively improved by having a multi speed transmission. (this is because even if theoretical motors have an infinite spread of torque, real ones don't and still make peak power (which is what matters for getting places) at a single rpm. And as copperlosses square with current applied (and mech torque is proportional to elec current), making large torque at the wheels is more efficiently done with a gear reduction and low motor torque, than via large motor torque and a numerically low reduction ratio.
Now the expansion ratio is really just a question of how much loading the engine can stand in terms of compression ratio, and is fairly size independant, but the surface are to volume ratio gets more favourable the large the combustion chamber gets.
Hence large marine engines and large stationary generating engines get much higher overall thermal efficiency than normal car engines.
It's a common misconception that electric motors don't require multispeed transmissions in traction applications. Yes, you can manage with a single (or twin speed) transmission. But vehicle performance and system efficiency is massively improved by having a multi speed transmission. (this is because even if theoretical motors have an infinite spread of torque, real ones don't and still make peak power (which is what matters for getting places) at a single rpm. And as copperlosses square with current applied (and mech torque is proportional to elec current), making large torque at the wheels is more efficiently done with a gear reduction and low motor torque, than via large motor torque and a numerically low reduction ratio.
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