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{Combustion engines are steadily increasing in technology too, due to emissions laws.} 100. If you ask me, it has reached the point of diminishing returns too

{Combustion engines are steadily increasing in technology too, due to emissions laws.} 100. If you ask me, it has reached the point of diminishing returns too (with respect to gains achieved vs added complexity). Take direct injection for example. It provides marginal gains in efficiency, but with that comes a ton of added complexity and side effects. Now you have to get your intake vales cleaned every 60k because there's no fuel spraying on them like with a normal port injection system. Now you have a high pressure fuel pump that is a common failure point on many cars. In fact, I'm surprised they even last as long as they do considering the pressures they run at (I think like 3000 psi under heavy load). Just look at the BMW N54 as an example... Also, the injectors are much more money to replace because of the pressures that they have to deal with (and they are known to go bad more frequently than port injectors). There are a bunch of other complicated things manufacturers are doing as well. BMW Valvetronic essentially uses the lift of the intake cam as a way of throttling the engine. I'm not sure on the reasoning, but it's probably an efficiency thing. However, this is also another failure point. Electric cars are much simpler mechanically. Sure, they may have more software and electronic complexity, but in reality, those types of failures are easier to deal with. Sure, a failure of some expensive piece of electronic equipment will be expensive, but I feel that those failures will be way less frequent and probably limited to manufacturing issues. Now, software on the other hand...

hvidgaard 11y ago
> It provides marginal gains in efficiency Some automakers claim 15% increased efficiency and 50% increased low end torque. That is not marginal.
- Unklejoe 11y ago
  There is absolutely no way you will achieve a 50% increase in torque (at any RPM) just by switching from ordinary port injection to direct injection. Do you have any references to this claim? The efficiency improvements are possible, mainly due to the better atomization of the fuel, but 15% seems pretty generous if we're talking about improvements from DI alone. Keep in mind that many manufacturers are adopting multiple new technologies at the same time they're switching to DI. Newer engines with DI also tend to come with wideband o2 sensors and more modern ECUs, both of which can lead to improvements in efficiency which makes it harder to determine the true contribution of DI. There's only one possible explanation for the 50% torque improvement claim: Many cars are switching from larger naturally aspirated port-injected engines to smaller turbocharged direct-injected engines. Maybe that's what they were talking about. Going from a naturally aspirated port-injected 3.8 liter V6 that makes 300HP and 280 TQ to a turbocharged direct-injected 1.8 liter 4 cylinder that makes 300HP and 350 TQ could very well explain those figures, but it's the turbocharger and smaller engine that are really the key here.
  - hvidgaard 11y ago
    They can control and modulate the injection far more with DI, because they're not limited to intake injection. I cannot give you much in the way of credible sources on the 50% claim from DI, only that I've read it from multiple sources - so treat it as marketing speak. But even if we're "only" gaining 5% efficiency from DI, it's a pretty big deal. I'm fairly sure a GP3 or GP2 engine supplier have stated that DI provides better mileage, power, and torque, especially with an FI engine, compared to MPI.

hvidgaard 11y ago

> It provides marginal gains in efficiency Some automakers claim 15% increased efficiency and 50% increased low end torque. That is not marginal.

Unklejoe 11y ago
There is absolutely no way you will achieve a 50% increase in torque (at any RPM) just by switching from ordinary port injection to direct injection. Do you have any references to this claim? The efficiency improvements are possible, mainly due to the better atomization of the fuel, but 15% seems pretty generous if we're talking about improvements from DI alone. Keep in mind that many manufacturers are adopting multiple new technologies at the same time they're switching to DI. Newer engines with DI also tend to come with wideband o2 sensors and more modern ECUs, both of which can lead to improvements in efficiency which makes it harder to determine the true contribution of DI. There's only one possible explanation for the 50% torque improvement claim: Many cars are switching from larger naturally aspirated port-injected engines to smaller turbocharged direct-injected engines. Maybe that's what they were talking about. Going from a naturally aspirated port-injected 3.8 liter V6 that makes 300HP and 280 TQ to a turbocharged direct-injected 1.8 liter 4 cylinder that makes 300HP and 350 TQ could very well explain those figures, but it's the turbocharger and smaller engine that are really the key here.
- hvidgaard 11y ago
  They can control and modulate the injection far more with DI, because they're not limited to intake injection. I cannot give you much in the way of credible sources on the 50% claim from DI, only that I've read it from multiple sources - so treat it as marketing speak. But even if we're "only" gaining 5% efficiency from DI, it's a pretty big deal. I'm fairly sure a GP3 or GP2 engine supplier have stated that DI provides better mileage, power, and torque, especially with an FI engine, compared to MPI.