Quote:
Originally Posted by Nerys
As for diesel engines no that is not entirely correct. it is not a combination of higher compression and higher energy.
its just higher energy.
Higher compression is a side effect of the lack of a spark plug and the need to "ignite" the fuel by SQUEEZING it to the ignition point.
IE its the "means" in which a diesel engine runs and has little directly to do with efficiency though it does result in more POWER efficiency (but this hurts Fuel efficiency if you USE this power increase in efficiency)
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Not sure where this myth with comes from, even very old diesel engines are more thermodynamically efficient than most gasoline engines accross various load ranges. The reasons are fairly simple
1. More refined, to spec designs,
diesel engines must be built to higher standards to physically function and gain some efficiency from better tolerances and design.
2. No throttle
Diesel engines operate at nearly the same efficiency across their "Normal" power band including idle and low load situations. Gasoline engines simply cannot do this, they use much more fuel than needed at low throttle positions.
That said I am certain you could outperform thermodynamically on many gasoline engines as compared to a diesel IFF you hold that gas engine at one RPM, but most cars are not used this way meaning a diesel wins out over normal driving conditions
Most diesel engines like gassers suffer from low efficiency near & at WOT especially naturally aspirated, so no race car driving for you.
Cheers
Ryan