On 13/05/2020 13:09, Tim+ wrote:
Dave Plowman (News) wrote:
In article ,
AJH wrote:
On 12/05/2020 17:16, The Natural Philosopher wrote:
None of this relates to fuel efficiency: That's is far greater these
days because of electronic injection and mapping allowing an optimal
fuel level and inlet pressure depending on the load and RPM. That and
lower friction materials nets you a more efficient motor overall.

That fits my understanding.

So why have such complicated engines when these above things can be
implemented on a simple OHV engine doing less than 5krpm and no variable
valve timing?

Because, like for like, BHP goes up with RPM.

Variable valve timing allows a much better torque curve. And the shape of
that curve is what matters for day to day driving.

Multi valve engines also are better for emissions.

Just what tricks they get up to on an F1 engine when all it has to do is
last once race of little relevance to a road car.

Turbos may be a nice cheap way of making an engine of a given output, but
with petrol engines are never as good as a larger NA unit of the same
output. Despite the marketing hype.


Youre ignoring the weight/volume penalty of a large N/A engine as opposed
to a turbo engine.

He is also ignoring frictional loses - larger in a big engine.


What weight engine would you need to replace a 600 hp 2 litre three
cylinder engine?

https://jalopnik.com/a-detailed-look...ing-1842073757

Tim





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