[Drivingforfun]

I know it's based on lots of things, but is there a rough gauge of what amount (percentage or number) of power & efficiency a typical engine loses over time?

Are the efficiency & power losses correlated? Or are they due to entirely different things?

[Rolebama]

There is no real figure for loss of efficiency. It varies from car to car even the same model. It really depends on how well the engine is maintained.
The bhp and mpg are reliant on how well the engine can convert fuel to energy, so both are reliant on efficiency. Most people don't notice power loss as it is quite gradual, and they won't notice the extra bit of throttle necessary for acceleration or an uphill gradient, but they will notice the more frequent fill-ups as the mpg decreases.

[olduser]

As Rolebama suggests there are many things that together add up to loss of efficiency therefore loss of power and MPG.

Mechanically the engine just wears out, the piston no longer seal in the combustion gases as the piston rings wear or the cylinders wear unevenly (score marks etc.).
Bearings wear, valves and valve seat wear, valve springs (fatigue), and cam wear all reducing engine efficiency.
Engine wear has much improved as we have learned to keep grit and dust out of engines, and improvements in lubrication.
Oddly, keeping dirt out of the crankcase, on some engines created a new problem.
With the crankcase venting into the engine air intake, the inlet valves were getting blocked with carbonised oil, with obvious effects on engine performance.

The ignition system has improved but spark plugs changing gaps are still a weak point, spark plugs have a short life relative to the engine.
Injectors can block but they do wear and no longer produce a spray of fine droplets but rather a jet of solid fuel.

ECU's usually either work or they don't so don't contribute to loss of efficiency.

It used to be said, an engine was at its best around 10,000 miles then it was down hill from there but that dates from when engines had to be run-in, I would guess these days the peek is reached at say a 1,000 miles with a very long band of good efficient running (assuming it gets serviced) until mechanical wear steps in.
The ECU steps in and tries to prevent serious damage by putting the engine into limp mode, and warnings when services are due etc.

[NMNeil]

@olduser
As the bearings bed in they will make it easier to spin the crank possibly making the engine more efficient, not less, same for the valve springs, which if weak will take less power to open the valves.
This leaves, as you say, piston sealing as the cause of power loss, decreased efficiency and increased fuel consumption.

[olduser]

Weak valve springs allow the valve's to bounce rather than closing as required, this reduces efficiency, and quickly wears the valves, and valve seats leading into even greater loss of efficiency.

The point I was trying to make was, these days, the production methods result in engines that don't require to be run in because the parts are made to fit, rather than the old system where where parts were made 'near enough', and then had to wear the tightness off.
This results in engines that are efficient from very early in their life.

As I understand it, these improvements have come about because we understand the machining processes better, and we now understand better the mechanical and thermal stresses on an engine, resulting in better design.

[NMNeil]

Originally Posted by olduser

As I understand it, these improvements have come about because we understand the machining processes better, and we now understand better the mechanical and thermal stresses on an engine, resulting in better design.

But why? As the ICE engine is on it's way out it's a lot like the Rolling Stones 19th nervous breakdown lyrics.
"Owes a millions dollars tax, and your fathers still perfecting ways of making sealing wax."

[olduser]

Originally Posted by NMNeil

But why? As the ICE engine is on it's way out it's a lot like the Rolling Stones 19th nervous breakdown lyrics.
"Owes a millions dollars tax, and your fathers still perfecting ways of making sealing wax."

Why?
Because at the time these developments were made, it was thought by the motor industry (pretty much like the tobacco industry) they could fool or buy off the worlds politicians, and populations.

I think, the strategy at the moment is to load EV's with unnecessary goodies to price them out of the market.
Consumer will get upset, and governments will have to backtrack to ICE.

If they had really thought about what they were doing, a better strategy may well have been to invest in Hydrogen production.
Their ICE technology would still have been valid, until fuel cells caught up, at that point ICE is finished.
But they could shift to EV with fuel cells, and they would own the fuel source but then the oil boys would/are working hard to scupper none ICE vehicles.

But that's only my opinion.

[NMNeil]

@olduser But the one thing that will see the end of the ICE engine is unavoidable.
https://www.worldometers.info/oil/

[olduser]

May be there is quite a lot of stuff going on about synthetic fuel.
Some are claiming to be ready for production.

I like the website it makes it's point clearly!

[NMNeil]

Originally Posted by olduser

May be there is quite a lot of stuff going on about synthetic fuel.
Some are claiming to be ready for production.

I like the website it makes it's point clearly!

I was wondering when efuels would be mentioned.
They have a basic flaw; the numbers don't add up.

[Rolebama]

Interesting. It would seem these are both promoting EVs big time. It would be an idea for them both to be on the same page with regard to energy losses.
I had a diesel 306 for some years, and there was no way the energy efficiency loss was as high as claimed, as heat was somewhat lacking on the creature comfort side. I replaced it with a 406, whose performance was pretty much the same as the 306, but with a definite advantage of heat on the creature comfort side of things. Both were quite capable of 65mpg at motorway speeds.

[olduser]

Hi Rolebama, relative to when we started motoring those are good MPG figures, diesels have the advantage of higher compression ratios so they should always win.
But taking the most up-to-date figures I can turn up, a modern diesel under ideal conditions can manage 40% efficiency with a petrol at 30%, so with the diesel out of 10 litres of fuel only 4 will propel the car along the road or for petrol only 3 out of 10, with other losses ignored. (drive chain, auxiliaries, etc.)

There is little wonder they mention EV's where including loses in batteries, motor, and drive chain the efficiency is 70% and it is still getting better, mostly from improvements in batteries.

If the electricity can come from green sources wind, solar, tidal then it looks like a no brainer.
I left out Nuclear because no one has any firm ideas on what we can do with the waste.

I have not seen any efficiency figures for Hydrogen fuel cell EV's that are from a reliable source.

[NMNeil]

The e-fuel debate goes back to another post regarding capturing carbon from the air, which is still impractical.
One factory that is actually producing e-fuel is in Chile because they can use the wind to generate the clean power needed. They still have to ship in tankers of CO2 though.
It has to be generated from clean energy as it's the only way the EU will allow it to get past the ICE ban in 2035.
Annoying guy, but he's actually been there.