Improve engine efficiency ?
 

So any suggestions to improve engine efficiency in a combustion engine dont tell me the classic ones with compress ratio any diy ideas to achive higher efficiency maybe it will be volumetric efficiency mod or a thermal efficiency any mod that can improve an engine efficiency

"So any suggestions to improve engine efficiency in a combustion engine dont tell me the classic ones"

That's what is called a big ask.

Define 'combustion engine'. Internal/external/both?

The 'classic one' would be to replace your cast iron flathead with an aluminum one.

Sorry for not justify but internal combustion engine we dont really use steam engines so often

The classic low hanging fruit mod is a warm air intake. It allows larger throttle openings for the same power output. Not something I'm personally interested in.

There's a hundred ways to make an engine more efficient; most of them are not easy.

In theory my car should get slightly better MPG running 91 octane since the timing will run more advanced compared to regular 89. Of course, the miniscule fuel savings doesn't make up for the extra expense.

External combustion is more than just steam

Whatever.

Scuderi Cycle engine is internal combustion/compressed air.

https://upload.wikimedia.org/wikiped...ne_-_Cycle.gif

Scuderi's heirs squandered his patent with a proprietary inline four engine, it 'wants' to be a dual port boxer four. The magic angle is 15 degrees.

If that's still too 'classical', then maybe plasmoid implosion?

Thunderstorm Generator | COMPLETE DIY BUILD GUIDE | Malcolm Bendall's Plasmoid Tech

A warm engine is an efficient engine. Anything to reduce warmup time will get the engine into its optimal thermal efficiency sooner. On my previous car I had installed a block heater and an oil-to-coolant heat exchanger, in addition to a partial grille block.

Warmer air going into the engine has more energy to extract - though this isn't clearcut in all cases. Past a certain point, the computer will start pulling ignition timing to protect against knock. Also, this will not help nearly as much with CVTs as with manuals or conventional automatics, as a CVT can often just spin the engine more slowly, and might actually be more efficient with a cooler, denser charge.

Any accessories that run on the engine are parasitic losses. Some are unavailable, such as the oil and water pump - although I have installed pulleys that slightly under-drive water pumps before. Toyota has gone beltless on their latest engines. Removing items such as an alternator, A/C, hydraulic power steering, or underdriving the water pump (be careful with this) will increase the percent of energy in the fuel that makes it to the wheels.

Running a thinner oil will reduce parasitic losses.

Increasing EGR can, in some cases, improve efficiency, for similar reasons a warm air intake works.

Using a higher octane fuel, along with extensive tuning, has the possibility to improve efficiency in certain areas of the map - particularly at very low RPM and very high load.

Similarly, a lean burn tune, with ignition timing adjusted to match, can also improve thermal efficiency - for similar reasons that Atkinson cycle or a warm air intake work.

Increasing compression ratio, along with running Atkinson cycle (or similar cycles e.g. Miller) can greatly improve thermal efficiency.

An offset crankshaft can improve thermal efficiency, by improving the portion of combustion pressure pushing down on a piston at an optimal crank angle.

Knife-edging a crankshaft so it cuts through the oil bath more easily can reduce parasitic losses. Similarly, a dry sump also helps (more).

Reducing friction in the engine (e.g.) through thinner or fewer piston rings improves thermal efficiency.

Roller rockers are an improvement over conventional, because they reduce friction.

Fewer cylinders at the same displacement generally improves thermal efficiency, because they have a greater volume to surface area ratio.

Anything to keep heat in the cylinder helps improve efficiency. A ceramic coated piston might help, or shaping the combustion chamber to increase combustion speed.

The holy grail of efficiency is compression ignition on gasoline engines. I'm only aware of Mazda having done this, with their Skyactiv-X engines. Thermal efficiency improvements can be as much as 20-25% (multiplicative, not additive).

"dont[sic] tell me the classic ones with compress ratio any diy ideas to achive[sic] higher efficiency maybe..."

Classic: Perfect Circle piston rings

Not classic: drill holes in the tops of the pistons to pressurize the top ring land.

Not knowing if the engine is spark-ignited or Diesel, and if it's spark-ignited there might be other factors influencing the suitability of efficiency-oriented mods. A port-injection engine might not react the same way to some mods compared to a direct-injection one.

As Cripple Rooster said - need to know whether it is a petrol or diesel.

In Petrol engines a Warm Air Intake will improve fuel consumption, but lower power.
In a Diesel a Cold Air Intake improves both.

Add a turbo to increase compression?

In general, do you need the efficiency while running, or to generally lower fuel consumption? Electric engine preheating will help the latter, so will regenerative braking and other hypermiling tips. But those won't do much for the thermal efficiency of a running engine that is already up to temperature.

Another thing research your engine's BSFC and try to drive as close to the "sweet spot" as possible. Instrumentation, like a ScanGauge, can help you with keeping an eye on Load and RPMs vs momentary fuel consumption.