Adjustable valve timing plays a big part. Every manufacturer has its own version of adjustable valve timing. Computers preform instant adjustments according to RPM and load so the engine runs as efficiently as possible.

The real freak is the Porsche GT3RS engine. All-motor 4 liter Flat six making 500 horses.

I don’t know what service intervals are like but the only things comparable imo are the LT6 and GT350 motor.

Turbos are less impressive imo because even in the 90s there were insane power levels from turbo charged engines, really even the 80s, it’s just that the power delivery got more linear with twin scrolls and sequential turbo systems.

There still is lag though. My M177 even lags sometimes. Rarely but it happens. NA motors don’t have lag but are generally peaky below 8 cylinders.

In generally the biggest advancement on ICE engines on last 20 yrs are materials (lower internal friction), better control of mixture forming and burnign (better control electronics, direct injection, etc)

Not all of these advancement are nessarily for good in terms of durability IMO.

But for you question, take std.M54B30 and slap couple of turbos to it and it gives easy 500hp. Rebuild it to suite and you have more with reliabilty, so you dont need modern engine to make power, those turboes does most of the work.

Direct injection.

The biggest technological change in most industries in the last 20 years has been computer software related. Same with the auto industry. Better computer modeling of the flow of gases in the engine (CFD) allow for better fine tuning of all passage ways and allows higher compression because of a better understanding of when the mixture will combust. Butter ECUs allow for better optimizing of the engine for different conditions (different loads, rpms, fuels mixtures, temporaries, etc). Better automation allows for more rapid iterations in physically testing everything which also resulted in an advance in material science.

Advancements have come from materials, intake and exhaust efficiencies. Motor size doesn’t matter like it used to back in the day of carbs, the old way was crude and so inefficient compared to the modern stuff.

The gains with the modern stuff is so small and minor, a few hp here and there but over the course of decades it became impressive. Turbo’s were never really all that great until recently and they have so much room to go…plus hybrid systems, you’ll be looking at extremely quick cars.

Problem is EVs are taking over, so much faster and r&d into ICE is going to stop.

Look in to the LF4 engine design from GM. Lots of cool tech in that one.

Precision through computer simulations, take 2jz for example, a huge and over-built in every corner of the block, but it’s extremely heavy and inefficient especially being a cast iron block.

Modern engines are smaller, lighter where mass are only necessary added based on the engine’s weak points. Materials selections have also improved for better costs to strength.

The e46 m3 had a v8 or a v10 that made 500 horse or aomeshit lol.

You have already named the big difference, and that is the turbo.

But comparing na VS na comes down to tighter tolerances and better fuel mixing for a more complete combustion.

Imagine modern engine materials and controls with early 2000s emission regulations. Now that would be power

Forced induction with stronger materials or build design. That’s literally it. You might have a few percentages from increasing efficiencies but it really is nothing but shoving more air into the engine and the block being able to handle it.

Direct injection, better materials, turbos, more precision and better tolerances (due to advancement is machinery).

Head design is a big one. Look at a fox body Mustang 5.0 and a current 5.0 ; DOHC, variable cam phasing, and direct injection. Put sophisticated intake manifolds on there (which go back to the 80s as a widely available tech) and you get a lot more power, when you consider things like the higher compression ratios the tech enables.

Well, your example invalidates the “other than turbos” part because the turbo is responsible for probably 80% of that power gain. So then the question is, why is everyone using turbos now and not before? Any competent engine builder could get 500hp out of a 3 liter turbo motor back in the 80’s, so what changed?

The big advancement is reliability and emissions. This is mostly driven by engine computer simulation driving better engine geometry design to help these high power engines burn cleaner, but probably the biggest factor is ECU technology and sensors. If you look at motorsports, drag racing in particular the advances in how much power those cars are making has continued right along with OEM cars getting more powerful. Faster ECUs that have faster sampling rates, along with individual cylinder sensing and individual fuel injection means that each cylinder can be run at its absolute peak performance. In the past you would have over cylinder that’s the hottest one, and that would be the first to detonate. Since engines used to be tuned all at once, all the other cylinders would have to be detuned to the same level, plus other environmental factors could not be controlled so the engineers would leave some margin for adverse conditions. With that latest tech, ECUs can detect each firing event and individually adjust fuel and ignition for peak performance without sacrificing reliability over a wider range of conditions.

The materials science has improved as well, especially for turbos, but the big advancement has been in the ECU and sensing.