My credentials are became the youngest ASE Master Tech when I was 20 years old. I was a mechanic as a sergeant in the US Army, I'm a VW and Audi Master Tech and I modify the spark, fuel, and boost maps in factory ECMs. So I'm really familiar with all the numbers and stuff like that.
Firstly a modern automotive engine is FAR more reliable and efficient than than these aircraft motors I think that because the EPA isn't all over these guys they haven't had to increase their efficiencies.
I googled the specs on the Lycoming IO 540, and I found it to be kind of pathetic. An 8.7 liter motor, running on 100 octane gas, making 300 hp!?! Compression ratios in the 8s, KILLING fuel too just due to displacement size.
The engine is a mix of old, inefficient, mechanically unreliable parts, that are high maintenance, and then new high performance tech.
For example, it has a direct gear driven overhead camshaft, which robs hp. The valvetrain is ANCIENT and sloppy.
It also runs a fuel injection system that seems to be like the Bosch L and K Jetronic, and CIS Motronic. So, instead of electrical injectors you have braided steel hoses with an orifice in the intake, those go to a fuel distributor, which varies the fuel pressure by modulating a plunger.
VW, Audi, BMW, Porsche, Volvo, ETC ran this system in the 80s and early 90s. When it runs, it runs well, but the fuel pattern isn't very good, and in my experience the nozzles clog and are unable to be cleaned, and the fuel distributor can cost a couple grand with the differential pressure regulator. I'd be VERY interested in seeing the spray patterns of one of them. They generally don't seal well when closed, and they will leak fuel out of the tips, spiddle out rather than a good solid cone shape.
Then, the cylinder heads have only 2 valves per cylinder, so they definitely flow like crap, and depending on their size if they're close to the cylinder bore it can block air flow. The solid tappet camshafts which will flatten if you aren't running high zinc oil. I figured it caused issues, googled Lycoming tappet failure, and what do you know, stories about it along with a roller upgrade.
Running the cam off the crank via a gear causes backlash forces on the bearings and friction parasitic draw of hp, so do flat tappet lifters, the roller lifters are a must imo. The lifters are hydraulic, so they don't need adjustment. One thing scared me, they have you push the lifter down to compress the hydraulic portion and then check the clearance between the lifter tappet and cam. The spec is .028 to .08...You'd think that maybe because they're hydraulic it doesn't matter. Then they state, if you're out of spec you install a longer or shorter pushrod, and to beware because the decreases valve to piston clearances. AKA, if you have a .028 and a .08 gap. Then one of your valves is opening .052 of an inch more than the other. That makes cylinders run unevenly.
HOWEVER one thing good, the engine has molybdenum nickel coating on the cylinder, which reduces piston and ring friction losses, modern cars just started using this. It's been used in racing a long time. Molybdenum is used in those friction reducing oils you see advertised, and they mix it with steel to increase machinability.
Otherwise it's a lot like a Beetle in ALL the bad ways. A split engine case that can leak, removeable pushrod tubes you have to install and seal between the block and head, that leak, uneven cylinder temps.
There's a lot of unknowns too, like how close do they match the factory pistons and rods for weight difference to balance best as possible?
There's NO WAY that engine is more reliable than a modern car that adjusts nearly everything. Soon cars will have electric solenoids to operate the valves, they're already doing it in test cars. This will allow infinitely variable lift and overlap. Once that happens, camshafts are obsolete, along with the timing belt or chain draws.
This motor has way too many metal on metal, non adjustible, wearable parts. You CANNOT make the cylinders make roughly the same hp due to the variations in the pushrods and the heat differences. Anybody who ever was into Beetles knows of the infamous 3rd cylinder meltdown issue. The heat differences between the cylinders cause massively different power output and cylinder balance.
I had many BMW Volkswagen customers with over 300,000 miles on their original engines with no issues and I had decent guys with close to half a million period in eight years of owning a shop I don't think I can say that I ever seen one engine fail that wasn't due to neglect like leaking coolant or not changing the timing belt. Crappy oil.
As far as the torque part numbers people are listening at 60 miles an hour on the freeway the torque load sense by the ECM is usually more like 20 to 25%if you could remap an engine computer like I can it's turbocharged you could call for Boost and stuff down lower then what it's from the factory.
I would find a way to run it off the cams that are the timing belt. But your engines are a joke my sisters 03 Jetta 1.8 Turbo puts out 300 horsepower to the wheels with the stock Turbo. There's no reason to have that big ass V8 that weighs a ton and makes no power. My sister's car gets 20 miles to the gallon when driven nicely.
Your engines have missed out on all the updates that that the car makers are had to do to keep up with the fuel mileage for example running a distributor takes horsepower semi hemispherical combustion Chambers adds horsepower, variable valve timing adds horsepower turbochargers with individual pipes that are separated all the way to the turbo to keep the exhaust pulses group add horsepower.
I don't have my license yet but I've flown a couple times and I was honestly a little scared before I went and took my first lesson but I was astonished at how shitty the technology was on the Cessna 172 and how it basically looks like 1940's automotive technology.
I would run a VW diesel engine or the 2.0 Turbo found in the 05 and up chat is golf's and A3.
The 2.0 T is direct gasoline injection like a diesel because of that and the fuel being injected right at top dead center it allows you to run extreme amounts of boost and ignition timing. There's literally not enough time before the spark event for the gasoline to detonate. Those engines run 16 to 1 air fuel ratio on the highway. They also make them up 210 horsepower stock and with just the tune they make 300 or more.
Quality Automotive electrical systems or absolutely nothing to fear they're redundant about the only thing that will keep one sideline from running would be a bad crankshaft sensor or bad fuel pump comma if you ran joule crankshaft sensors and dual fuel pumps there would be absolutely nothing to worry about.
So, take a look at this here. This is a 1.8t dyno, and a mild one. If you take a 2:1 reduction drive you end up with 200 hp at like 3000 rpm.
I don't get it, maybe it's like the reason truck engines need to be 6, 8 cylinder or more, because they need the increase in bearing size and rod size and strength for load?
But I ran a ton of computation, it doesn't seem to be under a VERY heavy load.
Anyway, Cessna was doing diesel car size motors that seemed fine.
I think it's the old guard not feeling comfortable with computers....I'm supposed to get a settlement soon. Maybe I'll build myself a Cessna with one:)