This is a VERY cool and informative video!

https://youtu.be/sTD7DqXfRno

I don't know what these idiots did with Youtube, but I can't paste the link so the video starts at the beginning.

The science behind generating HP out of an ICE is the same no matter if you're on the ground or in the air. An ICE is nothing more than an air pump. So the more air in and out and the denser the charge, the more HP is generated. Plus it helps if you feed it 100/150 grade avgas.

Great video and explanation why the Merlin Engine was a better design using better fuels.

http://www.wwiiaircraftperform.../150-grade-fuel.html

I believe I read once that the P-51's cooling system was designed to provide net positive thrust rather than net drag. Something on order of 50-100 lbs thrust. The Republic Rainbow 4-engine experimental aircraft used a similar system to cool R-4360 Wasp Major radials. A carefully designed nacelle used ducted air from primary cooling, oil, and exhaust ducted out a nozzle at the rear. Reports were up to 250 lbs thrust per engine were gained that way. This was the fastest piston 4 engined aircraft ever built. 475 mph at altitude.

An interesting read on Lee Atwood and the use of the Meredith Effect

http://www.historicracer.com/a...h-effect-lee-atwood/

I would have never thought that better fuel was the primary driver. I mean it makes complete sense, just didn’t know the Germans had such bad fuel.......

quote:

Originally posted by INTJ:
I would have never thought that better fuel was the primary driver. I mean it makes complete sense, just didn’t know the Germans had such bad fuel.......

Yes
and often the 95 was the "good" stuff

Fuel octane and manifold pressure made the difference.

The interesting thing is at 100/150 octane, there was enough lead in the mix to foul spark plugs after 15 hours so they just added more ethylene dibromide to get to 150 octane levels. Which caused lot of problems with valve seat longevity. But when you have a steady supply of parts and mechanics, I suppose that's not much of an issue.

Don't know why the Germans could not make higher octane fuels. Romania supplied most of their petroleum based fuels but they never really produced much of anything over 100 octane. They relied on water/methanol injection (now suddenly popular again with motor heads) to increase the charge density in order to avoid detonation, but would it would seem easier to just bump the octane levels, unless their engine designs couldn't handle the increase cylinder pressures/temps for some reason.

I am sure someone, somewhere knows all these answers...

quote:

Originally posted by Opus1:
Fuel octane and manifold pressure made the difference.

Don't know why the Germans could not make higher octane fuels.

I suspect it may have been related to the volume of fuel available. The Germans were hard pressed for volume to serve consumption. They needed fuel for tanks and aircraft. Higher octane fuels meant lower volumes of distillates and higher volumes of additives. They may have had to accept a lower level to keep fuel going to all.

But the death knell was the massive American supply of fuel in any octane and of vehicles. Impossible to overcome for such a small country.
They were simply overwhelmed by a massive industrial/military complex.

It all becomes a lot easier to understand that the Axis powers were fighting a war to steal resources particularly Petroleum from the rest of the world and at the time the United States possessed 84% of the worlds known Petroleum reserves, AND had pioneered the refining technology to create the high octane aviation fuels (without need of additives) and producing them in VAST quantities.

Gasoline rationing in the US during WW2 had almost nothing to do with a shortage of fuel, it was entirely about a shortage of the Natural rubber needed to manufacture tires, but even that only served to drive research into synthetic rubber.