Octane ratings

[Roscobbc]

I've been watching on-line the series of WW2 videos by James Holland and Al Murray on WW2 Headquarters (WW2 Headquarters) relating to the conflict and how the Allies triumphed against the Nazis.
Initially it seemed to be a re-hash of everything we already know about the war. But as I got more into the episodes some of the perhaps lesser known operational details became far more interesting and how well organised (compared with the Nazi's) the Allies really were. One thing I didn't relalise was how significant the quality of petrol became to aircraft performance operating ar higher altitudes.
130 octane fuel became the norm for fighter aircraft, and later, amazingly 150 octane. Sub-stories recalling how these and other changes were discovered and introduced were equally as interesting.

 

[Chevrolet]

Interesting above. The father of my elderly neighbor was a Spitfire Squadron Leader throughout WW2. He was telling me he has all his logbooks from that time and is gonna let me have a look.

 

[teamzr1]

Also FYI

Water methanol injection was used in World War II aircraft by America and Germany to enhance engine performance by cooling the intake air and preventing detonation, allowing for increased boost pressure.
This system significantly boosted horsepower, with some engines gaining up to 500 hp when using a mixture like WM 50, which was a 50-50 blend of methanol and water.

 

[Roscobbc]

Also FYI

Water methanol injection was used in World War II aircraft by America and Germany to enhance engine performance by cooling the intake air and preventing detonation, allowing for increased boost pressure.
This system significantly boosted horsepower, with some engines gaining up to 500 hp when using a mixture like WM 50, which was a 50-50 blend of methanol and water.

I just shows that nothing is really that new in the aeronautical and automotive world.........its just that 'today' we have the hindsight of 80 years or more of use of this technology.

 

[teamzr1]

Some may recall in mid 1970s with the oil, gas and SMOG crap going on
GM sold some models that came with Water/Meth installed and tuned for it

Problem was people were too lazy to fill the w/meth tanks and the engine had been tuned for it

I have used water/meth in all my Corvettes since the 1970s

 

[CaptainK]

Yeah it's interesting that changes in petrol can have a big effect. I was aware of it before your post, my Grandad worked on Mosquitos during the war, and thus I developed a bit of a fondness for some of the planes of that time.

 

[Roscobbc]

When 5 Star leaded fuel was discontinued in the 90's, 4 star unleaded fuel really didn't suit the rather high 11.3 comp ratio of the '71 429 SCJ Mustang I had at the time. The stock 550/600 rpm idle would only 'hold' for about 10 seconds when putting in to drive (even after 'tweaking; carb and timing settings). Raising the idle to 700/750 rpm could help but the 'chirp' from the tyres (and significant jerk in the cabin), with the need to hold the brake pedal down hard to stop the car moving was a problem. Before transporting cans of Tetra Ethyl Lead additive from the 'States was banned you could start the car-up, add the lead additive to the 4 star already in the fuel tank, (wait a few minutes whilst it drew through to the engine)......and be amazed how the irregular idle speed smoothed-out and would seeming hold indefinately when selecting drive and just drive like a different car.

Reading in more depth about the use of 130 octane in aircraft and it subsequently being raised to 150 octane significantly improved high altitude capabilities of allied fighters and bomber allowing much higher boost pressures to compensate for the much 'thinner' air........but the downside was greatly accelerated engine wear, spark plug burning/fouling and lead build-up in engine intake tracts significantly reducing service intervals......a relatively cheap price to ultimately secure victory over the Nazi's.

 

[Nassau65]

1969 L88 Octane warning decal

 

[Roscobbc]

1969 L88 Octane warning decal
View attachment 31922

And to think that even today the very best pump gas here in UK is 99 unleaded!

 

[Nassau65]

Can’t remember what I used to put in my GT500 (428ci) back in 1977. Most probably 4 star or maybe 5 star if the garage had it. Seems like a lifetime ago now.

 

[Roscobbc]

I do recall that TEL additive is extrememely toxic and you have to avoid breathing the fumes. Spill any on your skin and it is immediately absorbed into the bloodstream and you instantly have lead poisoning!