Defeating 15 % ethanol

[Powerabout]

Bmw had 11.5 cr 30 years ago in their engines its not direct inj that has changed that

[Fastjeff57]

Those BWMs had to use premium, high octane fuel. My lowly Focus is designed to run on 87 octane.

Jeff

[Master Oil Racing Team]

Somebody please explain the octane ratings. I believe there is some misconception between octane ratings, additives and fuel. I don't want to have to research all this, but maybe when I was just learning to drive the fuel had lead in it to increase octane. Ron Hill might want to add his say here because he is from the SoCal Motor Pool. He was there when all the cool car stuff and the surfing was going on.

[Fastjeff57]

Simply put, octane rating is the highest compression ratio (CR) a research engine can tolerate without pre-ignition. Believe it or not, these ingenious engines can change their CR while running! When "pinging" begins, the CR is backed off until it stops, and that's the octane rating number for that particulate fuel.

The problem began when fuels were developed (pre-WW II) that allowed CRs way above what was then possible with 100 octane fuel. The solution, as seen on some gas pumps, was a blending of the lab results (from the research engines) with theoretical octane numbers (pure mathematical calculations); the two were combined and averaged.

Finally, octane rating is improved when gas burns slower, with a greater delay before it "lights off". Faster light off causes detonation, so anti-knock additives (like lead) are there to increase the delay period.


Jeff

PS: Military aircraft in WW II ran 115 octane and higher--up to 145 in some cases. The spark plug life was horrid due to massive lead formation, requiring plug changes after every mission. On a Merlin V-12, the inner plugs were a b*tch to get to, so they were often left in place for a few missions, with the "easy" to get to plugs changed.

[zul8tr]

Simply put, octane rating is the highest compression ratio (CR) a research engine can tolerate without pre-ignition. Believe it or not, these ingenious engines can change their CR while running! When "pinging" begins, the CR is backed off until it stops, and that's the octane rating number for that particulate fuel.

The problem began when fuels were developed (pre-WW II) that allowed CRs way above what was then possible with 100 octane fuel. The solution, as seen on some gas pumps, was a blending of the lab results (from the research engines) with theoretical octane numbers (pure mathematical calculations); the two were combined and averaged.

Finally, octane rating is improved when gas burns slower, with a greater delay before it "lights off". Faster light off causes detonation, so anti-knock additives (like lead) are there to increase the delay period.


Jeff

PS: Military aircraft in WW II ran 115 octane and higher--up to 145 in some cases. The spark plug life was horrid due to massive lead formation, requiring plug changes after every mission. On a Merlin V-12, the inner plugs were a b*tch to get to, so they were often left in place for a few missions, with the "easy" to get to plugs changed.

During WW2 my dad was line foreman for the P47 Thunderbolt fighter plane in Farmingdale NJ. The radial engines in these planes used very high octane fuel and all measures were taken to increase life and reliability. As he explained to me one of the most successful to increase engine and plug life was water injection that also increased power output at all altitudes.

[Powerabout]

My father worked on the mustang line in oz doing the pre flights before delivery
We built 200 mustangs

[Powerabout]

Those BWMs had to use premium, high octane fuel. My lowly Focus is designed to run on 87 octane.

Jeff

Efi and knock sensors you could run anything anywhere in the world, same engine spec globally
Prior to that they did build engines for each market

[Powerabout]

http://en.m.wikipedia.org/wiki/Octan...ngQUOTE=Master Oil Racing Team;139859]Somebody please explain the octane ratings. I believe there is some misconception between octane ratings, additives and fuel. I don't want to have to research all this, but maybe when I was just learning to drive the fuel had lead in it to increase octane. Ron Hill might want to add his say here because he is from the SoCal Motor Pool. He was there when all the cool car stuff and the surfing was going on.[/QUOTE]
http://racefuels.com.au/newsDetail.asp?ID=19
http://en.m.wikipedia.org/wiki/Octane_rating

[Fastjeff57]

Trivia question: Who developed knock sensors, when and why?

Jeff

[7500Blizzard]

Bmw had 11.5 cr 30 years ago in their engines its not direct inj that has changed that

Maybe in Europe but in the 80's Pretty much all BMW's had compression ratios of about 10:1 and lower. (from what I've seen anyways) But even if they were at 11.5:1 back then the premium fuel of the 80's being 94octane would support that without problems. Even on todays fuels the ignition in those cars can manipulate itself enough to run on it.