Got an old book titled Mustang at war. It stated that in spring 44, they mustangs began using 130 octane gas. Germans were using 87 or 92 for the most part. My question is, how much performance difference does this make? for example, if a mustang ran on 87 octane, what would its top speed be? or vice versa, a 109 on 130 octane?
Another interesting quote was by a Mustang piolt who mentioned that he had to set 20 dgrees of flap to stay with the 109 at low altitude in turns.
high octane gas
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Black Baron
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Black B.
Luftwaffe pilot and friend Horst Petzschler told me that the Mustangs used 150 Octane gas and flew higher than his Höhenschütz staffel 2./JG 3 flying the Bf 109G-6/AS. these one o 9's were suppose to be the competiton to the fast P-51's but were always outnumbered and always competing for altitude and that being 30-32,000 feet. this was April through May's end of 1944 before Normandie. Horst was then transferred back to Fw 190 equipped JG 51 on the Ost front.
in reality the only way to really compete with the Mustang was to be in a better altitude position. also several pilots esepcially in night fighter staffeln had the pannel lines filled in and spray on polish was used. and another little secret was refining the engine oil for the alititude extremes. In one case we have confirmation of one nf 109G pilot exceeding 450 mph catching Mossie bombers near Berlin in the fall of 44.
E ~
Luftwaffe pilot and friend Horst Petzschler told me that the Mustangs used 150 Octane gas and flew higher than his Höhenschütz staffel 2./JG 3 flying the Bf 109G-6/AS. these one o 9's were suppose to be the competiton to the fast P-51's but were always outnumbered and always competing for altitude and that being 30-32,000 feet. this was April through May's end of 1944 before Normandie. Horst was then transferred back to Fw 190 equipped JG 51 on the Ost front.
in reality the only way to really compete with the Mustang was to be in a better altitude position. also several pilots esepcially in night fighter staffeln had the pannel lines filled in and spray on polish was used. and another little secret was refining the engine oil for the alititude extremes. In one case we have confirmation of one nf 109G pilot exceeding 450 mph catching Mossie bombers near Berlin in the fall of 44.
E ~
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Black Baron
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High Octane Fuel
RE: Fuel
Spitfires flew with low grade fuel prior to June 16, 1939. On that date the SS Bournemouth docked at South-Hampton with the first load of high octane American Aviation fuel. The fuel went directly to the RAF at Hucknall, where-upon both RAF and Rolls-Royce engineers tested the Spitfire-Merlin engined aircraft with the higher octane. This improved performance considerably, and Rolls-Royce was able to make appropriate adjustments to their engines to take advantage of the fuel, according to Roy Harker who worked for RR Ltd. Throughout the war American Aviatin Fuel had priority, shipment went directly to the RAF bases first before being used elsewhere.
DouglasR
Spitfires flew with low grade fuel prior to June 16, 1939. On that date the SS Bournemouth docked at South-Hampton with the first load of high octane American Aviation fuel. The fuel went directly to the RAF at Hucknall, where-upon both RAF and Rolls-Royce engineers tested the Spitfire-Merlin engined aircraft with the higher octane. This improved performance considerably, and Rolls-Royce was able to make appropriate adjustments to their engines to take advantage of the fuel, according to Roy Harker who worked for RR Ltd. Throughout the war American Aviatin Fuel had priority, shipment went directly to the RAF bases first before being used elsewhere.
DouglasR
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dazedandconfused
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I know this is being REALLY picky, but if it's over 100 octane, it's numbered with the PN (Performance Number) rating system. 100 octane=the performance achievable from pure iso-octane petrol. You can't get better than pure, so some clever bod came up with PN! Sorry for being picky but I must spread knowledge!!!!!!!!!!!! 
I am free of all prejudice. I hate everyone equally.
W. C. Fields (1880 - 1946)
Think of all the beauty still left around you and be happy.
Anne Frank (1929 - 1945)
W. C. Fields (1880 - 1946)
Think of all the beauty still left around you and be happy.
Anne Frank (1929 - 1945)
Hi guys,
actually, octane itself does not increase engine horsepower. If we put it simple, with higher octane fuel, one can put more boost/take more power out of the engine without the risk of detonation. Detonation at the mildest means slight "knocking" sound from the engine, and at the worst case burned pistons and destroyed engine.
Take an engine that makes 1000 hp at 45 psi blower boost with 100 octane gas. Rising the octane up to 130 does not have that much effect, if the fuel does'nt have any other improvements. Lets assume that the basic engine could mechanically hold up to 1300 hp, but if you try to make it the easy way, add more blower/supercharger boost, you have to do something to keep the chamber temperatures cooler, to avoid "glowpoints" in the heads (to avoid diesel-effect) and to make the fuel lite up equally in the chamber.
The engine could be modified to take the extra boost with the same 100 octane fuel, but it would require a whole lot of internal changes. By spraying water or methanol to the intake airflow one could also cool down the burning process inside the engine (and with water to even get some more oxygen delivered) , and even add some hp, but by rising the octane the air/fuel-mixture can take more compression in the heat of the chamber and you might be able to rise the boost up to, say, 60 psi and get for example 1300 hp and yet be on the safe side of engine explosion. More boost is good for power, but the downside is that the more you compress the intake air, the more it develops heat. And to controll the fuel burning process, more octane is most wellcome.
This was an oversimplified (is that a word??) example, and I know that hundreds of engineers will shoot me for this, but I hope someone could get my point and see how the higher octane effects. It doesn't give straight kick to more horsepower, but allows one to use more effective ways to get more power out of the engine. I'm not an expert of any kind, if WW II aircraft engines are the subject, but I think that they had to struggle with the very same problems than people face today when trying to pull out more power out of supercharged internal combustion engine.
About the 100+ octane ratings, at least commercially racing fuels up to 130 octane are available by several manufacturers, VP and others.
Max
actually, octane itself does not increase engine horsepower. If we put it simple, with higher octane fuel, one can put more boost/take more power out of the engine without the risk of detonation. Detonation at the mildest means slight "knocking" sound from the engine, and at the worst case burned pistons and destroyed engine.
Take an engine that makes 1000 hp at 45 psi blower boost with 100 octane gas. Rising the octane up to 130 does not have that much effect, if the fuel does'nt have any other improvements. Lets assume that the basic engine could mechanically hold up to 1300 hp, but if you try to make it the easy way, add more blower/supercharger boost, you have to do something to keep the chamber temperatures cooler, to avoid "glowpoints" in the heads (to avoid diesel-effect) and to make the fuel lite up equally in the chamber.
The engine could be modified to take the extra boost with the same 100 octane fuel, but it would require a whole lot of internal changes. By spraying water or methanol to the intake airflow one could also cool down the burning process inside the engine (and with water to even get some more oxygen delivered) , and even add some hp, but by rising the octane the air/fuel-mixture can take more compression in the heat of the chamber and you might be able to rise the boost up to, say, 60 psi and get for example 1300 hp and yet be on the safe side of engine explosion. More boost is good for power, but the downside is that the more you compress the intake air, the more it develops heat. And to controll the fuel burning process, more octane is most wellcome.
This was an oversimplified (is that a word??) example, and I know that hundreds of engineers will shoot me for this, but I hope someone could get my point and see how the higher octane effects. It doesn't give straight kick to more horsepower, but allows one to use more effective ways to get more power out of the engine. I'm not an expert of any kind, if WW II aircraft engines are the subject, but I think that they had to struggle with the very same problems than people face today when trying to pull out more power out of supercharged internal combustion engine.
About the 100+ octane ratings, at least commercially racing fuels up to 130 octane are available by several manufacturers, VP and others.
Max
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dazedandconfused
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That's not oversimplified at all. I think you got it just right! As for more than 100 octane, many people do make 100+ Octane fuel (I've used it myslf in a racing M/cycle engine on the Isle of Man at the TT), but it shouldn't, strictly, be rated on the octane scale. This has just become a shorthand for the performance rating of fuels.
Last edited by dazedandconfused on Thu Feb 10, 2005 7:06 am, edited 1 time in total.
I am free of all prejudice. I hate everyone equally.
W. C. Fields (1880 - 1946)
Think of all the beauty still left around you and be happy.
Anne Frank (1929 - 1945)
W. C. Fields (1880 - 1946)
Think of all the beauty still left around you and be happy.
Anne Frank (1929 - 1945)
Thanks folks for giving me a chance to lecture on the ignorant masses! First, Dazed is right. All figures above 100 are Performance Numbers where 100 octane equals 100 PN. What is more, PN is a linear figure. In other words, if we compare 100 PN fuel to 130 PN fuel, this means that the 130 fuel gives 30% higher IMEP (Indicated Mean Effective Pressure which is directly proportional to the power developed within cylinders) without knocking than the 100 PN fuel. 150PN fuel gives 50% better IMEP than 100 PN and so on.
Another mousetrap to be avoided is that avgas has two octane/PN ratings, lean and rich. Thus we have 100/130, 100/150. Now, according to the British reports published at http://www.fischer-tropsch.org, German C3 was close to 95/130 by Allied standards. Thus German engine shold have been able to match Allied performance as far as fuel is concerned. These same reports mention that in 1944 a new C3 was introduced with performance almost equal to the British 100/150 fuel. Another nail into the coffin for those whining about German poor fuels.
Max Boost, you boost examples are pretty unrealistic! 45 psi is about +30 lb boost by British standards and as the Merlin´s (it had the highest service boost of all WW two aircraft engines) highest service clearance was for +25 boost with 100/150 fuel...
BTW, what other improvements fuel needs? The power potential of spark ignition engine is directly linked to fuel´s anti-knock characteristics so basically all you need is higher PN (assuming the fuel ignites and distubutes properly). E.g. calorific value has no impact on power as such.
Another mousetrap to be avoided is that avgas has two octane/PN ratings, lean and rich. Thus we have 100/130, 100/150. Now, according to the British reports published at http://www.fischer-tropsch.org, German C3 was close to 95/130 by Allied standards. Thus German engine shold have been able to match Allied performance as far as fuel is concerned. These same reports mention that in 1944 a new C3 was introduced with performance almost equal to the British 100/150 fuel. Another nail into the coffin for those whining about German poor fuels.
Max Boost, you boost examples are pretty unrealistic! 45 psi is about +30 lb boost by British standards and as the Merlin´s (it had the highest service boost of all WW two aircraft engines) highest service clearance was for +25 boost with 100/150 fuel...
BTW, what other improvements fuel needs? The power potential of spark ignition engine is directly linked to fuel´s anti-knock characteristics so basically all you need is higher PN (assuming the fuel ignites and distubutes properly). E.g. calorific value has no impact on power as such.
BTW, the effect water injection has on power is two fold: first, it allows much more boost to be used (or increase CR but no sane person does that) and it also allows leaner mixture to be used. The 4% power increase in the DB 605 (as e.g. claimed by Hannu Valtonen in his catastrophic 109 book. Valtonen is one those authors who believe they are Gods who know everything) is due to leaner mixture, nothing more.
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dazedandconfused
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Doesn't water injection also cool the charge, thereby making the air denser and meaning you get more oxygen into the combustion chamber and a bigger bang?
I am free of all prejudice. I hate everyone equally.
W. C. Fields (1880 - 1946)
Think of all the beauty still left around you and be happy.
Anne Frank (1929 - 1945)
W. C. Fields (1880 - 1946)
Think of all the beauty still left around you and be happy.
Anne Frank (1929 - 1945)
That is untrue as such. Water injection lowers combustion temperature considerably and has no negative effects otherwise. In addition, water injection usually helps to clean unburnt deposits from the combustion chamber.Paul_9686 wrote:And doesn't water-injection also cause an aero-engine to wear out faster? Wouldn't it be necessary to change the engine ASAP after utilizing water-injection?
Yours,
Paul
However, if water injection is used to increase boost, the mechanical stresses will be greater due to greater pressures involved. But, if have two possibilities, getting the same power by going to 100/150 fuel from 100/130, or to have water injection with 100/130, the latter is likely to have less negative effects on engine life.