Peter Gunn
Master Sergeant
Eh, I've heard of 'em, doubtful they were an integral part of the equation though...
Japanese engines with water-alcohol injection
- Thread starter tomo pauk
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Eh, I've heard of 'em, doubtful they were an integral part of the equation though...
Hello Koopernic,
My understanding was that Aviation Gasoline is very close to 6 pounds per US Gallon and Water is 8 pounds per US Gallon.
Water-Methanol is a bit less dense than pure water but not as different as one might expect because a volume of water and equal volume of Methanol does not result in 2X volume when combined.
Is this really a problem considering that the temperature of the intake is quite high?
I know that in the automobiles I have played with that have had port fuel injection have typically had their injectors aimed at the intake valve (but those were single intake valve systems) and the intake valve typically runs pretty hot.
With the old carburetor cars, it was hot enough to form a very large lump of carbon on the back side of the valve.
Hello DarrenW et al.,
The full text of the report you quoted from and another rather interesting one can be found here:
Japanese Aircraft Performance
HoHun and I had a rather long discussion about the validity of the results quoted in your excerpt from the report.
I believe the data is probably good though it is not necessarily indicative of how the Japanese would have used the engine.
In other words:
The Take-Off Rating was intended for just that purpose and not as a War Emergency rating at altitude.
It MAY have been used that way but was not listed that way in the manual. (The notes in the TAIC Japanese Engine Tables suggest this.)
Some pilots on SOME aircraft (notably the Ki 43) DID actually use it this way as was noted in another report about "Flash Performance".
Japanese Aviation Fuel at its best was 91 octane for the Army and 92 octane for the Navy.
This is not to say that some lots might have been better. I have seen a report of testing captured fuel that stated it was a few points higher.
Obviously there was lower grade stuff for engines that did not need better.
There also was "100 octane" but it was generally for test aircraft and was imported from the USA before the war.
Not sure about the source during the war.
I believe Shinpachi (pardon me if it was really someone else) gave a listing of the fuel inventories of a few air bases on the home islands near the end of the war which gives a pretty good idea of the usage patterns.
From my own notes on the Nakajima Ha-45 / Homare:
+500 mm..........3000 RPM...........Take Off Power
+350 mm..........3000 RPM...........Rated Power (Model 21)
+200 mm..........2780 RPM...........Combat Cruise
+100 mm......... 2600 RPM...........Economy Cruise
Note that ADI starts at +180 mm which means that at anything at or above a "Combat Cruise setting, the engine is using Water Methanol injection.
- Ivan.
My understanding was that Aviation Gasoline is very close to 6 pounds per US Gallon and Water is 8 pounds per US Gallon.
Water-Methanol is a bit less dense than pure water but not as different as one might expect because a volume of water and equal volume of Methanol does not result in 2X volume when combined.
Is this really a problem considering that the temperature of the intake is quite high?
I know that in the automobiles I have played with that have had port fuel injection have typically had their injectors aimed at the intake valve (but those were single intake valve systems) and the intake valve typically runs pretty hot.
With the old carburetor cars, it was hot enough to form a very large lump of carbon on the back side of the valve.
Hello DarrenW et al.,
The full text of the report you quoted from and another rather interesting one can be found here:
Japanese Aircraft Performance
HoHun and I had a rather long discussion about the validity of the results quoted in your excerpt from the report.
I believe the data is probably good though it is not necessarily indicative of how the Japanese would have used the engine.
In other words:
The Take-Off Rating was intended for just that purpose and not as a War Emergency rating at altitude.
It MAY have been used that way but was not listed that way in the manual. (The notes in the TAIC Japanese Engine Tables suggest this.)
Some pilots on SOME aircraft (notably the Ki 43) DID actually use it this way as was noted in another report about "Flash Performance".
Japanese Aviation Fuel at its best was 91 octane for the Army and 92 octane for the Navy.
This is not to say that some lots might have been better. I have seen a report of testing captured fuel that stated it was a few points higher.
Obviously there was lower grade stuff for engines that did not need better.
There also was "100 octane" but it was generally for test aircraft and was imported from the USA before the war.
Not sure about the source during the war.
I believe Shinpachi (pardon me if it was really someone else) gave a listing of the fuel inventories of a few air bases on the home islands near the end of the war which gives a pretty good idea of the usage patterns.
From my own notes on the Nakajima Ha-45 / Homare:
+500 mm..........3000 RPM...........Take Off Power
+350 mm..........3000 RPM...........Rated Power (Model 21)
+200 mm..........2780 RPM...........Combat Cruise
+100 mm......... 2600 RPM...........Economy Cruise
Note that ADI starts at +180 mm which means that at anything at or above a "Combat Cruise setting, the engine is using Water Methanol injection.
- Ivan.
DarrenW
Staff Sergeant
Thanks for the link Ivan, I'll have to take a closer look at it....
DarrenW
Staff Sergeant
Oh by the way besides what you've mentioned so far, any idea why there's often such a wide disparity between performance figures given by the Japanese and what these tests of captured aircraft tell us? I have always wondered this and apart from some of these results being "calculated", one has to believe that the Japanese were very critical when it came to testing, while the TAIC tended to be overly optimistic. Any thoughts on this?
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Hello DarrenW,
You need to be a bit more specific as to which test results you are disputing
Some Allied tests seem higher than typical numbers published in books, some are much lower.
Sometimes the same basic aeroplane has both high and low test results from different captured examples.
Just remember though that condition, maintenance and spares are always a problem with captured equipment.
- Ivan.
DarrenW
Staff Sergeant
Yes, I was just talking in general, but to be more specific the TAIC reports regarding the Frank, Jack, and George. The speeds attained seem to be about 10-15% faster than sources that use Japanese test data alone.
And I realize that I'm sort of over my head concerning this discussion because a lot of what I'm regurgitating is from memory only. I was hoping that I can get a better picture of Japanese aero engines and aircraft as I read posts from people such as yourself.
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Shortround6
Major General
I have two observations on Japanese fuel and water injection and these observations could be 100% wrong.
1. I believe, but could very well be wrong, that the oil fields in the Dutch territories had a large amount of aromatics , which might result in better rich mixture response. However the Japanese may have had no way to test specific batches or specify a rich mixture response. Please note I am not claiming this brings Japanese fuel anywhere near 100/130 fuel. Also fuel from other oil fields might very well be quite different.
2. Unless there is a mistake in the Translation the chart for the Ki-84 given in Post #18 By DarrenW the Ki-84 carried around 4 times the water/alcohol of the F6F or F4U and about 40% more than carried by a P-47 Thunderbolt. Which would mean that it could use it for a much longer period of time than the 3 American planes. Or it was used under conditions where the American planes were still running without it.
1. I believe, but could very well be wrong, that the oil fields in the Dutch territories had a large amount of aromatics , which might result in better rich mixture response. However the Japanese may have had no way to test specific batches or specify a rich mixture response. Please note I am not claiming this brings Japanese fuel anywhere near 100/130 fuel. Also fuel from other oil fields might very well be quite different.
2. Unless there is a mistake in the Translation the chart for the Ki-84 given in Post #18 By DarrenW the Ki-84 carried around 4 times the water/alcohol of the F6F or F4U and about 40% more than carried by a P-47 Thunderbolt. Which would mean that it could use it for a much longer period of time than the 3 American planes. Or it was used under conditions where the American planes were still running without it.
Oh, but they were. That's why water injection never really worked in cars. Cars have drivers, not pilots...
Hello Vincenzo,
If anyone had told me the same thing a decade ago, I also would have been skeptical.
Consider though that the Japanese are running fairly high compression engines with a pretty good amount of boost and that their fuel was only 91 or 92 octane. This is supported by the fact that for an aeroplane such as the Ki 84 Hayate, it carries 700 liters of fuel but also carries 140 liters of Anti Detonant mixture. That is a lot of Water-Methanol for the amount of fuel carried.
As for a convenient reference, please check at the link I provided earlier which is listed again here:
Japanese Aircraft Performance
You will find a fairly detailed report on the rebuild and test of the Ki 84 at Middletown Air Depot.
On page 44 it states that the engine starts ADI at 37 inches Hg of Manifold Pressure.
This translates to +190 mm on the Japanese scale, so it is close enough to confirm especially considering that there may be a difference of how equipment actually behaves as opposed to a specification in a manual.
Also keep in mind that 91 or 92 octane was a best case. From the book "Genda's Blade" which gives accounts of the 343 Kokutai (Navy)operating from the home islands until the end of the war: Fuel shortages even forced combining pine root oil with aviation fuel which resulted in a mixture that was estimated to have an octane number in the mid 80's.
Hello DarrenW,
By my understanding, the Japanese did not use Emergency Power in their tests for maximum speed.
As I mentioned earlier, in reading through the TAIC engine data tables, they state that the throttle settings and power outputs were taken from operating manuals unless otherwise noted. In the case of all the engines I looked for, the WEP rating at altitude were "otherwise noted" as being estimated or calculated performance.
Another factor is that the Japanese often did not update the data on maximum speed as aircraft were improved.
Thus a maximum speed might be that listed for the prototype or an earlier version with an inferior engine which did not reflect what was in service. This is working on the assumption that you are actually seeing the numbers from Japanese specifications.
Often the numbers that are shown in commonly available books may be taken out of a context that would make them not representative of the type. I can think of a case of maximum speed carrying drop tanks and another while carrying cannon pods.
- Ivan.
DarrenW
Staff Sergeant
I've heard this before and it's definitely plausible. The only problem is that I can't remember for the life of me seeing any allied combat reports concerning these late war Japanese fighters where they "out-ran" their American or allied counterpart, although I haven't seen them all of course. Do you happen to have any examples, as I'd find them very interesting to say the least.
I'm also quite aware that reduced performance could very well be due to the use of inferior fuels, poor maintenance, or substandard workmanship, but one would think that a Ki-84 of even modest condition would still far out-strip the performance found with obsolete types such as the Zeke or Oscar.
I guess what I'm getting at here is what really is the best source today for Japanese aircraft performance data? I have collected countless references over the years that give figures no where near the TAIC findings, which is very confusing to say the least. Now I'm sure that there is published data that's been out there for half a century or more which is dubious in nature but was never really challenged until only recently. Where did Green, Taylor, Swanborough, Munson, Angelucci, Francillon and others get the Japanese aircraft statistics for their books ?
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DarrenW
Staff Sergeant
Sorry, double post....
Deleted member 68059
Staff Sergeant
- 1,058
- Dec 28, 2015
may have appeared like advanced; actually, I think it was dictated mainly by desperation. Indeed, nowadays we've many supercharged cars: how many have a methanol-water injection?
Water injection is in extremely extensive use in nearly all forms of automotive racing; and its popularity is only rising. It is not popular to use in "passenger" cars, because its seen as very bad for sales to the public to have a car that needs a bottle topped up with distilled water once a week, and even LESS popular to use Methanol because it is extremely toxic and more importantly burns with NO visible flame what so ever. So your whole engine bay can be on fire and you will only notice when you feel the heat - nobody else will know you are on fire either - except that you appear to be running around yelling alot !!! So no, it is not a popular fluid for sales in vehicles to people who take McDonalds to court because their coffee burned them....this does not apply to racing engines, which are meticlously maintained after ever few hours running by expert mechanics.
Higher fuel octane will only prevent detonation at higher temperatures, it will not lower the thermal load on the engine. If you are at that limit anyway you are out of options unless you cool the intake charge - and you will have noticed a lack of 130 /150 grade on sale your local garage. You certainly CAN fit an intercooler, which then needs a pump, and pipes and ANOTHER radiator somewhere, which will cause you a lot of aerodynamic drag. If you are in a situation where weight is preferable to drag, MW injection is an excellent choice, if your airframe is already designed, it is very difficult indeed to retro fit a new external radiator - but possibly far less so to retrofit a tank and some pipes. Hence why it even fitted in a 109.
Not to mention that you can spray water into your compressor eye, and get a large power boost by reducing the work needed to achieve a certain level of compression OR choose to get more boost for the same work input.
The control systems in place by the end of the war for MW injection - especially by Jumo were very complicated and were a lot more than a water bottle with a pipe and a valve.
Naturally the Luftwaffe & Japanese Imperial Air Force`s were desperate for anything to augment the power in the war, but it would be a significant mistake to assume that means MW injection is not a very useful and interesting engine boosting idea - which as I have said is being used more and more. You will certainly see it soon on even some road cars at the very high end of the cost scale (but still without the methanol !)
Ooops no I`m wrong - BMW are already selling it since 2016...in the M4-GTS
"Bosch says water injection helps cool the engine internally, leading to more power and higher fuel economy"
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soulezoo
Senior Airman
I've been running WM injection in my diesel for 10 years now. Not a new concept although to be fair, mine has nothing to do with emissions and everything to do with reducing EGT.
Spark plugs are a good issue most neglect, Guessing for say a Me109 going from 800hp cruise @1.05ata? to 1800hp boosted @1.8ata? would not ideally be using the same heat range plugs, if you want to avoid fouling from too cold or pre-ignition from too hot.
I suspect water injection was kinder to plugs under high boost than neat 150 octane would have been? Apparently the Allies 150 octane had so much "lead" it fouled plugs in 20-30 hours so there were no clear technical winner. And as that US test on the Frank admits water injection was a very economical solution.
Hello Taly01,
Actually the opposite was true. Spark plugs tended to wear out faster with MW50 (at least with the FW 190A) which is one of the reasons they stopped using it for a while and went to C3 Einspritzung. The problem with that idea was that it used too much fuel which also happened to be scarce.
The following is a bit of speculation regarding water injection in automobiles:
The usage pattern of an automobile engine and an aero engine are quite different.
With a car, unless you are racing on an oval track, the chances are that you won't be running full throttle for many minutes at a time.
A blast off from a stop light should not take more than 6-7 seconds.
A quarter mile drag race should finish in about 15 seconds.
Even in Formula 1 racing, full throttle power is not necessarily the most important part of the power curve as Honda proved with their revisions for more optimal part throttle performance a few years back.
From normal operation, it takes a while for an engine to "heat soak" to get past its optimum operating temperatures and get into the detonation range. Some drag racers in the old days used to even put bags of ice on their intakes to cool them before a speed run....
On the other hand, vehicles such as mobile homes tend to have the biggest commonly available automotive V-8 engines to haul a rather heavy carcass around. Those engines may be big (think 7.5 liter) but the vehicle is bigger and the engines tend to run at near full throttle for long periods such as when going up a mountain road. Those engines also tend to be equipped with water injection.
The same probably applies to trucks as well, but I haven't spoken to enough truck drivers about the subject.
Regarding Exhaust gas temperatures:
A lot of folks probably already know this, but the idea of keeping exhaust temperatures lower is to prevent the formation of nitrogen oxides which cause "acid rain". The typical solution in passenger cars is Exhaust Gas Recirculation (EGR) which takes the exhaust gas and plumbs it into the intake system as an inert and un burnable gas to lower combustion temperatures. At wide open throttle, the EGR valve which has a vacuum sensor detects the change in manifold pressure and closes the EGR system.
- Ivan.
DarrenW
Staff Sergeant
Hi Tomo,
What details do you know of regarding the Mitsubishi Kasei and it's use of water-methanol injection?
- Thread starter
- #40
For the Kasei I don't have that much of data (table about Kinsei) is posted at post #1 here.
The TAIC institution states that late versions of the Kasei use water-alcohol injection (ADI), along with 92 oct fuel, to make 47.7 in Hg boost for war emergency power at 2600 rpm. Military power for those was attained with 41 in Hg boost and 2500 rpm. The gain due to ADI and extra 100 rpm was asumed at around 200 HP (asterisk = asumed).
(Kasei looks every bit as good, if not better than the BMW 801D here)
One of the TAIC tables (rest are available on this forum, Techincal section):
The TAIC institution states that late versions of the Kasei use water-alcohol injection (ADI), along with 92 oct fuel, to make 47.7 in Hg boost for war emergency power at 2600 rpm. Military power for those was attained with 41 in Hg boost and 2500 rpm. The gain due to ADI and extra 100 rpm was asumed at around 200 HP (asterisk = asumed).
(Kasei looks every bit as good, if not better than the BMW 801D here)
One of the TAIC tables (rest are available on this forum, Techincal section):
