[Diy_efi] Water metanol turbo assist

[Patrick Cahill]

WEP (War Emergency Power) was used on many high performance military piston
engines. In the case of the Merlin XX engines they would overboost them with
water injection to give a useful boost of 300-400HP. They had to keep an eye
on how much they used it because they only carried so much water. So when
the water runs out the engine goes bang!

Bearing in mind that the first of the XX series had to run on 87 octane and
it wasn't until 1940 when they got the first lot of 100 octane. They would
run 8-9lb of boost and the second "stage" would pump it up to 15lb.


At 12:31 AM 1/10/03, Mike wrote:
>yes I remember a british pilot saying they used water injection
>(at quite a high rate) on the spitfires (1942), but they said it was
>only reserved for emergencies and a log needed to be kept of
>how often it was used on a particular engine, anyway the pilot
>said the effect was dramatc - made a big improvement to engine
>output power ! I guess thats not normal WI then,
>
>rgds
>
>mike

Water is heavier than petrol, and I would all but BET that they preferred
to put the extra weight in ordnance rather than better engine performance
--EXCEPT-- in emergencies !!

Greg
>
>
>
>At 11:13 AM 1/9/03 -0500, you wrote:
>>The SAE published a book by Graham White on WW2 Allied Aircraft piston
>>engines.  In it he talks a bit about oil filtration,  they sure were not
>>using spin on cartridge filters.
>>Some applications used engine driven centrifugal filter.  Their filtering
>>requirements included dealing with Aviation gas injected into the oil
>>(lowers viscosity) before engine down so it would be easier to start up in
>>the cold.  ADI (water/methonol injection) was only for perfomance
>>enhanement, to lift an over loaded bomber or help you out run someone who
>>was shooting at you.




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