water injection question

[Brett Dikeman]

At 3:07 PM -0800 3/17/04, Jim Green wrote:

><Stephane.Livolsi at investorsgroup.com> wrote:
>>  All this talk of water injection has got me thinking
>>  about following
>>  through and finally doing it.

Be prepared to buy a new exhaust with regular frequency; high 
temperature steam is extremely corrosive.  Also, you need to use 
rather pure water or you can expect a lot of mineral buildup in all 
the wrong places, and it's a LOT harder to get off than carbon 
deposits and such.  You will get fantastically clean exhaust valves 
and combustion chambers though!

Also, you need to make absolutely sure you don't have any drips/leaks 
when the engine is shut off, or you will have a very nasty surprise 
next time you go to start it up!  Another problem is condensation; if 
it's not finely sprayed enough, it'll condense on the walls of the 
intake system and pool somewhere.  Freezing is another consideration, 
so now you need to add something to the water to keep it from 
freezing.

>  > 1 question I have is about the engine management.
>> 
>>  water injection helps reduce detonation under high
>>  pressure and let's
>>  you advance the timing. right?

It reduces the intake charge air temperature and can provide some 
in-cylinder cooling, depending upon where you inject and so on.

>  > 
>>  So, if you install water injection, will the ecu
>>  'understand' that it
>  > can advance the timing and do that autonomically

Charge air temp reduction, yes- in cylinder cooling, no.


>With WI, you
>could probably increase the boost without getting into
>knock, then you wouln't be in the dangerouse situation
>of having your knock sensor control your timing for you.

Proper engine management doesn't use knock sensors to "control" 
timing nor boost.  It is only designed to prevent engine damage; a 
very important distinction there.

I believe Corky Bell's book states that "a properly designed 
turbocharger system does not require water injection".  I got the 
distinct impression he considered it a hack.  Could have him confused 
with someone else though.

Brett
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