[Diy_efi] water injection

ian spyro
Thu Sep 6 13:35:10 UTC 2007

On Wed, 2007-09-05 at 15:02 -0700, Klaus Allmendinger wrote:
> Why?
> Water injection on a gasoline engine is mainly there for knock
> supression. A diesel operates on "knock".

Not true. Knock (explosive combustion) will shred a diesel as quickly
(if not quicker, due to the pressure) than a petrol engine.

>  It lives by compression
> ignition, which in a spark ignited engine is the reason for knock.

no. compression ignition doesnt imply knock. in fact, a diesel will have
a nice, constant burn as fuel is injected.

>  The
> only reason I can think of for using port WI on a diesel is for slight
> NOx reduction. In a diesel with port WI this results in an increase in
> CO and HC emissions and a slight increase in fuel consumption from all
> the research papers I read.

My engine is turbo'd. cooling the air will result in a denser air
charge, and thus more power under boost.

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