[Diy_efi] Knock sensing - water injection

[Greg Hermann]

At 10:32 AM 2/25/05, Geoff Harrison wrote:
>Hi all.
>IIRC, knocking = pre-ignition = detonation,

NOPE.

Pre-ignition does NOT equal detonation.

The other things which you are stating as 'sort-of' facts are also pretty
wildly distorted.

If you look through the archives, there is PLENTY of info on what H2O
injection can do, and why it does it. Your so-called 'rate of expansion'
ain't it at all--but water's very high latent heat of vaporization has
quite a lot to do with it--as does its ability to facilitate hydrocarbon
combustion.

"slowing down the burn rate' is about the opposite of what you want to
avoid end gas detonation---

Greg

 which occurs if the c/r is too
>high for the fuel being used. Will also occur if the ign is advanced to far.
>We used to fix the problem with lead. Can't and shouldn't do that. Modern
>practise is to retard ign.
>Why not have an injector which adds a bit of something to the mix. Could be
>anything that will slow the burn rate or reduce internal temp or combination
>of both, like methanol or avgas. Even water.
>
>I used to have an acquaintance that used water injection on a small V8. Once
>on the highway would turn it on. Had to shut it down 5 mins before shutting
>down engine. Apparently water has a greater expansion rate than air for a
>given heat rise, making the engine more fuel efficient. Recent searches on
>water injection only come up with spray units for intercoolers. Any one have
>thoughts or experience along these lines.
>
>Regards,
>Geoff
>
>Geoff Harrison IT Services.
>Port Macquarie  NSW.
>Tel 65827181
>Mob 0401324639
>_______________________________________________
>diy_efi mailing list
>diy_efi at diy-efi.org
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