[Diy_efi] Water metanol turbo assist - was Argon turbo

[Axel Rietschin]

----- Original Message -----
From: "Ohio Benz" <ohiobenz at yahoo.com>

> I would suppose that the ideal condition has the H2o
> vaporizing as it enters the turbine so that the full
> velocity of the vaporization increases the turbine
> speed - which is what the goal is.

Probably, but it will be very hard to reach, let alone maintain, your ideal
condition given the very rapidly changing conditions in the manifold
(pressure and temp). Also the water is very likely to boil in the nozzle or
even before reaching it, vapor-locking the injection system.

As far as reducing spool-up and increasing throttle response another
approach would be to use a deliberately small sized turbine housing, and
then aggressively open an oversized waste gate to reduce back pressure as
soon as the turbo is up to speed. For this to work optimally you'll need to
use a turbo speed sensor and target a certain turbine speed instead of the
usual MAP or MAF. If you use a desmodromic wastegate actuator (with your
classic PWM control signal feeding the 'opening' side and its inverse
applied to the 'closing' side) you can use very little preload on the
actuator and you end up with a very quick and accurate control the
wastegate. With a capable ECU, a properly tuned PID loop and appropriately
sized turbo components, you get rid of most of the lag and backpressure with
a reliable system. On top of that, for off-road/competition use, you can
then implement an electronic anti-lag system (with TPS-based air bypass,
cylinder cut and ignition retard - and also a MAR-M-247 turbine & shaft if
durability is on your whish list) and you end up with an absolutely zero-lag
turbo engine. Ultimate examples of those include World Rally Car engines
which, by the way, run about 11:1 CR and use intake WI along with 102 RON
fuel.

Hth,
Axel



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