OT: HHO (Browns Gas) Conversion For Your Car
torriem at gmail.com
Wed Jun 11 17:00:17 MDT 2008
Levi Pearson wrote:
> Turbos don't generally increase efficiency, though, at least not by a
> great deal. A turbocharger creates an exhaust restriction, which, due
> to thermodynamics, can't be completely compensated for by the intake
> acceleration it provides. This will somewhat lower the efficiency of
> the engine, since it saps a bit more power to expel the exhaust during
> the exhaust stroke. The turbo adds a lot of power gain, though,
> because when it's not pumping out the wastegate, it allows a
> greater-than-atmospheric pressure in the intake manifold, which means
> more combustion, more fuel usage, and more power. During cruise,
> though, the manifold is in some degree of vacuum and the turbo isn't
> really helping.
This is fun!
Turbos can and *do* increase overall efficiency. Remember that
efficiency is not measured in fuel per time, but rather fuel per unit of
work done per unit of time (or something like that :). I only have
experience in turbos on large diesel engines, but they do increase power
*and* efficiency in that application. For example, suppose a naturally
aspirated diesel produces 250 HP. With a turbo, the same engine can
produce 320 HP, but as you say it does burn more fuel to produce 320 HP.
But the amount of fuel required to generate 320 HP in the naturally
aspirated engine would be a lot more than the turbo 320 HP uses.
Efficiency is about decreasing the rate of increase in fuel consumption
as you increase in speed, or work done per unit of time.
> If efficiency gains are seen after adding a turbo to an engine (and
> they sometimes are), you can probably chalk them up to a more
> efficient engine control map than the factory one in the non-boost
> area or perhaps more time spent with the engine operating in a more
> efficient power band, thanks to the extra power available.
The ECM cuts fuel flow for a given rpm because the turbo has boosted the
efficiency of the engine (as well as power, etc), reducing the amount of
fuel required to maintain that RPM over the amount that would be
required without it. On Alex's car, for example, At 90 MPH with the
turbo working at peak, you're definitely burning *more* fuel than you
did before the turbo kicked in at 70 MPH, but your MPG is way up.
Efficiency in this case is about how many miles you can go on a gallon.
Turns out that, on alex's car, driving 90 MPH with the turbo screaming
is more efficient than driving 70 without the turbo.
In conclusion, we've proved anecdotally that a turbo charge in fact can
increase overall engine efficiency.
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