[Diy_efi] RE: Throttling intake air

[Perry Harrington]

> It will have a lower pressure before the turbine, and
> therefore will require more energy from the exhaust to
> overcome that low pressure.  What might be worth
> looking at is the pressure DIFFERENTIAL between the
> throttle side and the engine side, vs. the pre-turbine
> side and the pre-throttle side if the throttle was
> moved between the turbine and the engine.
> 
> Slowing the turbine side, by whatever means, will
> increase exhaust backpressure, and therefore will
> "eat" some of the power produced via increased
> pressure at TDC, as well as cutting down scavenging.

Please state your reasoning.  If you plug up the intake
of a vacuum cleaner or a water pump both will simply cavitate
and draw less power.  I would expect a compressor to cavitate
and draw less power from the turbine.

> 
> Seems like that would be a worse solution than a
> wastegate, in the sense that it would decrease
> efficiency.  It could slow the turbine more than a
> wastegate, but I doubt it would function very well as
> an engine brake.

What do you think an exhaust break on a diesel is?  Since diesels have
no throttle they use an exhaust brake to generate closed throttle torque.
I believe it's called an engine brake or "jake brake".

> 
> =====
> | Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |

--Perry

-- 
Perry Harrington			Data Acquisition & Instrumentation, Inc	
perry at dainst dot com					 http://www.dainst.com/

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin

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