Brian Carlsen wrote:

General question: Is there any point in using a turbocharger to slow the

exhaust pulse and act as

a noise reduction device?? Carrying on from that, can you use the turbo

(with gearing) to drive a

alternator, water pump, vacuum pump, fuel pump, etc. If as the evidence

suggests that 50% of power

goes out the exhaust, is it feasible to use the turbocharger to drive

the propellor via  a

reduction gear???

Works great. One of the reasons I am going with a turbo. Not to
mention high altitude cruise advantages.

Paul Lamar

Do not be misled by the "50 percent out the exhaust" . Most of that cannot
be retrieved by any
practical means. A recovery of about 5 percent (of BHP) might be recovered.
This is enough
to possibly use for accessory drive but little else. Turbcharging is the
most productive use
at our scale. - Vance

You are forgetting the results achieved  on the R3350TC Vance.
They must have recovered about a third to a half of it or they would not
have achieved these results. The HP went from about 2800 HP
for the non turbo compound R3350 to about 3800 HP for the turbo compound
version. That's a fact.

Paul Lamar

But did the fuel consumption also increase? Not the BSFC, which probably decreased, but the
overall fuel burn in btus/hr. Adding a turbine to the exhaust stream increases the engine's
backpressure, adding to the pumping work the engine performs. The tradeoff is that with a properly
engineered system, the overall package may meet the application's needs better than a non
turbocharged or turbocompounded engine. The power density may increase, the efficiency may
increase, but I agree with Vance that only a small portion of the exhaust energy is
thermodynamically available for producing shaft work. In other words, you can't put a turbine in
the exhaust of a 100hp engine and get another 50hp out without also increasing the energy input
(fuel) to the system. You may be able to get the 50hp out by increasing the energy input by an
equivalent of only 40hp, thus making it attractive from an efficiency standpoint. Then you have to
see if the added complexity is worthwhile.

Jon

You guys are really hard to please. The BSFC greatly improves as does the
power and you guys are not convinced :) If you are concerned 
about the absolute fuel burn make the turbo compound engine smaller
to generate the same power and enjoy the highly reduced fuel burn.

BTW Jon how are your supercharged rotary boat engines doing?
They should be really great for water skiing. I was thinking
you ought to make your own gear boxes out of cheap Ford A4OD
planetary parts.

Paul Lamar
 
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