David Leonard wrote:

HI Don,
I think a turbo is not a bad idea and will definitely add available horse power.  But first a reminder of a few of the downsides:
Added weight and complexity
Additional cooling requirements
Some loss of efficiency due to exhaust back pressure.
 Ok, now forget about that stuff and lets pick out a turbo.

 On Sat, Feb 6, 2010 at 6:21 PM, Don Wallker <drwalker@gbis.com <mailto:drwalker@gbis.com>> wrote:

    Dear list, Turbo flyers and especially David Leonard,
      I've 16 flying hours on my RV-8 with a Renesis and all of
    Tracy's stuff and a Catto 76/88.  The airplane flys great, just
    like an RV, no gliding time, and about 36 hours on the ground. SPECS
    Full throttle 8,000'   174 mph indicated, 2450 on the prop, water
    185, oil 205,
    Climb out 110 mph, rate of climb, 1250'/min.  Field elevation 5046.

    These are not bad numbers, but I would like better.

How much better are your really looking for, Don?  I've been working on a "turbo" solution that either minimizes or eliminates the drawbacks that David lists.  The solution I have doesn't allow for nearly as much manifold pressure, but adds no additional moving parts to the engine.

I'm taking the intake air from around the side of the gearbox, through its mounting plate.  The flywheel will have an impeller attached to it.  I built a fiberglass shroud to enclose the area between the gearbox mounting plate and the engine.  Intake air is taken from this centrifugal pump.

Pros:
-I never have to worry about surges, wastegates, pop-off valves, etc.  The blower will never exceed the engine RPM.
-I don't have to deal with an intercoolers, wastegates, pop-off valves, etc or the problems that failure of these things would cause.  I'm not pumping the pressure up that high.
-I don't have to deal with exhaust back pressure.
-I don't have to deal with exhaust heat.
-Lightweight.  I'm getting away with just the weight of a shroud and an impeller.  Projected to be less than 5lbs.

Cons:
-Power increase will be limited to about 20Hp.  Exact figure won't be known until I get it put together.  The test will be several static run-ups, with intake air taken from the pump, without the pump, and without the pump with the air blocked.  The last test is to see how much Hp the pump is eating.
-I still have to install a real muffler.

At this point in the development, I have a gcode program to mill the impeller out of foam on the CNC mill I built.  The foam model will be used for casting.  I've built a furnace capable of melting enough aluminum to do the casting from.  I nearly have the lathe I bought in the fall set up so that I can do some post-cast cleanup.  I just have to finish building the quick change tool post holders.

Once I get the impeller built, I just have to finish building the muffler and a prop and I'm ready for my first start.


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