Bob (and Pete),

 

Your analysis is right on.......

 

Drag reduction, such as with cooling, returns speed for free.  There is one other item that gives me 6-8 Knots - gap seals - they also yield better control response.

 

Grayhawk

N92EX

 

PS: IO 320, 9:1 CR, Dual Plasma III (base timing 20 BTDC), ram air plenum fed shrouded injectors, cooling air entry diffusers, flared cowl air exit, interesting Hartzell 70" CS prop, harmonic damper, internal trim systems and gap seals. 

 

Some numbers:

KLAL->KGAD (415 NM) @ 6500 MSL, 7500 Dalt, 17C OAT, 25" MAP, 2490 RPM, 10.2 GPH, 180 KIAS, 200 KTAS.

3R9 (Austin, TX)->KARR (827 NM) @ 9500 MSL, 10600 Dalt, 10C OAT, 22" MAP, 2490 RPM, 6.8 GPH (LOP), 166 KIAS, 193 KTAS, 27 DBTDC.

 

 

Pete Cavitt asks...
> After 13-years of pokin' along behind my 150 HP powerplant, I'm starting to explore what's available
> for having my existing engine modified for more HP.

Do you want more HP or less drag?
Less drag makes you go faster. More HP makes you climb faster and
cruise a tiny little bit faster.
Personally, I like BOTH, but drag reduction nets more go per buck.

I am not familiar with the particular guts of the -E2D version of the
Lycoming O-320.
Several ideas come to mind, two or three of which will affect the HP
output of the engine:

0) remove excess weight from the airplane. Taking a few pounds out it
just like adding a few HP.

1) increase compression ratio - as long as we have 100LL (or 100UL?),
the compression
can be increased to around 10:1. There are pistons available for 9.5,
10.0, 10.5, 11.0 etc.
I have the 9.5 pistons. Higher compression will reduce detonation
margin and increase
stresses on heads, valves, pistons, rings, rods, gears, and prop.
Higher compression will also improve high-altitude performance.

2) Put together an good exhaust system. I have a crossover exhaust
tightly wrapped around the
O-320-A2B sump.

3) Fuel injection does not increase power. But it does make it easier
to balance
the fuel flow to all cylinders. In the carburated engine, if fuel flow
is not balanced,
small changes in intake runners and manifold design may make a big difference.
If the engine runs smoothly 50 deg LOP, then there's little gain to be
had by switching
from carburetor to injection.

4) Make sure your prop is delivering the power to the air. If you have
a C/S prop,
consider a much lighter fixed pitch prop.

5) Make sure that cooling drag isn't robbing too much of your power.

6) seal any gaps in the canopy, gear doors, etc that can be letting
air carry away power.

7) The O-320-E2D originally came with disposable Slick Mags -- which
is the right thing to
do with them, in my opinion. A good electronic ignition might be best,
but the Bendix mags
are better than the Slicks with a hotter fatter spark. Higher cylinder
pressures, as produced
by higher compression, require higher voltages and energies from the spark.

8) well.... one more. There's no replacement for displacement.
If you really want more go-go, consider an O-360 or O-390 engine.
You might have to rebuild the cowl, move the battery, extend the fuel tanks...

Make the 2 hour flight to RHV and you can directly compare your bird to a
235/O-320-A2B with 9.5 pistons and crossover exhaust. It is probably making
~20-25 HP more than the -E2D at sea level.


-bob

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