o and io engines

wrote:

A 180 hp O-360 Lycoming has parallel valves, the 200 hp IO-360 has
angle valves. With the 540's the typical cut-off for parallel valve
heads is 250 hp.

O540-E4B5, which is 260 HP has parallel valves. I think 300 HP is
where the angled valves start in the 540.

Robert M. Gary wrote:
For the Lyc 360, the difference is 20 horsepower.

-Robert

But that's not a universal truth. In fact, there are sometimes
different HP ratings for the same major engine major series...
IO-470's for example come in different HP ratings based on the
suffix (an IO-470-C is like 240HP, where an -H gets 260).

On 4-May-2006, "Robert M. Gary" wrote:

Ok, I'm still confused. The O-360 engine puts out 180hp on 9gal hr. The
IO-360 puts out 200 hp on 10 gal/hr. The difference between the two is
just that that IO-360 is fuel injected. So how is it that you can say
"And slightly less fuel burn than if it had a carburetor". That
certainly doesn't seem to be the case here.


In my limited experience with an O-360 in an Archer I generally planned on
burning very close to 10 GPH at 75% (of 180 hp), running as lean as possible
for smooth engine operation. In our Arrow with an IO-360, I burn about the
same, or maybe just a tiny bit more, at 75% (of 200 hp). The IO-360 thus
has a lower specific fuel consumption (the per-hour fuel flow required per
hp produced). Reason: I think the main one is that the better fuel
distribution on the FI engine allows operation with a leaner mixture.

-Elliott Drucker

wrote:
: In my limited experience with an O-360 in an Archer I generally planned on
: burning very close to 10 GPH at 75% (of 180 hp), running as lean as possible
: for smooth engine operation. In our Arrow with an IO-360, I burn about the
: same, or maybe just a tiny bit more, at 75% (of 200 hp). The IO-360 thus
: has a lower specific fuel consumption (the per-hour fuel flow required per
: hp produced). Reason: I think the main one is that the better fuel
: distribution on the FI engine allows operation with a leaner mixture.

That must be it. Although the book calls for 10 gallons/hour for an O-360, if leaned to "best economy," it's
more like 9-9.5 at 75%. I know I get between 8-8.5 at 65% on my O-360.... not comfortable leaning all the way when
running at 75%, so 65-70 is as high as I'll go.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote)
The IO-360 thus has a lower specific fuel consumption (the per-hour fuel
flow required per hp produced). Reason: I think the main one is that the
better fuel distribution on the FI engine allows operation with a leaner
mixture.


Curious - If approval from the FAA was NOT a factor:

How difficult, practical, expensive, etc, would it be to convert an O to an
IO?

What all would be involved? What would go, what would stay, etc?

Thanks.


Montblack

The main reason the IO engine is more efficient is the compression ratio is
higher. The compression ratio is in the numerator of the efficiency formula,
so there is a direct relationship.

Karl
ATP CFI ETC
"Curator" N185KG


"Montblack" wrote in message
...
wrote)
The IO-360 thus has a lower specific fuel consumption (the per-hour fuel
flow required per hp produced). Reason: I think the main one is that
the better fuel distribution on the FI engine allows operation with a
leaner mixture.


Curious - If approval from the FAA was NOT a factor:

How difficult, practical, expensive, etc, would it be to convert an O to
an IO?

What all would be involved? What would go, what would stay, etc?

Thanks.


Montblack