fuel consumption Jabiru 3300

karel wrote:

Out of curiosity I started to look for fuel consumption figures for the
Jabiru 3300.
I found a figure of 0.46 lbs/HP/hr which is not particularly meaningful to
me.
Moreover it said "at cruise power" without further specification.
So I started to assume 65% powser for cruise, calculating from
the rated power of 120HP this gives some 78 HP.
So 78*0.46 gives me 3.6 lbs/hour, or 6 USG per hour or close to 23
liters/hour.

Is this way of calculating correct and do the numbers seem reasonable?
I had expected this engine to be less fuel hungry than the Lycomings &C...
Do not Rotax claim something like 15 liters/hour?

TIA

PS do not tell me that the rated power of 120 HP is not for
continued application, I knew that. Seems similar to the Rotax 914S.


According to the Zenair web site: (seems a bit optimistic)



Specifications: Jabiru 3300 A
Displacement: 3300 cc. (200 cu.in.)
Bo 97.5 mm.
Stroke: 74 mm.
Compression: 8.3 : 1
Prop Rotation: Clockwise
Firing Order: 1 - 4 - 5 - 2 - 3 - 6
Power Rating: 100 hp @ 2750 rpm (see above)
Fuel Consumption @ 75%: 5.0 US Gal/Hour (gph)
Fuel: 100/130 Avgas or 92+ octane Mogas
Oil: Aeroshell W100 (or equivalent)
Oil Capacity: 3.5 qts. (3.75 l.)
Spark: NGK D9EA (common automotive)


My Cessna 150 manual (for a continental o-200) shows a spc of .448 for 75%
(75 HP) operation. The above table works out to a SFC of .4 which looks
low.( note they derate the J 3300 to 100 HP) your figure of .46 looks more
real. Hey but who knows unless you've flown one!
John

"karel" wrote in message
...
Out of curiosity I started to look for fuel consumption figures for the
Jabiru 3300.
I found a figure of 0.46 lbs/HP/hr which is not particularly meaningful to
me.
Moreover it said "at cruise power" without further specification.
So I started to assume 65% powser for cruise, calculating from
the rated power of 120HP this gives some 78 HP.
So 78*0.46 gives me 3.6 lbs/hour, or 6 USG per hour or close to 23
liters/hour.

Is this way of calculating correct and do the numbers seem reasonable?
I had expected this engine to be less fuel hungry than the Lycomings &C...
Do not Rotax claim something like 15 liters/hour?

TIA

PS do not tell me that the rated power of 120 HP is not for
continued application, I knew that. Seems similar to the Rotax 914S.

Isn't that a six-banger with 3.3 liter displacement? I'm surprised it
doesn't use more fuel than that. It revs higher than your average Lycoming
or Continental too.

In article ,
"karel" wrote:

Out of curiosity I started to look for fuel consumption figures for the
Jabiru 3300.
I found a figure of 0.46 lbs/HP/hr which is not particularly meaningful to
me.
Moreover it said "at cruise power" without further specification.
So I started to assume 65% powser for cruise, calculating from
the rated power of 120HP this gives some 78 HP.
So 78*0.46 gives me 3.6 lbs/hour, or 6 USG per hour or close to 23
liters/hour.

Is this way of calculating correct and do the numbers seem reasonable?
I had expected this engine to be less fuel hungry than the Lycomings &C...
Do not Rotax claim something like 15 liters/hour?

Your method is correct -- but it is 36#/hr, not 3.6! Yes, it does work
out to about 6 gph. BTW, 0.46 #/hp/hr is right in the ballpark for
aircooled piston, gasoline engines.

PS do not tell me that the rated power of 120 HP is not for
continued application, I knew that. Seems similar to the Rotax 914S.

23 liters for the 3300cc Jairu is conservative. My 80hp 2200cc Jabiru
uses only 13 liters per hour at 2500rpm cruise revs.
Cheers,
Joe

karel wrote:
So 78*0.46 gives me 3.6 lbs/hour, or 6 USG per hour or close to 23
liters/hour.

Is this way of calculating correct and do the numbers seem reasonable?

On Tue, 9 Aug 2005 15:21:44 -0000, "karel"
wrote:


"Joe McGaw" wrote in message
oups.com...
23 liters for the 3300cc Jairu is conservative. My 80hp 2200cc Jabiru
uses only 13 liters per hour at 2500rpm cruise revs.

Thank you, this is kind of useful information.
In what aircraft, please?
KA



ask jabiru direct in bundaberg.
www.jabiru.net.au is the web site.
if you call it up you will be able to get the specifications sheets in
pdf form.
just checking it now jabiru say that 26litres per hour at 75% power is
the consumption. varies with power used and prop installed.

Stealth Pilot
Australia

A couple of weeks ago I traveled to Mexico MO to take a demo flight in
the Zenithair Zodiac 601XL. It had a Jabiru 3300 and according to the
factory pilot I flew with the fuel consumption was 6 GPH.


AZ

wrote in message
oups.com...
A couple of weeks ago I traveled to Mexico MO to take a demo flight in
the Zenithair Zodiac 601XL. It had a Jabiru 3300 and according to the
factory pilot I flew with the fuel consumption was 6 GPH.


AZ


Did you go through the rudder workshop? What did you think? Are you a Zodiac
builder now?

karel wrote:
"Joe McGaw" wrote in message
ups.com...
23 liters for the 3300cc Jairu is conservative. My 80hp 2200cc Jabiru
uses only 13 liters per hour at 2500rpm cruise revs.

Thank you, this is kind of useful information.
In what aircraft, please?
KA


A fellow by the name of Kerry Fores did some test flights to evaluate
the fuel consumption of his Sonex with the 3300. I believe it was
equipped with an Aerocarb. The results IMHO are quite amazing. If his
results are accurate with the 3300, I'd like to know what the results
would be with an Aerocarb equipped 2200. I got his article off the
Sonex website. I'll try to send the URL.

Neal

http://www.sonex-ltd.com/Sonex_35_Hamburger.html

karel wrote:
Out of curiosity I started to look for fuel consumption figures for the
Jabiru 3300.
I found a figure of 0.46 lbs/HP/hr which is not particularly meaningful to
me.

This is actually a pretty reasonable number. Most of the big bore
lycomings are in this range, if I remember the discussions I have had
recently on power and fuel consumption.

The value being discussed here is "BSFC" or brake specific fuel
consumption. This is part of the universal "truth" regarding horsepower
in internal combustion engines. HP takes fuel. More HP takes more fuel.

Is this way of calculating correct and do the numbers seem reasonable?
I had expected this engine to be less fuel hungry than the Lycomings &C...
Do not Rotax claim something like 15 liters/hour?

As others have already pointed out, you had one decimal out of place..
(36 pph) but the rest of the math was about right..

As for the 15 liter per hour claim.. that is likely the power setting
(and fuel flow) for max range/best economy. Airframe and engine
manufacturers like to "play" with the numbers to suit their needs. None
of this overrides the fact that you have to burn more fuel for more HP.

With a BSFC of 0.45 (essentially the same as your engine, and similar to
Lyc's and continentals). I am not positive at what mixture this is being
computed at, but stoichiometric (1:14.7) seems to be the most logical.

250 hp = 18.75 gal/hr
200 hp = 15 gal/hr
150 hp = 11.25 gal/hr
100 hp = 7.5 gal/hr

The way you can use this BSFC to your benefit is in evaluating engine
efficiency claims on your own, independently of marketing claims. Your
fuel burn for given power setting can be calculated.

If an engine maker, particularly a new-comer, wont release their values,
then their claims of power and efficiency should be viewed as suspect
and with skepticism.

Dave


TIA

PS do not tell me that the rated power of 120 HP is not for
continued application, I knew that. Seems similar to the Rotax 914S.

wrote:

karel wrote:

"Joe McGaw" wrote in message
roups.com...

23 liters for the 3300cc Jairu is conservative. My 80hp 2200cc Jabiru
uses only 13 liters per hour at 2500rpm cruise revs.

Thank you, this is kind of useful information.
In what aircraft, please?
KA



A fellow by the name of Kerry Fores did some test flights to evaluate
the fuel consumption of his Sonex with the 3300. I believe it was
equipped with an Aerocarb. The results IMHO are quite amazing. If his
results are accurate with the 3300, I'd like to know what the results
would be with an Aerocarb equipped 2200. I got his article off the
Sonex website. I'll try to send the URL.

Neal

http://www.sonex-ltd.com/Sonex_35_Hamburger.html

I think the key is the Aerocarb. You can manually lean those. I
believe the Bing carb the 3300 normally comes with has a set mixture
(approximately rich of peak). That and the Sonex has pretty decent
mph/hp