Engine Choice Jab' vs Rotax

[jetjr]

Watch the weight. of your final combination choice

 

 

[Yenn]

Of all those engines quoted, none are bad. Jabiru have had a lot of attention from CASA, who have put restrictions on them. My theory is that a lot of whingers made a lot of noise about Jab engine failures. CASA had a look at the figures and jumped in with restrictions, but they havn't come up with any valid arguments as to why they did what they did and some of those failures were not failures, but things like running out of fuel.

 

Rotax water cooled 4 cylinder engines have a good record and I think most of their failures have been electrical. Lycoming are very reliable, probably more thirsty than others. they also need regular use, so don't use them if the plane could sit a couple of months unused. Reason being that the camshaft is above the crank and the oil drains off.

 

Continental C200 is a good engine, I know very little more about it, possibly thirstier than the Jab or Rotax. Corvair could be variable depending on who converted it to aircraft use.

 

Personally I would go for the Jab 6 cylijnder, but I am biased, being a long time jab user. They do prefer avgas in my opinion although Jabiru say mogas is OK. It is my opinion that Mogas can be very variable.

 

Rotax, basicly reliable, cheap to run, but not direct drive and prefers mogas. Initially expensive and major repairs would be expensive.

 

 

[kasper]

Whilst you are after 100+hp your decision is different to mine.

 

BUT If you are comparing apples and apples even within the 912 series you really MUST look at the 80hp separate from the 100hp as their operating histories are fundamentally different and the costs of maintenance are materially different. with the 100 a much more maintenance and cost intensive engine to own and run than the 80.

 

For me if its an 80hp R912 I'm perfectly happy taking what is effectively a time expired (1500-2000+ hr engine) and running it on condition in an experimental airframe ... and I am. I accept that to get the best out of it it must run on mogas for the majority of the time (lead in avgas is an expensive thing in a 912 - shorter oil changes and more clogging up) and I will face some expensive parts cost over time BUT its reasonably bullet proof and less sensative to installation cooling issues

 

The 100hp 912s are less forgiving of time expired running on condition - esp the slipper clutch - so its a less clear decision for me between 100hp r912 and the J3300

 

I think is reality it will come down to your budget and the installed weight

 

 

[Narrabeenrick]

So many good points of view and issues raised. No one has mentioned ULPower yet!

 

Any reason? Any opinions?

 

 

[Admin]

In your opening post you only noted the Jab and Rotax engines but what about the D-Motor...is that viable...I can't remember the specs etc

 

 

[jetboy]

Hi, your list of choices doesnt include the Viking (Honda) which I'm sure is suitable and probably the best of the auto conversions

 

My pick for a CH650 would be O-200 mainly because I had many good hours behind one

 

but both those engines were unsuitable for my CH701 because of weight

 

 

[Narrabeenrick]

In your opening post you only noted the Jab and Rotax engines but what about the D-Motor...is that viable...I can't remember the specs etc

Yes that is right but I am trying to keep an open mind and open to other options.

Cheers

 

Rick

 

 

[dlegg]

It all comes down to price. A new Jabiru and FWF is by far the cheapest (new) and cheap to run and maintain. The European UL and DMotor Rotax etc cost can go into the $30k + regions.My Jab is flawless, burns 17 lph 98 premium, cheap for oil and filters, plugs etc. The 601/650 does much better on 120hp than on 100hp.

 

 

[johnm]

Recentli purchased a radiator cap for a 912 - $

 

75 ! - plus post - an impressivde price

 

By comparison i rang jabiru - they'll check parts and get back to me with a price

 

 

[kasper]

So many good points of view and issues raised. No one has mentioned ULPower yet!Any reason? Any opinions?

If you quote two specific engine both with reasonable numbers in use and start comparing failure rates you will not get general comments on alternate engines with very few installed and low fleet experience.

For me if weight were not an issue like others an O200 would be an option. If you are not terrified of two strokes I'd direct you towards the hirth and saurer engines ... you can get a 100hp water cooled fuel injected triple inline engine with an installed weight less than an 80hp 912 for less than the cost of a 80hp jabiru. But you are going to pay for the $ saving over time in fuel BUT it's an option.

 

Oh and Saurer do VW based fourstrokes up to 110hp (100 continuous) with turbo ... so there are options.

 

But you limited the request to two well known engines so that's why you got limited responses.

 

 

[wideblueyonder]

Rotax is available in both four stroke and two stroke. I'd be astounded if those Rotax failure statistics referred to the 912 series 4 stroke. The 4 stroke Rotax should be compared with Jabiru for reliability, to even the playing field.

 

I have flown a Zenith 650 powered by a 100hp continental. Goes well, ultra reliable. Gets off and cruises adequately, even with two persons onboard and sounds tough.

 

For the 100 hp produced, it is heavy when competed to other power plants that are also suited to this airframe.

 

A current series (gen4) 6 cylinder jabiru would make it a much more lively performer for a similar fuel burn of 95 or 98 RON auto fuel. Ron is a "research octane number" not to be confused with "octane" which is an actual power value or the resistance of the sample fuel to detonate ( in simple terms). It does not specifically require avgas because it is not a classic slow turning engine where detonation may occur on low octane fuels at low rpm under load. I use 95 ron with no problems in both of my 2.2 four cylinder jabiru motors. Fresh fuel is the ticket. Metal jerry cans for purchace and pumped into the plane through an apropriate particle and water separating filter is the go. The volatile elements of unleaded ( that replaced tetra ethyl lead) is the first thing to evaporate from a fuel container if given the chance, leaving you with expensive 91 Ron or less, where detonation is almost guaranteed in a Jabiru motor.

 

A Rotax 912S (100hp) is also very nice, but as others have indicated, expensive. But you do get a reduction gearbox so you can potentially swing a bigger diameter prop a bit slower than that of a jabiru, giving better takeoff and climb performance ( through efficiency). Rotax do not suffer from heat soak of the cylinder heads.

 

( leading to valve seats becoming loose)The engineers at Bombardier thought of that and designed the heads to be liquid cooled making them marginally quieter as an added benefit.

 

Forget the 80 hp for the '650. Very reliable, just not enough horses for the '650 in my experience.

 

I operated an 80 hp Rotax in a flying school plane for over 800 hours and the only maintenance I had to attend to other than the regular oil and filter changes, was to replace the oil pressure sending unit ($24.00 from Repco). Superb engineering, quality, time proven materials, smaller capacity engine turning a bigger diameter propeller through a propeller speed reduction gearbox is a modern solution and good engineering practice.

 

Just my AUS$0.02 worth

 

 

[kgwilson]

Recentli purchased a radiator cap for a 912 - $75 ! - plus post - an impressivde price

By comparison i rang jabiru - they'll check parts and get back to me with a price

A radiator cap for a Jab? They will be scratching their heads a bit for that part.

 

 

[kgwilson]

Best bang for your buck. Jab 3300. Rated at 120HP but most get around 128 - 130 when tested on a dyno. They have had a bad rap but it was mostly from those who failed to maintain them to the manufacturers specs & somehow managed to convince a few CASA xxxxheads. Use BP 95 or 98 if used at least weekly. 98 is best but won't last long as the aromatics like toluene evaporate off first. Avgas will end up fouling plugs & leaving deposits on the head due to the lead but it is quality controlled unlike the variables found in most Mogas. BP seems to have the best quality control of Mogas products.

 

 

[waraton]

Does anyone have recent experience with Hirth? Specifically the H30 equivalent 3002 E/V.

 

 

[ozbear]

I've had both Rotax and jabiru I personally prefer the Rotax

 

 

[Narrabeenrick]

Thanks for all of the advice, suggestions and comments from everyone:clap:. Very informative! Probably even more confused than when I first asked the question I don't think I could go an auto conversion, I've had zero experience with them but just wouldn't feel right, I think it would had to go with a dedicated/designed aero engine, as for which one, still a while before needing the engine, looking at purchasing the kit this Xmas. { As look as the wife lets me!} It will be interesting to see how the new designed jab goes by the time I need to make my purchase.

 

Cheers guys again for the advice

 

Rick

 

 

[Narrabeenrick]

I've had both Rotax and jabiru I personally prefer the Rotax

Hi Oz

Any reason why ? Maintenance reasons? reliability? cost?

 

Cheers

 

 

[ozbear]

Hi OzAny reason why ? Maintenance reasons? reliability? cost?

Cheers

Reliability ,dealer backup ,more Power but not cost

 

 

[turboplanner]

I plan on touring

If this is what you are planning to do you are better off going GA.

 

RA is better for pottering around, just enjoying flying for an hour or two here and there, going to the odd breakfast in the local area, but when you seriously commit to touring, the GA aircraft have the endurance and reliability, much less downtime ferrying jerry cans from various towns, the ability to fly longer kegs faster, and so make use of larger airports with more facilities, and provide the option of IFR training so you can get the aircraft back home within a weekend.

 

While RA has a lower cost per hour, when you are flying an hour at a time, the figures come out differently when you are covering touring distances; the faster the aircraft the lower the hours for a given distance, and even within GA, if you are talking about regular touring, the optimum aircraft are up the range from the C172 abd Cherokee Warrior.

 

Also, when you break down the costs per person touring, the more seats, the lower the cost.

 

I did this spreadsheet comparison in 2013, and it more or less shows that if you just want to have a fly around the local area, a Gazelle is fine, but if you want to tour, the Cherokee 6 is a low cost aircraft per person.

 

 

 

[horsefeathers]

the ability to fly longer kegs faster

Surely you mean BIGGER kegs faster - I cant see the point otherwise

 

 

[turboplanner]

*legs

 

 

[Narrabeenrick]

Reliability ,dealer backup ,more Power but not costThanks mate

[Jabiru Phil]

If this is what you are planning to do you are better off going GA.RA is better for pottering around, just enjoying flying for an hour or two here and there, going to the odd breakfast in the local area, but when you seriously commit to touring, the GA aircraft have the endurance and reliability, much less downtime ferrying jerry cans from various towns, the ability to fly longer kegs faster, and so make use of larger airports with more facilities, and provide the option of IFR training so you can get the aircraft back home within a weekend.

While RA has a lower cost per hour, when you are flying an hour at a time, the figures come out differently when you are covering touring distances; the faster the aircraft the lower the hours for a given distance, and even within GA, if you are talking about regular touring, the optimum aircraft are up the range from the C172 abd Cherokee Warrior.

 

Also, when you break down the costs per person touring, the more seats, the lower the cost.

 

I did this spreadsheet comparison in 2013, and it more or less shows that if you just want to have a fly around the local area, a Gazelle is fine, but if you want to tour, the Cherokee 6 is a low cost aircraft per person.

 

[ATTACH=full]48111[/ATTACH]

Hi Yenn,

Appreciate your posts but have to reply to your comments above

 

We did a trip ex Victoria, NT centre, west coast WA and home via Kalgoolie, port Lincoln.

 

I can tell you truly that the Jab 230 out performed fuel wise better than the C206, Warrior and Technam, and C 172.

 

Fuel stops planning were mainly to satisfy them when we could have cut our flying time by heaps.

 

I still have the log if interested further.

 

Regards.

 

 

[Mick]

In response to comments re the Jab 6 cylinder having more power than a Rotax 912 100hp, I met a guy last week that fitted a Rotax 912uls in his Jab J230 after getting sick of problems with the Jab motor. His performance did not change. In theory 120 hp versus 100hp but in practise not much difference.

 

 

[turboplanner]

Hi Yenn,Appreciate your posts but have to reply to your comments above

We did a trip ex Victoria, NT centre, west coast WA and home via Kalgoolie, port Lincoln.

 

I can tell you truly that the Jab 230 out performed fuel wise better than the C206, Warrior and Technam, and C 172.

 

Fuel stops planning were mainly to satisfy them when we could have cut our flying time by heaps.

 

I still have the log if interested further.

 

Regards.

The figures are hire rates including fuel, so fuel economy for the aircraft is factored into them.

The 230 would have a cost per nm per pax advantage over the 160 and 170 for the type of long trip you mentioned.