Camit engines - anyone got one?

[Oscar]

One of - possibly the worst - 'own goal' Rod Stiff ever made with Jabiru engines was to broadcast the statement 'run them hard', without qualifying what he meant by 'run them hard'.

 

Jabiru has subsequently amplified on this, by explaining that it means they should be allowed to SPIN fast - i.e. WOT for climb BUT not loaded too heavily by pulling the nose way up and going for best climb angle, but by keeping the climb AIRSPEED up - which simultaneously keeps a rich mixture through widest throttle opening and keeps cooling airflow up, thereby reducing the incidence of detonation / high CHT's.

 

Add to that the fact that Jabiru engines, with a single carburetor and a fairly constricted inlet tract from the airbox ( that introduces serious swirl to the airflow to the carby and therefore tends to create uneven mixture distribution to the individual heads that varies with the inlet tract air mass speed) and with incautious operation, it is all too easy to destroy a Jabiru engine in one climb-out.

 

Those of us who grew up driving relatively high-compression, carburetor engined cars with manual transmissions, became rapidly familiar with 'pinging' (detonation) if we loaded the engine too hard. Alfa Romeos, with no vacuum retard on the distributor, were particularly prone to this. That stick between the front seats was there for a damn reason: if you were heading up a long hill and got to mashing the accelerator onto the floor to maintain speed, you changed down and let the engine rev.

 

With modern EMS and auto gearboxes, the accelerator does little more than control the speed of the vehicle. With cruise control, you can drive for literally hundreds of k's without every having to use your right foot - because all the parameters of engine management INCLUDING compensation for varying fuel quality, local QNH, OAT etc. has been already incorporated in your car by software engineers... You don't have to think about engine management any more, just concentrate on not getting booked.

 

Does anybody remember the vehicles of the 30's? Where there was, usually on the steering wheel quadrant, levers for spark retard/advance? My first car was a Peugeot 203, complete with an advance/retard knob in the centre of the dashboard, and one very quickly learned to play the thing for best performance, on a hill-by-hill basis. That was an object lesson in 'feeling' how the engine reacted to increasing load; there was no mixture control and a very crude induction system, but the 203, properly managed, was a very quick car for its time point-to-point. Witness, a story by David MacKay, of driving Sydney-Melbourne in a 203, with a contemporary Bently in company: MacKay had to stop and wait several times for the Bently to catch up!.

 

A Jabiru engine (along with basically most carby-equipped Lycontinentals etc) is fundamentally a 1930's EMS technology engine; mechanical-injection Lycontinentals are a bit of a step forward but again, no unreliable electrons are involved. That is what the international standards require: it seems that the FAA etc. have yet to accept transistors as viable engine control components, except under fairly ludicrous standards of system duplication etc. One has to wonder whether the people setting the standards all drive 1952-model cars to work, because they don't trust the new-fangled devices.

 

Which puts us back in the regime where 'engine management' tends to fall back on the operator. I doubt any Gypsy-engined operator is not attuned to the engine; Lycontinentals are fairly forgiving by being low hp/lb; 2-strokes are low TBO and if abused at all, will bite remorselessly.

 

What CAMit is doing, I believe, is trying to remove any intrinsic engineering problems of the basic Jab. engine. However, that HAS to be viewed within the 'box' of the the regulations under which these engines operate - and that 'box' de facto requires that the operator uses the engine intelligently.

 

 

[Oscar]

So.........backing off power to 2900 revs, climb speed 85 is " bad " ?????

Russ: use WOT AND keep the speed at no less than 85 in climb, and your engine ought to run full TBO, no worries.. Just don't climb at WOT for more than 5 minutes at a time.

 

 

[Yenn]

with an air cooled engine it is extremely hard to hear detonation. First clue is rapidly increasing CHT. It can go from normal to extreme in just a few seconds and the only cure is to back right off on power. Then you can richen and try again. I have had it happen using poor quality mogas and I don't have EGT and only CHT on 1 and 4 cylinders. Luckily I didn't do any real devastating damage.

 

 

[Russ]

Russ: use WOT AND keep the speed at no less than 85 in climb, and your engine ought to run full TBO, no worries.. Just don't climb at WOT for more than 5 minutes at a time.

Maaate...........i can't do it, it just goes against my own engine management self training ( 50+ yrs )..........hate revving the ring out of my engines. ( be nice to me engine, it'll be nice to me )

 

WOT and leave it there........mate, i'll be having nightmares tonight just thinking about it.

 

 

[jetjr]

egt will show up leanng for sure, if your looking a all cylinders, but doubt detonation would except by nasty outcomes like throughbolt breakage

 

You can back off throttle position significantly and loose just 100 rpm, in some cases this reduced egt spread.

 

You also drop the nose a little to achieve suitable speed to cool things off.

 

I'm with Russ but have to say current engine is the first one id actually be able to maintain wot without overheating something

 

 

[Bruce Tuncks]

how about a multiple-point pressure gauge? If you had 2 senders and a digital readout you could see the pressure before and after the mechanical pump. Is this what you have been looking at jetjr?

 

 

[facthunter]

There is a lot in Jabiru literature about overloading the engine with too draggy, big, wrong pitch etc PROPS which will lower the revs you can get. It's like starting in top gear.

 

An engine is an air pump and if not enough revs attained on full throttle you are first of all down on produced power and also the dashpot on your carb will not go full UP which is OPEN . A CV carb responds to mass airflow to get the richened mixture you need on take off. The butterfly throttle is not linked in any way to the dashpot. It only gets all the way open when the pressure differential across the passages lifts it there, against the light spring.. Until it's nearly all the way up you don't get the richer mixture, provided from the needle's profile. Nev

 

 

[jetjr]

Jabiru talk about overloading but have little advice on what is "enough revs"

 

Beyond that experienced with basic wooden props they supply, whoch vary alot and flex under load.

 

Also no advice much on manifold presure or even what 75% power is.

 

There has to be a more technical measure of engine load than static revs with a particular prop

 

Im just measuring downstream of mech pump but did do lots of flow tests at several points in the system. From this was able to work out where headloss was incurred. Elect pump and fuel flow sensor were the key problems.

 

 

[jetjr]

Just digging through some data and after opinions. Trying to make sense of info.

 

A sample new engine dyno sheet says 129hp @ 3300rpm........so 75% power at just under 3000rpm

 

On an actual engine in aircraft

 

Manifold Press at WOT around 25, in cruise 19. In both instances around 2900rpm

 

At 3000rpm in flight its around 22, max rpm 3150 S&L

 

This means if set up as specified you almost can't go over say 86% power and recommended cruise loads are around 57%

 

Unless this loading is correct how can EGT or mixtures be set correctly?

 

My thinking is there should be a MAP number for optimal cruise load.

 

 

[facthunter]

I don't think dyno figures would replicate "in Air " performance. It's difficult without a torquemeter plus RPM which is there already. Your manifold pressure will be most affected by pressure altitude. (as well as throttle position and losses through the carb., air cleaner etc. Nev

 

 

[jetjr]

ok

 

But how to determine what is suitable load and then set carb and egt around this

 

Seem to be doing the opposite and wondering why theres variable results

 

 

[facthunter]

Not easy. If you can get an indication of where the dashpot actually is at certain times that would help tuning it. Nev

 

 

[Geoff13]

So without going through all 22 pages, I would like to go back to the original question.

 

Does anyone have one that is flying, what sort of hours are on it? Pros and cons?

 

 

[jetjr]

Yes, there are lots, even more with major CAE components

 

mine only new, around 20hrs, there are several with no issues at 400hrs and one at 700hrs

 

All Pro no con except you cant fit them to LSA

 

 

[Russ]

Yes, there are lots, even more with major CAE componentsmine only new, around 20hrs, there are several with no issues at 400hrs and one at 700hrs

All Pro no con except you cant fit them to LSA

You can't legally exceed the road speed limits........but hey, we've all done it.

 

Can't bolt in a camit........sure can, but mums the word.

 

 

[Oscar]

Geoff, that's a somewhat difficult question to answer! Ian Bent is the ONLY person who can give you an authoritative answer and he doesn't contribute to Rec Flying threads, any more than does anyone officially from Jabiru.

 

CAE engines have been a 'work in progress' for a number of years now, as CAmit continues to develop the changes is has been making, test them, and refine them in some cases.. That is why they remain 'experimental'; there are complex reasons why this remains the case, including the CASA restrictions and some other factors that have yet to be finalised.

 

However, I believe that in excess of 100 'CAE-plated' engines have been delivered to customers in Australia, N.Z., the USA and South Africa and possibly also the UK. A considerably greater number of engines not officially plated as CAE, incorporate components from the CAMit development programme. I personally have one such 'hybrid', which so far has only engine test cell running hours on it.

 

Because nominally 'CAE' engines so far have often had a combination of both standard Jabiru and CAE-improved parts in them, the experience of users needs to be modified against the actual configuration of the specific engine. It would be facile to say: 'well CAMit are using its customers as test pilots' - because CAE engine operators understand that that is exactly the situation they are in, and they provide feed-back to CAMit. In the current parlance, you might call it a'crowd-sourced engine development programme'.

 

You have asked: 'the pros and cons'.

 

I would suggest that the 'pros' are: experience of over 5k engines manufactured as a basis for development, a detailed R&D programme based on analysis, development, testing and experience feedback.

 

The 'cons' are: a limited number of high-hour examples of a fixed specification from which to prove conclusive statistics and a certified/certificated model specification for the derivation of such data.

 

But: let's cut to the chase here. If you fly an aircraft that enjoys the advantages afforded by the weight/power delivered by a Jabiru/CAMit engine, then getting the 'best' engine is of serious interest to you. If you fly an aircraft that has been designed for a Rotax 9x-series, then your interest is curiosity: you are not going to suddenly decide to remove the Rotax and insert either a Jabiru or CAE engine. That in NO WAY means that Rotax owners ought not to have interest in Jabiru vs CAE engines, but 'skin in the game' provides a perspective that is, I believe, important in this context.

 

 

[Geoff13]

Oscar. Your last paragraph is one of the main reasons for my question. 12 months ago I purchased an aircraft that was fitted with a Jabiru engine. I considered fitting a CAMit engine but for a couple of reasons went to the additional expense and weight of a Rotax. Not in the least of that was CAMits inability at the time to provide a delivery time frame.

 

That certainly does not stop me from having a continuing interest not only in the further advances at both Jabiru and CAMit or for that matter the D Motor which I also considered. I would be interested in real life examples of running CAMit motors more so than the hybrids though as that is the way I was looking at going.

 

In addition to that, one never knows where ones next project could lead.

 

 

[Oscar]

Geoff:

 

Wow, 12 months ago, the excrement had totally hit the rotating airflow augmenter for CAMit... but your point is extremely valid. I sincerely believe that in the next 6 - 9 months, we are going to see a whole lot of useful information come from CAMit, but even now, it is in 'consolidation' mode rather than full-on 'production' mode.

 

 

[JohnC]

Dear All, I would like to reopen this thread as Camit appear to be moving quickly with new products etc, and they certainly appear to know whet they are doing. I am considering replacing my Jab3300 with a new Camit engine as I have been unlucky with the Jab engine including snapped flywheel bolts, misfires / coil problems, a forced landing, low compressions and, needless to say, my confidence in the Jab engine has completly gone. When operational all the t&p's were perfect with a "by the book" maintenance regime and good in-flight engine management with full EMS and all cylinder temperature monitors - the engine started giving problems around the 500-600 hour mark. My question is has anybody got a Camit engine with a few hundred hours and has the experience been positive and problem free? I can not and will not throw any more time or money at the Jab engine as this engine, in my opinion, has major design, assembly and material application issues.

 

 

[Jaba-who]

My understanding is that there are relatively few CAMit engines in the field. I have heard that there have been some problems with Pistons. Something about the beefed up barrels not expanding and the skirt of the Pistons becoming tight. But it was just a murmuring from a jabiru employee.

 

Anyone heard anything about that?

 

 

[jetjr]

I wouldnt trust anything heard from Jabiru regarding Camit.

 

I have a CAE 3300, but low hrs, runs beautifully, product and support is everything it should be.

 

 

[facthunter]

The "beefed up" barrels would expand at the same rate as the previous ones as it's the material that determines the rate of expansion. The pistons run hotter and are made of aluminium alloy which even if they were high silicon would still have a rate of expansion greater than the cylinder. Getting the right clearance is the key and not overheating the engine. Slipper type pistons don't get the heat to the cylinder as well as plain skirted ones, so the amount of oil circulating plays a big part. Nev

 

 

[David Isaac]

The "beefed up" barrels would expand at the same rate as the previous ones as it's the material that determines the rate of expansion. The pistons run hotter and are made of aluminium alloy which even if they were high silicon would still have a rate of expansion greater than the cylinder. Getting the right clearance is the key and not overheating the engine. Slipper type pistons don't get the heat to the cylinder as well as plain skirted ones, so the amount of oil circulating plays a big part. Nev

You are being gentle Nev.

 

 

[jetjr]

Camit use many chnages, enough to make it a quite different engine.

 

Underpiston oil cooling is one, better head material and barrells less likely to distort are some

 

 

[coljones]

I wouldnt trust anything heard from Jabiru regarding Camit.I have a CAE 3300, but low hrs, runs beautifully, product and support is everything it should be.

Give us an hour by hour heads up. How many hours have it done?