Camit engines - anyone got one?

[DrZoos]

Let him experiment I say, who knows what he might stumble upon. After all isn't that what this category of flying is all about? Stand fast LSA! I know of a few 'Camaru' engines floating about at the moment.

There is also a few Jabirutax floating around now

 

 

[eightyknots]

When the redbull wingsuit dude wanted to fly with hydrogen peroxide strapped to him they said it was too dangerous, couldnt be doneWhen the first guys started changing cams in the yamaha dirt bikes back around 2000 they where told they couldnt and now its one fo the first upgrades many make on any dirt bike... and believe me it works far better than the engine supplied by the mighty Yamaha...

 

Lets not kill creativity, lets just ask that it be done safely

That is the kernel of the issue. Experimenting should be:

 

(a) encouraged ...that is how you get progress; and,

 

(b) be done as safely as possible.

 

Flying a hybrid JabiCamit engine through CTA does not fit (b) very easily.

 

 

[DrZoos]

Who said anything about CTA

 

 

[eightyknots]

Who said anything about CTA

Post No 371 of this thread.

 

 

[jetjr]

CAE make both the original parts and the new design parts, hardly two manufacturers

 

Several upgrade kits are deliberately produced to change engine spec including an entire core engine incorperating many of the upgrades

 

Some here are commenting like using altered parts is without advice or instructions. Some of the most experienced Jabiru maintainers in the country are doing exactly this as they feel Jabiru wont make the required changes

 

It is ONLY applicable to experimental aircraft so aside from a few VH versions they cant do CTA anyway. Its also implied that upgraded bitza engines arent an improvement over standard Jabiru offerings. You cant have it both way criticising Jabiru reliability AND criticising the use of improved components.

 

Id suggest it could easily end up that CAE becomes the only source of parts for older models and im grateful for that

 

 

[DrZoos]

FEA's etc why do some think they can do better in the home garage.Aldo

Because the Jab has got issues that havent been resolved to thier satisfaction...many of the worlds biggest challenges have been solved in garages by those who thought they knew a better way than the big guys... while others had access to all the tools necesary. Eg steve Jobs

The multibillion dollar auto after market parts industry is based on this concept...thousands of little guys who knew a better way than the original manufacturer, who ultimately probably had to settled for a compromise. possibly based on R&D cost

 

 

[Oscar]

CAE make both the original parts and the new design parts, hardly two manufacturersSeveral upgrade kits are deliberately produced to change engine spec including an entire core engine incorperating many of the upgrades

Some here are commenting like using altered parts is without advice or instructions. Some of the most experienced Jabiru maintainers in the country are doing exactly this as they feel Jabiru wont make the required changes

 

It is ONLY applicable to experimental aircraft so aside from a few VH versions they cant do CTA anyway. Its also implied that upgraded bitza engines arent an improvement over standard Jabiru offerings. You cant have it both way criticising Jabiru reliability AND criticising the use of improved components.

 

Id suggest it could easily end up that CAE becomes the only source of parts for older models and im grateful for that

jj - my own engine is in fact a 'hybrid' containing many CAMit improved parts and some non-CAMit parts - including very early barrels and the second-earliest series heads ( thick -finned, and not even the chamfered exhaust pipe seats, though that was changed using an Ian-Bent hand-made on the spot tool, and requiring a special jig (also hand-made by Ian, on the spot) for drilling the oil-inhibitor holes. We had to hand-drill and form ( not tap) the cht sensor pick-up holes as well.

 

So it might seem that I am being hypocritical to suggest that one shouldn't mix-n-match. In fact, there are some CAMit parts that are simply better by any measure and will not introduce any new problems: an example is the improved rockers and rocker bushes, which cannot have any adverse effects either downstream or upstream in the 'systems' of which they are a part. Changing the cam and cam followers from solid to hydraulic is absolutely NOT in that category.

 

However, let me amplify a little on why I think this is NOT something that one should just do in the 'back shed'.

 

We had two engines for 'donor parts' use: one, from our own aircraft, that had suffered an EFATO (through-bolt failure) at 375 hours; one that had been sitting unused other than for the build-test proof run and inhibited for nearly 8 years. Both were dismantled, and cleaned (and cleaning a used crankcase it a seriously intensive task to get it scrupulously clean - the Jabiru case-joining compound takes more work to remove completely than it is worth for CAMit to use an old crankcase in their core rebuilds - it is more economic to use a brand-new case! I would not have believed that, if I hadn't done the damn work myself.)

 

Then, the first candidate case was put through the full CAMit new-case laser measuring check. If you don't happen, as a back-yarder or even a highly-experienced Jab engine builder such as Keith Rule, to have a temp-controlled laser-measuring facility with the requisite measuring programme, you can't get 'factory' compliance accuracy. I have no doubt that a Keith Rule can measure every critical component to a very acceptable accuracy, but I am sure Keith himself would not claim to be able to reproduce the level of accuracy that CAMit employs for the factory-built Jab or CAE engines - and sometimes the 'cumulative error' factors can gang-up collectively to produce a bad result. The 'Factory' check sequence allows the cumulative differences to be collated into a 'go-no-go' summary.

 

Our first candidate case, from the EFATO engine, was 'no-go'. Back to the cleaning and washing.... The second case, from the 'OTS' engine, was a 'go'. Then we drilled it for the CAMit through-bolts, using CAMit workhop equipment ( not yer Bunnings drill press, let me say!) and having been trained by Ian Bent in how to do the drilling, using drills specially ground for the job. THEN - the cases went onto the CAMit machines for drilling the piston-cooling jet holes. Even the best operators can't match by hand what a $M CNC machine can do for accuracy.

 

The shaft from the EFATO engine - despite the thing having done a dead-ants overturn - was a 'go', so we only had to remove the welsh plugs, clean it out, and re-assemble it for use using the factory gear - a mere half-a-day for two inexperienced people operating with the guidance of Ian Bent and his assembly guys to guide us. Oh, and the factory assembly tools and assembly bench.

 

Then, we looked at the compatibility of the CAMit through-bolts and nuts and the early-series barrels. Another mix-n-match exercise. Now, the average back-yarder - and indeed, ANY L2 or LAME in the country - won't have the actual machining CAD programmes to hand. But CAMit does, and Ian spent some time dragging up the CAD drawings of the actual barrels we were using plus his CAE components and matched them, to find that they would fit - with slightly more than a hair's breath of clearance. ( I might remind people that the Jab 7/16 through-bolt 12-point nuts required hand-grinding of the nut base radius to fit.) Let me say that it is QUITE impossible to see by any visual means whether there is clearance or interference.

 

The old (in year of manufacture) but almost brand-new (in terms of operational-life) barrels were honed to the better pattern and depth that has been found by racing-engine experts to be more effective. Then using the CAMit ring-seat inspection tool, each ring was gapped. It's not just ring-gap but ring circumference that needs to be inspected: how many back-yarders or even L2s or LAMES have an inspection tool to ensure that the production ring seats evenly around its entire circumference? On OTS rings, the ends have some distortion: the gap doesn't show that distortion, but every engine that comes out of CAMit has the rings checked to see they don't introduce a low-sealing area from the manufacturing process. I think we had to polish about 60% of the first two rings for each cylinder, to get sealing around the entire barrel sides.

 

Thence to head preparation and checking of the valve seating via a leakdown test. Inserting seals. Setting up the coils, potting the HT leads, etc. etc. etc. So many processes - and so many tricks and traps for the inexperienced.

 

At the end of it, we had a fine-running engine which we built, with only the entire backing of CAMit experience and advice, multi-$M's worth of equipment, and mentoring from people who have built 5,000-plus engines to assist us. Do we think we could do it again, in the backyard shed? No EFFING way.

 

All of which, to produce an entirely hybrid engine that has an intended future as mostly a test-bed for research; any recreational flying we can manage will be a bonus. And we fully accept that whenever we fly it - it is a research engine, so we won't be blasting off over Bindook with the belief that we have a bullet-proof powerplant.

 

To those who advocate 'experimenting' - good luck to you. But do not assume that you have found the silver bullet to reliability / performance until you have serious hours to back up your ideas and do not put yourself or your passenger in harm's way until you have serious hours of proof that your bright idea has been a total goer. Lycoming has long passed the idea that the individual can be trusted to get it right, neither Jabiru nor CAMit should be held responsible if your idea fails.

 

 

[facthunter]

I would agree that CAMit will be the logical source of parts (support) for most jabiru engines. The later Jabiru ones may be more difficult as they diverge in design. Just how difficult it will be depends on just what form later motors from both sources take. Compatibility may reduce ability to improve the engine, in the same way as motors being certified does.. Nev

 

 

[jetjr]

All good Oscar, youve done serious work and with solid direction

 

OP didnt indicate it was backyard work, and if your not splitting case the risks are much slimmer i think

 

Consider that your comparing justt fitting std jab parts or cae ones. Problems with skill of operator is the same

 

In my case the time and risk wasnt worth it and got a new one. Others value time and risk differently.

 

If CAE supply bits and advice regarding compatability i dont see the problem

 

The whole issue of resposibilty and expectations is at the core of LSA Jabiru complaints

 

 

[Bruce Tuncks]

There is a CAMIT engine at my club with a fuel-pressure problem where the mechanical pump sometimes does not deliver enough fuel . The pressure can drop below 1 psi. It's not a serious engine failure problem, because turning on the electric backup fixes the running but I am curious about the cause.

 

Now I know that the carby float-valve cannot cope with excessive pressure ( I think 4.5 psi is the max ) so the pressure from the fuel pump can't be too high. We once had a Jabiru engine stop when the electric pump was turned on as part of the pre-landing checks, and I reckon this was caused by too much fuel pressure and flooding.

 

The CAMIT engine has the same mechanical fuel pump as the Jabiru, but it has I think been modified, maybe by replacing the spring with a weaker one to lower the fuel pressure to avoid incidents like that.

 

Apart from putting in a fuel-pressure gauge ( already done), what else could we look at doing? Apart from this , the engine is going well.

 

 

[DrZoos]

There is a CAMIT engine at my club with a fuel-pressure problem where the mechanical pump sometimes does not deliver enough fuel . The pressure can drop below 1 psi. It's not a serious engine failure problem, because turning on the electric backup fixes the running but I am curious about the cause.Now I know that the carby float-valve cannot cope with excessive pressure ( I think 4.5 psi is the max ) so the pressure from the fuel pump can't be too high. We once had a Jabiru engine stop when the electric pump was turned on as part of the pre-landing checks, and I reckon this was caused by too much fuel pressure and flooding.

The CAMIT engine has the same mechanical fuel pump as the Jabiru, but it has I think been modified, maybe by replacing the spring with a weaker one to lower the fuel pressure to avoid incidents like that.

 

Apart from putting in a fuel-pressure gauge ( already done), what else could we look at doing? Apart from this , the engine is going well.

Thats a pretty serious and dangerous issue..

 

 

[jetjr]

Firstly talk to Ian and he will tell you about free fuel flow and why its important to have it available to the pump as specified on install manual, 1.5 x max rate.

 

Failing that youll get a new spring to fix the problem just like Jabiru do. Its pretty easy to overdo it like youve outlined

 

Lots of Jab fuel systems are very restrictive especially with addition of fuel flow sensors and this needs fixing, elect pump or more spring pressure masks the problem

 

Measuring low pressure is hard, std senders from VDO are 0-30 and dont read much difference below 5. Kavlico have some low press ones to suit dynon

 

 

[deadstick]

Best to talk to Ian bent on the topic, trouble shooting jabiru fuel delivery issues is in the manual, they state s minimum fuel flow check in the pre first flight checklist in the build manuals.

 

 

[frank marriott]

Bruce,

 

1. Check the fuel flow on the engine pump. Should be 50 to 60 litres per hour otherwise replace.

 

2. Electric pump the same 60 litres per hour. Some off the shelf similar looking pumps have 8psi - too high.

 

Rotax have a similar problem with too high a pressure from their engine pump and have an ad putting a bypass after the pump to take the excess fuel pressure back to before the pump. IMO better to have the correct pump pressure in the first place, but that's just me.

 

I don't know what Zoos is on about but so be it.

 

 

[jetjr]

Be aware CAE and Jabiru test methods are very different, Jab permit use of electric pump to achieve 60lph, CAE do not, which makes sense as if you loose elct pump or power you may not lnow it and could lose power under load or run lean.

 

Also should be done with low fuel in tanks, think these are std aviation methods and limits

 

I can write a page on my experience trying to get this fuel delivery right

 

Flow sensor and elect pump are BIG restrictions, hose is generally too small too.

 

Mine was delivering just 12 lph without elect boost, got it up to 50 by rearranging things. And hose layouts

 

 

[DrZoos]

I don't know what Zoos is on about but so be it.

I was just a bit concerned with Bruce's statement that:

 

It's not a serious engine failure problem, because turning on the electric backup fixes the running but I am curious about the cause.

[aj_richo]

Bruce, re fuel pressure issues with the CAMIT engine.

 

There is quite a bit of discussion on the Yahoo Jabiru and Camit Aircraft engines group.

 

I would contact CAMIT in the first instance based on Ian's findings into similar problems.

 

Here is Ian Bent's response, there are about 50 messages in the thread (not sure if you have to join group to view )

 

https://groups.yahoo.com/neo/groups/JabCamit/conversations/messages/454

 

"The fuel pump issue is developing into a root-cause issue which needs to be fully understood.

 

We could easily just fit a stronger spring which “may” work most of the time.

 

The starting point has been that the CAE spring outputs 2-2.5 PSI during dyno testing where the pump is raising fuel from a small tank positioned below the pump (on the floor, outside the test-cell to prevent siphoning –fires)

 

The fuel supply line is as long and small as in any recreational aircraft. Why is a stronger spring required?

 

We’re finding significant problems with aircraft installations. Free flows (no electric pump) as low as 12LPH (3.1GPH) have been found in an installation where the engine needed at least 40 LPH at full throttle. The difference between the two means that there will be a reduced pressure at the pump inlet which will reduce the efficiency of the mechanical pump. Apart from the potential for partial leaning at high power settings, this will also affect the fuel vaporisation characteristics of the fuel (more so with unleaded).

 

Using an emergency pump to conduct a fuel flow test may not be an appropriate procedure as the emergency pump is not used at all times by all pilots. It should be considered as part of a separate, redundant system.

 

The mechanical pump is usually less efficient due to positioning (drawing instead of pushing fuel) so the test should make sure the mechanical pump is able to supply enough fuel “plus a margin” to allow for system degradation between annuals.

 

There are a lot more factors to be considered here such as, added fuel system components(fuel flow sensors), non-serviceable tank finger filters, aged fuel, tank linings, alcohol, etc. so the problem is how best to adequately test the fuel system in a simple manner. We will be able to supply stronger springs in app 1 week which seems to solve the apparent problem in some installations, but I don’t see this as a first option. The plan at the moment is to make sure that fuel systems are able to be appropriately tested before making changes which don’t necessarily address the root cause issue.

 

Ian

 

CAMit "

 

 

[Nobody]

If this issue just happens and didnt in the past also check that any filter (if fitted) isnt starting to clog up. Many of the automotive type ones can be poor in this regard.

 

 

[jetjr]

Make sure flow test is done over long period, 10 min at reqd flow.

 

You will notice it drop off using some paper filters

 

The new spring comes with good instructions.

 

looking for "min 30lph, Spring is only to be fitted if flow>30lph and there is still problems ie fuel flow drop or high EGT at full power"

 

1 psi is still OK, I saw big drop when elect pump turned off, seemed to stabilise back to 2-3psi after second or two

 

 

[Bruce Tuncks]

My experience with a faulty mechanical fuel pump was with a P76 car I once had. The car went just great for 600,00 k so don't call them lemons to me.

 

But one day we were coming home from Mildura, with a glider trailer, demanding wife, 40 degrees C and 2 small kids and the mighty P76 lost power and slowly stopped.

 

I got home and saved a domestic crisis by pressurizing the fuel-tank to about 5psi with an air-bed pump. You couldn't do this with a modern car, but you could with a Jabiru. You need to keep the pressure up to account for it dropping as fuel is used. The cause for the P76 was later found to be a worn push-rod driving the fuel pump. A mechanical pump needs a certain stroke to deliver a rated quantity and just because the driving cam has enough stroke doesn't mean that the fuel pump sees all of that stroke.

 

How do you test a mechanical pump? By turning the engine over with the starter and measuring cc per revolution? Or by setting up another fuel source and running the engine on this alternate fuel while you measured the output from the mechanical pump?

 

I haven't seen either of these procedures described, and I have only done the electric pump flow test , which as has been pointed out doesn't really answer the question, although it would show up a gross blockage.

 

Anyway, some good points thanks guys. I reckon finding out if there is any impediment from the electric pump to the fuel flow is a good next step. And I didn't know that a filter can look good until 10 mins of flow. Anything in the fuel-line is possibly bad news. There was an incident report where an engine failure ( Rotax I think) was attributed to the installation of a fuel-flow sender and its effect on the flow.

 

 

[Oscar]

Bruce, attached is a fuel flow test procedure accepted by CASA for several Australian aircraft certifications, including the LSA55 Jabs, the original Skyfox, and the carburetored Sunbird Seeker models.

 

Please Note: Southdown Engineering no longer exists since Dafydd Llewellyn retired as a CAR35 engineer. However, the procedure remains valid.

 

fuelflowcarb.doc

 

fuelflowcarb.doc

 

fuelflowcarb.doc

[jetjr]

Yeah testing mech engine fuel pumps is tough, performance is rpm related, Fortunately they are highly reliable. Jabiru/CAE one is from a Peugot ??, with some modifications inc spring and top port being 90 deg id guess.

 

Have to be careful after fitting spring that diaphram is seated and movement is free. Plunger should move 2-3mm and return.

 

 

[jetjr]

An update

 

Overall CAE 3300 running great, more power, cooler, better egt spread

 

Had a few reething issues with plug leads working off and tailoring cooling ducts. Oil a little cool and new waxstat to be installed.

 

Re fuel flow, with new low pressure sensor fitted, saw variable fuel pressure, jumping around and setting off low press alarms. No leaning under full flow but did drop down below 1 psi often. Stable at high flows though

 

Fitted higher press spring, everything got worse, still variable but over wider range going both high and low pressure limits.

 

After watching closely it seems in cruise that needle shuts and opens, doesnt sit in mid position so pressure jumps around. More pressure doesnt help........pretty much what Ian said.

 

So old spring going back in and alarm limits changed to suit

 

 

[Downunder]

Not involved with jab or camit engines personally but as pressure =resistance to flow.

 

If a carb was using just about all a pump could pump, volume wise, I would expect pressure to be low.

 

The pump is doing its job and fuel is flowing freely to the wide open float needle valve.

 

As the need for fuel reduces at lower rpm, the floats raise and restrict the flow of fuel into the carb.

 

This restriction and loss of flow causes an increase in pressure.

 

 

[facthunter]

A system is expected to flow fuel at a rate well above maximum expected. I don't know the exact figure but in a basic (crude or gravity) system it would be a higher % because it's more imprecise. It's rate rather than pressure, that you are looking at.

 

The top entry float set up is the best but too much pressure is not desired. The float needle should meter well with the level pretty constant over the operating range but naturally to get the higher flow it will be sitting lower at high flow rates. Check pump flow rate.. Nev