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VFR Pilot

Liquid cooled heads

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I was surprised Rotec did not copy jab heads they have a coller on the guide so the guide can't move down, but that does not mean you can do shoddy work over drill the guide holes and still fit the guides in. I would never buy aftermarket parts of these small so called company,s I have seen Camit factory so professional trust them 100%.

 

 

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I have set of LCH heads on, and no oil or water leaks, in fact it's taken me 15 months to redo the mod to the plane, flaps, canopy, covering etcand the thing I never had to pull apart or tamper with was the motor, and I have a water pressure gauge fitted into the system, and it kept a pressure right through the 15 months.

 

In winter it was down around 4lbs & in summer it would be around the 7lbs mark, the only water

 

I lost was from the overflow bottle when we turned the fuselage over to cover the bottom.

 

I will agree that they were a bugger to fit, to the point where I elongated the pipes "a Bit" where they pass between the pushrods and took a foofteenth of the sides of the pusrod cover pipes

 

so I got a space and a good seal with the O rings.

 

I used a radiator that was the close to the size of a Rotax 912, but its a duel core and with a 1 Litre header tank as well, I can't keep any heat in the water, ( My highest reading was 45 degrees C,) so it looks like I might have to cover up some of the frontal area.

 

I have a quad CHT (Left over from the air cooled days) and from under the plug they get to around 120 - 130 on climb then settle to 80 -95 on cruise.

Hi mike how many hours have you done with LCH on I can tell you for sure when you remove the heads those lower water pipes will be seized in and no they never leaked water. Yes no heating problems for me but I will never fit them again to much trouble.

 

 

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Sounds like a case of tradesman blaming their tools , when in fact , the poor old tool just carnt get it right !

 

 

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CHT gauge how can I check if it reading right I put the end in boiling water it only showed 100 deg. Maybe it does not register in water the right way. I would think it would read 212 deg F.

 

 

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Guest Andys@coffs

I presume the thermocouple is a K type, in which case the voltage it produces at ambient should be circa 1.2mV to 1.6mV (20C to 30C) at 100C it should produce 4.5mV

 

These are very small voltages and you will likely need a DVM that has a thermocouple input (and usually comes with a thermocouple probe) Jaycar has these from about $40 and if you buy a cheapie and need a reference thermocouple, they are available (type K) with an appropriate plug for about $12.... I seem to recall mine cost about $60 and came with a thermocouple and did just about all electronic components measurements (V/R/L/C/Transistor Hfe and Temperature).

 

As I said very small voltages so any dodgy connections will destroy the effect. Automotive spade connectors for crimping etc are imho crap and I personally prefer to solder, however understand that you are creating another junction in doing that (as you are with crimping) if the 2 materials being joined are not the same metallic content. there is plenty of guidance material on the net about extending thermocouples and what to do and what not to do.....

 

I personally am not so interested in actual measurements, in flight, but rather am looking for changes in flight....I recall that the very original temp gauges that were fitted didn't even have markings for voltage/or temp other than something that said each increment on the gauge was X degrees...again your looking for delta's in flight, but you do need to know they are working accurately to start with, which is why a DVM with a reference thermocouple (known good) can be used to fault find, your engine thermocouple, or your dash meter, or any thermocouple extensions (avoid if at all possible)

 

Andy

 

 

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The LCH are cast. The others are machined from billett material. Castings if not elaborately done can be porous. This may/will cause leakage of oil and possible coolant displacement by combustion gases, dependent on where it occurs. Nev

 

 

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Fo

 

The LCH are cast. The others are machined from billett material. Castings if not elaborately done can be porous. This may/will cause leakage of oil and possible coolant displacement by combustion gases, dependent on where it occurs. Nev

For example: 1054182119_PorosityinCastLCheadNatfly2014.jpg.41aac05de32f9a18f2e4e8930e41d1b0.jpg

 

 

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Yes I believe Rotec have changed there way of making these LCHeads but that does not help me. If he would have done more stringent testing instead of just running the engine for a few hours. He should have come to the party and gave me 4 new heads?????. But at the end of the day I would not have anything from his shop on my aircraft.

 

The later ones are not machined fron a billet like jab heads. Cheers Nev

 

 

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I personally wouldn't touch anything from that company

Landing is mandatory ....... I like that quote,

 

 

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Landing is mandatory ....... I like that quote,

 

I was thinking last night would it be great if CAMIT cam up with cross flow heads for jabiru engines that is intake

 

On the top of the heads not from under as they are now. Would alimenate different cyl temps I am sure? I know Camit would be the company to make them. They would sell like hot cakes.

 

 

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The best place for the carburetter(s) is under the motor for safety reasons. With direct or port injection it wouldn't matter. The actual cross flow does not do much for heat variation, but designing more fins around the hot parts and flowing cooling air correctly, does. Most of the engines we are considering don't have extra cooling around the exhaust side of the heads and are symmetrical pretty much as far as ports are concerned.

 

It would be practically impossible to billett machine an LCH as you can't do the water jackets without subsequent welding or an extra gasket, or join.

 

Most aero air cooled engine cylinder heads are cast with some being forged. This is really high quality work with metal dies and vacuum casting techniques. High cost and prohibitive for low volume. You get what you pay for. Nev

 

 

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If you want liquid cooled heads, why not buy a Rotax? bound to work out of the box, no problems, set and forget, turn the key and go.

 

 

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A correctly designed aircooled motor is satisfactory and simpler. No water pump, radiators hoses etc. There's no vehicle more suited to air cooling than an aeroplane.

 

With liquid cooling there are advantages for things like glider towing, crop dusting and para drops. Nothing is absolute in all this. Nev

 

 

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If you want liquid cooled heads, why not buy a Rotax? bound to work out of the box, no problems, set and forget, turn the key and go.

Well there's always the problem of engineering approval, fitting, plumbing, weight & balance......

 

 

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Lack of power for many, absurd cost, expensive parts...........

 

 

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...and that horrible clunk when they shut down.

But it does seem to be mainly when I turn the key off:surrender:

 

Lol couldn't help myself OK:victory:

 

 

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Guest Andys@coffs
Well there's always the problem of engineering approval, fitting, plumbing, weight & balance......

And assuming you need all of those with the rotax then which of those can be avoided with the alternate?

 

 

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And assuming you need all of those with the rotax then which of those can be avoided with the alternate?

Well , if I changed the word "fitting" to " fettling" I would suggest almost all of them could be avoided.

 

The original post in this thread referred to a problem fitting LC heads to a Jabiru engine and FT asked why not fit Rotax, I Would suggest that replacing a jab engine with a jab engine (like for like) would need none of those steps I mentioned apart from , obviously, fitting the thing. As a cautious person, I would check that the plumbing for air, fuel and exhaust remained suitable and the w&b remained as before and complete all necessary paperwork.

 

 

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Guest Andys@coffs

Which was what I was getting at, LCH or rotax, both are not minor and imho all those things are really needed for both. I do accept that the engineering analysis needed for the rotax is more substantial, but the LCH isn't imho plug and play.

 

 

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Which was what I was getting at, LCH or rotax, both are not minor and imho all those things are really needed for both. I do accept that the engineering analysis needed for the rotax is more substantial, but the LCH isn't imho plug and play.

Ah. Sorry, I misread your meaning of alternate. I thought you meant it in the wider sense of an alt engine. My oops.

 

 

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