fly_tornado Posted April 8, 2015 Share Posted April 8, 2015 If you want liquid cooled heads, why not buy a D-motor? bound to work out of the box, no problems, direct drive, FADEC, set and forget, turn the key and go. Fits on a jababoreu mount 1 Link to comment Share on other sites More sharing options...
gandalph Posted April 8, 2015 Share Posted April 8, 2015 1 1 1 Link to comment Share on other sites More sharing options...
hyundai Posted April 8, 2015 Share Posted April 8, 2015 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 Rotax and vw have xflow heads and they are very reliable engines. So how do Rotax do there heads xflow and water cooled. You say we are considering a engine who are we. Link to comment Share on other sites More sharing options...
hyundai Posted April 8, 2015 Share Posted April 8, 2015 If you want liquid cooled heads, why not buy a D-motor? bound to work out of the box, no problems, direct drive, FADEC, set and forget, turn the key and go. Fits on a jababoreu mount The D motor is very old school, side valve, who know,s it may be a very good engine. Side valve engines stopped being Made 50-60 years ago. Link to comment Share on other sites More sharing options...
skeptic36 Posted April 8, 2015 Share Posted April 8, 2015 : the orings still wear out or flatten or soften up, Are you using Viton O rings? I have used them in a hydraulic application and they increased the maintenance interval ten fold. 1 Link to comment Share on other sites More sharing options...
Kai Lyche Posted April 8, 2015 Share Posted April 8, 2015 Viton- yes, of course! I have a feeling the problem is not so much the orings: it´s more their installation. In order to seal properly they are made a VERY tight fit: so tight in fact that I think they get damaged during the installation process when the rocker shaft with the installed oring is inserted into the head. A little material is shaved off the oring surface. The manual says to install the shaft with "a twisting motion". Maybe I am not twisting enough :-( Link to comment Share on other sites More sharing options...
hyundai Posted April 8, 2015 Share Posted April 8, 2015 I for one am one happy user of the LCH´s on my (previous broad finned head) mech lifter 2200A. From the production # it is evident that my heads were manufactured sometime in late 2013. I was forced to make a choice between new aircooled narrow finned Jab heads and LCH when I due to plain ignorance overheated my two rear heads during ground running and they went "plastic".Pricewise the LCH conversion kit from Rotec won hands down, as it turned out I would have to substitute my heads with the newer narrow finned ones. Another reason for making this swap was an intense desire to reduce the possibility of detonation. A "happy user" does not imply that everything was initially plain sailing with these heads. I went through the first ordeal when I test pressurized the cooling system: the connector banjo´s on top of the heads refused to seal properly. I am embarrassed to admit that it took a while before I discovered that I had installed the banjos upside down :-( Things perked up after this! Still with comparatively few hours on the LCHs (apprx 50), mainly due to dismal winter weather (I HATE those stories of beautidul flying weather that always seems to prevail both Down Under and in the US), the next issue was lubeoil leakage due to worn o-rings on the rocker shafts. It turns out that center groove for the 1/4" capscrew intended to lock the rocker shafts in place, is too deep: the shafts were oscillating along with the rockers and could not be kept still. Substituting the capscrews with others having an unthreaded part, solved this- but not the entire oil leak: the orings still wear out or flatten or soften up, or whatever. Presently the leak is just annoying and I have a program going trying to introduce some super sealant as well in the oring grooves. If that does not help I will substitute the shafts with 12mm diam close tolerance bolts, using bolt head and nut as a positive sealing surface. BUT the heads are cooling as advertized. Very seldom I have as much as 90C on the cooling liquid and 120C on the cht. A far cry indeed from the previous 170C on the aircooled heads. Well it's good to read that another LCH owner is happy with the temps but unhappy with oil leaks, you say your rocker shafts are turning there is only a grove on one side of the shaft so it is not possible to turn. Link to comment Share on other sites More sharing options...
facthunter Posted April 9, 2015 Share Posted April 9, 2015 It's easy to damage an "O" ring when installing. You could make a tool for holding it clear of the sharp edge easily. Just a bush with a gradual lead in on the inside bore. Similar to some rapid instal piston ring compressors. Non adjustable, fixed size A bit of grease and a slight twist.. Nev 1 1 Link to comment Share on other sites More sharing options...
kasper Posted April 9, 2015 Share Posted April 9, 2015 The D motor is very old school, side valve, who know,s it may be a very good engine. Side valve engines stopped being Made 50-60 years ago. But if you are after a direct drive engine running in the range of the props we use then a side valve engine disadvantages over OHV rapidly disappear. Its a nice engine from what I have seen of them flying in the UK and it really does weigh installed what they say it does ... an installed weight of the Jab or R912 is not even close to the advertised 'weights'. Still a very expensive engine but its an option. 1 4 Link to comment Share on other sites More sharing options...
AVOCET Posted April 9, 2015 Share Posted April 9, 2015 Some one should make a side valve liqid cooled jab head , Probly not as crazy as it sounds ! Mike , Ps , "i thunk of it first ", ( line out of O brother where art tho .) Mike 1 1 Link to comment Share on other sites More sharing options...
Geoff13 Posted April 9, 2015 Share Posted April 9, 2015 Some one should make a side valve liqid cooled jab head , Probly not as crazy as it sounds !Mike , Ps , "i thunk of it first ", ( line out of O brother where art tho .) Mike And they could put a whole new bottom end under it, fuel inject it, make it about 10kgs lighter and call it a D Motor. Probably not as crazy as it sounds either. Ps, "i thunk of that one first" 1 Link to comment Share on other sites More sharing options...
bexrbetter Posted April 9, 2015 Share Posted April 9, 2015 The D motor is very old school, side valve, who know,s it may be a very good engine. The D-Motor performs a function, it however does that no better or cheaper than other manufacturers while needing to navigate around the bigotry and bias towards being a side valve engine - so the score ends up a bit on the negative side, a score of 'D' maybe. Side valve engines stopped being Made 50-60 years ago. Side valve motors have never stopped being made. There's some schools of thought about the use of air cooled, pushrod engines out there as well, and it's not pretty. I know Rotax history quite well, they are a leading engine technology company and I can just imagine the engineers at the meeting given the parameters for an aircraft engine, they must have thought it was April 1st. Link to comment Share on other sites More sharing options...
fly_tornado Posted April 9, 2015 Share Posted April 9, 2015 There are millions of side valve engines thanks to Briggs and Stratton. The "L head" are a good design suited for a low revving, high torque arrangement. 1 Link to comment Share on other sites More sharing options...
facthunter Posted April 9, 2015 Share Posted April 9, 2015 Their main attribute is low height.( Compact). Their shortcomings are bore distortion due to proximity of exhaust port and poor breathing due to gasflow impediments and the lack of high compression ratios being practical. Nev 2 Link to comment Share on other sites More sharing options...
hyundai Posted April 9, 2015 Share Posted April 9, 2015 There are millions of side valve engines thanks to Briggs and Stratton. The "L head" are a good design suited for a low revving, high torque arrangement. O yes B/S they come into the question Of aviation no I don't think so. Every one must sleep with the light on. Link to comment Share on other sites More sharing options...
kasper Posted April 9, 2015 Share Posted April 9, 2015 O yes B/S they come into the question Of aviation no I don't think so. Every one must sleep with the light on. Well not the B&S engine themselves BUT read through the other posts: Low mass Compact size Lower compression Lower reving/High torque applications Can you see how a direct drive might work for an aircraft ... particularly the ultralight end of aircraft? Dmotor does work. Yes, it's not 'sophisticated' mechanically and its not the most ultra efficient high power engine but the 4 pot lf26 is putting out more than a standard 80 HP 912 (93 max 88 continuous) at much the same prop RPM but with a lovely flat torque curve that make prop selection easier and it weighs less to boot. Add to that the fuel injection and less spiderwork plumbing and it looks pretty good to me - particularly as the fuel injected 912is is really poisonously expensive and the electrics box is enormous. 1 2 Link to comment Share on other sites More sharing options...
fly_tornado Posted April 9, 2015 Share Posted April 9, 2015 Vastly more successful than Jabiru by any measure Link to comment Share on other sites More sharing options...
bexrbetter Posted April 9, 2015 Share Posted April 9, 2015 running in the range of the props we use then a side valve engine disadvantages over OHV rapidly disappear.Its a nice engine from what I have seen This is nicer IMO http://www.donovanengineering.com/Blocks/ModelDBlock.html It's a modern version of the A-model Ford engine for hot rodders with vast improvements of course such as 5 main bearing crank. Very expensive, well not in terms of aircraft engines, but of course, limited production as well. Some design limitations because they wanted to keep it very A-model of course, that was the point, but these guys should go a step further and make aircraft versions from a clean sheet using it as a foundation. For those who haven't heard of Donovan, very famous in the USA, they have been building 10,000hp drag racing blocks and components for a very long time and are at the top of the tree. The D-Motor is a strange one to me, IMO they really stuffed it up. For example, some of you know a deficit of flat heads is large combustion surface area robbing heat that should be pushing the piston down, so what did D-Motor do? Gave their engine a huge oversquare bore to increase that loss. I understand they wanted to make the engine as narrow as possible but they were way too fixed on that I believe and lost a lot of potential. There are other port and head design considerations that baffle me, apparently they just copied some 1940's design and didn't bother to consult people in the 21st century. Could have been so much better. 'D' for effort. Vastly more successful than Jabiru by any measure Yeah, Jabiru is cowering with their 9000 engines sold compared to D-Motor's 90 (if that). 3 Link to comment Share on other sites More sharing options...
facthunter Posted April 9, 2015 Share Posted April 9, 2015 The larger surface area to volume (as you state), contributes to reduced efficiency by wasteful heat loss. The suggestion they develop more torque is NOT correct. Torque is related to gas flow where the sidevalve layout is at a distinct disadvantage as a higher compression motor will create lower intake manifold pressures and therefore more ability to move combustion gases and develop power. Low compression engines will be more smooth at very low revs (assuming there is plenty of flywheel), giving the impression of lugging well. It's not relevent whether it is SV or OHV in this respect. The larger and odd shaped combustion chamber is not conducive to good burning characteristics either for the fuel mix. Heating of the cylinder near the exhaust port is very unhelpfull as it distorts and doesn't seal as well at high outputs. This affects ring sealing and also valve seat stability dimensionally. Nev 1 1 Link to comment Share on other sites More sharing options...
gandalph Posted April 9, 2015 Share Posted April 9, 2015 Vastly more successful than Jabiru by any measure I'm curious to see what metrics you use to support that assertion FT. Care to give it a go? Or are you just going to continue to sit back and throw carp? Same old, same old. 1 Link to comment Share on other sites More sharing options...
AVOCET Posted April 9, 2015 Share Posted April 9, 2015 And they could put a whole new bottom end under it, fuel inject it, make it about 10kgs lighter and call it a D Motor. Probably not as crazy as it sounds either.Ps, "i thunk of that one first" Get rid of the sump , replace with flat plate , separate oil tank , flip the motor upside down , run the exhaust and intake to the top , For my pusher application on the Avocet . Its already fuel / inj. The only thing thats stopping me thus far is the return oil flow down the pushrod tubes . Definably wont be a Jabiru after this ! Mike Link to comment Share on other sites More sharing options...
fly_tornado Posted April 9, 2015 Share Posted April 9, 2015 How many OEMs use Jabiru gandy? Link to comment Share on other sites More sharing options...
Geoff13 Posted April 10, 2015 Share Posted April 10, 2015 Get rid of the sump , replace with flat plate , separate oil tank , flip the motor upside down , run the exhaust and intake to the top ,For my pusher application on the Avocet . Its already fuel / inj. The only thing thats stopping me thus far is the return oil flow down the pushrod tubes . Definably wont be a Jabiru after this ! Mike OK I'll bite, why does it need to be inverted? What am I missing? It already fits a Jab mount and it has a dry sump. Link to comment Share on other sites More sharing options...
gandalph Posted April 10, 2015 Share Posted April 10, 2015 How many OEMs use Jabiru gandy? Mate, answering a question with a question, you'll need to do better than that. You're the one that made the statement that the D motor is "vastly superior" to Jabiru's, not me. I'm not knocking the D, I'm just inviting you to justify your assertion. How 'bout it? Link to comment Share on other sites More sharing options...
Geoff13 Posted April 10, 2015 Share Posted April 10, 2015 I'm curious to see what metrics you use to support that assertion FT. Care to give it a go? Or are you just going to continue to sit back and throw carp?Same old, same old. Google "D motor engine failure" and check results, then Google "Jabiru engine failure" and check results Now before anyone says but there are buggar all flying, that may be correct but to date the are "0" reported failures. Ps. I can't believe that I just made a post in defence of one of the trolls outrageous statements. Link to comment Share on other sites More sharing options...
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