Rotec Radial

[Guest Lucifer]

For those interested in the classic look and sound of an aircooled radial engine, then you may wish to look at one of the Rotec radial engines - the 7-cylinder and 9-cylinder.

 

We are setting up as the Queensland agency, so any technical questions, sales or service advice - let me know.

 

Also check out the website - http://www.rotecradialengines.com/index.htm

 

Cheers

 

martin

 

 

[Guest spacewalker]

Very impressive !

 

 

[dazza 38]

i loved the renagade spirit photo, it finishes off the aircraft nicely.

 

 

[Guest check-in]

I want one, but it would not fit the Sonex. However, ROTEC's fuel injection system for Jabiru engines looks like it will be good. Anyone out there tried it yet?

 

 

[Guest spacewalker]

Rotec Throttle Body Injection

 

Definitely ! There a number of people now running the Rotec TBI on Jabiru engines with good results, not the least of which is the ability to control the mixture in-flight.

 

Although my personal experience is with the TBI on a radial, I have also supplied them for Lycoming and Subaru installations. More info should be forthcoming from Jabiru themselves in the near future.

 

I am happy to answer any queries and supply units at a good price if anyone is interested.

 

Cheers

 

Martin

 

 

[Yenn]

I will be looking closely at the Rotec TBI for use with a Jab 6 cylinder engine. I just need a little more power than the 120 advertised HP for the RV4 I shall be building.

 

 

[Guest spacewalker]

Well, here's another thought. Why not use the 150 hp Rotec in the RV4 ? Weight and hp are perfect, all you need is to round up the cowling like I did on the Spacewalker...

 

Martin

 

 

[Guest Maj Millard]

Lucifer, Congrats on your dealership. I would like to share with you the 'word around the hills' so to speak from up this way on the Rotec radial, with one recent report from close to the factory, a gentleman who is familiar with the owners. I have been watching them closely as I love a round engine, having worked on many over the years as an engine rated engineer. They do look great in bikes also of course. The Jab injector unit looks good also, and anything that might improve the longevity and/or reliability of Jaburu engines I'm sure would be welcome. This unit is not of course a "fuel injection unit" or EFI as mentioned, but more a fuel throttle body similar to the Ellison throttle body, which has been around for some time. I would imagine it is more of a simple fuel metering unit, to use in place of a carb, and does not inject fuel individually into each cylinder like true 'fuel injection'. As you may know carbs used to be this simple in the begining, before someone decided that carbs should be as complicated and troublesome, as you can make them !.

 

Has the cylinder hold down bolts been up graded yet ?....my information tells me this is a great engine ideal for certain 'period looking' aircraft, but that they are real thirsty compared to others on the market, are heavy, and can't really be considered as a serious, and reliable cross country engine yet, if you want to go somewhere. Your comments please..............................................

 

 

[facthunter]

Radial as in ROTEC.

 

I have kept an eye on these engines since they were first produced. Don't the weights end up a little high? even though both engines have reduction gearing which should be an advantage.

 

I don't think any more RV's are going on the RAAus register as they require light build to make it. Also a cowl would reduce cooling drag . Has anyone built such an item?and would there be comparison figures with and without.. Nev..

 

 

[Guest spacewalker]

Hi guys,

 

Some issues here that deserve comment. The cylinder hold down studs were upgraded a long time ago, after one instance of a cylinder coming loose, so lets put that one to bed.

 

As for being thirsty, I wonder compared to what. Any draggy airframe, such as what the majority of Rotecs are going into, would be 'thirsty' by virtue of their speed/ power required. All 4-stroke petrol engines fall into a narrow band of fuel usage. My Lycoming-powered RV burns 24 litres/hr. A Rotax 912 (80hp) would burn 12 ltrs/hr. Which is the thirstier when the RV cruises at 150 kts and my old Karatoo cruised at 75 kts ? They both go the same distance on the same amount of fuel, but one is certainly more efficient. I believe a 150 hp Rotec with a nice cowl would be able to perform as good (and better in climb) as a Lycoming O-320 in an RV-4. Or put it this way, which is 'thirstier' a 912 powered Storch or a 912-powered KR-2 ?

 

Any arguement over a sleek in-line engine having less drag than a bulbous radial cowl was disproved many times over during the war.

 

As for more RV's going onto the RAA register, my understanding is that provided they meet the regulations, there is no problem. The problem occurs when they become registered RAA and the builder adds back in the stuff he took out to meet the regs....they just screw it for the rest of us.

 

I hope I have answered your queries. If not, just let me know

 

Best Rgds

 

Martin

 

 

[Methusala]

This one for Yenn!

 

Mate, I have flown 550 hrs using an EFI Revmaster then Aeropower VW conversion. I got the hardware (Bosch Jetronic) from a wrecked 1600TS engine and used a Haltech F9 programmable computer to drive it. Very successful with no alternate air system required. It is a very good way to distribute even mixture to all cylinders. It even has a reostat (10k/Ohm variable resistance) that allows manual leaning/enrichment 10% either side of what the program delivers. Point is that I doubt that any greater power was delivered than using carby. We also had a Subaru EA 81 with a Haltech F9 and these units have a very good name among the duff duff crowd. No great power increase though. Just for the record, I know that it is popular to believe that a magic formula chip or whatever will give untold power. Be sceptical of such claims.

 

Kind regards, Don

 

 

[Guest spacewalker]

I fully agree Don. Very little evidence that EFI can provide any increase in power over a good carb set up. The ideal is to have one carb per cylinder as on motorcycles, but cost can be more than EFI. The real benefit of EFI is helping to keep an engine tractable at low revs where a hot cam and big carbs can make for rough idle and lousy bottom end performance, or in recent times, to get vehicles past emission standards.

 

If we are talking say, Bing versus Rotec TBI, then I would hazard a guess that there may be little difference in performance, though in my experience the TBI often provides a few more static rpm. The benefit is in having a manual mixture control and being able to lean off in cruise. On the other hand, the Bing by virtue of its Constant Depression design automatically compensates for altitude, so is simpler in that respect.

 

Cheers

 

Martin

 

 

[Guest Maj Millard]

Don't believe this is an EFI set-up we are talking about here folks, more a simple throttle-body fuel metering set up, as a replacement for a carb. Doubt if there would be much change in performance really. Similiar one's have been around for a while, so it's nothing new, and they haven't really set the world on fire in past years. They tend to have a few less parts than a carb, and are therefore simpler to some, but only those who insist in messing around with their carbs unnecessarily, in the first place.........

 

 

[Guest spacewalker]

Correcto Mondo ! The TBI unit is another form of flat-slide carb and should not be confused with a pressure injection system. However, by its very design it does not rely on a restrictive venturi and/or throttle plate hence can flow more air/fuel, therefore allow the engine to make a little more power.

 

Cheers

 

Marty

 

 

[Guest Maj Millard]

With the emphases on 'little more power' ??....besides they do have a throttle plate, it's just in a changed form...nothing world-changing or new here, they been around since the dawn of aviation...........................................

 

 

[Guest spacewalker]

Well, not entirely. A throttle plate by its very nature will restrict airflow - that's what it is for - but a butterfly plate like on a Bing sits in the airstream at all throttle positions, even at Wide Open Throttle. A slide-type or barrel-type throttle is completely out of the airflow at WOT and therefore allowing more air/fuel mixture to pass, hence the potential for a little more power at take-off....

 

Cheers

 

Marty

 

 

[Guest Qwerty]

FYI the presence of a butterfly valve in the air stream at WOT has no PRACTICAL impact on efficiency of flow of the air/mixture. This is a simple fact of physics. If you don't believe me, grab a text book on thermodynamics and do the calcs, you will surprise yourself.

 

Have a Good Chrissy, Qwerty

 

 

[Guest spacewalker]

Thanks Qwerty, I am prepared to stand corrected. It certainly goes against simple logic. Wonder how many tuners worked tirelessly to eliminate such restrictions, all to no avail.

 

I would love to learn more, so can you provide me with a link to the info,

 

Cheers

 

Marty ( never stop learning)

 

 

[Guest Maj Millard]

Being that most aircraft fuel induction devices (carbs or whatever) actually spend about 30 seconds to a minute at flat-out full throttle each flight, makes this almost a muted point anyway doesn't it ? .

 

 

[Guest Qwerty]

Spacewalker, I don't have a link. I studied thermodynamics, including supersonic flow, hydraulics and a heap of other stuff. I have text books somewhere but It would take forever to find them. It shouldn't be difficult to find the info.

 

Maj, You are right about only using full power for 3 or 4 min, but a huge amount of effort goes into getting all the power that's there. even 1% additional power is worth chasing, the throttle butterfly won't have anything like that sort of impact on output.

 

Happy Christmas, Right now, I'm taking a few minutes quiet time away from the mob. Cheers, Qwerty

 

 

[Guest spacewalker]

Ok, I will do a bit of research and see what I find.

 

I can agree that chasing the last little bit of power from an aircraft engine is not what it is all about. On the other hand, maximising efficiency is certainly a worthwhile exercise.

 

I figure we have flogged this horse long enough. Enjoy what's left of Xmas and hope to catch up at a fly-in sometime. Maybe Temora at Easter ?

 

Cheers

 

Martin