jab 8 cylinder

[poteroo]

We have had 2 RV9A's built with the Jab 8 cylinder, and both have since been re-engine with either an 0-320 or a 0-360 Lycoming EXP version. I understand that they are now both in use in crayfishing boats.

 

I helped with the Phase 1 flyoffs for both. Yes, once you got them running - nice and smooth. But 180HP.....not at sane RPMs anyway. Managing temperature was an issue, as was the ignition system. Wooden props and rain? Couple of unscheduled paddock landings - which probably never made it to ATSB much less RAAus!

 

Perhaps these engines could have been refined and a fit found for them in EXP aircraft: but it seems to me that they were quietly abandoned.

 

As van Grunsven, (the MAN), has said on many occasions 'the best alternative engine for our RV's is a Lycoming'

 

 

happy days,

 

 

[Mike Borgelt]

Why?Just look at it- that is enough for me. It is a visual feast of billet alloy, tech but old school.

 

 

Besides its looks, it should be a lot lighter as a package and sounds lovely, smoother and is not a lycosaurus .

 

It also has a smaller frontal area, so would be great for something real slick and quick.

 

General characteristics

 

• Type: Flat-8
   
   
  
• Bore: 97.5 mm (3.84 in)
   
   
  
• Stroke: 85.0 mm (3.346 in)
   
   
  
• Displacement: 5,077 cm³ (310 in³)
   
   
  
• Length: 960 mm (37.79 in)
   
   
  
• Width: 638 mm (25.12 in)
   
   
  
• Height: 445 mm (17.54 in)
   
   
  

 

 

 

 

 

A Lycoming O-320 A weighs 268 pounds dry or 123 Kg. Not sure what that includes but weight difference not a great issue.

 

I've flown that RV7A even some time logged as PIC when the owner's AFR had lapsed and he wanted some practice to get up to speed. Engine is very smooth and willing but then, in my experience all the Jabs are. I've flown every type of them. The 1600, 2200, 3300 and the 8 cylinder 5100.

 

One thing to remember is that the Jab engines are NOT low stress lazy engines. They put out about as much HP per cubic inch as the maximum considered wise for air cooled engines and rev higher than most aero engines. May be the cause of cooling issues and CHT limits are MUCH lower on Jabs than Lycomings. Ability to remove heat by conduction depends on temperature difference between cooling air and cylinder temp so you need a LOT more air for the Jab per horsepower.

 

As for not being a Lycosaurus, there's nothing wrong with those engines. Put lightweight starter, lightweight alternator, dual electronic ignition and fuel injection and then tell me where you want to save some weight. You can't except by going to a carbon or magnesium sump (available from ECI). There's nothing like 80 years of development for improving reliability. If you get one of the clones from Superior or ECI etc you'll get the benefit of some design improvements done by people who have overhauled thousands of them.

 

I'll stick with my O-320A2B for now but the CAMIT engine looked pretty good to me as a fixed and improved Jab. A nice little two seat EXPERIMENTAL twin with CAMIT 6 cylinder engines would be great. Like a Twin BD-4 for example.

 

I did tell Rod Stiff when they were considering the Jab 8 that he should build a 10 cylinder two row radial from Jab bits. Think of one of those in front of an RV or our BD-4.

[spacesailor]

Our local drag-car engine builder pushes his motor to:

 

17,000 RPM: (red line)

 

V8 of course,4 cams 24 valves, and a super sized super-charger.

 

Used to say "It's got 1,000hp, then tells " that the Dyno gauge only went to that figure".

 

Home made

 

spacesailor

 

 

[Shortfielder]

The Jabiru 5100 from the RV is for sale on the gumbo tree for $12,800 with some type of composite prop. It has run only 38 hours in 10 years !!! Deal or no deal...target drone for the professionals at Amberley or ideal homebuilt power plant?