Jabiru turbo

[winsor68]

 

• Jabiru turbo engine walk around and running with "draw through" with carb. I will try a Aerocarb 45mm.
   
   
  
  Posted by Winsor68 from Youtube... this poster has some good aviation engine videos on his channel.
   
   
  

 

 

 

 

 

 

[Staunch]

Can someone tell me if its possible to turbocharge a jab 3300?

 

I'm sure it is but have not been able to find any information on it.

 

Any assistance on the issue is greatly appreciated.

 

 

[turboplanner]

Can someone tell me if its possible to turbocharge a jab 3300?

It's possible to turbocharge any engine.

 

The increased pressure in the cylinders will produce more power, but this pressure substantially increases the loads on conrod, big end and main bearings along with pistons, conrods, crankshafts........and through bolts.

 

It's normal for a manufacturer to increase the size of all these components for a turbo engine.

 

If the base engine is overdesigned in these components retrofit turbocharging will work well provided the boost is correctly designed.

 

I wouldn't turbocharge a Jabiru engine without redesigning the bottom end first.

 

 

[Admin]

I was fixing the video in the opening post at the same time you posted the video Tomo so I removed your post

 

 

[Guest Maj Millard]

Quote turboplanner, "It's possible to turbocharge any engine."

 

Not exactly correct Turbo, the compression ratio of the engine needs to be low , generally below 9:1 or less

 

for turbocharging. This is why the Rotax 914 is the 80hp engine with a turbo on it. The 100hp 912 by comparison has a 10;1 compression ratio so was unsuitable.

 

The P&W 985 radial as used in the Beaver and many others has an integral supercharger run off the back of the crank but the compression ration is a low 8:1 or so.

 

Tubocharging or supercharging high compression engines can cause great heat generation due to possible pre-ignition or detonation leading to expensive engine damage..............................................................Maj...

 

 

[facthunter]

. A turbocharger will run as a jet engine, if you just burn fuel in the middle of it.

 

Any engine can be supercharged and the power will increase because you are burning more fuel (+ oxidant) . The efficiency won't normally increase, ( infact it may decrease, There can be some exceptions) so more HEAT will have to be dissipated. The Jabiru has trouble in that area already, particularly exhaust valves. This is one of the last engines I would try to supercharge. You won't be able to cool it. In my opinion a total waste of effort, unlees you want a short burst of power for some particular reason, and don't need reliability. Nev

 

 

[Gnarly Gnu]

unless you want a short burst of power for some particular reason, and don't need reliability.

And that is what the Jab NOx system is for.

 

 

[Thirsty]

Turbocharging isn't necessarily about more power. It is used also to keep making the same power as you gain altitude. I agree though that turboing the jab engine isn't really the best option. Bolt on a Subaru EJ20T if you want lots of turbo power :)

 

 

[Staunch]

Thank you for all your comments.

 

I should have included the fact that I wanted to put the jab 3300 on a sonex.

 

have not been able to find any specific info on turbo chargimg the 3300.

 

Jab 2200's have successfuly been modified, along with the aerovee 2.1. Sonex now claims that the aerovee (80hp) is now 100HP after charging. http://www.eaavideo.org/video.aspx?v=1021202823001

 

In fact there is an aerovee for sale, modified to 125HP. This one is very cool.

 

http://www.barnstormers.com/Light-Sport, Sonex Classifieds.htm

 

If I had to choose between the two I'd go for the aerovee given the success of the engine over rcent years and the fact that modified componentry is also available though Edge Peformance.

 

But my preferred choice is still the 3300. Since the 2200 has been modified, surely the 3300 is a contender.

 

I just have to work out how?

 

Any further thoughts?

 

 

[Staunch]

Here's some online commentary on figures achieved on a jab 2200. Still no news w.r.t TBO.

 

http://forums.matronics.com/viewtopic.php?t=58847&highlight=turbo

 

 

[Bandit12]

It is doable - but debateable obviously. You will have to look at lowering the compression, preferably with suitably designed pistons (expensive) or perhaps a thicker headgasket (custom copper one?). I would also want to know what my manifold pressure is.

 

 

[turboplanner]

The basic principles don't alter. An engine which unexpectedly comes apart at the cylinder head pressures is was designed with will come apart faster if you shave the head, put in high compression pistons or turbocharge it.

 

It's simple maths, known to their cost by just about every race engine builder. I could get 125 hp out of a Jab just by some flow work, valve change, head work, and timing work including valve overlap, but there'd be a big bang sooner rather than later. Even 20% power increase puts a huge extra load on components.

 

Once you go down the increased power path it's amazing how the pressure increases on the engine components, including through bolts tearing the threads out of casings. I remember one guy drilling all the components and fitting four 19 mm hi tensile bolts which clamped from the bottom of the lower casing to the top of the head before he was able to control separation.

 

So beware of people who offer these conversions. The dyno figures are usually true, but you pay the cost in casings, through bolts, bearings, valves and pistons, and in an aircraft you have the added risk of a forced landing in the wrong spot or at the wrong time with catastrophic consequences.

 

A better way to go is an 80 hp Jab is not enough, is to put in a 100 hp Rotax, and before the Major starts to salivate, not for the brand name, but because the engine was designed for 100 hp by engineers who designed each component, then tested it at that power.

 

 

[facthunter]

Just a comment on engine design for turbocharging. At one stage I owned a Twin Commanche that had factory fitted turbocharged Lycoming O-320's. The superchargers were only used to fly at high altitudes and didn't increased the engines maximum Horsepower. Just maintained it to a higher altitude.

 

That engine, while looking much like the "base" model O-320 was totally different inside , including oilsquirters to cool the pistons, reinforced heads and cylinders and Crankcase. ( and probably just about everything else. ) This is to only maintain the rated power to altitude, not INCREASE it. Lycoming wouldn't go the the trouble if it wasn't necessary. Nev.

 

 

[dazza 38]

Just a comment on engine design for turbocharging. At one stage I owned a Twin Commanche that had factory fitted turbocharged Lycoming O-320's. The superchargers were only used to fly at high altitudes and didn't increased the engines maximum Horsepower. Just maintained it to a higher altitude.That engine, while looking much like the "base" model O-320 was totally different inside , including oilsquirters to cool the pistons, reinforced heads and cylinders and Crankcase. ( and probably just about everything else. ) This is to only maintain the rated power to altitude, not INCREASE it. Lycoming wouldn't go the the trouble if it wasn't necessary. Nev.

Sounds like a Turbo Normalized engine set up.Would that be correct Nev?

 

 

[facthunter]

Could be the term for it. The plane was used in the Rockies ( not by me) and had an oxygen system as well. Nice set-up although the turbo's didn't get any use and that doesn't help them. I removed them and used the beefed up engines without the turbo's Nev

 

 

[Staunch]

Turbo charging a 3300 is possible, according to the notes provided by the following poster on the jab yahoo group.

 

--- In [email protected], "promod69camaro" <shawn-bishop@...> wrote:

 

>

 

>

 

>

 

>

 

> Hi,

 

>

 

> My name is Mike.

 

>

 

> I have been a long time member of this group, but do not post very often. I

 

am a mechanical engineer by trade, and used to drive a promod drag car on the

 

weekends. Due to health problems, I am not currently flying or racing, but I

 

still keep up with whats going on. I hope to be back in the saddle again soon.

 

>

 

> I have a lot of experience with alcohol injection and blown race car engines.

 

I have broken every part that can be broken at least once. With experimentation

 

and testing, I now have the engine worked out so that nothing breaks as long as

 

I take care of between race maintainence, and perform regular engine tear downs

 

to replace consumables like crank bearings, etc. It took a while to get there,

 

but I can make over 3000 hp reliably for about 6 seconds. That was the goal.

 

Drag car engines see manifold pressures over 40 psi all the time. There is no

 

reason why an aircraft engine can not be reliable with 4 to 6 lbs of boost.

 

>

 

> > I'll agree with that sentiment - boosting is fraught with problems on an

 

engine that is just holding together as it is.

 

> >

 

>

 

> I think you are wrong in stating that boosting a Jabiru engine will be nothing

 

but problems. And stating that the engine is just holding together is plain

 

wrong. You can boost that engine. You just have to know how to do it, and not

 

get carried away.

 

>

 

> > a one time small helicopter company tried turbos on some 3300s here in NZ.

 

My understanding is they lost 2 engines possibly 3 before moving on & out. Main

 

problem being too much heat.

 

>

 

> The helicopter company you are refering to is TGR Helicopter. Several years

 

ago, I have spoke in great detail with Trevor, the owner of TGR, about using

 

turbo's and fuel injection on the Jabiru engine. He said that the engine was

 

one of the best built engines he has encountered. Their problems were that they

 

needed around 200 HP continuous power. This created challenging cooling

 

problems because of the helicopter configuration. Their biggest challenge was

 

that the customers wanted the engine to be diesel powered. The engine was just

 

not the right fit for their program, but they were successful in their EFI and

 

turbocharging efforts.

 

>

 

> When I last spoke to Trevor, he said that they were going to clean up that

 

engine and display it in the main office, to demonstrate their research

 

committment to customers. I believe he told me that the engine still operates.

 

And in testing, they were able to make either 160 or 180 HP all day long. If I

 

remember right, they were running the engine at around 4000 RPM.

 

>

 

> I tried to get Trevor to sell me that engine, but he would not because of

 

liability issues. I also tried to get his engineering specs, but he was

 

reluctant to share that information as well. Just know that it has been done

 

successfully and can be done again.

 

>

 

> Someone commented that they would not have anything that did not have

 

hydraulic lifters...why?

 

>

 

> I use solid rollers in my race car because they are extremely reliable.

 

Hydraulic lifters have to pump up to operate properly. While they are very

 

reliable, they are not as rugged as a solid roller lifter. Hydraulic lifters

 

are nice for the operator because you do not have to worry about valve lash.

 

But what happens if you loose oil pressure to the lifters?

 

>

 

> Years ago, I purchased a solid lifter 3300 when I found out that Jabiru was

 

going to hydraulic lifters. I did not even have a project for the engine yet.

 

I just wanted that engine design while I could get one new. I have always

 

planned on installing EFI and a turbo on that engine. After my run in with

 

cancer, its knew it was going to be difficult and expensive to maintain a class

 

3 medical. So I purchased the engine because its light and can make reasonable

 

power while being dependable. At the time, I was thinking of building a RV9A

 

that meets the Light Sports rules. I was planning on using a turbocharged, EFI,

 

3300 Jabiru as its power plant. But lately, I have been thinking of building a

 

Lightning and hanging it on the nose of that. I am just not quite up to the

 

task of building yet. Maybe one of you will build one and let me know how it

 

goes or take me for a ride.

 

>

 

> Good luck to all of you.

 

>

 

> Signing off,

 

>

 

> Mike

 

ANY THOUGHTS!

 

 

[Staunch]

Turbo charging a 3300 is possible, according to the notes provided by the following poster on the jab yahoo group.

--- In [email protected], "promod69camaro" <shawn-bishop@...> wrote:

 

>

 

>

 

>

 

>

 

> Hi,

 

>

 

> My name is Mike.

 

>

 

> I have been a long time member of this group, but do not post very often. I

 

am a mechanical engineer by trade, and used to drive a promod drag car on the

 

weekends. Due to health problems, I am not currently flying or racing, but I

 

still keep up with whats going on. I hope to be back in the saddle again soon.

 

>

 

> I have a lot of experience with alcohol injection and blown race car engines.

 

I have broken every part that can be broken at least once. With experimentation

 

and testing, I now have the engine worked out so that nothing breaks as long as

 

I take care of between race maintainence, and perform regular engine tear downs

 

to replace consumables like crank bearings, etc. It took a while to get there,

 

but I can make over 3000 hp reliably for about 6 seconds. That was the goal.

 

Drag car engines see manifold pressures over 40 psi all the time. There is no

 

reason why an aircraft engine can not be reliable with 4 to 6 lbs of boost.

 

>

 

> > I'll agree with that sentiment - boosting is fraught with problems on an

 

engine that is just holding together as it is.

 

> >

 

>

 

> I think you are wrong in stating that boosting a Jabiru engine will be nothing

 

but problems. And stating that the engine is just holding together is plain

 

wrong. You can boost that engine. You just have to know how to do it, and not

 

get carried away.

 

>

 

> > a one time small helicopter company tried turbos on some 3300s here in NZ.

 

My understanding is they lost 2 engines possibly 3 before moving on & out. Main

 

problem being too much heat.

 

>

 

> The helicopter company you are refering to is TGR Helicopter. Several years

 

ago, I have spoke in great detail with Trevor, the owner of TGR, about using

 

turbo's and fuel injection on the Jabiru engine. He said that the engine was

 

one of the best built engines he has encountered. Their problems were that they

 

needed around 200 HP continuous power. This created challenging cooling

 

problems because of the helicopter configuration. Their biggest challenge was

 

that the customers wanted the engine to be diesel powered. The engine was just

 

not the right fit for their program, but they were successful in their EFI and

 

turbocharging efforts.

 

>

 

> When I last spoke to Trevor, he said that they were going to clean up that

 

engine and display it in the main office, to demonstrate their research

 

committment to customers. I believe he told me that the engine still operates.

 

And in testing, they were able to make either 160 or 180 HP all day long. If I

 

remember right, they were running the engine at around 4000 RPM.

 

>

 

> I tried to get Trevor to sell me that engine, but he would not because of

 

liability issues. I also tried to get his engineering specs, but he was

 

reluctant to share that information as well. Just know that it has been done

 

successfully and can be done again.

 

>

 

> Someone commented that they would not have anything that did not have

 

hydraulic lifters...why?

 

>

 

> I use solid rollers in my race car because they are extremely reliable.

 

Hydraulic lifters have to pump up to operate properly. While they are very

 

reliable, they are not as rugged as a solid roller lifter. Hydraulic lifters

 

are nice for the operator because you do not have to worry about valve lash.

 

But what happens if you loose oil pressure to the lifters?

 

>

 

> Years ago, I purchased a solid lifter 3300 when I found out that Jabiru was

 

going to hydraulic lifters. I did not even have a project for the engine yet.

 

I just wanted that engine design while I could get one new. I have always

 

planned on installing EFI and a turbo on that engine. After my run in with

 

cancer, its knew it was going to be difficult and expensive to maintain a class

 

3 medical. So I purchased the engine because its light and can make reasonable

 

power while being dependable. At the time, I was thinking of building a RV9A

 

that meets the Light Sports rules. I was planning on using a turbocharged, EFI,

 

3300 Jabiru as its power plant. But lately, I have been thinking of building a

 

Lightning and hanging it on the nose of that. I am just not quite up to the

 

task of building yet. Maybe one of you will build one and let me know how it

 

goes or take me for a ride.

 

>

 

> Good luck to all of you.

 

>

 

> Signing off,

 

>

 

> Mike

 

ANY THOUGHTS!

[Staunch]

Something I found in my search!

 

http://www.cirruspilots.org/blogs/braly/archive/2009/02/09/turbonormalizing-vs-turbocharging-understanding-the-important-differences.aspx

 

Turbonormalizing Vs Turbocharging.

 

Understanding the important differences

 

TN and TC engines share the following characteristics:

 

• Both involve compressing outside ambient air to make it available as denser air to the engine induction system so that the engine can make more power.
   
   
  
• The degree to which the air is compressed is just a matter of design choice when one decides to specify the engine and its ability to make horsepower across the normal range of desired altitudes.
   
   
  
• Any time you compress air - you make it hotter. (As discussed below - almost everybody in the early days missed the importance of intercoolers.)
   
   
  
• Both TN and TC systems use an exhaust driven turbine to drive a centrifugal compressor - at speeds that may range as high as 120,000 RPM on some units.
   
   
  
• Both TN and TC systems can use the same turbo components.
   
   
  

 

 

The TN system designer typically starts with a normally aspirated engine and asks the following question:

 

• What is the minimal number of changes one can make to this existing NA engine and still have that engine make sea level power at altitude (typically > 18,000 feet)?
   
   
  

 

 

The answer includes a laundry list like this:

 

• New exhaust system to get the exhaust to the turbo housing.
   
   
  
• Add turbo charger or two of them.
   
   
  
• Add some way to control the speed of the turbo charger - ie, a wastegate.
   
   
  
• Manual or automatic control over the wastegate?
   
   
  
• Intercooler ? Very desirable, but not absolutely mandatory.
   
   
  
• Fuel injectors that have the air side referenced to the output of the turbocharger compressor.
   
   
  
• Fuel pump and fuel metering changes that will let the engine work gracefully with the higher pressure air over a broader range of operating conditions.
   
   
  
• Need to enhance the cooling of the overall system (both cylinder head and possibly oil cooling), since it will be flying in thinner air at altitude that inherently provides less cooling.
   
   
  
• Mechanically support the weight of the turbochargers.
   
   
  

 

 

The reality is that the TC system designer actually started with the same question. Keep in mind that almost all of the fundamental design decisions for the TCM TSIO series of engines and the Lycoming TIO series of engines were made back in the 1963 to 1968 time frame.

 

In 1963, at TCM, the question was something like this: "What can we do to modify the existing 260 Hp IO-470, or the new 285 Hp IO-520 normally aspirated engines - to make a turbocharged engine to sell to Cessna?" [History note: The first C-320 aircraft (in 1964) were equipped with TSIO-470 engines. A couple of years later, they switched to TSIO-520 engines with 285Hp, just like the Cessna 310s were also switched to IO-520 normally aspirated engines.]

 

[Another history note: Remember, Jack Riley was running amok back then putting Lycoming normally aspirated IO-540s on C-310’s with turbochargers and operating them as "turbo normalized" engines and calling them Riley Rockets! TCM just HAD to come up with a turbocharged engine or they ran the risk that Cessna might go to Lycoming for engines for the C-310. The term "turbonormalized" was not used, until later.]

 

And guess what? TCM ended up developing exactly the same basic list of 9 items (see above) as for the TN engine - but with one additional item.

 

[some more history: The then universe of general aviation piston engine engineers mostly had a background in the big supercharged radial engines - all of which had very low compression ratios (often down around 6.5:1). All of those engineers just assumed that they would have to reduce the compression ratio on their new turbo-supercharged flat six cylinder engines in line with their previous big radial engine experience.]

 

So that is exactly what they did. TCM reduced the CR from 8.5:1 down to 7.5:1. Lycoming typically went from around 8.7:1 down to 7.3:1. There were some variations.

 

So, now, take the list of nine items above, and add item number 10.

 

• Change the piston geometry to reduce the compression ratio by about 1 point, from ~ 8.5 down to 7.5:1.
   
   
  

 

 

When you do that you have identified the only meaningful "difference" in the hardware between our common terminology of turbonormalizing and turbocharging.

 

Yes, it is true that the typical turbonormalizer on a 285 Hp IO-520 TCM engine only uses around 30" of MP and the typical early Turbocharged engine (TSIO-520D in the 1968 Cessna 320F, for example) uses around 32.5" Hg to make the SAME 285 Hp at sea level.

 

However, bear in mind, the extra 2.5" of manifold pressure (from 30” up to 32.5” Hg) is there to make up for two things: First, some minor losses in the exhaust system back pressure and second, and more important, to make up for the fact that the air was HOTTER in the non-intercooled induction system in the Cessna 320 and was therefore "LESS DENSE" and it took higher MP to get the same total mass air flow through the engine - in order to make the same 285 Hp - and to make up for the loss in overall efficiency because of the lower compression ratio.

 

Important note: None of those early turbocharged or turbonormalized engines had intercoolers! Not the Cessna T-210. Not the Cessna 320. Not the Cessna 310T. Not the Bonanza V35TC. Not the Bonanza A36TC nor the Bonanza B36TC. None of them. There were, in the early days, a number of RAY-JAY "turbo normalized" after market STCs that were added to several Mooneys and to some Bonanzas. None of them worked well. Most were really bad. That caused some early heart burn with the OEM’s who condemned those early non-intercooled non-OEM 8.5:1 compression ratio installations - and often for good reason. Had those early aftermarket STC’d installations with the 8.5:1 compression ratios been equipped with good intercoolers and good cylinder and oil cooling, the valid engineering reasons to object to them would have been eliminated, although, undoubtedly, Lycoming and TCM would have still found an excuse to complain, just for marketing reasons.

 

[Another history note: For a while, the Piper factory did do installations of what we now call turbonormalized engines using the RAY-JAY hardware. There were no intercoolers. This was done on some Comanche and Twin Comanche aircraft and some Apache aircraft with Lycoming IO-540 engines. Then Lycoming changed to low compression pistons and provided an OEM engine to Piper as a TIO-540x series engine. Again, there were no intercoolers. Forty years later, the earlier, higher compression configuration engines are, today, much preferred by knowledgeable pilot-owners, as opposed to the later models with the typical 7.3:1 compression ratio engine configurations.]

 

If, in the years around the 1963 time frame, TCM (and, later, Lycoming) engineers had readily available cost effective air-to-air heat exchangers (intercoolers) and had the airframe OEM companies then been willing to go to the trouble and expense to integrate the somewhat more complex design required to employ the intercoolers effectively, it is likely that some engineer would have realized that it would be “a good thing” if the early turbocharged engines used in the Cessna T-210 and Cessna 320 and the Piper Comanche would have kept their original 8.5 (8.7):1 compression ratio engines. Thus, the several problems (mostly heat and temperature and fuel consumption) associated with 7.5:1 compression ratio engines would have largely been avoided.

 

But the OEMs were in a hurry for a quick fix - or a "drop in" turbo engine that would be a “one design” that would fit in a broad cross section of existing Cessna and Piper air frames without extensive airframe modifications. That was a lot easier to do by changing the piston to get a 7.5:1 compression ratio than it was to keep the 8.5:1 compression ratio and figure out a way to stuff a good intercooler into the multiple different cowlings that existed among dozens of different airframes.

 

A current technology "good" intercooler design can reduce the induction air temperature so that turbocharged or turbonormalized engines see induction air temperatures that are much more comparable at all altitudes and power settings to a hot day normally aspirated engine than they are to a non-intercooled turbocharged or supercharged engine. But nobody back in the 1963-1970 timeframe was properly focused on the importance of the intercooler to optimize and make truly successful the highly desirable change from normally aspirated engines to turbocharged engines.

 

The routine absence of intercoolers in the design of the early turbocharged (and early turbo-normalized) engines in the 1960s resulted in a series of unsatisfactory engine life operational experiences for the owners. Those unsatisfactory experiences became widely circulated as the prevailing "wisdom" of the time. Those old perceived "truths" are very hard to correct in the often tradition bound aviation community.

 

Worse, because of the routine absence of the intercoolers in the design of the early turbocharged (and early turbo-normalized ) engines in the 1960s, the owners ended up having a series of unsatisfactory engine life operational experiences. Those less than good experiences became widely circulated as the prevailing "wisdom" of the time. Those old perceived "truths" are very hard to correct in the often tradition bound aviation community.

 

Intercoolers are Really Important

 

Example: On a hot day (100d F) day at Denver, the TN SR 22 has a calculated full power induction air temperature of ~ 125 to 130d F.

 

Many people think the presence of the red hot glowing turbocharger turbine section must cause a large rise in the induction air temperature. But because the mass air flow through the compressor is so large ( think in terms of something short of a TON of air per hour) the temperature rise due to the proximity of the turbocharger is relative small. It gets lost in the calculations it is so small.

 

As an aside, the actual measurement of the induction air temperature on the TN SR 22 agrees with the calculations to a very close margin ( +- 5 d). (Note, even a normally aspirated aircraft on a 100d F day at Denver will have elevated induction air temperatures around 110dF just due to the heat rise in that simple induction system.

 

But, if you take away the specially designed (not at all like the standard TCM intercooler design) intercoolers from the calculation you get something like 155 to 160 dF - - even using the extraordinarily efficient compressors that are on the TN SR 22.

 

If the compressors used were not well matched on the compressor maps to the specific aircraft engine application - - then that number would go much higher.

 

Something like 170 to 190 dF.

 

Those kinds of numbers are difficult to deal with. That is why carefully selecting aircraft compressors that have compressor maps that put the operating point near the center of the "island" of maximum efficiency on the compressor maps and designing and using highly efficient intercoolers are all essential ingredients in the "SMART TURBO"® which Cirrus decided to bring to market.

 

Many people only think of detonation in terms of fuel octane or in terms of spark timing. But people knowledgeable in the industry know that detonation is strongly influenced by still another factor - - induction air temperature. There is lots of good data on that subject, going back to WWII.

 

A couple of more points. Even the TN SR 22 is not "fully turbo normalized". By that is meant, that on hot days, the turbos fully make up for the loss of ambient pressure as one goes to altitude, but without a controller that can compensate for higher than standard outside temperatures, then while the turbo normalized engine does very well in horsepower - - on hot days it will not make full rated Hp unless something more were done to fully compensate for BOTH ambient low pressures and ambient high temperatures. This requires a very expensive hydro-mechanical system to fully compensate for density and the only airplane I know of that even attempts to do that is the Piper Navajo Chieftain.

 

Last, the pilots and mechanics should really be aware that there is nothing "magic" about 29.9" Hg manifold pressure verses 32.5" Hg manifold pressure or even 36 or 38" Hg manifold pressure. One is not necessarily "harder" on the engine than is the other. The engineering parameters that "make a difference" are evident in other data that the pilot never sees. The important constraints on good engine durability are only evident in the data from the individual combustion events and that is primarily the magnitude of the maximum instantaneous internal cylinder pressure and its occurrence with respect to top dead center of piston travel, along with the magnitude of the operating cylinder head temperature.

 

If a design engineer properly manages the instantaneous peak internal cylinder pressure (which is a VERY different parameter from the more widely known BMEP) and the cylinder head temperatures, and the induction air temperature, then the magnitude of the manifold pressure becomes very much less important in a discussion of engine durability.

 

Keep in mind, we have learned over the last 15 years that it really is not how hard you run the engine, but rather, how you run the engine hard.

 

If you have comments, questions, or criticism about this article, please contact [email protected]

 

 

[Staunch]

And More

 

Yes- it has been done on a 2200A. Purely as a proof of concept project, boosted

 

to 5-6 psi. Static rpm with same prop increased from 2800 to 3200. I believe the

 

shop put something on Youtube. Climb performance changed from mediocre to

 

spectacular; care had to be taken not to go through Ne in level flight WOT

 

(Kitfox). Success story, in other words!

 

But the fuel suppliers were happy too, EGT's had to be kept fairly low in order

 

to avoid detonation (even with 100LL), so consumption was let's say tsunami

 

like. The engine did not seem to mind the increased manifold pressure very much,

 

with one exception: with the increased boost the lack of seals on the valve

 

stems pressurized the sump through the pushrod tubes to such a degree that

 

lubeoil oozed out of every pore like the Jab. was some sort of ancient radial.

 

Not to mention what came out over the piston rings!

 

We also found that it is extremely tricky to use the universally preferred

 

pressurized carburettor setup with the standard Bing. It tends to lean out with

 

increased boost. You therefore have to pressurize the float chamber, which

 

collapses the hollow floats and compromizes the float bowl seal. You need to

 

raise the fuel pressure above that of the boost, which is not so easy with the

 

existing mechanical fuel pump (and there is not enough charging capacity for

 

more electrics). So this project was set up with an Aerocarb in front of the

 

turbo, which also gave us an opportunity to manually control mixture (VERY

 

important). But tuning the thing to an acceptable operational level was to put

 

it mildly, a chore. We did one 2 hour cross country trip with the thing over

 

mountainous terrain. We are not going to do it again!

 

Could I give you more details?: yes. Will I do it?: no. But coming winter we are

 

going to tackle this project from another angle. Next summer might render some

 

more promising results. I will keep this group posted when we have something to

 

communicate.

 

Kai

 

--- In [email protected]

 

 

[Guest Maj Millard]

Can we maybe get a little realistic here ?.....Boosting any engine will increase the strain on many engine internal components. Even with a low boost pressure (2-3 inches), you still get additional strain on pistons, rods, crank, cylinder heads etec , etc. Jabiru can't even keep cylinder through-bolts in one piece in their engines at this stage. And the new ARP nut mod which was supposed to solve that problem, has had failures also. Valves also continue to fail at relativly low engine hours. And you want to boost the engines for additional horsepower ?...I'd suggest you look at getting the basic strength of the engine up to square 1, before attempting to go to square 2............................................................................Maj...

 

 

[Staunch]

Rolled Thread Engine Through Bolts Available as alternative

 

Discussion in 'Jabiru' started by JabSP6, Jun 29, 2011.

 

Page 1 of 3 1 2 3 Next >

 

JabSP6 Member

 

Good news Forumites.

 

Finally i have been able to source an alternative to the standard Machined Thread Engine Through Bolts supplied by Jabiru. To go along with the ARP Nuts (rolled thread) that are supplied now as the fix for the failing through bolt (machined thread) issues we all know about, i have spoken at length with a manufacturer in Western Australia and he has imported in the correct thread dies to be able to manufacture a complete set of new Rolled Thread Through Bolts. There are 10 long studs and 4 short studs to make up a complete set. They are made out of 4140 round bar and will have a much higher strength due to the rolling process than the standard 4140 machined threads that are the only option out there at the moment. He is producing the first 10 sets for me tomorrow and will hopefully post them over to me early next week. They will be the slightly longer length so that you will still have a couple of threads protruding out of the new 12 point ARP nuts. The cost of these sets are currently around the $120 mark plus postage which is a great price. The more orders he recieves the cheaper he will be able to manufacture them for as he can buy in more material at a bulk discount.

 

For those of you that are in need of replacing the engine through bolt and would like a set to match the new ARP nuts i have included the manufacturers details and you can deal straight with the Director of the Company.

 

TL Adlard - 0430135816

 

Alliance Fasteners

 

8 Coolibah Way

 

Bibra Lake

 

Perth, WA 6163

 

I must stress that i have no interest in this company and i am not interested in becoming a supplier of these bolts but i thought that i would pass on the information for those of you who would like to eliminate the potential of the through bolts failing once and for all. I am not the first to use the rolled thread through bolts and, as i have always tried to do, i am just trying to find ways to improve the reliability of this jabiru motor.

 

I hope this can be of help to you and if you have any questions just ask.

 

Regards

 

Andrew

 

 

[Guest Maj Millard]

Thanks for posting that Andrew, You may remember, and I'm sure it's still all in the past posts somewhere that I was one of the first to suggest the rolled-threaded studs as an alternative to that currently used. I still feel it is the way to go to solve that problem.

 

As with any major change to an engine component, a couple of years in service will tell the true story.................................................................Maj...

 

 

[turboplanner]

As with any major change to an engine component, a couple of years in service will tell the true story.........................Maj...

That's the whole point, these people never provide test data confirming numbers of engines with 2000 hour life cycle, they never understand that if you make more power you need extensive modifications to take more power, or it's just as series of expensive blow ups.

 

It's a fantasy world.