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Turbo Injectors and Rails for YIO-540

Aiki_Aviator

Well Known Member
I have a question for the group relating to Turbo injectors and rails for a non-turbo engine in a standard RV-10.

I am in the process of receiving a YIO-540 Thunderbolt with AFP Fuel Injection and purge valve. I have been told by a college that I should get the turbo injector nossels and rails for the engine as this will add to the higher level performance without an impact on the lower level performance.

I understand the theory relating to this, due to the bleed vale and atomisation of the fuel, however, I wanted to get a show of hands on who has done this (i.e. Turbo injectors and rails system) with a standard RV-10 plenum, AND who has gained performance to warrant getting it in the first place.

The differential cost at present would be low, however, later significantly higher, so any thoughs welcome.
 
Don, the owner of AFP, is a frequent poster here, and would be an excellent source to contact about your question.

In fact, he may just see this thread, and post the answer for you on his own.

AFP if good stuff, you are lucky to be getting it.
 
Mark put Turbo nozzles and rails on my airplane, Ole '84.

They work great. no issues... His fear was that the pitot cowl would raise Manifold pressure high enough that the air flow in the injectors might not work, so the rails have a ram inlet in the cowling inlet.

Tailwinds,
Doug Rozendaal
F-1 EVO
 
IIRC, some of the -10 operators using the Sam James cowl/plenum have had to install the rails and turbo nozzles to get the engine to operate LOP correctly, apparently due to airflow issues with the stock nozzles.
 
The question being raised is more about the issue of injector stability at LOP settings. A large number of us here, Deems Davis Tim Olson to name a few went through this 2 1/2 years ago.

They problem found was with not only James cowls but the standard Vans cowl generates Ram Air effect and when running LOP the fuel atomisation is affected due to DP(differential pressure) between intake manifold and outside the injector body. At lower flows this produced variable results when try to balance air fuel ratio's and get consistent LOP operations.

This has nothing to do with performance increases in terms of power or anything, just consistent results LOP.

Don at AFP so far has not realised that even the Vans cowl generates this pehnomena.

As Doug has pointed out, and he is one of the big guns around here....Put em on :)
 
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I have the stock Van's cowl with an Iflyrv10.com plenum. LOP worked for me with this setup, but I felt like it was not as good as it could be. My old Bonanza with GAMI injectors worked really well, so I had that as a baseline. So, I went to AFP and worked with Don and Kyle to balance my nozzles and LOP now works great for me. My LH inlet is also different because of the air conditioner compressor, so whatever differential pressure issues I may or may not have, are pretty much unique to my airplane. At any rate, LOP works great with my setup.
 
Since my name was used in the thread, I'll throw in my 2 cents.
I don't 100% support the hypothesis that David Brown has on LOP operational fixes on the RV-10. What he found for himself does not coincide with what I have gathered from talking to most people about this. He is one of only 1 or 2 people (certainly less than a handful) with the standard cowl that I've ever heard of having a problem with running LOP. I just have not been able to figure out what the difference is with his setup. Beyond that, the problems have basically almost universally been with James cowl (ONLY on the RV-10 mind you...the James cowl seems to not have issues with the other RV's) users.

There is a lot of individual variants of things that can affect the pressures related to the cowl and plenum. Ram air, for one thing, can worsen the problem or even make it mandatory for you to need turbo injector nozzles. As David mentions above, it all involves the differential pressure between the air coming in the intake, and the air plenum above the engine where the injector is. The injector has an air bleed hole. This air bleed hole has many things that can affect it. One is clocking of the hole. One is if the hole is in direct airflow. One is the air pressure around it. We found that on the front (especially #2) cylinder that the blast of air coming in the front (again on James cowls for the most part), could cause issues from hitting the nozzle just right. Perhaps changing the clocking even a few degrees may change an individual's issue with this. Ultimately, the issue is, you need higher air pressure outside the injector than in the air intake (near the tip of the injector inside the head), because the injector needs air to bleed through the hole to properly atomize the air. The people with the James cowls apparently either have air pressure that's lower than it needs to be above the cylinders, or higher ram air effect coming in the snout. In this situation, air won't bleed in and you won't get the atomization. The turbo nozzles work by basically sticking a mini ram-air tube in the airstream somewhere (sometimes put in the intake snorkel) that brings air pressure up and surrounds the injector body with a sealed air chamber, forcing the air pressure to be higher than what the plenum has in it. That gives the atomization you need, and all is well. I've seen RV-10s operated without that rubber seal between the airbox and snorkel intake, so I know not everyone out there has a standard setup, which makes every aircraft's individual problem unique somewhat.

I do not support his theory that this is a universal problem. For the standard cowl users, most (other than 1 or 2 people I've talked to) do great by just doing the injector balancing using airflow performance injector inserts. This process is one that many builders simply either don't take the time to do, or don't do it with dedicated precision and multiple test flights. If a builder does the procedure, gets good reliable and repeatable data that shows the pattern, and adjusts for it, they should be able to balance the injectors plenty well to run LOP....but for the James cowl users, they may need to take the step to go to turbo rails. I doubt that turbo rails will hurt in anyone's case, but it's a lot of unnecessary work for most people with a Van's cowl, and I doubt they'd see much improvement. If you have a Van's cowl and can't run LOP, my first recommendation would be to look at ignition timing, and your ignition system as well. I run a Lightspeed ignition and perhaps the advanced timing helps in LOP ops. Look closely at your snorkel intake, cylinder fins, baffling, sealing, and everything else related to your air chambers both above and below the engine. You may need to equip with manometers and do some pressure testing in flight. But, if you're using the standard cowl, you'll be a rare breed if you can't get LOP to work for you without turbo rails. If you're running the James cowl on the RV-10, then definitely, you've got a process to go through and may end up needing them.

Tim
 
Bleed Air Rails-To Be or Not To Be

In the experimental world it?s extremely difficult to make a blanket statement; one fix covers all.

In the eyes of the United States Federal Aviation Administration, an Experimental Homebuilt Aircraft is not constructed by a licensed aircraft manufacturer. Instead, at least 51% of the aircraft is constructed by a private individual; the remaining 49% percent can be purchased from a kit manufacturer.

By the very nature of this it can be realized that there will be variations between aircraft of the same type due to differences in builder ability, details, and ideas. Tim Olson?s post is spot on. These installations must be taken as an individual basis based on testing. I am not smart enough to predict what the pressure differential on the nozzles will be for these different installations. As one piece of test equipment we have says ?One Test Is Worth One Thousand Expert Opinions?. I also have to be able to be honest with our customers. Why sell them a bunch parts that are not necessary. A set of bleed air rails and turbo nozzles for a six cylinder Lycoming adds $713.00 to the price of the kit. I know most customers don?t want to spend needless money. We would rather take each case separately as the majority of installations run just fine with the stock parts.

With that in mind I will work with each of you individually to do nozzle tuning. We have plenty of engine/aircraft data compiled, and even that shows that on the same engine and airplane the nozzle stagger is not the same. There are just to many variables on a home built aircraft.

Don
 
Don,

Thanks for jumping in, and also, thanks for being a great provider for our RV's. I owe my nicely balanced injectors to you, because without the ability to swap those inserts, I wouldn't have mine where they are today. I ran LOP a long time before using them, but after balancing them with your inserts, I was able to keep the peaks much closer, allowing me to run a little richer LOP. This gives me a bit less airspeed loss (and a tad bit more fuel flow) for my X/C flights.
It really is great that you offer such a thing. I encourage everyone to balance their injectors at minimum, if for no other reason than to have a better running engine.
Tim
 
Tim, thanks for your reply, however we should take a few more things into account here. Firstly when the group "think tank" happened a few years ago there were a few of us with standard cowls seeing vastly inconsistent results. In other words at no time would we ever see the same spread or order of peaks. Sure there is a small variation each time, but we were getting vastly differeing results such that every test was so different you could not make any adjustment as the next result defied the change even.

You might recall when I pulled the Alternate Air source, I found a large DP, and then and only then could I get a consistent "GAMI Spread" test a few times in a row.

I also recall the issue of stumbles when LOP, some of us were keen to get to the stumbles stage at least, as tuning was a nightmare.

The very instant we fitted a "turbo" injector system, all this went away. Tuning became predictable and consistent.

You might recall we all went to great lengths to be as scientific as we could, and not react to just heresay. I do wonder however, if those folk who do not seem to have a problem have different setups and for that matter are not operating at higher altitudes and WOT.

The problem is created as you say by DP. And if you are at low level, pull the MP back to 23", the problem seems to go away, less pressure inside than out.

Now my expectation is that everyone has a pretty well sealed upper deck, cooling is good, CHT's from 300-330 typically, and they have the air intake rubbers sealing well. If they do this, I then expect they will generate some ram air effect and have a higher pressure in the intake Vs the upper deck or ambient.

All that being equal...........and here is my point, now that you know that this is a likely scenario....and you will build a good low leakage cowling etc, and you want to tune for good LOP operations, and you do not want to be like a dog chasing its tail, AND you live in Australia a long way and time/expense for everything later on, you would be far better off ordering the engine with Don's injection and turbo rail setup from the start.

If I ordered a new engine tomorrow, I would have Dons system installed before it was shipped, or at least all the parts sent with the engine in a box so I could install it.

It cost me thousands $$ in time, fuel, airfreighting injectors, flow bench adjusting and a few damaged threads, so why would I expose myself to all that when for a few hundred dollars I could have the better option from the start. It is just so much easier to do when the airflow to the bleed hole is perfect.

Of the three folks down here, that eventually fitted my home grown turbo kit which uses standard injector bodies, we all found an instant fix. This was not just a one off.

Why did I build my own? First it was not money, it cost about the same, but it was at least 2 weeks quicker, I made them suit a stock injector which we tuned locally, and could buy locally. I had two other folk down here needing them so it was worth the trouble.

Would I do that again? No, apart from the fact my "fit a standard Injector" is better for us, if I had to do this again I would order an engine and have all the bits done for me.

A set of bleed air rails and turbo nozzles for a six cylinder Lycoming adds $713.00 to the price of the kit. I know most customers don?t want to spend needless money. We would rather take each case separately as the majority of installations run just fine with the stock parts.

Don, I certainly can't speak for all your customers, but are you sure that is exactly how all your customers think. I do not think your customers are thinking this through long term. Your Turbo Nozzle kit is not cheap, nor is it expensive, but for $713 compared to the REAL COST of mucking around, it is cheap. And is it cheaper if they fit this from the start? Less the standard injector? Might only be $550 then.

Folks....please do not read this post as me attacking Tim or Don. A lot of us spent a lot of time and money sorting this out, I just do not see the small investment compared to the benefit as being that trivial, especially when you live down here.
 
Thanks for all this - some notes on my experience

First, thanks to David for taking me through the basics on the phone and passing along many of the pertinent links.
Thanks to Tim for the excellent injector tuning write-up on your site.
Thanks to Don and Airflow for talking me through some issues and making the injectors available at a very reasonable price.

I'm running LOP pretty successfully at this point after a couple of rounds of data collection, analysis and injector replacement. No question about it, LOP operations pays for itself in just a very few cross country flights. And I'm convinced that over the long term it is not harmful to the engine, but rather extends the useful life of the engine. It sure extends the life of a gallon of petrol!

I've been able to get 5 of my 6 cylinders to peak essentially at the same time but that pesky #1 cylinder is just a bit out of line - maybe just .1 or .2 GPH. I've been able to bring #1 in with a leaner injector, but I'm convinced that it then runs too lean at full power so I backed that out and seem to be running fine.

That did raise the question for me, "since we tune to peak EGTs by using leaner injectors, is it possible to go so lean that we are too lean at peak power when running full rich on takeoff and initial climb out?" Seems like that's a real possibility and one to be avoided. I think Don mentioned to me a minimum range of EGTs one should get between full rich and peak EGT, or perhaps between full rich and LOP operations. (I forgot the range).

Can anyone comment on how to be sure we don't get so lean with the restrictors that full power operations could expose us to problems? Is it a real risk?

In anycase, I'm very happy as I am right now and am waiting for my next long trip at 7K or above to confirm it. In my last test flights, when I run LOP the engine is smooth right down to the point where it stumbles a bit before wanting to just die... oh, does anyone know what causes EGTs to go back up when you get down into the stumble area? Just curious.

Another note; I discovered that my alternate air door was not secure and that it fell off a couple of times without me being aware. Based on what I learned in this thread, that could have an impact on results so now that I've fully secured the alt air door, I'm going to do another data run.

One more; Per the advice of one of the leaning gurus (can't remember the name and lost the link to his talk - think it was an EAA or AVWeb video), I started using EGTs to do my mag checks. Provides more insight than just looking for an rpm drop.

...and a PS; I was hanging out with a mechanic buddy who was installing EGT and CHT probes along with a guage to read them on a Baron. Can you imagine flying around in a Baron for 10 years with 1 CHT and 1 EGT per engine? I guess you just make sure it has enough fuel flowing to smooth things over.
Bill
 
David from Oz... slightly OT but not really

When you said, "...AND you live in Australia a long way and time/expense for everything later on", I know you meant that in a way that just doesn't resonate for many of us "up here".

Some years ago a made a couple of trips down to Oz. Two things struck me; 1) it's one of the few places in the world that is 'younger and newer' than the US of A, and 2) it's REALLY a long way away from most everything 'up here'.

I like history books but trying to get an angle on Oz history is tough - there just isn't that much history. But the book I found and enjoyed immensely was "The Tyranny of Distance", subtitled "How Distance shaped Australia's history", Geoffrey Blainey. Not news for David, but if any of us 'up here' want to get a sense of what David is referring to with regards to "... a long way and time/expense for everything..." give it a read. Imagine shipping ice.

I remember during my build when UPS would darken my doorway daily with another box of miscellaneous goodies from Aircraft Spruce and the like. What the h*ll do you do in Oz? (no answer required)

Bill "thankful for the help" Watson
 
Nozzle Tuning

Bill,

Obviously you have a fuel flow indication in your aircraft or you couldn?t be doing this nozzle-tuning thing. So before you started swapping restrictors (if you bought them from us) we asked you what your fuel throttle fuel flow was and what your inlet fuel pressure was with the boost pump off at take off power. From this we can calculate what the minimum size restrictor that can be used. As a check you should have been watching your take off fuel flow after you switched restrictor sizes to make sure the total flow at take off was the same as it was with the original restrictors. The nozzle size will not change the total flow as long as the minimum fuel pressure to satisfy all the pressure drops in the system is not exceeded (don?t try this with a Continental fuel injection system). And as long as you were taking the nozzle tuning data at a fuel flow higher than what the flow divider would influence the division, the nozzle stagger should be correct at full throttle also. Don?t let the EGT number fool you into thinking a cylinder is rich or lean. If you check the EGT difference from full rich to peak for a given cylinder and you get 185-225 degrees change then the full rich mixture is correct. This should be tested at around 3500 ft and 24 square.


Don
 
Great Info

Hi all,

Thanks for the feedback. I have definitely learned a lot of information especially when it comes to LOP and balancing (which I think I will complete when flying).

Ths is what makes for a safer, better educated and prepared community. Thanks to all.
 
I have a set of turbo rails sitting in a box in my hangar. I installed them on my Rocket to fix a stumbling problem going to LOP, but it did not help. So I removed them to just simplify things.

I also worked with Don to tune my injectors. I flew down to his shop and spent the day with him. Great guy and great team and I highly recommend him and his products.

I would start with the standard set up and then move to the rails later if you think there's a need. Don is right, every airplane, engine, plenum, etc is a unique combination.
 
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