What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Honda 1.8L on RV6A Now Flying!

creating 160 HP - stock injector over 100%

Things are progressing nicely at this stage of the project.

I am up to 38-40 inches of manifold pressure with my stock injectors at or over 100% duty cycle. These are 185cc injectors which I have read will handle 160 HP at 100% duty cycle. This is a very rough estimate and could vary by probably 15% so take this with that in mind.

Another perspective is that this engine in stock form is 135HP when at 30" of MAP. So this also stands to reason that at 40" you would see about 160HP. Just some rough numbers, nothing to bet the farm on.

Thankfully the SDSEFI controller shows the injector duty in the display - which is very helpful.

Fortunately there are a lot of the larger 2.0L and 2.4L Honda 4 cyl engines that have 310cc and 410cc injectors. I have a new set on order. Ill post more when I load the engine up to 40+MAP using the new injectors. I am hoping for 80% duty cycle at 45" at 5000 RPM. This is roughly 5lbs of boost which is just find by me.

Charlie Rosenzweig
 
Last edited:
update on Honda Civic project

I have not posted for a while.

I have been carefully working on different settings of ignition, fuel ratios and various changes in the settings to verify what works well and what doesn't.

I am not sure how much interest really is out there so I will keep this fairly simple. I am happy to go in to more detail if there is interest, just let me know.

One thing I experienced was what I will call a stumble right at 5000 rpm. Since I pushed it a bit too hard with the last engine, I was very conservative with various changes in the set up as I worked to find a cause.

The compression issue last time was certainly pre-ignition. I made several changes to prevent this from happening again. Those include:

1) Retard the ignition from 28 down to 16 at 5000 rpm. My current setting has a slight curve in the profile that I can go in to more detail later.
2) One level cooler iridium spark plug.
3) Richer AFR (air fuel ratio) from 12 down to 11 especially under heavy load.
4) Always 93 octaine fuel.
5) Careful watch in IAT (Air temps).
6) Addition of the knock sensor being "active" to retard the timing when it senses what it thinks is pre-ignition. (more on that below).

As it turns out, the stumble on the "newer" engine was my overzealous programming of the sensitivity of the knock sensor that was causing the computer to send it to retard the timing 8 degrees. So I carefully lowered the sensitivity value of the knock sensor setting and constantly watched the plugs to make sure it was not being caused by pre-ignition. GOOD NEWS it wasn't. It was just a setting that was too sensitive. I had it set to value of "32" which is the most sensitive setting that is available. I backed it off to "28" and now things are great.

I am progressive through 5000 RPM to 5500 rpm just fine. This is quite the "ride" considering this engine is on a test stand, with PSRU and 68 prop - while in my parking lot at home secured to my truck.

I cannot say enough great things about the flexibility and functionality of the SDS EFI computer. Very easy and intuitive to change settings and see immediate results. Ross at SDS is always great about helping me work through my project.

My next move is to re-install the turbo and an intercooler and load it a bit. I would be happy with only 5lbs boost at 5000 RPM. This testing will include IAT before and after the intercooler to get real world numbers to verify the efficiency of the intercooler. Keep in mind this is very subjective as it will not be on the plane.

If that works out, I will do some testing with water/meth injection. This will also include temps before and after the water/meth injection to see how much delta drop there is in the temps.

A project like this is a ton of fun, and absolutely viable but it is really for those who enjoy the mechanical part of experimental aviation - which for me is as much fun as drilling holes and squishing rivets.

Charlie
 
Last edited:
Please keep posting. I'm certainly interested, and posting updates may well offer useful info to others who are working on alternative powerplants.
 
Please keep posting. I'm certainly interested, and posting updates may well offer useful info to others who are working on alternative powerplants.

I do appreciate the feedback. I am not looking for compliments but rather I just was not sure anyone was interested, so thanks for the follow up.

I know the proof will be when it flies and of course how successful the project is. I certainly think it has potential to be a good "fit" for some folks who like myself are open to new ideas and the desire to take advantage of all that experimental aviation has to offer.

For me, my day job just keeps getting in the way of all this fun!

Charlie
 
410cc injector upgrade

I realized that I did not follow up on the injector upgrade. The engine comes stock with something like 180cc injectors.

Fortunately there are quite a few Honda engines that use the 410cc injectors so I bought some aftermarket ones.

They work perfect. I was at 100% with the original injectors at 5lbs boost.

I have not reinstalled the turbo yet so I cannot say for sure what the new ones will be at at 40" at 5000 rpm but Ill go out on a limb here and say that I suspect it will only be about 60%.

I am only at 35% duty cycle on these running normally aspirated at 5000 rpm which is about 30" Manifold pressure.

I will should add that I had to buy new injector plugs as the 410cc ones have a different shaped top that the injector plugs fit in to. The new plugs were very inexpensive and widely available on Ebay.

Which brings me around to my overall appreciation for using something as common as a Honda Civic engine. There are TONS of aftermarket and OEM parts that are very affordable and readily available.

Charlie
 
I'm following your progress here too Charlie. Running it all on a test stand was a very good idea to work out the bugs. You don't need these issues while you're up in the air.
 
I'm following your progress here too Charlie. Running it all on a test stand was a very good idea to work out the bugs. You don't need these issues while you're up in the air.

Ross,

Yes, and it makes it very easy to work on it and make improvements and changes with ease.

Charlie
 
What was the internal failure? Pistons or valves? Failures tell us what is weak. Keep the progress coming.
 
Wonderful project. I am thankful that there are others out there that are tinker minded and put the experiment in experimental.

I am wondering why the R18 was chosen instead of the R20. Wouldn't the R20 be a free 10 or 15 hp for little or no weight penalty?

Is it cost, availability, technical, or some other reason?

Thanks again for sharing.
 
I've been looking at this thread on and off since it's inception.

I had my thoughts on how Honda engines would fair with being put into this type of situation. More specifically I was wondering about the VVT and how it would be, it seems that this is an issue. I wish the OP the best of luck in this en devour and he may over come those issues.
 
Wonderful project. I am thankful that there are others out there that are tinker minded and put the experiment in experimental.

I am wondering why the R18 was chosen instead of the R20. Wouldn't the R20 be a free 10 or 15 hp for little or no weight penalty?

Is it cost, availability, technical, or some other reason?

Thanks again for sharing.

Dog,

Thank you and great question on the R20. They are viftually identical, with a few exceptions. The R20 having a longer stroke of course. Also it has a counter rotating shaft to offset additional rotational vibration that very long stroke induces. Both are great engines in my book. I chose the R18 because it is slightly lighter (I am not sure how much), and more importantly, there are more R18 in production, I.E. in junk yards. There are a few more minor differences as well. Either would work great, imho.
 
I've been looking at this thread on and off since it's inception.

I had my thoughts on how Honda engines would fair with being put into this type of situation. More specifically I was wondering about the VVT and how it would be, it seems that this is an issue. I wish the OP the best of luck in this en devour and he may over come those issues.

Thanks. Good to hear. It is important for readers to know that VVT and V-Tec ( or i=Vtec) are quite different.

The VVT has to do with variable or adjustable cam shaft gears. This has been been widely used in(primarily) older honda engines and is designed to create additional power at higher RPM in many Honda, but NOT, the R18 or R20.

The R18 and R20 use i-VTEC which is quite the opposite. (see more detail in previous posts in earlier posts in this thread). But in short, i-Vtec uses an oil control (spool) valve to activate the cam lifters between the default "power" lobes or when it senses a low load it activates the lifters to have the "economy" lobe profiles.

In my case I simply hard wired the spool valve so it would presurize the lifters to always use the "power" profile cam lobes.

Charlie
 
What was the internal failure? Pistons or valves? Failures tell us what is weak. Keep the progress coming.

Bill,

Good question.

It was primarily my stupidity for not watching the plugs close enough during testing. I mistook that stumble at 5000 rpm as the engine "missing" when it was really pre-ignition. It did not have that tell tale typical sound to me.

I could have reground the cylinders, but when these engines are only $550 with less than $20k miles on them it was an easy choice to just get another one.

Hope this helps.

Charlie
 
Bill,

Good question.

It was primarily my stupidity for not watching the plugs close enough during testing. I mistook that stumble at 5000 rpm as the engine "missing" when it was really pre-ignition. It did not have that tell tale typical sound to me.

I could have reground the cylinders, but when these engines are only $550 with less than $20k miles on them it was an easy choice to just get another one.

Hope this helps.

Charlie

Charlie, I was not implying that you did the wrong thing. That engine is 10.7:1 compression ratio, meaning that any boost will amplify combustion issues. A teardown to see what how things fared would be revealing. If the PI just burned a hole in the piston, but the rings and skirts stayed cool enough not to gall, then that shows good cooling. If the rings stuck and then skirts galled along with the crown melting, then one might still be concerned about overall piston temperatures even with desired heat release. This is why I asked. Auto engines running under full power for hours will exhibit different failure modes than short dyno runs. or race car engines. It's not that auto engines (in general) can not be used in aircraft, but the weaknesses must be revealed for correction before they affect people. Either super instrumentation or teardowns with some careful test progression are needed to do that. Teardowns would be suggested simply to understand the health of an engine as it progresses to flight configuration. Repairs are not necessary. Many other parts can be inspected in a teardown. (like bearings, wrist pins, etc)
 
Charlie, I was not implying that you did the wrong thing. That engine is 10.7:1 compression ratio, meaning that any boost will amplify combustion issues. A teardown to see what how things fared would be revealing. If the PI just burned a hole in the piston, but the rings and skirts stayed cool enough not to gall, then that shows good cooling. If the rings stuck and then skirts galled along with the crown melting, then one might still be concerned about overall piston temperatures even with desired heat release. This is why I asked. Auto engines running under full power for hours will exhibit different failure modes than short dyno runs. or race car engines. It's not that auto engines (in general) can not be used in aircraft, but the weaknesses must be revealed for correction before they affect people. Either super instrumentation or teardowns with some careful test progression are needed to do that. Teardowns would be suggested simply to understand the health of an engine as it progresses to flight configuration. Repairs are not necessary. Many other parts can be inspected in a teardown. (like bearings, wrist pins, etc)

Bill,

No mystery on the lost of compression on two cylinders, it was my error for allowing pre-ignition to happen largely because of way too much advance, and a few other issues, like too lean AFR settings. A lesson learned.

In other words it is not the engine, and certainly not the 5 lbs of boost. It was "pilot error".

The good news is that this is all happening on a test stand in my parking lot, and there is a lot success happening, and of course an occasional set back once in a while, just like with all projects, right?

The parts.....there was galling on the piston sides and some scuffing on the cylinder walls, and the rings were in poor shape. The piston tops and head domes were all in good shape.

Ill be adding all those solutions that I listed a few posts back.

Ill also be testing water/meth injection - hopefully tomorrow. This is an often overlooked very simple solution to reduce IAT. Once I have completed that testing, I will add an intercooler. But I am purposely taking things in steps to verify if there are advantages or not.

Charlie
 
Last edited:
Things looking great

Good success with the addition of the solutions I listed earlier.

I transitioned through 5200 RPM at 35" MAP with breeze today.

I added water/meth injection but I developed a leak in the pressure gauge connection so I did not use it long. My initial impressions are that it dropped the IAT 10*F. This is with only a M1 nozzle which is very small. A lot more to play with on this concept. There should be more like a 20* drop if things are set up correctly.

I suspect there may be some water being sucked in to the intake at high vacuum settings so the temp results may be skewed. A lot of people add electric valves to prevent this, but I am a fan of keeping things simple so I wont add that until I am sure it is needed.

The most important to me is that there was no hint of stumble or miss, or preignition at all and this validates the list of solutions I previously identified. Anyone who may want to venture out on a project like this should do the same.

I am hoping for 40" at 5000 rpm and right now I can only get 35" at that RPM. I am at 19* pitch on the prop, and I can add more but I think much more and I will be past the point of the prop being efficient. It is only a 68" 3 bladed tapered warp drive prop. Great Prop, I love it, but I might need a 70" or 72" prop to get me at the settings I want to be at.

I do have a bleed valve on the turbo wastegate, and I plan to do some air bleeding, but I suspect without more prop pitch or diameter, this will only increase RPM......

I encourage others to chime in here and offer thoughts.....

Charlie
 
The parts.....there was galling on the piston sides and some scuffing on the cylinder walls, and the rings were in poor shape. The piston tops and head domes were all in good shape.

Not a setback at all, just part of the development process.

From my experience, if the crown was not melted, then it is a deficiency of skirt cooling. Obvious, but it would mean the piston cooling jets might need to be enlarged.

It is typical in heavy duty engines to see a skirt failure with a cooling jet problem. Just something you might want to adjust in this engine for continuous high power.

Actually, this is a good indicator for the strength of the piston crown!!

Keep up the reports!
 
Not a setback at all, just part of the development process.

From my experience, if the crown was not melted, then it is a deficiency of skirt cooling. Obvious, but it would mean the piston cooling jets might need to be enlarged.

It is typical in heavy duty engines to see a skirt failure with a cooling jet problem. Just something you might want to adjust in this engine for continuous high power.

Actually, this is a good indicator for the strength of the piston crown!!

Keep up the reports!

Bill,

The engine is one of the most advanced featured and turbo friendly engines on the market and it would be crazy for anyone to alter any of the internal components. The only error was on my end, certainly not the engine.

It is running excellent now with steps I listed a few posts back.

Here is an excerpt from Fullrace.com that highlights some of the advanced features on the engine. I think you and other readers will find this very informative.


Top 10 things that make the R18 perfect for boost.

ultra-lightweight engine, and transmission, showing cylinder head with integrated manifold.

Bore and Stroke are identical to the legendary GSR and ITR B18
The R18 uses a full 1-piece main bearing girdle

“Long-rod” Forged Steel Connecting rods with rod BOLTS (not studs – easy to upgrade to ARP hardware)

The R18 has a 10% reduction in friction from a special cylinder wall hone and moly-sulfide bead blast and ion treated piston rings. High durability and low friction.

Pistons cooled by built-in oil jets (typically only found on high end Honda motors). This is important for a turbocharged engine which has increased piston temperatures.

Cylinder head design is an ultra efficient way to deliver high temp exhaust gasses immediately to a turbocharger

Easy to disable EGR using OE Honda components

The R20 is available for more power and any R18 guys looking for BIG power can do a bottom end swap to the R20 (or sleeve your R18 to 2.0L!)

Hondata FlashPRO is available!! MAF based engine management makes tuning very accurate and simple.


I agree with you, all I have learned about this engine, is that it is very well designed and an excellent choice for my project.

Charlie
 
Last edited:
Meth Injection Update

I did some more indepth testing today of the meth injection system. I am very happy with the results. I can add photos if anyone wants to see them let me know.

I am using a M2 spray tip. This is roughly a 150cc/min tip at 115psi. Or just about 2 Gal/Hr.

I am using 50/50% water/Meth.

I see a 22* drop in temp in the Air Intake Temp when I add meth while at 5250 RPM which is 35+ Manifold Pressure. It drops from 150* down to 128* very fast. This is a very simple proof-of-concept set up. A $30 diaphram spray pump, a pressure gauge and the nozzle. Thats it. About $50 total.

This is really all I need at such a low boost setting. I may add an intercooler just to see how effective it is, but at these settings it will probably be more time and money than it is worth.

Let me know if anyone has questions.

Charlie
 
Are you actually running methanol mix, and not ethanol? If so, any issues with materials degradation in the methanol path?
 
SMH. Yes...that is shaking my head. Humm. being a previous engineer at Honda, I can only imagine the reaction from the engine designers as they shake their heads and pound the table pondering 'what, wait just a second, but I didn't design the engine for that. If they wanted that I would've done this.'
Humm. Not too sure about this. You need to second think that engine ideal your chasing.
 
What is Meth injection?

SMH. Yes...that is shaking my head. Humm. being a previous engineer at Honda, I can only imagine the reaction from the engine designers as they shake their heads and pound the table pondering 'what, wait just a second, but I didn't design the engine for that. If they wanted that I would've done this.'
Humm. Not too sure about this. You need to second think that engine ideal your chasing.

RV7CHarlie .... KSDflying .....

My apologies, no, I am not adding methanol directly in to the fuel.

This is injection of a finely atomized (mist) mixture of 50% water and 50% methanol in to the intake plenum. It a very common procedure and has many benefits to cool the IAT. It was first used in WWII to cool the IAT on B-17 Bombers and has been widely used every since by people who have turbos and are interested in reducing their IAT. It is a simple method to either reduce temps and therefor reduce stress on the engine,which is why I am looking into it. Or, for others, it is also a way to allow the engine to safely operate at higher performance settings.

Some readers may be asking themselves....so...if it is so good why don't we see it in mass production of OEM turbo cars? I have seen this questions posed to OEM engineers and invariably point to what they know the average car owner will do, or more importantly, NOT do.....refill the 50%/50% mixture. For the forgetful car owner, this will only result with a bad reputation for that car and for that reason we will not see it in mass production.

I'm not really saying this is for everyone, but for those with a desire to learn and adopt some of the added benefits of some of the slick advances in technology it can be something worth looking in to and trying.

Charlie
 
I understood that you were using it to as a charge cooler. Just wondering why methanol instead of ethanol, given the more corrosive nature of methanol. Is it really that superior to ethanol, as a charge cooler?

Are you planning for it to be an octane booster, in addition to cooling the intake charge?

I assume you're not using it continuously, but only while under high boost?

Charlie
 
I understood that you were using it to as a charge cooler. Just wondering why methanol instead of ethanol, given the more corrosive nature of methanol. Is it really that superior to ethanol, as a charge cooler?

Are you planning for it to be an octane booster, in addition to cooling the intake charge?

I assume you're not using it continuously, but only while under high boost?

Charlie

RV7charlie,

Ethanol is doable. Probably 90% of the people chose methanol. It cools a bit better than ethanol, and it is about 25% of the cost of ethanol. Since this is being induced in to a plastic Intake, and aluminum head the corrosion issue, as compared to ethanol is not a concern for most people.

This is simply a way to best reduce IAT which has several benefits. It allows for a bit more advance of ignition, which of course allows for better performance. It increases safety margins from detonation. And you can add more boost, but for me, it is more about the engine being less stressed at lower IAT than it is about trying to squeeze extra power out of it. Hope that makes sense.

I am not flying with this set up yet so my decision is a bit "up in the air". Sorry I could not pass on the chance for some lame humor. That being said, I suspect the injection would be for limited time, like at or above 35" of M.A.P or when intake temps are above 150F degrees. For me, that will be a limited part of the flights. I am not a racer by habit. Also, I have not began the intercooler testing yet. With the success of this meth injection it is tempting to pass on the time, weight, cost of an intercooler. But I am just too dang curious to pass on the testing so I will probably do it.

Charlie
 
Last edited:
Also, water injection will remove carbon from the combustion chamber.

Gasman,

Funny you should mention that. I have seen several pictures of pistons that come out of meth injection engines and they look steam cleaned compared to a non meth injected engine.

So far my plugs, which I pull frequently, look very nice. But I honestly do not have very many hours of operation under the meth injection so I cannot say that this is really a meaningful trait - yet.

For me, it just a proof of concept that looks very encouraging for sure.

Charlie
 
I have not heard of a lot of guys going that extra step, and I think as long as it was properly filtered it would not be necessary, but that is just my thoughts.

Charlie

Absolutely not. Use distilled, no dissolved solids, or get a TDS meter and use something less than 100 ppm.
 
A buddy of mine had a "sleeper" street race 5.0 Mustang a few years ago. The engine was essentially a stock 87 5.0 but he had headers and a great exhaust. The car would routinely run in the low 10 second range at the dragstrip - fast even by todays standards. There were lots of covert suspension mods and a light car, but the real secret was a significantly overdriven Paxton supercharger. There was no intercooler of any kind and even if there was, the stock compression engine should never have survived the level of boost being thrown at it. The whole key to making this work was a boost activated pump moving mass quanities of methanol to a nozzle in the inlet of the supercharger. This dropped the intake temp significantly and added the detonation suppression needed to make the power. The downside is running the methanol tank dry at high power - the engine instantly experiences catastrophic detonation and is rendered junk.
 
A buddy of mine had a "sleeper" street race 5.0 Mustang a few years ago. The engine was essentially a stock 87 5.0 but he had headers and a great exhaust. The car would routinely run in the low 10 second range at the dragstrip - fast even by todays standards. There were lots of covert suspension mods and a light car, but the real secret was a significantly overdriven Paxton supercharger. There was no intercooler of any kind and even if there was, the stock compression engine should never have survived the level of boost being thrown at it. The whole key to making this work was a boost activated pump moving mass quanities of methanol to a nozzle in the inlet of the supercharger. This dropped the intake temp significantly and added the detonation suppression needed to make the power. The downside is running the methanol tank dry at high power - the engine instantly experiences catastrophic detonation and is rendered junk.

Michael,

Yes, the issue of running the tank dry is really the only issue that seems to creep on guys. There are many fail safe solutions on the market today. I for one am just not going to push things hard enough that if the Meth Injection stops, anything catastrophic will happen. But I know this can be a real issue for people who are pushing their engines to the limit. That wont be me.

Also, I see by your signature you are going to use the SDS EMS? I absolutely love my SDS and cannot imagine launching a set up like this without one. Super easy and great support from Ross and the folks at SDS.
 
Meth injectdion videos.

I thought I would post two videos I made for youtube here. The first one is of the engine on the test stand where I describe the components of the set up.

https://nam02.safelinks.protection..../hkGfMpvzfnYGwxVM61w/iHomsf8IeYv8=&reserved=0


I hope that link works, will someone please let me know.

Also Part 2 is of the actual run up. It is too loud for me to try to talk in to the phone to narrate what you are seeing. Sorry. But please watch the "AT" air temp creep up to 150 degrees F. I am running at 5000+RPM and at about 35" of Manifold. with a 68" 3 blade warp prop at 20 degrees pitch. It is pretty harry. But you will see the AT drop 27 degrees to 123 degrees in about 30 seconds. Amazing in my opinion.

Here is the link to video #2.

https://nam02.safelinks.protection....+TY+LYXYwnPIl1kRNKOhNK9y5hwGIlCF8=&reserved=0

Let me know if both of these videos run for you. If not I can try a different way to link them.

Charlie.
 
Charlie

How soon do you think before airborne trials begin?

Has the engine been previously fitted to airframe?
 
Charlie

How soon do you think before airborne trials begin?

Has the engine been previously fitted to airframe?

I wish I could tell you that it will fly soon, but my day job and honey dos keep getting my time!

If the intercooler testing goes well, I will build the engine mount. The airframe is 99% done, but I have the panel to build, upholstry, etc. Which to me means probably about a year out before completion.

The more testing I do the more impressed I am with the set up.

Thanks for asking.

Charlie
 
Intercooler installed with pics

I have my test stand engine set up with the intercooler installed. Please remember this is a test stand engine to run the engine with the new options to see how they perform. This latest test is a follow up to the testing with the meth/water injection system.

I have not ran the engine with intercooler yet. I hope to do that this weekend.

You will see in the pics i had to "clock" the compressor housing to allow the new routing of the intake tubes with the intercooler.

This required a moving the waste gate to fit the swing valve. The old custom adapter would not work, so I welded up a new apater. The waste gate rod is threaded with 6mm x 1.0 T.P. threads. I just welded a SS 6mm coupling nut to a 0.65" think steel, worked great.

Here are some pics.

http://halie.com/oeK.jpg

http://halie.com/oeU.jpg

http://halie.com/oeZ.jpg

I would appreciate at least one person to let me know if you could see this pics OK.

P.S. I am going to reduce the size down further to see if it post a pic, rather than a link....

http://halie.com/oei.jpg


Please post questions if you have any.

Charlie
 
Last edited:
Intercooler tested

Update:

For those that may occassionally want an update. I tested the intercooler installation this weekend.

I was very impressed with how effective it was. even though it was a $90 ebay intercooler, I found it was very well made.

I did a run up to 5200 rpm only about 38-40 " MAP. The ambient temp was about 80 f and max temp temp as about 82*-84* IAT. Test before the intercooler I would see my IAT head over 150*.....

I then activated my #2 meth injector and it dropped down to 68*-69* . This is a very small injector and if I wanted it to drop further I would double it to a #4. some go as hight as #10. These numbers generally equate to gallons per hour and you can get them from McMaster Carr for only a few bucks a piece. They come with built in fine mesh screen. Excellent in expensive nozzles....

So for me, if you are running a turbo, you really do benefit with an intercooler - IF - you have room and can afford the extra weight.

If you don't have room for an intercooler I would definitely use meth injection.

Here is a link of a short video of the engine running on a test stand up to 3000rpm.

https://youtu.be/752RATYxUBk

There is a lot to share on Wide Band AFR systems but that will be on another post later.

I would appreciate if at least one person can tell me the video link above worked for you.

Feel free to ask questions.
 
Last edited:
Wide Band AFR (air fuel ratio) "O2" systems

A while back I said I was going to share some information about Wide Band AFR systems/gauges.

The important point I want to make with this post, is that I do not want to convey this is about WHAT AFR to use, but rather to stress the importance for pilots to KNOW what AFR their system is operating at. (Sorry for the caps but I suspect if I did not say this it was spiral out to the never ending debate about what AFR is better and that is for another thread).

I am far from being anything close to an expert on this topic, but I thought I would share what I have learned.

In short, I would not fly without one.

These devices are incredibly accurate and very affordable. They quickly show you what your true air to fuel ratio is.

Most of us who have been flying for more than a few years learned to lean the air fuel ratio (usually) to be slightly rich of peak EGT. At least that what I was taught. (I know there are many purist who run LOP (Lean of Peak) but that is for a whole other thread. )

The commonly referred to "ideal" ratio is 14.7:1 air to fuel ration. This is called Stoichiometric and it is the precise ration where complete combustion takes place. It is ideal in sterile conditions but it can be way too lean for many common set ups so do not take this setting as the "gospel" ratio to aim for in many cases.

There many factors that need to be learned in order to know what AFR your set up should be operating:

1) Compression Ration
2) Timing
3) Fuel Octane Rating
4) IAT (inlet air temperature

These are the common things to know when considering your AFR.

I started out using a APSX D2 Wide band Meter. I was very happy with it. Very precise, affordable ($130) and easy to use. The only draw back to it is that it uses the slightly outdated Bosch LSU4.2 O2 sensor. This is a good sensor, but not as durable as the newer LSU4.9 sensor. You can see this in operation in several of my videos in this thread...

After a bit of research I ended up purchasing the GEN 4 PLX Wideband system. I am super happy and impressed with this set up. It has several advantages over many Wide Band systems.

1) It uses the more durable advanced Bosch LSU 4.9 O2 sensor. It has a 10 year expected shelf life. It withstands methanol, ethanol, etc.
2) It has a "Smart" gauge (DM-6) that has programmable warning settings so you can have it flash warning LED when user limits (high or low) are set.
3) It can be piggy backed with other sensors, i.e. Voltage, temp, pressure sensors that can be viewed with s single gauge or combined gauges. etc.
4) Cost is less than $200.

This set up combined with the SDS EFI controller makes it a breeze to adjust the AFR from - say - 13.1 to 12.5 in the quick rotating of the fuel adjustment knob.

It is many times more accurate than leaning with an EGT. Personally I would never go back to leaning via EGT unless I had to. To put this another way, you could be wasting fuel, or missing out on horsepower using only an EGT and not even know it.

https://www.plxdevices.com/PLX-MultiGauges-and-Sensors-s/108.htm

There you have it. My 2 cents.

P.S. This is not to be confused with the "Narrow Band" O2 sensors that are very much outdated. Narrow Band sensors have 2,3, 4 wires. A wide band sensor has 5 wires.

Feel free to comment.

Charlie

P.S. Next topic will be my experience testing different thermostats and radiators and the results.
 
Update: Cooling

Just an update. I changed out the factory radiator for one that was more streamlined. Even thought it is on the test stand I wanted to have something that was more viable when the engine is moved over to the airframe. The new one is 6" x 19" x 2.5".


So far it is acting a bit odd. It will over heat (boil over) if I push it harder than 20" of Manifold Pressure. The weird part is that it gets over 240 degrees as measured as exits the heads but yet only gets up to 160 degrees as it exits the radiator.


A good friend who has a ton of experience at this suggested I swap the radiator flow direction and suspects there may be air trapped in the latest set up.


I hope to try those changes this weekend.


Below is a pic of the new radiator.....


http://www.halie.com/ovW.jpg

If there are radiator/cooling experts, feel free to comment - especially if you have every operated a water cooled airplane..

Charlie
 
Last edited:
So far it is acting a bit odd. It will over heat (boil over) if I push it harder than 20" of Manifold Pressure. The weird part is that it gets over 240 degrees as measured as exits the heads but yet only gets up to 160 degrees as it exits the radiator.

Charlie

80F delta across the engine is quite high. Not that there is some law, but typically it is 10F for peak conditions and pushing limits up to 20F. Ross may tell us what he gets on the Subies. Is this a bypass closing thermostat and is it installed?

Aircraft break so many standards for cooling systems. Lack of static pressure head to the pump suction, delta T, tube velocities, and more.

Do you have a shunt style system? A shunt is a non flowing hose from the inlet of the pump up to the expansion/fill tank. It seems like it does nothing, but is very effective in extending the cavitation limit at the pump inlet (the root of all liquid cooling evils).

The high delta T is likely the result of inadequate radiator heat rejection under it's air flow conditions, (low airside mass flow.
 
I see about 12-15C drop across my rad in flight, depending on coolant temp, ambient temp, airspeed and exit flap position. As Bill said, I don't understand how you could get such high delta across your rad. Never seen anything close to that in all my testing.
 
cooling

Bill has a good idea about bypass system not closing. Your thermostat may not be moving far enough to close the recirculation port and direct all hot coolant through the radiator.

mike
 
Bill has a good idea about bypass system not closing. Your thermostat may not be moving far enough to close the recirculation port and direct all hot coolant through the radiator.

mike

I haven't seen setups where they close off the bypass flow when the thermostat opens but maybe they exist. The fact that a much larger aperture opens with less flow restriction, ensures that most flow heads to the radiator. On the Subaru, I measured the flow with the open 'stat and something like 88% went through to the rad.

You could test this case by removing the 'stat and plugging the bypass hose.
 
Back
Top