Oooooh, Ivo. You make me feel so good.

[KenSandyEggo]

I finally got a bracket fabricated that holds the brushes firmly in place. After a little more shakeout, I'll remove it and round the corners, clean up the edges and polish it. Today was the first time I went out and had the thing work properly for the whole flight. The brush bracket just has to be very sturdy. A pic is attached.

Also are attached some inflight photos. I found that if I leave the throttle at full power and bring the prop back to full cruise mode, the engine rpm goes down to 4200. After settling in for a moment while I level off, she cruises at 88-90 m.p.h. This one is the last photo after the climbing one. Actually, when I took the 90 m.p.h. one, you can see that the tank is still almost full.

I then tried mimimum power at full cruise pitch and got down to about 3800 engine rpm. She would cruise at 75 to 78 m.p.h. I tried 3500 rpm and she settled in at about 55 m.p.h. for awhile, but eventually started losing speed and slowly sinking as I tried to keep her in level flight. The "sweet-spot" appears to be at an even 4,000 rpm. She's cruising smoothly at 80 m.p.h.

I actually should get a better speed at full power and full cruise-pitch, because I have a limiting washer installed. I just guessed when I put it on. I should have left it off. I need to take it off the cruise end and place it on the climb end with the one I installed there. She over-revs a little on take-off at full take-off pitch. I need to drop it a few hundred rpms to about 5400. I'll turn as much as 5600, which is just wasted, as max h.p. is developed at 5400.

Climb rate with the IVO seems much improved. The climb photo shows full power at about 5100 rpm and 58 m.p.h. The VSI to the right of the airspeed indicator is almost straight up at about 900 fpm. This is with my 200 pound butt in it and 3/4ths tank of gas, about 20 gallons at least (the top of the tank, which is the skinny seat-back goes down faster than the wider seat bottom). I'm really pleased with the prop so far. :D Weather was about 65 degrees with light and variable winds to 5 knots. All speeds are indicated speeds.

[CLS447]

Sounds pretty good, Ken! How's the prop noise?

[KenSandyEggo]

The prop noise doesn't seem any different than the Prince, but of course that's subjective. The whole thing seems to be very quiet cruising at 3800-4000 rpm compared to my old 4600-4700. That's a pretty huge reduction in engine rpm, 7 to 800 rpm. The engine sounds like it's loafing now. I'll probably have this prop paid off in gas savings in about....oooh....maybe.......should be about.........AH! Who cares? :p

[Screw]

Screw-In

Sounds real good Ken. Glad your happy. Why the Leather gloves and SANDELS?

Screw-Out

[KenSandyEggo]

My hands were cold and my feet weren't. Actually, my hands get a little cold even when it's not too cold out because of no doors and the wind whipping across my throttle hand. I wear the other glove to keep it balanced.

[birdy]

Sounds like a good paddle Ken,my Ivo is still tick'n over good too.
The pitch I set it at for winter[cruise at bout 4200] don't need changing for summer[4500].Reckon those big blades are just more efficiant ay.
Btw,my rrpm on a cool dry day is bout 330,but tody,with a 42c ,20k wind blow'n they were spin'n at bout 365 S/L.

Another BTW.
I had an absolute **** day today,but I won't spoil your thread with my cry'n.

[StanFoster]

Ken: Sounds like a good prop setup. BTW....whats the latest on your pre-rotator. That is one improvement I want to do to my RAF when I do the annual late winter.

Stan

[KenSandyEggo]

Stan, all I have to do is drive about 3/4 mile to the hydraulic hose and fitting shop and pick up about 9 ft. of braided hydraulic hose and 2 fittings and then assemble it on the gyro and bleed it, which should take less than an hour. I don't go in to work for about 6 hours today, but..............the weather is absolutely perfect, so it looks like I'll have to go flying instead. I'll shoot for this coming week to get it done.

[Heron]

Ken "The Pioneer Spirit" Janulewicz, you are "The Man" ! :)
thanks
Heron
is that Ianoolehfitz?

[Mike Hook]

Ken when you get a chance check to see where your fuel consumption per hour is now at your new engine cruise speed.


thanks,

Mike

[bones]

Ken, mate i'm sorry but i gotta ask what the hell have you got that spanner in your hand for?? fine tuning or something

[KenSandyEggo]

Mike, I've been wondering about that. I've been flying around the last few days, including Saturday, and the fuel seems to go down as fast as it did before. I'm only guessing though, as I didn't calculate anything.

What I'm wondering about is everyone, when I'm at full throttle at take-off and leave it there and repitch the prop to cruise mode and the engine rpm drops from 5400 to 4200, and the throttle is still wide open, am I burning less fuel? The throttle is wide open, but the load from the prop drops the rpm way down, so surely there is less fuel going into the engine at the lower rpm.....right? Or is full throttle full throttle, never mind the load? Am I like driving up a steep hill in fourth gear? :confused:

Geez, next I'll need a fuel-flow gauge. I'm concerned about putting too much load on the engine and damaging it somehow, or is that impossible? I'm going to hook up my manifold pressure gauge, but I'm not sure what the heck it's going to tell me and why and what I do with the readings. :confused:

[KenSandyEggo]

Mark, I get a waxy buildup in my ears sometimes and can't hear the radio so good, so I use it scrape the ears out once in awhile.

Actually, I'm temporarily using a bicycle cable and handle for my prerotator, the handle is too small to get a good grip, so I attached the spanner....does that mean wrench?....to the small lever to extend it to get more leverage.

[jos]

Hello Ken,

Regardless the engine or prop rpm,the power your gyro needs to fly at a certain speed is constant. If your machine needs 60 hp to cruise at 80 mph and you change your engine and prop rpm it still needs 60 hp for that given airspeed.
The power an engine produce comes from the quantity fuel air mixture burned. Sinds you do not change the required power for your aircraft, why should it burn less fuel?
The fuel cosumption might differ if your prop performs better at lower rpm.Mostly slowing down the prop rpm improves the performance
Lower rpm to do the same job also means higher pitch. High pitch and low airspeed (35 m per sec is slow) do not improve performance.
You should also look at your engines torque curve and make it run close to max torque. It is not a good thing to load the engine for 100%( wide open throtle) at low rpm.
In a fixed wing a variable pitch allows to fly faster at a reasonable engine rpm.
In a draggy gyro flying faster requires a more to a lot more power and by consequence a lot more fuel.
Do some measurements and let us know.


JOS

[birdy]

A full open throttle and revs held low with a big load for extended periods[driving uphill in top cog a 30mph.] can also do long term damage,if the engines not desigened to do so.
Accelerated cavitation of sleeves or localised boiling for a start.

[bones]

Ken,
THat explains the SPANNER thing(bloody Yanks), if your engine is working harder it may show up in your temp gauge, if your temp hasnt gone up it may not be working any harder with the throttle open and being pitched back.
Just a thought

[KenSandyEggo]

JOS, how do I make it run at max torque? I believe max torque is at 5400 rpm, as is max h.p., if I'm reading the chart I have correctly. Measure what.......gallons per hour? The water temp is no different when I'm running at full throttle with max load from the prop. Slowing the prop definitely improves the performance. At 4200 rpm and full throttle, I'm honking along at around 90 m.p.h., where with the fixed-pitch, I had to turn about 4600 just to stay up in the air, and that was at a much slower speed, maybe around 70 m.p.h. 5400 is best rpm for take-off. So at full throttle, I'm loading the prop from 5400 down to 4200.

I have a manifold pressure gauge ready to install, but this is all Greek (sorry, wife) to me, and I'm not sure what to set with it and how. My prop is reduced 2.1:1. HEEEEELP!

[automan1223]

Ken,

Take the wax out of your ears. The only down side of this is if you load down a full throttle engine it can ping and detonate if you get the combustion temps/pressures too high. Coolant temps are a comforting factor but if you have ever had bad gas then you know what to listen for. That 'marble noise is killer on pistons (blows holes) and cylinder head gaskets. Can lead to catastrophic engine failure so you DO want to keep an ear open for it. With the aluminum heads though you can get away with a lot more than if your engine had cast iron heads (better heat removing properties) .

Its still something to listen for, if you dont go below 4 grand then you should be ok.

Whats your cranking compression ?
What fuel are you using ?

Jonathan

[KenSandyEggo]

I'm burning premium auto fuel and at the last compression check, all cylinders were perfect....I don't recall the exact numbers. How could I possible hear the "marble noise" with all that din? At full throttle, 4200 is as low as I can go when I completely pitch up the prop to max cruise pitch.

[jos]

Hello Ken,

Max torque on a ej22 Is at 4800 for the 136 hp version.
For the ej 22 128 hp version the max torque is at 4400 rpm.
The main difference between the two versions is the lenght of the intake manifold.
The 128 hp versions have the longer intake manifold.
The reason why the manufacturer did this where the complaints regarding fuel cosumption.The fuel cosumption on the 136 hp version was higher because in normal traffic use the car never ran at such high rpm. By reducing the max torque rpm the car ran closer to this rpm in normal use and the consumption got better.

If you instal a manifold pressure gauge you will see that at full throtle and max pitch on the prop the pressure will be close or comletely atmospheric.
This is a 100% max load situation for the engine
The engine performance curve gives you the engine power for this rpm.
When you reduce the pitch engine rpm will increase and the pressure gauge shows a vacuum. The load on the engine is reduced and less then 100%.
The absorbed power of the prop is equal to the engines delivered power.
Now to find out you must consider there are a number of variables.
The most important ones are the following: Airspeed and airdensity, engine rpm and prop engine cosidered as one variable because of the redrive, prop pitch.
A simple way to find out is to fly with identical airspeeds in similar weather conditions , temp and humidity.
You first go with the old prop pitch and engine rpm for an hour.
Next you go with a bigger pitch for an hour third step you go with the max pitch.
Do carefully measure the fuel consumption. Put the aircraft in the excact same place and fill up to the top after every fligh.
The 3 numbers will give you answers to a lot of questions.
In the mean time measure the temp of your redrive system.
With 100ù throtle opening or engine load the torque is the highest your engine can produce for that given rpm. In the old situation the torque was less but the revs higher.
Torque x rpm= hp
Another 3 numbers that will give you important info.
Let us know.

JOS

[automan1223]

Ken,

Even with all that racket I heard it on my engine when I was setting timing. If you know what to listen for you can hear it among all the noise. When it gets real bad you will have no problem hearing it. I think you should be fine.
The max torque (twisting force) comes in earlier than max hp. It is true max torque is where the engine is most efficient. At peak torque This means the engine is filling the cylinder to its best and using the most of the air fuel charge. Above that rpm the volumetric efficency goes down. The trick is you can always make more hp at a higher rpm, more power cycles in a give time is more HP. power. The trick is to have a tuned system and know where your peak torque and hp is and then start measuring the variables,fuel, speed, engine temps etc. I was going to say 4400 is most likely the best or lowest point of loading the engine.

Jonathan

[KenSandyEggo]

O.K., we now have an expert's opinion here. I was at Hammerhead Aviation talking to Robert about my hydraulic prerotator actuator and mentioned all the discussion about my prop. He told me that Whirl Wind Propeller Co. happened to be located on our field. For those unfamiliar, they make quality carbon-fiber props mostly for competitive acrobatic planes, like the Extra. Their smallest, bottom of the line prop is $7500 and the prices go rapidly upwards. Robert told me that the owner, Jim Rust is a real nice guy and probably wouldn't mind my running this by him.

I drove over to the other side of the field to his shop and spoke with Jim. I explained what I had along with the reduction drive and ratio. He asked what I turned on take-off with the Ivo, and what rpm was I showing in cruise at full throttle with the IVO. He also asked what rpm did I take off with and cruise at with the fixed-pitch prop.

He saw me pull up in my VW and asked if I thought I would hurt anything if I shifted into 4th gear, got on the freeway and floored it. Of course my VW will run all day like that. "No difference," he said. He said that if I got down to 1800 rpm, that would be a different story. He said that at 4200 and full throttle, all I'm doing is running in 4th gear and that there was no way I could damage anything at that rpm. He told me not to worry about it as there was no possibility of any harm being done to the engine. So that's that, I guess.

P.S. I bought the hydraulic line for the prerotator and fittings for $62, a can of H5606 aircraft brake fluid for 6 bucks and a brake bleeder pump at NAPA for $52 that Robert told me would cost about 7 or 8 bucks. Right. It's cool. It's a suction pump and won't put any air into the line like a small oil can will. I should have that in the test stage in a couple days.

[KenSandyEggo]

Thanks everyone for all the comments. I will check the fuel consumption per JOS' recommendations to see where I get the best balance of speed and economy. I'm guessing around 4,000 rpm. When pitched to full cruise at full throttle, which is 4200 rpm, it is very noticeable when I drop the throttle down to indicate 4,000. It takes a bit of throttle movement. Seems the parameters are shortened quite a bit with the adjustable prop.

IVO mentioned being able to climb if the prop ever fails in the full cruise pitch in order to get home....or wherever. I'm O.K. I'm cruising along in the high 80's, tickling 90 at those setting. If I just raise the nose a little to drop the speed to around 60 m.p.h., she climbs O.K. at around 300-400 FPM.

[KenSandyEggo]

Dumb-ass me showed up for work this afternoon and I was asked what I was doing there. It's my day off! I got the first hint when I saw the person there who I relieve on her days off. 2nd time I've done that. I haven't worked shift work or weekends for about 15 years, so now every day melts into another one and I have to stop and think to figure out what day it is.

Anyway, there I was, in my Lion King scrubs and a plastic bag with 2 White Castles, a Jello, a Yogurt and an almost rotten banana, looking for somewhere to go. Hmmmmm. I was part way to the airport, so off I went. I tackled the rest of the prerotator hydraulic activation system. I unboxed my new $52 brake bleeding pump and proceeded to get about 1/2 the can of hydraulic fluid on my pants, my shoes, the cabin floor and the hangar floor. Good thing I got an expensive one. I bled it the best I could from both ends, but I still got a spongy feel anyway. The handle would go all the way down to the stick, but the slave piston was moving, so I hooked it up.

Pulled her outside and cranked her up. I started prerotating and I'll be darned....it worked. Even with the spongy system, I managed to get up to over 150 rrpm. It was so spongy, I was surprised it worked at all. Now I have to find someone who actually knows how to bleed a system help me. That puppy should really whistle when it's solid. It feels like when you step on a brake pedal and it goes down to the floor. I didn't have my camera, because I thought I was going to work, so no pics until next time.

[pwendell]

Ken,

It sounds like you may be introducing air into the system as you're attempting to remove it. I've never bled a pre-rotator before, but I have bled lots of motorcycle brakes. It is important to have vacum on the bleed nipple before you open it and to continue the vacum until after it is closed. It is also important not to open the nipple too much. 1/4 of a turn should be plenty.

Of course if your pre-rotator doesn't have bleed nipples like brake calipers, then please ignore my useless advice...

[GyroTyro]

Dumb-ass me showed up for work this afternoon and I was asked what I was doing there. It's my day off! I got the first hint when I saw the person there who I relieve on her days off. 2nd time I've done that. I haven't worked shift work or weekends for about 15 years, so now every day melts into another one and I have to stop and think to figure out what day it is.
.
.
.
I Keep doing things like that, I'll go into a room with determination and once there I stop look around and ask myself "What am I Here After". It'll happen more frequently with age.
.
.

If you take a tube and attach it to the bleed valve and then submerge that tube in hydraulic fluid or brake fluid it will prevent air being sucked back into the return line, open the bleed valve then fill the master cylinder and actuate the brake when the Master cylinder is near empty refill it and continue until the system is air free. With both ends submerged in fluid all it can do is expel the air. Be sure to close the bleed valve before you expose the end of the tube to the air.

.
.
Walt

[KenSandyEggo]

Both the master (stick-mounted lever) and the slave (actuating piston) have bleed nipples. I tried it from both ends. The master is hard to fill by hand because the nipple is the only opening and it is on the bottom of the cylinder. I held it upside down and tried filling it with a little rubber cup that came with the kit, but it held about 5 drops. Once I repeated the procedura numerous times, fluid was coming up the clear tube and staying there, so I figured it was full. I attached a hose to the nipple on the slave and stuck the other end into the can of fluid. Still no luck. There are enough "rats" at the airport who can give me a hand. They all have hydrualic brakes. Just happened to not be anyone around yesterday.

One other aggravating factor is that if the "Buna" cup in the slave slips all the way down, it blocks any fluid from coming in or out. So I had to keep playing with that to keep the cup and piston away from the bottom a little.

[asmuzsr]

Ken
I had the same problem on my plane with the Tracey O'Brien brakes. They use the Heger master also. Here's how to do it and you'll get no air in the system. First get the old style pump squrt oil can. Put a piece of tubing over the end of it and then over the nipple of the wheel cylinder. Take the cylinder out of the handle on the stick and have some one hold it upside down with another piece of tubing coming off the nipple long enough to reach out of the cabin into a bucket. Open the nipple on the cylinder on the stick, and keep it pointing straight up. Now crack open the cylinder on the wheel cylinder and pump in the fluid your using till no bubbles come out the top of the stick cylinder. Tigthen the wheel cylinder and then the one on the stick. If you have been careful you'll have on air in the system. Worked for me and I had to do it by myself, not easy.
good luck.

[KenSandyEggo]

Tony, I tried a pump oil can, and I noticed that each time I let go of the handle and then pumped again, there was a big air-bubble entering the clear line. Maybe I got a cheap one. Probably have to get one that costs at least $52. I used to use an oil can to bleed the brakes on my Ercoupes and never had any problems. I have a Matco lever.

[TomCarlisle]

Ken: make sure the hydrolic fluid and the o-rings in the cylinders are compatable. I had some extra fluid from my aircoupe and used it to overhaul the brakes on my volkswagen. The o-rings on the volks expanded and when I put the brakes on, they locked and would not release. I had to completely redo the volks brakes using DOT fluid and everything was fine. If that happens on your system, it will lock the pre-rotator in and thats not a good thing. By the way----what was the score of the New Mexico-SDSU game last saturday?

[KenSandyEggo]

Tom, I already went through that when trying it out with a 1 foot piece of hydraulic hose. The slave cup distorted and I had to order Buna cups to be compatible with the master.

Score? What was it, soccer or a gymnastic competition? :cool:

[asmuzsr]

Ken
Maybe it is a bad hand pump. I never had that problem and I just used a cheapy from the auto parts store, I think. Well some where any way.

[KenSandyEggo]

Thanks, Tony, but a $52 vacuum pump should do the job correctly. I think it's the nut behind the handle that's causing the trouble.

[Ron Marlett]

Ken
I don't think you are going to experience much fuel saving by flying around with the engine at full throttle all the time. I mean unless you want to keep the speed up to dodge SAM's out of Karjackistan, you are going to use up fuel at the same or higher rate than you used to. And as was mentioned, the engine is at full power output so how long is it going to last?

I liked the analogy of the car at highway speed going to full throttle. It is true that in that type situation, such as climbing a hill, the engine should experience no harm but the car will burn fuel(and generate heat) at a very high rate the whole time.

I like to think of a controllable pitch prop as an overdrive, or the ability to match the prop bite to the incomming airspeed/density. Your fixed pitch prop was a comprimise of low and high speed performance and was most likley optimized for climb performance. At higher speeds, the faster airflow into the prop required a higher RPM just to keep a reasonable ammount of acceleration(thrust) to the air. Kind of like running a vehicle with a 5 speed transmission down the highway in 4th gear. You are making enough thrust to maintain highway speed but the engine is running at higher RPM to keep up. By shifting into 5th gear, you lower the engine RPM nearer the peak output range, without appreciably increasing the throttle setting to maintain the same speed, resulting in greater efficiency. That jump from 4th to 5th gear is usually the smallest gear ratio change in the transmission and only makes a few hundred RPM difference for the same speed. If the jump was too big, the additional load and throttle required to maintain speed would cancel out any gains from lower RPM.

I would think in your instance for efficiency that after climbout, you should reduce your Throttle to achieve your desired cruise speed(you said on the old prop it was found around 4600-4700 RPM) and then increase prop pitch to lower the engine RPM to the peak torque RPM. In theory that should give you better fuel economy for the same cruise speed than your fixed pitch prop did. Lowering the RPM should also ease the wear on your engine and redgear

Just my .02

[Vance]

The alure of running at peak torque is that is when you are getting the most complete cylinder filling and generaly the engine is more efficent. As your rpm increases past peak torque you end up with less complete cylinder filling, lower compresion and more mechanical drag. It is realy about horse power required and the range of engine efficency isn't all that wide. I can tell you that my car gets better milage if I have it in high gear than if I leave it in third. It is turning about 2200 rpm in 5th at 70 miles per hour which is well below the torque peak. My wifes car has a fuel computer and an automatic transmision and the computer says we do better if we don't down shift for hills. I would suspect that your fuel economy is going to be better the lower you rev it.

I am very enterested in your experiments and they seem to support Ivo's claims. thank you, Vance

[rehler]

Ken,

The best way to work with a varible pitch prop (or helicopter rotor) is to run the engine at it's best rpm and adjust the prop (or rotor) as needed to get the thrust desired. That's why helicopters run their engine at the same rpm all the time (on the ground, hover, cruise, landing, etc.).

[KenSandyEggo]

Thanks, guys. If you recall, one of my posts was that it seemed to still be gulping fuel at full throttle (4200) and when I went to 4,000 rpm it seemed much "sweeter" running. I am going to look into a fuel-flow gauge without the bells and whistles, if one exists. I think that would be a handy addition to actually see how much gas is burning per hour. I don't mean after an hour is up, I mean the ones that give an instantaneous readout as I tool along. I'll do a web search later. I appreciate everyone's contributions to this thread.

[Chuck Roberg]

Ken, this is a link from Norm's old forum;

http://www.vitelectronics.com/nm41.html

$159 does not seem to bad a price for some one with your kind of money. :D

[KenSandyEggo]

Wow! Thanks, Chuck. Aircraft Spruce wants $299 for it and I thought I did real good finding it at $189. $159? I can't pass it up. My kind of money? Bwaaaahaaaahaaa.

[KenSandyEggo]

Whoops! I just thought of something. I couldn't install the vane-sensor in my fuel line; mine is a recirculating system. It pumps way more fuel than the engine burns and then the rest comes back to my tank via a return line. It would probably show 55.769 gallons per hour. Unless......there is somewhere to install the sensor in the line to the jet of the throttle body, but I'm sure that's all internal and way too small. The ad also says it's designed for carbureted engines. Maybe this is why. Good thing I didn't order it. Maybe I'll call Airflow Performance and ask if they have a way of gauging fuel burn per hour.

[Chuck Roberg]

I have the same problem with my Hirth. The fuel pump puts out 60# then the pressure regulator tones it down to 41#. The excess fuel goes back to the tank. I was thinking I could put the fuel flow meter in past the pressure regulator. Any fuel past that point (I think :rolleyes: ) would go directlt to the injectors. :cool:

[Ron Marlett]

Chuck
It is common on most Fuel injection systems today that the regulator is at the end of the "fuel rail" or the fuel manifold where the injectors get their fuel from. The regulator trys to maintain the pressure on this manifold reguardless of how hard the injectors are firing(within the limits of the pump to supply). It maintains this pressure by bleeding off fuel and returning it to the fuel tank. If you put a flow meter on this return line(after the regulator) to the tank, it would read inverse of actual fuel used. At full power, the flow meter would read low as more fuel is going into the engine and less is being returned to the tank. At idle, the flow meter would read higher as less fuel being injected means more fuel being sent back to the tank by the pressure regulator. This reading would only be a relative figure anyway as you do not know how much fuel is being pumped from the tank initially without a second flow meter.

[KenSandyEggo]

I got the answer from Airflow Performance. I can put a fuel flow-meter in the line that goes to the fuel distribution block, also called the flow-divider, which feeds the injectors...duh, on my part. It's similar to a Bendix unit.

There is also a gauge port on the flow-divider which is now plugged. I can attach a pressure gauge into this port, and they sent me a curve chart which shows fuel flow relative to the pressure readings.

[Chuck Roberg]

Ron, I think I can do the same as Ken can. From the fuel pump it comes to a "Y". One branch of the "Y" goes to the regulator. The other branch of the "Y" goes to the injectors.

[mceagle]

In a correctly set up injection system, the fuel bypasses all the injectors before the excess exits through the regulator. this stops any air or vapor problems being trapped in the injector line, and allows for instant starts, even from a "dry" system.
A fuel flow meter anywhere in the line from the inlet to the fuel pump to the outlet of the return line will give incorrect and extremely high readings.
The simplest way to get a correct reading is to mount a small "header tank" below the level of the main tank, and draw the fuel and run the return through this tank. The header tank is gravity fed from the main tank and this is the line that you put the fuel flow transducer in. The header tank needs a breather from the top back into the top of the main tank to avoid any air or vapour build up. The header tank can be as small a few hundred millilitre if desired. The header tank has another advantage in that it can avoid temporary fuel starvation from uncovering the fuel outlet in the main tank during manouvers with low fuel.

If you didn't wish to run a "header tank", you can return the fuel into a tee on the suction side of the pump and run the transducer between there and the main tank. This system however cannot purge air or vapour from the system and you could end up with an intermittent miss.

[Aussie_Paul]

"The simplest way to get a correct reading is to mount a small "header tank" below the level of the main tank, and draw the fuel and run the return through this tank. The header tank is gravity fed from the main tank and this is the line that you put the fuel flow transducer in."

That is exactly as I have mine arranged, and it works well.

Aussie Paul. :)

[MichaelBurton]

"The simplest way to get a correct reading is to mount a small "header tank" below the level of the main tank, and draw the fuel and run the return through this tank. The header tank is gravity fed from the main tank and this is the line that you put the fuel flow transducer in."

That is exactly as I have mine arranged, and it works well.

Aussie Paul. :)
Would it be ok to tee the return line into the suction line ahead of the fuel flow transducer?

[mceagle]

Michael, see post #45. It can be done but you may need another Tee between the return line and the pump suction. It would need to be facing up with a pin hole in it to return to the top of the main tank. Fuel line sizes become critical so that there is no restriction in the return line and no restriction in the suction side of the pump. The only restriction should the pressure regulator.

[mceagle]

I will try to post a picture of a typical "surge tank" The fuel flow meter transducer can be seen in the line from the main tank.

[lanichol]

Hello Ken,

Max torque on a ej22 Is at 4800 for the 136 hp version.
For the ej 22 128 hp version the max torque is at 4400 rpm.
The main difference between the two versions is the lenght of the intake manifold.
The 128 hp versions have the longer intake manifold.
The reason why the manufacturer did this where the complaints regarding fuel cosumption.The fuel cosumption on the 136 hp version was higher because in normal traffic use the car never ran at such high rpm. By reducing the max torque rpm the car ran closer to this rpm in normal use and the consumption got better.

If you instal a manifold pressure gauge you will see that at full throtle and max pitch on the prop the pressure will be close or comletely atmospheric.
This is a 100% max load situation for the engine
The engine performance curve gives you the engine power for this rpm.
When you reduce the pitch engine rpm will increase and the pressure gauge shows a vacuum. The load on the engine is reduced and less then 100%.
The absorbed power of the prop is equal to the engines delivered power.
Now to find out you must consider there are a number of variables.
The most important ones are the following: Airspeed and airdensity, engine rpm and prop engine cosidered as one variable because of the redrive, prop pitch.
A simple way to find out is to fly with identical airspeeds in similar weather conditions , temp and humidity.
You first go with the old prop pitch and engine rpm for an hour.
Next you go with a bigger pitch for an hour third step you go with the max pitch.
Do carefully measure the fuel consumption. Put the aircraft in the excact same place and fill up to the top after every fligh.
The 3 numbers will give you answers to a lot of questions.
In the mean time measure the temp of your redrive system.
With 100ù throtle opening or engine load the torque is the highest your engine can produce for that given rpm. In the old situation the torque was less but the revs higher.
Torque x rpm= hp
Another 3 numbers that will give you important info.
Let us know.

JOS

I am reviving this old link to review the 2.2L torque & hp vs fuel consumption with the IVO medium variable pitch prop. Very similar to Stan's work with the 2.5L & max variable IVO.

Just as a comparison, I have an automatic 97 Cummings Dodge 4x4 diesel that I am getting 23 mpg if I keep the RPM down to about 1800 (approx 63 mph in overdrive). I use Lucas oil and fuel treatment to lubricate both the upper and lower cylinders. The fuel treatment also increases the centane and cleans the injectors. I know of few 3/4 pickups that get this mileage in an automatic. (I also have Michelin tires that tend to get better mileage.)

In the subaru, wide open, you are maxing the amount of fuel to the injectors, no mater where you put the pitch. There must be an ideal rpm where the fuel burns best depending on the injector/airflow and hp. From this point it would be logical to increase the pitch as in an overdrive. I don't think the MAP with tell you this, but a fuel flow meter might. Maybe a combination of both. Or the addition of a turbo might be ideal.

Mine is an airflow performace which is a low pressure mechanical injection system that does not require an oxygen sensor. It just dumps fuel depending on throttle setting. Probably has a poor method for atomizing the fuel. (So is there a problem burning leaded AV fuel?)

In the case of the cumming diesel there is overkill on HP and requires very little throttle. But it is a tubo. Would a sub with the delta cam grind and a turbo be overkill in hp, but ideal in fuel consumption?

It would be interesting as in this old post to compare the fuel mileage of the various years of subarus.

Does anyone have experience how to get the most mileage from the various subaru autos. I know this may depend on the transmission and gear ratios.

[StanFoster]

Larry: Glad you bumped this thread. Interesting reading that I had forgotten about.


When I first started considering a variable pitch prop....I decided on the Ivoprop. I knew I had seen Kenny J's glowing account of some variable pitch prop back in the archives somewhere. I did a search and found it...and was pleased to see he had used and Ivoprop. His report had me ordering one and to this day am very glad I did.


Stan

[PW_Plack]

Larry said...

In the subaru, wide open, you are maxing the amount of fuel to the injectors, no mater where you put the pitch.

Larry, that is true of your Cummins, but not the Subaru.

Your diesel has no throttle, because it doesn't care how lean it runs. Power is controlled by how much fuel is injected.

Because the gasoline engine needs to stay at about 14:1 air/fuel for the ignition system to reliably ignite the mixture, it is necessary to control both fuel and air, hence the throttle. The power control on the Soob opens a throttle body, and the amount fed to the injectors follows, regulated by a computer.

If the Soob is producing 100 HP at 3700 RPM wide open, or 100 HP at 5700 RPM at 80% throttle, the amount of fuel injected per second will be about the same. At 5700, the amount per cycle will be less, but the total will be close.

The reason we burn more fuel at 5700 than at 3700 for the same HP is that friction increases, and more power is consumed pumping gasses around.

[lanichol]

Larry said...

In the subaru, wide open, you are maxing the amount of fuel to the injectors, no mater where you put the pitch.


Because the gasoline engine needs to stay at about 14:1 air/fuel for the ignition system to reliably ignite the mixture, it is necessary to control both fuel and air, hence the throttle. The power control on the Soob opens a throttle body, and the amount fed to the injectors follows, regulated by a computer.

If the Soob is producing 100 HP at 3700 RPM wide open, or 100 HP at 5700 RPM at 80% throttle, the amount of fuel injected per second will be about the same. At 5700, the amount per cycle will be less, but the total will be close.


Thanks.

My fuel system is an airflow performace mechanical injection. In this system to test the injectors you unscrew the lines and place them in a cutoff pop can. As you open the throttle, the fuel flow from the injector lines increase, they also increase if you blow air across the throttle body. The mixture is mechanical. I guess the airflow across the venturi tube partly controlls the mixture by some kind of diaphram. Interesting system. I am not sure how well it atomizes the fuel.

So where is the balance in Soobs in HP vs friction vs fuel consumption? There has to be an ideal engine configuration (ie hp) to get the best fuel consumption. So I guess it is fuel consumption vs hp. If you have a large jump in hp, but a marginal increase in fuel consumption, you win. As contrasted to a lower hp that require a large increase in fuel consumption.

PS. Soob anounced this year a diesel in their opposed cylinder configuration. Which means were could be running jet fuel or biodiesel in our gyros.

[PW_Plack]

Larry,

I would think the best combination of RPM/power for low fuel consumption would be at or below the RPM at which the engine makes best torque. That RPM will be the one at which the cylinders fill most efficiently. Any faster from there, and you just increase friction.

In the cars, they spend much of their time below 2500 RPM.