Fuel injection?

[LARRYEBOYER]

I am new to fuel injection. I understand a carberator and how to make an engine run with it. FI is another story. Could someone give me suggestions on how to set up the fuel pump system. I have the high pressure pumps and hose. Do I need a return line. Can I use one fuel exit line on the bottom of the RAF tank to feed both pumps and the other bottom exit line on the tank to be a return? I have a 1992 ej-22. How do I route the rubber fuel lines and to which metal lines on the top of the engine do the go. Also there are what appears to be metal vacume line. Do I need them?

[rfi]

Larry,
You need to connect the two pumps to the two lines that come out of the tank on either side, then "T" the output of the pumps together and run a high pressure line to the top metal 5/16" line on the intake manifold.

The bottom metal line is the return line and it should be connected to the top of the fuel tank. The best place is to remove the filler neck and have a 5/16" nipple welded to the side of the neck.

you do not need the metal vacuum line. The only vacuum line that needs to be connected is the one to the bypass fuel pressure regulator which is on the left front of the engine. It is olive drab in color.

If you need any more information, call me at home (918) 823-4610. I will be out today and through the evening since it is our 41st wedding anniversary and we have to celebrate a little.

[Aussie_Paul]

Congratulations Don, and obviously your wife as well. :D

Great effort in this day and age of marriage break ups. You both must use the same persistance with your marriage as you do Don with your Subaru work!!!!!!!!! LOL

Aussie Paul. :)

[PW_Plack]

Don,

Echoing Paul, congrats! You're obviously as careful with maintenance as you are with design. ;)

[davreich]

HI,
Be advised the fuel injected hose is not everyday fuel line. It is in the JC Whitney catalog but the high pressure stranded steel hose is the way to go. Good Luck with the install. Also the fuel rail pressure is about 16 psi,if I remember correctly, anything more is overflow.

[CLS447]

How is the pressure to the injection regulated, with an open return line to the tank? I'm gonna be learning with Larry.

I got my Thrustbuster scale from AC last night....Nice unit. Gonna go flying with Larry B. this morning & do a thrust test on his carbed RAF. Will post results.

[rfi]

Thanks for the flowers, guys. It has been a long and enjoyable 41 years together but seems like it was only yesterday when we married. Mary is truly my soul mate.

FYI, Larry called me almost before I finished the post and we got everything straightened out over the phone along with some other details on the engine sensors.

The fuel pressure is regulated at 36 Psi by a bypass relief valve that returns the fuel to the tank. Single Point (throttle body) Fuel Injection (SPFI) uses lower pressure but MPFI runs around 35-40 Psi on most automotive systems.

BTW, I have done about 300 or so Subaru EFI harness modifications and am presently backlogged with over one dozen, so I am not totally retarded yet. We did finish the last issue of Homebuilt Rotorcraft (August issue) and Bob Stark will be here this weekend to pick up our printing press, colator, and booklet maker which folds, staples, and sometimes mutilates the magazine.

[CLS447]

Thanks Don! So the relief valve bypass is built in to the engines injector system?

How much HP is gained when going from carb to fuel injection?

I flew with Larry yesterday morn. It was hot(85) & humid(?). His carbed RAF did not want to climb so good with the 2 of us. Took about 5000rpm just to maintain altitude. Does this sound standard?

Did thrust test.... without verifying the accuracy of the scale ,it pulled 435lbs.

Took off 1 degree and it pulled close to 10lbs more. Gained 200rpm static. He liked it.

[Aussie_Paul]

Chris, when I went from the Raf carby set up we reduced fuel consumption by 20% eliminated carby ice and picked up 80 to 100 engine rpm.

A win win win situation. :D

Aussie Paul. :)

[rfi]

Chris,

The bypass fuel regulator is on the fuel rails, on the left front side. It is olive drab in color and has a vacuum diaphram that functions as an accellerator pump. All modern automotive MPFI systems work essentially the same way.

The Fuel injected EJ22 will typically get around 575 pounds of static thrust on a 70 degree day at or near sea level. The EFI equipped EJ22 will develop 130 Hp. A carbureted EJ22 will develop around 125 under optimum mixture setup and less if the mixture is off.

[KenSandyEggo]

Chris, The EFI equipped EJ22 will develop 130 Hp. A carbureted EJ22 will develop around 125 under optimum mixture setup and less if the mixture is off.

But at what rpm, Don? Doesn't Soob list the max h.p. at around 5400 or 5500? Most of us turn around 5,000 on take-off, so wouldn't the actual h.p. be less? When I get my cockpit-adjustable IVO installed, should I adjust pitch take-off rpm closer to Soob's numbers to get more h.p.?

Congratulations on your anniversary. You made it to double of what I made.

[CLS447]

Thanks Don, I'm sure we'll have more dumb questions for you though.

Ken, this stuff gets interesting, let's keep this going....... & get that prop on there!

[KenSandyEggo]

Chris, I tried rubbing my Prince bolts with Viagra, but they wouldn't get any bigger, so I'll have to wait for the longer ones to come in. I knew I shouldn't have believed that jerk down the row. I put the Prince back on today so I could go flying.

[PW_Plack]

Ken, it would have been temporary anyway. Didn't you see the fine print?

Any elongation of bolts lasting more than four hours is a symptom of a serious hardware condition and should be reported at once to your hardware professional.

[Brian Jackson]

Ken, try the Princess bolts.

[KenSandyEggo]

Gee Paul, did you get that off your bottle and just change a few words? How do I know? Nunna yer biznis!

Brian, what's neat is if you click your mouse on the center of one of your photos and move it to the edge of the picture, you can make yourself fall off your chair and barf on the floor....or dog, if it doesn't get out of the way soon enough.

[rfi]

Ken-The engine develops its rated Hp at 5400 Rpm. You could adjust the prop pitch so that the engine turns around 5400 and back it down as you level out.

Chris-there is no such thing as a "dumb" question. The lack of knowledge which can be cured by obtaining the desired information. Stupidity is another matter all together.

[ben]

rfi,
at what rpm does a ea 81 make it's max horse power? and what would be redline rpm thanks ben

[KenSandyEggo]

Thanks Don. I'm turning 5200 at full power with the Prince now that I cleaned out the Trapp mufflers, but it seems like I burn a lot of fuel cruising around. So the IVO should give me a better deal at both ends of the spectrum. I'll have to remember 5400. I'll be back in a week asking again. :o

I have to maintain 4500-4600 usually in cruise to maintain altitude and a little less if I burn off most of the fuel. Almost identical numbers with the 3-bladed Warp. That's solo. If I can turn 5400 on take-off and turn 4,000 or a little less in cruise, I'll be one happy puppy. I can't wait to get those honker bolts and try it out.

As an aside, and I believe I mentioned this before, I think that the RAF supplied engine tachs are way off. I used to cruise at 4200 solo, or so I thought. I installed 2 VDO tachs, one to each Electroair ignition system and my engine rpm for cruise jumped 400 rpm on each tach with no other changes at the time.

[Aussie_Paul]

I doubt if the Raf tachs are off Ken. They always match the laptop tuning the ecu. I think that your VDO spring return tachs would not be as accurate as a digital signal.
Only my experience, not gospel.

Aussie Paul. :)

[KenSandyEggo]

I'll have to check it further Paul. Each tach is outputted from the tach output of each ignition system. Seems a long shot that I'd get identical readings from 2 different ignitions......no? I have one of those hand-held rpm checkers and will see if I can point it at the prop while flying in cruise flight and get a reading....uh-oh....then I have to convert somehow by the reduction ratio of 2.1:1. Someone have a quick and easy formula? What gets divided by what? Or do I take a reading of the prop rpm and multiply by 2.1 to see what the tachs should be reading? Aaaaargh. I'm getting a math headache already.

[KenSandyEggo]

Another thought. When I first installed my Prince, I still had the RAF tach and was turning the same top rpm that I am now. The difference seems to be in the cruise mode only.

[StanFoster]

Ken: Just set up a ratio. Then cross multiply.


1 /2.1 = prop rpm/engine rpm


In short......multilply prop rpm by 2.1


Stan

[rfi]

The EA81 rated power Rpm varies. If it is a stock engine built for North American cars the engine makes its power at 4800 Rpm. If the engine is out of a Brat pickup the rated power Rpm is 4200. If it is the high output, dual carb engine that we never got in this country the rated power Rpm is 5600.

And, if you have modified the engine camshaft the rated power Rpm can vary from 5000 and up depending on the cam grind.

[PW_Plack]

Could a factory Subaru cruise-control be used to make a CAP into a constant-speed prop? For example, take off, get to straight and level cruise, then lock the cruise at 4000 RPM, and use the prop pitch control as your thrust control. Dial in more pitch, get more thrust, and the engine automatically increases throttle to maintain 4000 RPM.

Kind of a poor man's FADEC?