# Electronic Fuel Injection for 2-stoke

### Help Support Homebuilt Aircraft & Kit Plane Forum:

#### mmatt

##### Well-Known Member
Has anyone installed one of these systems on a 503 (or similar engine)?

http://www.ecotrons.com/products/2_stroke_small_engine_fuel_injection_kit/

I'm interested in it for both improved fuel efficiency and not having to constantly adjust my carbs between seasons. (I live in Canada and fly in temps ranging from 35C all the way down to -15C. (95F to 5F)

The system is listed at $600 but since I run dual carbs, I guess I'm looking at closer to$1200. I currently spend about $20/hr in fuel. If it cuts the fuel consumption by a quarter, I'd have to fly 240 hours just for the system to pay for itself. That's 2 years of flying for me. So in that regard, it's sort of worth it. But I'm not sure if that's a realistic expectation or not. But not having to constantly adjust the carbs would definitely make it worthwhile for me. The other concern I have: if you reduce the fuel consumption, do you not also reduce the available lubrication for the engine? How low can you safely go in a 2-stroke before you start to see accelerated wear? #### pictsidhe ##### Well-Known Member armilite was apparently going to try something from them. Haven't seen him for a while, likely because he caught so much flak for his plans to extract 40-50hp from a 277. You want an ECU that will run two throttle bodies. That could be as simple as adding a couple more output transistors or beefing up the existing ones and wiring injectors in parallel. Attempting to sync two seperate systems is not a good idea. Here's one thread that has a few leads: https://www.homebuiltairplanes.com/forums/showthread.php?t=27776&highlight=injection #### Werner ##### Active Member We dont need the small injector. Our range is aprox. 50-120%. Can we regulate separatly oil and fuel? Are the injectors able to spray the same quantity also with different oils, poor solutions etc? A lambda feedback is ok, but is not absolutly safe. A electric system is not fail safe. The exaust gases are mixed with fresh fuel, oil,... The lambda inside the chamber can bee dramatically different from the exaust lambda. Normally we need resundancy, maximal diversity between the redundances and fail safe equipment. All this is possible, also in a 2 stroke motor. #### pictsidhe ##### Well-Known Member Some outboards and snowmobiles have injection now. They'd be worth studying. #### Arthur Brown ##### Well-Known Member If you can control the oil mix then feeding oily fuel during low power periods may prevent low lube causing seizing when at low power. #### Dana ##### Super Moderator Staff member The other concern I have: if you reduce the fuel consumption, do you not also reduce the available lubrication for the engine? How low can you safely go in a 2-stroke before you start to see accelerated wear? It would be a problem if you used premix, but on an engine with an oil injection pump (later 503s and 582s as well as many outboards) the oil is metered according to rpm and throttle position independent of fuel flow. Dana #### Armilite ##### Well-Known Member Has anyone installed one of these systems on a 503 (or similar engine)? http://www.ecotrons.com/products/2_stroke_small_engine_fuel_injection_kit/ I'm interested in it for both improved fuel efficiency and not having to constantly adjust my carbs between seasons. (I live in Canada and fly in temps ranging from 35C all the way down to -15C. (95F to 5F) The system is listed at$600 but since I run dual carbs, I guess I'm looking at closer to $1200. I currently spend about$20/hr in fuel. If it cuts the fuel consumption by a quarter, I'd have to fly 240 hours just for the system to pay for itself. That's 2 years of flying for me. So in that regard, it's sort of worth it. But I'm not sure if that's a realistic expectation or not. But not having to constantly adjust the carbs would definitely make it worthwhile for me.

The other concern I have: if you reduce the fuel consumption, do you not also reduce the available lubrication for the engine? How low can you safely go in a 2-stroke before you start to see accelerated wear?
=============================================================

Haven't been on here in a while trying to catch up on other projects. Yes, a guy named John, I forget his last name, adapted a Hirth Fuel Injection onto his Rotax 503. He's on the Challenger List, Google "Bullet Proofing the Rotax 503" and you will get a link to him.

There is a Kit called Dial a Jet to make quick Jet Changes.

No, you don't need (2) Complete Systems, just a 2nd Throttle body. You can use just (1) Throttle Body also. If your looking for more HP I would use Dual Throtle Bodies, if just looking for GPH I would run (1). Rotax 503's came in both Single and Dual Carbs.

With EFI, you would probably see a 1.0gph over using Carbs, but you also get a Smoother Runing Engine, better Starting Engine. You have at least 2 choices that I now of Ecotrons or Mega Squirt and your looking at $500-$1000 depending on how much you can do, and make for yourself. There are cheap Throttle Bodies out there if you can make the Adapters to fit on your 503, etc. I suggest READING all off, both Ectrons and Mega Squirts web site mulitple times, lots of Good Info.

You can Source out the Parts cheaper than some of these kits.

Like here is a 40mm Throttle Body, fairly cheap and and a Adapter I designed for a Rotax Single Cylinder Sled Engine. Also for the 503. I've been working on my other projects so I haven't finished up my EFI Setup yet. Google "SFS Single Throttle Body Spec's" and you will find these.

#### Attachments

• 17.6 KB Views: 2
• 10.2 KB Views: 3
• 111 KB Views: 6
• 9.8 KB Views: 2
• 30.6 KB Views: 4

#### Armilite

##### Well-Known Member
armilite was apparently going to try something from them. Haven't seen him for a while, likely because he caught so much flak for his plans to extract 40-50hp from a 277.
You want an ECU that will run two throttle bodies. That could be as simple as adding a couple more output transistors or beefing up the existing ones and wiring injectors in parallel. Attempting to sync two seperate systems is not a good idea.

=================================================

Nope, just working on my other projects and Honey do's chores. If you Big Bore a 277 to a (82mm x 66mm)348cc, it's not a 277 any more is it?

Rotax 277 45hp and was having Ignition troubles. Once figured out all the kinks he was making around 55hp on 268cc!

#### Armilite

##### Well-Known Member
Some outboards and snowmobiles have injection now. They'd be worth studying.
Some Sleds have had Fuel Injection since the late 70's, Arctic Cat is one. Skidoo had a 580 EFI for one year I think 1992. Called a 580 EFI Plus. Then didn't have EFI till after 2000.

#### Armilite

##### Well-Known Member
It would be a problem if you used premix, but on an engine with an oil injection pump (later 503s and 582s as well as many outboards) the oil is metered according to rpm and throttle position independent of fuel flow.

Dana
===========================

Dana, just the opposite, if you Premix your Gas you always have that 50:1 Oil/Gas Ratio, Oil Injection is based more off the Rpms and it fluctuates 50:1 to 100:1.

#### Armilite

##### Well-Known Member
If you can control the oil mix then feeding oily fuel during low power periods may prevent low lube causing seizing when at low power.
=================================================

If your Theory was correct, Sleds would be Seizing all the time.

Seizures, are caused by many reasons from Detonation, to Cylinders not Bored & Honed Correctly with Torque Plates, to using Poor 2 Stroke Oil, to People not Premixing there Gas/Oil right, to Oil Injection not metering right, to People Over Reving their Engines just getting them to Hot, etc. Don't make rapid throttle changes and also don't make quick descents that can cause Shock Cooling.

With EFI you make AFR Tables in the Computer. Like 14.7 is considered ideal for Internal Combustion Engines at Sea level, but for a 2 Stroke you are using more like 12.3-13.2

#### Attachments

• 54.6 KB Views: 15

#### pictsidhe

##### Well-Known Member
=================================================

Nope, just working on my other projects and Honey do's chores. If you Big Bore a 277 to a (82mm x 66mm)348cc, it's not a 277 any more is it?

Rotax 277 45hp and was having Ignition troubles. Once figured out all the kinks he was making around 55hp on 268cc!
What's the TBO at 55hp?

#### Armilite

##### Well-Known Member
What's the TBO at 55hp?
TBO has nothing to do with MAX HP made. It has more to do with the Person who is maintaining it, what Octane Gas their burning for the CR used, what Oil & Ratio there using, how they Store it when not being used for long periods of Time, and how they Fly or use it. It also has to do with Who Built it in the first Place and what Parts and other things they used. The only Improvement Rotax done in 40 years, was the Cageless Rod Bearing in 1993 for all UL Engines, and the Ceramic Water Pump Seal, and Head Change for the Water Cooled Engines that I can think of.

Hirth, use's Nikisil Cylinders, lowered to 9.5cr on almost all their Engines, use a Tuned Pipe, and has their own Full Synthetic Oil for a 1000hr TBO. Simonini has done the same, but only give a 600hr TBO. There are a few things that can be done yet to Improve them, that none of them have done yet.

So IF, it was built right, like I said originally to a Big Bore 277, to (82mm x 66mm)348cc I would assume at least twice what Rotax gives 300hrs/ 5 years to 600hrs/10 years. That's Porting the Cylinder & Case, using the different Engine Coatings, Designing a Good Tuned Pipe, using the Hybrid Crank Bearings, going Cageless on Both Rod Bearings, using a Dual Slotted, with Dual Oiling Holes Rod. I would keep the 11.8cr and run probably 100LL, which solves Detonation and Bad Gas. It has a 5 year shelf life and it runs Cooler. There is some better Case Seals out today, High Temp, and EFI would be a nice add on.

Simonini's Single 362cc at 6500rpms with 9.5cr makes 44hp. So a Rotax 348cc Big Bore Single with 11.8cr and 6500rpms with a Good Tuned Pipe should equal or beat that. I figure [email protected] Adding EFI won't really make you any more Hp that you would really notice, but it would give you a better GPH, and Smoother Starting and Running engine.

You have to look at all aspects of your Engine, where can you make it run Cooler, Gear/Belt Drives, the Flywheel/Stator, Oil used, Jetting used, Engine Coatings used. Those Drives use Bearings also, and Oils. You can drill Cooling holes or Slots in Flywheel. The Stock 277UL actually Dynoed by R&D, made [email protected]!
http://www.rotaxservices.com/dyno.html#13

277(268cc) [email protected] is possible.
or
277 Big Bore (348cc) [email protected] is possible.

#### Armilite

##### Well-Known Member
What's the TBO at 55hp?
TBO has nothing to do with MAX HP made. It has more to do with the Person who is maintaining it, what Octane Gas their burning for the CR used, what Oil & Ratio there using, how they Store it when not being used for long periods of Time, and how they Fly or use it. It also has to do with Who Built it in the first Place and what Parts and other things they used. The only Improvement Rotax done in 40 years, was the Cageless Rod Bearing in 1993 for all UL Engines, and the Ceramic Water Pump Seal, and Head Change for the Water Cooled Engines that I can think of.

Hirth, use's Nikisil Cylinders, lowered to 9.5cr on almost all their Engines, use a Tuned Pipe, and has their own Full Synthetic Oil for a 1000hr TBO. Simonini has done the same, but only give a 600hr TBO. There are a few things that can be done yet to Improve them, that none of them have done yet.

So IF, it was built right, like I said originally to a Big Bore 277, to (82mm x 66mm)348cc I would assume at least twice what Rotax gives 300hrs/ 5 years to 600hrs/10 years. That's Porting the Cylinder & Case, using the different Engine Coatings, Designing a Good Tuned Pipe, using the Hybrid Crank Bearings, going Cageless on Both Rod Bearings, using a Dual Slotted, with Dual Oiling Holes Rod. I would keep the 11.8cr and run probably 100LL, which solves Detonation and Bad Gas. It has a 5 year shelf life and it runs Cooler. There is some better Case Seals out today, High Temp, and EFI would be a nice add on.

Simonini's Single 362cc at 6500rpms with 9.5cr makes 44hp. So a Rotax 348cc Big Bore Single with 11.8cr and 6500rpms with a Good Tuned Pipe should equal or beat that. I figure [email protected] Adding EFI won't really make you any more Hp that you would really notice, but it would give you a better GPH, and Smoother Starting and Running engine.

You have to look at all aspects of your Engine, where can you make it run Cooler, Gear/Belt Drives, the Flywheel/Stator, Oil used, Jetting used, Engine Coatings used. Those Drives use Bearings also, and Oils. You can drill Cooling holes or Slots in Flywheel. The Stock 277UL actually Dynoed by R&D, made [email protected]!
http://www.rotaxservices.com/dyno.html#13

277(268cc) [email protected] is possible.
or
277 Big Bore (348cc) [email protected] is possible.

#### pictsidhe

##### Well-Known Member
TBO has nothing to do with max hp made? Seriously? Go on, stroll up to a winning race team (any one) and try telling them that, and see how long they laugh at you. Then try the guys who blew their motors during the race.

#### Armilite

##### Well-Known Member
TBO has nothing to do with max hp made? Seriously? Go on, stroll up to a winning race team (any one) and try telling them that, and see how long they laugh at you. Then try the guys who blew their motors during the race.
Max HP made at these INDUSTRY STANDARD 6500rpms for Ultralight Engines, your not Turning these the same RPMS as RACERS Do!!!! It's not Rocket Science the Higher Rpms you turn any Engine, the Shorter its life span will be. Almost Every fricking Engine in the World is made in mulitple HP's at the same Standard RPMS!!!! Making more HP at the same Standard RPMS doesn't make them more unreliable, it makes them more EFFICENT! IF you you was half as Smart as you thought you was, it would be a miricle! Most of the Heat in an Engine is from the Piston rubbing on the Cylinder Walls, it's Called FRICTION, so the Higher Rpms you turn an Engine the more Heat made.

On 2 Strokes they mainly change the Carb Size used, the CR used, the Exhaust Type used Muffler vs Tuned Pipe and they can Vary Greatly, sometimes a different Cylinder is used that has better Porting, like the Standard Engine vs a TNT or Blizzard, on Older Sleds they use (3) Rpm Ratings, like 5500rpms, 6500rpms, 7500rpms, to make different HP Class's! In 4 Stokes, they use different CAMS(3000+), different Valve Sizes, different Heads some with better Ports, different Carb CFM's, different Exhaust.

I have never Promoted Turning any of these 2 Stroke Engine Higher Rpms, except the 277, which was only rated at [email protected] for Ultralights, [email protected] for Scat Hover Craft, in a Sled they went up to 7500rpms Stock. I said, I wouldn't go over Industry Standard of 6500rpms on them.

#### blane.c

##### Well-Known Member
If I had connections and money (I don't), I would pay Stormy Daniels to go up and give Armilite a big hug.

#### Aesquire

##### Well-Known Member
Brake mean effective pressure and rpm determine engine life all else being equal.

Load on the bearings and friction. Piston speed alone is a decent indicator. But not perfect.

In an automobile V-8 you can alter cam lift & timing and produce the same peak power at very different pressures and rpm. It's harder on the crank to make high torque at low rpm than to spin it faster with lower torque....... up to a certain point where the piston speed and reversing loads dominate the failure causes. Valve spring resonances and cam wear at high valve spring pressure dominate high rpm limits. Once you lose control of the valves, you've hit your rpm limit even if it's well below the crankshaft limits. Synergistic effects.

A 2 stroke, specifically a piston port model, has no valve problems. Disc valve versions have friction issues and reed valves disintegrate. ( but generally harmlessly if carbon fiber ) 2strokes run lower pressures but make more heat. The size and shape of the ports determine peak output rpm. Basically a musical instrument. The purpose of disc and reed valves are to improve lower rpm power.

If the rod bearings are adequately oiled and designed they aren't the limiting problem in piston port engines. It's ring flutter and catching on port edges. Simple chamfering the edges helps.

If you used plain bearing pressurized oil bottom end & piston bearings you'd eliminate most moving part failures at the expense of an oil pump and lubrication system. ( not insignificant ) but you need to use a multi part crank like a P&W R-2800. I'm ignorant of anyone doing so, but it's possible.

All in all it's the heat rejection that's the limitation of 2 strokes. You're simply burning more fuel per second than a four stoke of the same power. Lighter and fewer parts. TANSTAAFL.