No thanks, it's not my bag.
No thanks, it's not my bag.
Drew faith based intuition is great for giving you a direction to look in and being able to put (rough) numbers to something like TeeZee does can tell you if you are on the right track or not. Numbers can save you from a lot of wasted time.
Time at 13k rpm = 4.6ms for a complete 360 deg crank revolution.
Transfer opening to closing 130 deg. 1.7ms.
From exhaust port opening to closing 200 deg. 2.6ms
From exhaust closing to ignition. (with ignition timing 18 deg BTDC). 72 deg. 0.8ms.
Pressure in the cylinder ATDC greater than the 3 bar fuel injection pressure 90 deg, 1.2ms.
So somewhere between 1.7 and 2.6ms for injection, 0.8ms for fuel homogenization.
2-3ms required to open and close the injector 2-3ms required to deliver the fuel another 2-3ms or so to homogenize it.
Total time required:- 6-9ms
Drew, is there enough time to get everything done? I am picking not, and I am picking TeeZee doesn't think so either.
Factual Facts are based on real Fact and Universal Truths. Alternative Facts by definition are not based on Truth.
With EFI, "Time" is King.
.
Injector Position
Attachment 331035 Attachment 331038
Central injector fires through a slot into the underside of the piston.
My favourite low speed injector position has been to fire under the piston. This seems to help enormously with fuel homogenization at lower and off pipe engine speeds.
Attachment 331036
My least favorite and less successful position has been to inject directly across the crankcase into the oncoming inlet air stream. During periods of air flow reversion fuel gets blown out the inlet. And also at higher speed low throttle there is not enough time for a small squirt of fuel to travel right across the crankcase for even fuel distribution.
Attachment 331037
Looking at a piston positioned slightly below transfer port opening the two clean spots at the edges look to me like marks left from air/fuel short circuiting from the A ports and washing the carbon away.
When I showed this to Flettner and asked about injector positioning. He suggested an injector in each of the A and B ports.
Attachment 331033
Flettner suggested the B port injectors should handle the low speed fuel demand leaving only fresh air short circuiting from the A ports.
And any short circuiting is most likely at lower engine speeds before the reverse pressure wave action from the pipe blocks the exhaust port as the motor gets up into the power band.
At higher engine speeds when the motor is up on the pipe, then have the A port injectors chime in. That way with fuel injected into all four A and B ports the mixture should be pretty homogeneous. Flettner's idea sounds better than what I have been doing which is trying to combine two purely air streams from the A ports with two overly rich streams from the B ports and have them properly mix together in the cylinder.
As for problems coming back on the throttle after shutting off for a corner Nath88 suggested that at less than 20% throttle the EFI ECU needs to be able to differentiate between when the engine is firing and the pipe is sucking and creating a higher bulk air transfer through the motor and therefor fuel demand verses when the wave action in the pipe has totally collapsed and much less fuel is required.
The Alpha-N map cant do this by itself, there needs to be some way for the ECU to tell if the engine is firing and the pipe sucking or not. Nath88 suggested measuring the return positive pressure pulse at the exhaust port. It is a great idea and I like it but unfortunately, I have not found a way to get my Ecotrons EFI software to do that.
Flettner suggested measuring the internal pipe pressure at the dwell section in the middle of the pipe. He pointed out that the pressure must drop when the wave action collapses and that by using a VE table below 20% throttle/load and Alpha-N above that I might be able to train the ECU to recognize when the motor is firing and wave action in the pipe is increasing demand for fuel.
I like Flettners idea of low speed injectors in the B ports and secondary injectors in the A ports that chime in when the fuel demand under full power/load requires all four injectors.
Attachment 331034
I have ordered more parts from Ecotrons and my next challenge is a lack of room and to figure out how to fit a secondary injector close to the power valve actuator.
When I followed Nath88's very clever idea about using the return pressure wave at the exhaust port to see when the motor was firing. I ran into a problem, my ECU software averaged the low suction pulse and high plugging pulse and arrived at a lower average for on power open throttle compared to closed throttle. Makes sense when you think about it but I could not figure out how to get the ECU to make sense of it. Basically it needed to reduce fuel when the average pressure was higher and increase fuel when it was lower. This is opposite to the way EFI ECU's think.
In the mean time I am going to get this Beast going again and try Flettners idea and see what sort of average pressures are in the dwell mid section of the pipe and if the EFI ECU can make sense of them.
I have personally run an Ecotrons small injector at 13,000 rpm in my 125cc two stroke engine ... http://www.ecotrons.com/components/fuel-injectors/
Links to a whole bunch of EFI projects. Mostly amature home tuners, and all great work.
EFI Kawasaki Bighorn on the dyno https://youtu.be/ifSEql1X4R0
EFI Kawasaki Bighorn Trail ride 1 https://youtu.be/eleqBGvOM4M
EFI Kawasaki Bighorn Trail Ride 2 https://youtu.be/CnIemdISKrM
EFI Kawasaki Bighorn VMX https://youtu.be/v8i6ps0PdVI
Maramarua classic forest trail ride https://youtu.be/ZqzOgOJuJ1E
EFI YZ dyno run https://youtu.be/UEQli7nuak4
EFI YZ250 look around and first start up https://youtu.be/hOGZ5llowoU
EFI YZ250 trail ride 1 https://youtu.be/1YG9ko8-Nwk
Nath88?
EFI first start up https://youtu.be/wIRF3VJUqBk
EFI ride around the block https://youtu.be/4Zsz26QmfAU
CVT EFI NOS and everything else https://youtu.be/A9d-atuQO7Y
EFI and Turbo Snow Cat https://youtu.be/U1uz7gdS-cA
SeeDoo Etec https://youtu.be/LhNHcy9si5o
1975 Suzuki GT250 road bike fuel injected start up https://youtu.be/A7fONUsJQD4
1975 Suzuki GT250 road bike fuel injected road test https://youtu.be/BePHcg5dNjw
Fuel injected 1971 Yamaha R5 https://youtu.be/qzVHgHJ9PWI
Athena Direct Injection https://youtu.be/h-F_IndOm5I
BRC 250 EFI kart engine https://youtu.be/dNat9ZwWbq8
BRC 250 EFI kart engine https://youtu.be/Kfx61bUOznc
Racing EFI Vespa https://youtu.be/_sjx2i4xFlY
EFI Banshee first start https://youtu.be/e1WHVVT6d9c
EFI Banshee run https://youtu.be/eznxX_ndpII
Direct injection https://youtu.be/IpjWi-0qTJg
Will direct injection DI save two strokes https://youtu.be/ql2-wW0LuWY
Orbital direct injection https://youtu.be/fIoB0zTeUAY
EFI Dragbike Thailand https://youtu.be/VB6Q_fQQ_PY
Mega Squirt YZ125 https://youtu.be/Di8FuHApLKA
Aprilia RSi 125 EFI Part 1 https://youtu.be/S1xvr_VXzx4
Aprilia RSi 125 EFI Part 2 https://youtu.be/j5FOUn7V3nc
Aprilia RSi 125 EFI Part 3 https://youtu.be/WBaiMJb6ntY
Aprilia RSi 125 EFI Part 4 https://youtu.be/pZl5KPwvm0s
EFI 125 kart engine https://youtu.be/4D8WRjDxan0
EFI 125 kart engine https://youtu.be/b1YbPdw00Ww
EFI 125 kart engine https://youtu.be/r5ljaDdaH_o
EFI 125 kart engine https://youtu.be/uexMJbtyZdU
EFI 125 kart engine https://youtu.be/uzbSsYh8Z9w
EFI 125 kart engine https://youtu.be/XIcX9-GsMGQ
Fuel injected Kart https://youtu.be/R5_KlcefQ8k
2017 KTM dyno https://youtu.be/8g0uSIisMtI
2017 KTM demo ride https://youtu.be/nf1tfdUtjJI
EFI CR250 https://youtu.be/VlHyRcmlLgU http://www.supermototecnica.com/2015/09/10/sviluppi-del- sistema-iniezione-diretta- indiretta-due-tempi/
EFI YZR500 https://youtu.be/tNAtmKzqo9A
EFI CR500 https://youtu.be/BskSxMoQrwA
2T Nitro Engine visible combustion https://youtu.be/aO5Qkzlo2Kw
2T visible combustion https://youtu.be/G7PSec7RjRw
More 2T Visible combustion https://youtu.be/BrWpF6YiSDs
Fuel Burn in a side valve 4T https://youtu.be/jdW1t8r8qYc
4T Visible fuel burn https://youtu.be/31mtOdHGbB4
Looks like High Gain Tuning may have solved the issues that are holding me back and sell a kit for DIY two stroke EFI.
http://twostrokemotocross.com/articles.php?id=336
Careful. This guy showed up on the RZ forums with a hiss and a roar, and lots of self promotion in a wayonly Americans seem comfortable with,. . . got upset when people asked questions (how dare they) and then disappeared never to be heard of. Note article 2011.
Don't you look at my accountant.
He's the only one I've got.
Hello
Anyone know why I get this message when I want. To try
Auto tune " ecocal can't find the auto tune table
In the al2 file ?
al1 stack over flow.
Resynchronise the initial constituants.
Don't you look at my accountant.
He's the only one I've got.
Absolutely
Yes my first effort at porting the NSR cylinder lost power. And I think you are right about the reasons. I tried leveling the top of the exhaust port off by eye but totally stuffed up the exhaust port timing, got something like Ex opens 74 ATDC and to get the timing anywhere sensible I trimmed 2mm of the bottom of the barrel. The Ex was then 78.5 atdc and trans 122. To get the trans back to 113 I angled the A's up at 25 deg and the B's at 15 but the whole thing was a shambles.
So I started again.
Attachment 332289
There are actually only two "logical" injectors, one big one small. The two "physical" injectors in the B ports are there for symmetry of fuel distribution and are fired together as one Logical injector. I use three physical 124g/min injectors but the EFI CPU sees only two logical injectors, a 124g/min slow speed injector and one 248g/min high speed injector.
But it is not about injector size but time available to get the injecting done. If you only have half the time, then you need an injector twice the size to get the job done. And you need a small one for tune-ability when there is plenty of time like <9k 2T rpm (equivalent to 18k 4T rpm) and a much bigger one to deliver much the same amount of fuel when time is getting short like above 10k.
The reason you can't use the big injector for slow running is because an injector must be turned on for a minimum amount of time to get it completely open and controllable. And a big injector just spills to much uncontrolled fuel while it is opening for idling speeds and small throttle opening.
15,000 4T maxed out rpm "Time" for an injection cycle is just about where my 2T is starting to come on the pipe and get going. A 4T has twice as much time to get things done so only needs an injector half the size of a 2T, ie something about the size of my slow running injector.
It is "Time" not injector size that is the real issue with EFI.
Another issue with 2T EFI and throttle body injection is that unlike a carburetor which adds fuel to the air stream all the time, regardless of whether the air is being sucked in or blown back out of the crankcase ie fuel standoff.
A fuel injector squirts fuel in discreet blobs. And is just as likely to add all the fuel to the air stream as its blown back out as it is to the air stream being sucked in. So there could easily be rpm patches where you could wind up with little fuel at all in the crankcase.
This is less of a problem with transfer port injection. Where the bulk of the fuel is concentrated in the transfer duct and not the inlet tract where it can be more easily ejected. And will be one of the reasons why 2T EFI can show improved fuel efficiency over a carburetor.
And another reason for injecting into the B transfers is that the bulk of charge short circuiting happens from the A ports and if there is little fuel in the short circuiting air then the motor is cleaner and more fuel efficient. Another win over the carburetor which would have loaded all the crankcase air with fuel. With a carburetor all blow back and short circuiting air loses fuel and pollutes the environment, with 2T EFI not so much.
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