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Analog fuel injection controller with 555 timer https://slantsix.org/forum/viewtopic.php?f=26&t=53817 |
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Author: | Reed [ Sun Nov 10, 2013 10:35 am ] |
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Tell us more about the fuel injection system! |
Author: | Dart270 [ Mon Nov 11, 2013 12:07 pm ] |
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Very cool project! It is satisfying to design and build things like this yourself, so that you know how every little feature and component works. Enjoy the drive... Lou |
Author: | Sam Powell [ Fri Nov 15, 2013 5:04 am ] |
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I am impressed with all aspects of this. The engineering is cool, and the craftsmanship appears excellent. As Lou said, this must feel really rewarding. Very well thought out, and clever ideas. Keep us up to speed with the project. I suspect you may get better results in the end with smaller injectors. I started my project with 36 pound injectors, and ended up with 24. Mine may still be a bit large. The stock chevy small block comes with 18 pounders. The economy and drivability got better. Smaller ones have a longer open time at idle, which improves the ratio of transition time to open time, thus making it all more predictable and consistent. If you can monitor your open time at idle, it is best to keep this at 2 ms or above to maintain your target AF ratio at idle. Smaller injectors will allow you to use longer times, and get a leaner idle that is still smooth. Again, congratulations! Sam |
Author: | Sam Powell [ Sun Nov 17, 2013 6:47 am ] |
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Very well thought out, and mostly above my head technically. Explain the keyring thing please. Did you make that? I notice it is on the coil wire only. Is it for suppression of interference? I had great difficulty with this on my set up. Also, explain the inductor core as well. Thanks. Sam |
Author: | lgu32 [ Sun Nov 17, 2013 7:26 am ] |
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The round keyring over the spark plug wire will take a small part of the electrical energy of the spark in to it. Every electric wire which carries current have a magnetic field around the wire. If the current is alternative (AC) the magnetic field is also alternative. A small part of this alternative magnetic field will go to the metallic circle over the wire. Anything magnetic will do it. As soon there is some alternative magnetic field in the metallic ring, another wire thru the ring will generate voltage. The complete set, ingition plug wire, metallic ring and the "other" wire are together a transformer. This transformer will "stole" a small part of ignition energy and this energy can be used as a signal to ECU. So this transformer is acting like a sensor. Of course its possible to put a connection direct to plug wire but it will have its challenges as the voltage there is about 15'000 volts and the signal level good for ECU is just few volts. Use a keyring (you can find a chromed ring there over one plug wire as well a thick brown/orange thing, that's the inductor core). Depending of needs, physicians and chemists have developed for electricians many kinds of magnetic materials with different features. An old style transformer core for 115V/60Hz mains is made from steel plates which are not so far away the sheet metal Chrysler used for cars. That metal is good enough because that mains electic is doing changes so slow. Modern transformers are made materials which are also based to "iron" but the construction of the material is closer to ceramics than steel. That material, ferrite is faster and better for electonic transformers and inductors. There is lot of different ferrites. This one used in my example was special (and expensive) material which makes much more inductance than conventional ferrite. It has like the best parts of conventional transformer sheet metal and ferrite together. I just had a set of different cores in an electricians test set, then I went to the garage to make tests. All were usable and then I did a look to my Dodge keys. Could that keyring work? Yes it did but the signal was so weak I rather will use "more professional" inductor cores than keyrings. Playing with ignition signals includes always some risks. Either the spark can kill some electronics and it isnt really healty to get that voltage to human body especially the person has heart problems. A dead electrician is not either a good thing at all. I have had some test drives at friday and saturday. I have pretty good mixture now and the warm engine feels strong. Of course the engine is a bit complicated as the camshaft and the stock turbine are not the best pair, but as I mentioned I can live with it, But the starting with dead cold engine is hard to do. I have to made some soldering again to make 1st start extra fuel circuit to my ECU. How easy it would be with Megasquirt! But I have choosen my way and I will keep it to the end... I have to do it as some of my friends are still thinking I cant with survive this project... Updated. I have finished my fuel injection project and the car is ready for fun. As it is just snowing and getting cold I probably keep this Dart garaged until spring. I also have updated my controller schematics above in my previous postings. Someone with some electronics experience can now read better the schematics. Before trying yourself I will write few words of operation of this type "almost-analog" controllers. This kind of stuff has to be tuned in a car with several road tests. So I do not recommmend anybody build a similar thing as it could cause harm to the car or person itself if something goes wrong - it was little confusing to drive with all meters and oscilloscopes on the dashboard. It could also be illegal to build such a things in a car. In Finland we dont have pollution rules for such an old car like my '66 Dart. So I was free to play with injection and ethanol. But if you feel so, why not. I have done my "electrojector" as they called the first electric fuel injection at 1950's. And what happened? All of them were collected back as the quality was ... |
Author: | lgu32 [ Sun Dec 15, 2013 5:11 am ] |
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I have done some street and road tests. At first I refueled the tank up with fresh ethanol fuel. The local "RE85" mix contains 70-85% ethanol depending of the season, the rest of it is premium fuel. Just couple of checks with lambda and then I went to the streets and roads: Everything above 2000 rpm was fine, even better than with a (318 V8 BBD) carburetor and gasoline. Road driving was the best. Even I have 3,55 gears and only 185/70R14 tires the driving was fine. The best comes just when it is WOT and engine speed goes over 3500rpm. There comes the power peak and seems it continues well above 5000rpm which I used shift point with my tests. A engine with MP268 cam and 318 BBD is "under carbureted" in my opinion. The engine does not get air/fuel as much the cam like to deliver at high engine speeds. It feels its going to die. With my home made efi the high engine speeds felt more "natural". The engine didnt stop once without shutting it down by key. Reliable, yes. Either I didint get not one firing inside the intake manifold or exhaust pipe during my 1st test day. The idle is quite worse as well driving with lowest engine speeds below 1500 rpm is not very comfort either. It is probably because the weather was below freezing point (-5 centigrades) and this car does not have heater for manifold or even for the air cleaner. I have used only one day and about 40-50 miles for tune up so there is still potential improment as I get more test sessions done. Even the ignition timing is still as it was with gasoline and carburetor. I am little surprised how easy it was built a "home made" fuel injection... To do: together with low speed improvements I have tune the transmission link to get more line pressure for 904. Now it feels to run up with 1-2 as well 2-3 shifts in some conditions. Probably I will add later a shut off (motor braking) feature so that the fuel delivery is off at high vacuum and high rpm. Otherwise I will need more brake pads and shoes. Narrow band lambda was pretty close to 0,5 volts at road test. i think i will not go any leaner until summer conditions. As the car was "so nice" I went for official inspection which we have to here for all cars annually. Everything was fine except the left rear brake was lost the friction. Probably there is some hypoid oil from diff gears. Its good that it was found there as this car really needs all the braking power it can get. |
Author: | sandy in BC [ Sun Feb 09, 2014 7:43 am ] |
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Your work is inspirational! Its nice to see someone using science and simple parts to make a sophisticated and unique system. |
Author: | lgu32 [ Wed Apr 09, 2014 9:38 am ] |
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Hello all you slant people. There comes my measured performance: http://youtu.be/Zlee_aBRMUI I did just a couple of test rides. I have a G-tech performance meter for results. No tuning of car or engine, no other tricks but just tests with different shift rpms. This was done with 5200 rpm shifts. 15,94s and 144km/h (89,5mph). I am pretty sure there is some tenths of improvement after fuel mixture and ignition adjustment. I havent "thought" the absolute performance when building this. I have used what I already have in my storage. I am happy with this performance. |
Author: | Dart270 [ Wed Apr 09, 2014 1:27 pm ] |
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Excellent work. You must have done a good job porting your head, in addition to the nice EFI. Lou |
Author: | Matt Cramer [ Fri Apr 18, 2014 9:30 am ] |
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This thing is like a home-engineered and homemade Bosch D-Jetronic. Very cool. |
Author: | lgu32 [ Sat Jun 14, 2014 5:01 am ] |
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Now the performance is confirmed at race track. It was my 2nd trial and the result was 15.987s and 138.3km/h. As usually also this time it started rain so no there was no possibility to test anything like AFR or ignition timing. Next point of this project should be to built in car test bench to compare acceleration/speed/engine rpm to get this tuned "in garage or near it". |
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