When you mentioned "higher engine speeds this is not possible since injectors are just about full on (90%). ",
does it actually mean that the injectors are spraying fuel into the cylinders even during the exhaust stroke?
When you mentioned that "running an engine lean at high speeds will create a hole in the piston", does it mean that the piston rings will wear off or literally a big hole will form in the middle of the piston?
A lean condition creates excessive heat, lean at high speeds more so. Literally a large hole in the center of the piston. PWM for the injectors would be something you would want as a current limit on low impedance injectors, or peak and hold where the injector is opened with a current spike and holds open on lower current.
Direct driving low impedance injectors creates excessive heat. Look at fuel injectors as a current controlled device instead of voltage......
Also, yes they can be open on the exhaust stroke but the intake valve is closed so they are spraying fuel into the intake tract, look at it as "precharging" the intake tract so that the fuel is ready when the valve opens and the piston sucks the fuel and air in....
When a injector is properly sized to an engine (for conventional automotive applications) there is not much room left at the top end to get all the fuel in during the intake stroke.· There will be some fuel left behind in the intake port·but not much of it is pulled over to the exhaust side during valve overlap since the exhaust pressure is much higher than the intake pressure (at high engine speeds and WOT conditions).
When I mentioned lean conditions can result in a failed piston I was refering to the fact that cylinder temperatures can get very hot under lean·conditions.· And·these are usually high speed and WOT conditions.· What usually happens·is the spark plug starts to melt and becomes a source for preignition. This causes an over-advance-condition on the engine and pistions get very hot.· Normally piston crown temps are·in the range of 500 °F and when the engine gets into preignition·these localized temps can·exceed 1300°F. Thus a hole will form in the center of the piston, directly below the spark plug. ··
Thank you for your kind input.
I would think that the piston alloy is made withstand high temperatures, so literally creating a hole in the middle is unheard of in my country.
If the AF ratio is intentionally made rich as a "coolant" to cool the piston, wouldn't it be killing fuel efficiency?
I still think that we don't need PWM to drive the injectors, b'cos the on time is only a matter of a few milliseconds.
I think modern engines directly inject fuel into the cylinder, not into an intake tract, unless it is a "indirect injection diesel engine" like in a 2000 Ford Ranger.
Time to learn how to use Eagle: 1 complete board (grin). In other words, I went from concept to a finished PCB and by being determined to figure it out, I learned the product. They have a great support forum also which is free just like the program. I never did figure out how to do a rectangular hole for the 2.5mm power jack that I used on my PCB. I just have to get on the forum and ask.
In time, I think I worked on a schematic for about 6-8 hours one day and I was pretty dangerous with the program. Probably another 4-6 hours learning how to draw new parts, layout the PCB and how to draw "restricted" zones and ground "pours". From there is was a matter of tweaking my design and learning new techniques.
Most parts I physically had in my hand so I measured them with a digital caliper then drew them and added them to my "library".
The board turned out much better than my expectations and needed only a few wire "fixes". One trace was too close to a mounting hole, the holes for the diodes were specified as being too small, etc. All of the errors were mine, not the PCB manufacturer (PCBCart).
I think the best thing about learning it is that it will work with ANY PCB fabricator. Thus, I can now pick and choose the fabrication house that I want.
Finally, I would equate the learning curve to something like Adobe Photoshop. Some of the commands in Photoshop are not exactly intuitive. Same with Eagle. However, those that have learned Photoshop would not go back to any other program because of its versitility. I guess I feel the same about Eagle.
William,
Just about any motor could be leaned out enought at WOT to pop a hole into the piston no matter how good of a alloy its made out of.
Also if you dont plan to use PWM and you plan to use just a pulse how are you planning to time the pulse?
To time the pulse, I think we could start with longer pulse to aid starting, ( making the AF rich ), then slowly within the next few seconds reduce the pulse width until the O2 sensor detects some oxygen. This is just my idea, it could be wrong.
John,
I am also starting to learn Eagle, ( I was using ExpressPCB ), but when I printed the Schematics, the texts came out as black blocks.
The silkscreen text on the PCB also printed out as black blocks. What is the problem?
On the screen it looks ok.
William,
Their are two types of injectors that I know of their is the High impedance (12-16 ohms) and Low impedance (1.2- 2.4 ohms). most of your typical port injectors I.E. one injector per cylinder are Low Z (impedance) injectors and they use PWM to control the current to them so they do not get hot. The High Z injectors can handle the full load and use just a pulse width to control it. But you can add a series resistor to the Low Z injector to limit the current and then treat it like a High Z and use just pulse width then.
Here is the formula for the series resistor.
resistor ohms = (alternator voltage / 2.0 amps) - injector resistance
I think ECU design is a bit science mixed with a bit of art.
It could this art portion that creates myths surrounding ECU design.
We need to keep a clear and logical mind to separate myths from facts.
GAF has stated quite clearly that injectors only go on or off, no in betweens. I tend to agree.
Why would any injector manufacturer want to design a injector that can work with 2V when they know that
every electrical device in a car runs on 12V? Beats me.
He also mentioned that at high RPMs, the injectors are on about 90% of the time.
On this point, I want dispute.
As far as I know, injection only starts at the end of the intake stroke and has to stop before the power stroke.
That means, at the most it should be injecting fuel only 25% of the time.
At normal cruising RPMs, I would expect the injectors to be on less than 5% of the time.
So considering that 95% of the time, the injectors are in off state, over heating of injectors would not happen at all.
GAF has also recommended MOSFETS that can handle at least 200V.
I tend to disagree with this recommendation.
Assuming the injectors has a inductive coil inside it, yes it will induce a high voltage when it is switched off.
But by having a free wheeling diode across each injector, the voltage build up should not exceed 24volts.
Based on this explanation and my experience, I would continue to recommend the IRL510 as the injector drivers.
Port and TB injectors can be open beforethe intake valve opens, which can be in excess of a 180 deg crank rotation.· For TBI the injectors can be open for 90% of the time, since they feed multiple cylinders.
It's kind of like Direct Injection on 2 stroke engines. Up to a certain rpm the injector can fire while the exhaust port is closed. But at wide open throttle the injector is firing at BDC, while the exhaust port is·all the way·open. That's why an expansion chamber still works on a DI 2 stroke. It's to bad that·2 stroke myths killed further development of 2 stroke DI's.
GAF,
Are there injectors that require more then 12 v?, ·significantly higher like 200v? , or
Can I drive a 12v injector, using 5v to power an Inductor that produces 12v for the injectors and 300 v for an ignition coil?
Also, have you written any papers that are pertinent to this discussion?
SAE's online search engine isn't so great. If so do you remember their #, If not I'm going to take a drive to Cal Poly Pomona and look all your material.
Bill
Post Edited (Capt. Quirk) : 6/7/2007 5:40:46 PM GMT
William, ·· Low Z injectors are called "Peak and Hold" the injector is switched on high for the first portion of the signal to overcome the internal spring then it switches into PWM mode to keep the injectors from obtaining to much current. See my attachment to understand what I am saying more.
High Z on the other hand you can just turn them on and keep them on and they will not get to much current.
But like I said you can use series resistors to limit the current the treat Low Z injectors like High Z.
Also a motor does not use much less than 30% duty ever most that I know of use atleast 30% to idle and yes they do spray at 90% of the time at WOT.
Captain Quirck, ·· You can not open a Low Z injector with just 5V it is a peak and hold it takes 12v for a certain amount of time and the datasheets will tell you what the opening time is and then you use PWM to cut back on the current.
Guys I have not had time to put my Car 96 Rivi with Low Z injectors and my 91 Chevy truck with HIGH z injectors on a Oscope to show you the signals but I will try this weekend.
Post Edited (bennettdan) : 6/7/2007 4:55:22 PM GMT
William, · I dont think its so much art as someone having a very clear undestanding of everything that goes on in an internal combustion engine, as well as the capabilities of the electronics. To my understanding the idea behind a peak and hold injector is to allow you to use excessive amounts of current to produce a very fast opening time. The closer an injector pulsewidth is to a squarewave the more consistant and predictable, OR it could just be fuel pressure related.
Anyway, ECU design requires a very high level of skill in several disciplines, or a very well coordinated team of those disciplines.
Almost all gasoline engines in the U.S. are indirect injection, I'm sure there are some exotic DI's but dont know of them. Trust GAF, everything he's said has been spot on.
I think you set the text too small. Remember you can set the text to as small as .01 so even an ant would need glasses! I set mine at about 0.07.
Another thing to consider is the size of the schematic. If you put a lot of stuff on it, Eagle will size it to fit on the page and thus shrink everything.
Download my schematic and look at the font sizes and print it out. That way you can at least verify that Eagle can print a schematic and board layout.
Let me clarify, I want to use an Inductor that produces 12 volts or more to drive 1 or 2 injectors (For Model Airplanes, lighter is better,lol). The inductor would have a 3 to 5v battery powering it. That same inductor board would also produce 300v primary voltage for a multi spark ignition system
What it comes down to, what is the amperage reqirments of a Low z and High z injector.
Post Edited (Capt. Quirk) : 6/7/2007 5:55:34 PM GMT
Capt. Quirk,
The low Z injectors only need about 2 amps to operate. High Z you dont have to current control them but they are probaly to big for what you want.
The smallest injector I know of it a 9lbs/hr injector, do you plan to run the plane with a bosch style injector? I dont know if you could get a low enough amount of fuel out of it and not flood the engine.
If that is the case you might would start with two 44lbs/Hr injectors their are a few Ford SVT vehicles that use that size for their stock injectors also the TBI injectors on the early 90s chevy trucks are around 80lbs/hr and they use less fuel pressure the SVT injectors will need more fuel pressure, you might be able to find a few in a junk yard to play with.
Post Edited (bennettdan) : 6/7/2007 8:42:01 PM GMT
Just reading over the notes where we a talking injector flow rates etc.· How much thought is given to the fuel pump and the required fuel pressure to get these flow rates.· Most injector flow rates are specified at a nominal pressure·usually 40 psi but I gave seen some higher. I know this is·not a problem for the guys working·on existing vehicles, but trying to adapt an EFI system to a small engine presents serious design problems, though not impossible.
Capt. Quirk,
For Nitro Methane·the stoichiometric A/F is:· 1.7 lb air / 1 lb fuel.· It is interesting to note that Nirto Methane has only about 1/4 the heating value of gasoline. The high power levels achieved with this fuel are a result the large mass of the fuel that is required for combustion, almost hydro lock.
Fortunately we only use 25 to 30 % (about 4:1), But me and Mr. Hydro Loc met last summer, while running our 160cc twin opposed Unlimited engine. That cylinder popped off so Fast & 1 second later the whole engine was trash.
My mechatronic [noparse]:)[/noparse], system works fine right now without an injector.
For my system with an injector,I am trying to do it without adding a gear pump to the crank. The airplanes run 4 psi max fuel pressure, so either I need to modified a TBI or make my own injector. That was part of todays diddling.
But in the near future I'll be building a system for a 2180cc VW (HairDryer, lmao) and then for a modified Olds 215ci aluminum block V8 w/ Land Rover heads and injectors.
I guess you have a point on the PWM thing.
Anyway, we can go ahead with the board design since PWM or no PWM, the driving circuit is the same.
GAF,
What is your opinion on Isuzu's DMAX 2.5 Direct Injection diesel engine which seems to blow all competition away, even the CDI engines.
They claim 1,400+ km on their 4x2 truck with just one tank of 76 litres of diesel.
Does this mean that Indirect Injection is grossly inefficient?
William if you use the resistors I have talked with a few people that have and it adds about 1 millisecond to the injector opening time and sense most take one second then allo for that in your code.
I did find some time and put on the new throttle body and did some reprograming. tryed to develop a 3d equation from info i gathered for my VE table. and i also put all the wires in a nice harnes. took it out today for a little ride on some trailes. gotta say worked way way way better then the old carb that i had on it!. but it still needs some fine tunning of the code to make it perfect. i tryed using the serout command so i could see what is going on inside the ecu as its running. i programed a little monitoring program in PERL, of all langueges, to read the serial port and desifer the infromation and then show it on the screen. for some resone i could only run the sx serout command at a maximum but rate of 38400 witch is kindof slow. but any faster then i would get data corruption. probably bad cables im using, two 6 foot serial cables. i had to make the sx only send one byte every engine revoution. if i were to make it send too much then it would take to long and then the sx wouldnt be ready to read the hall effect sensor.
havent made use of the little eeprom that is on the board yet. not sure how i want to go around makeing use of it. maby eventualy use it to store the variables so they can be changed with out haveing to pull the crystal and used the sx-key. i think that ill just used the equation to get my VE, i think it would be faster then sending a comand to the eeprom then haveing it send back the info.
The IC's im useing to drive the injectors work fine for my application, did not lean out at high rpm and they just got a little warm while i was driving. i have a waterproof plastic box that the pcb board is designed to fit perfectly in. i think what i can do to keep it cool is do what they sometimes do with prossesors and heatpipes. i could just have 2 heat sinks on for the inside of the box and the other for the out side. and have them connect to each other with some copper and make sure that i seal the hole in the plastic. but right now everything runs fine with no heat sinks at all. but once its inclosed im sure it will start to warm up.
GAF, quick question
in the automotive industry, when building an engine and desigeing the fuel injection system for it, what is the basic proccess of getting the programing code tuned really good? do they used a dyno and get the proper variables (A/F, VE, ADVANCE) from trial and error? or is there a easer way to do it?
Thanks
the engine im running is called K532· its made by kohler.·· its 842 cc horizontal twin air cooled.· i got it from my uncle, it was on a machine for pulling 100's of feet of sprinkler pipe throught the ground, it had been siting for years and was all rusted up. the cyclenders were seized solid. i rebuilt the whole thing and the carb originaly wasnt good, and after it being so old it was really crappy.· hence came the idea of fuel injection for it.· plus with fuel injection i can easly run boost on it.· the engine is faily low compression and its a flat head.· so i think i would get more power·by haveing boost rather then upping the compression.·· maby if i get the urge i could add water injection on it as well to help cool the engine while its under load.... but thats another project for another time.·
To get the proper data to program the EEC many hours are spent on the dyno going through a process call Engine Mapping.· This is where at each speed load condition·all possible parameters are swept though there full range,·eg. spark is swept from full retard to full advance.··One of the main parameters measured during this process is fuel flow, so we can plot fuel flow vs spark advance, this determines the optimum spark setting for each speed load condition (the·A/F is held constant at Stoich for part throttle and around 12:1 for WOT or is EGT limited).··The Mapping process takes about a month, 2 shifts a day 6 days a week.· I am over simplifing this process but I think you·get the idea.
Comments
When you mentioned "higher engine speeds this is not possible since injectors are just about full on (90%). ",
does it actually mean that the injectors are spraying fuel into the cylinders even during the exhaust stroke?
When you mentioned that "running an engine lean at high speeds will create a hole in the piston", does it mean that the piston rings will wear off or literally a big hole will form in the middle of the piston?
Thanks.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.fd.com.my
www.mercedes.com.my
Direct driving low impedance injectors creates excessive heat. Look at fuel injectors as a current controlled device instead of voltage......
Also, yes they can be open on the exhaust stroke but the intake valve is closed so they are spraying fuel into the intake tract, look at it as "precharging" the intake tract so that the fuel is ready when the valve opens and the piston sucks the fuel and air in....
Many happy ventilated pistons...
When a injector is properly sized to an engine (for conventional automotive applications) there is not much room left at the top end to get all the fuel in during the intake stroke.· There will be some fuel left behind in the intake port·but not much of it is pulled over to the exhaust side during valve overlap since the exhaust pressure is much higher than the intake pressure (at high engine speeds and WOT conditions).
When I mentioned lean conditions can result in a failed piston I was refering to the fact that cylinder temperatures can get very hot under lean·conditions.· And·these are usually high speed and WOT conditions.· What usually happens·is the spark plug starts to melt and becomes a source for preignition. This causes an over-advance-condition on the engine and pistions get very hot.· Normally piston crown temps are·in the range of 500 °F and when the engine gets into preignition·these localized temps can·exceed 1300°F. Thus a hole will form in the center of the piston, directly below the spark plug.
··
Thank you for your kind input.
I would think that the piston alloy is made withstand high temperatures, so literally creating a hole in the middle is unheard of in my country.
If the AF ratio is intentionally made rich as a "coolant" to cool the piston, wouldn't it be killing fuel efficiency?
I still think that we don't need PWM to drive the injectors, b'cos the on time is only a matter of a few milliseconds.
I think modern engines directly inject fuel into the cylinder, not into an intake tract, unless it is a "indirect injection diesel engine" like in a 2000 Ford Ranger.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.fd.com.my
www.mercedes.com.my
Time to learn how to use Eagle: 1 complete board (grin). In other words, I went from concept to a finished PCB and by being determined to figure it out, I learned the product. They have a great support forum also which is free just like the program. I never did figure out how to do a rectangular hole for the 2.5mm power jack that I used on my PCB. I just have to get on the forum and ask.
In time, I think I worked on a schematic for about 6-8 hours one day and I was pretty dangerous with the program. Probably another 4-6 hours learning how to draw new parts, layout the PCB and how to draw "restricted" zones and ground "pours". From there is was a matter of tweaking my design and learning new techniques.
Most parts I physically had in my hand so I measured them with a digital caliper then drew them and added them to my "library".
The board turned out much better than my expectations and needed only a few wire "fixes". One trace was too close to a mounting hole, the holes for the diodes were specified as being too small, etc. All of the errors were mine, not the PCB manufacturer (PCBCart).
I think the best thing about learning it is that it will work with ANY PCB fabricator. Thus, I can now pick and choose the fabrication house that I want.
Finally, I would equate the learning curve to something like Adobe Photoshop. Some of the commands in Photoshop are not exactly intuitive. Same with Eagle. However, those that have learned Photoshop would not go back to any other program because of its versitility. I guess I feel the same about Eagle.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
John J. Couture
San Diego Miramar College
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
John J. Couture
San Diego Miramar College
Just about any motor could be leaned out enought at WOT to pop a hole into the piston no matter how good of a alloy its made out of.
Also if you dont plan to use PWM and you plan to use just a pulse how are you planning to time the pulse?
To time the pulse, I think we could start with longer pulse to aid starting, ( making the AF rich ), then slowly within the next few seconds reduce the pulse width until the O2 sensor detects some oxygen. This is just my idea, it could be wrong.
John,
I am also starting to learn Eagle, ( I was using ExpressPCB ), but when I printed the Schematics, the texts came out as black blocks.
The silkscreen text on the PCB also printed out as black blocks. What is the problem?
On the screen it looks ok.
Thanks.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.fd.com.my
www.mercedes.com.my
Their are two types of injectors that I know of their is the High impedance (12-16 ohms) and Low impedance (1.2- 2.4 ohms). most of your typical port injectors I.E. one injector per cylinder are Low Z (impedance) injectors and they use PWM to control the current to them so they do not get hot. The High Z injectors can handle the full load and use just a pulse width to control it. But you can add a series resistor to the Low Z injector to limit the current and then treat it like a High Z and use just pulse width then.
Here is the formula for the series resistor.
resistor ohms = (alternator voltage / 2.0 amps) - injector resistance
For example:
resistor ohms = (14.0 volts / 2.0 amps) - 1.2 ohms
=> resistor ohms = 7.0 - 1.2 = 5.8 ohms
and use atleast a 20 to 25 watt resistor.
I think ECU design is a bit science mixed with a bit of art.
It could this art portion that creates myths surrounding ECU design.
We need to keep a clear and logical mind to separate myths from facts.
GAF has stated quite clearly that injectors only go on or off, no in betweens. I tend to agree.
Why would any injector manufacturer want to design a injector that can work with 2V when they know that
every electrical device in a car runs on 12V? Beats me.
He also mentioned that at high RPMs, the injectors are on about 90% of the time.
On this point, I want dispute.
As far as I know, injection only starts at the end of the intake stroke and has to stop before the power stroke.
That means, at the most it should be injecting fuel only 25% of the time.
At normal cruising RPMs, I would expect the injectors to be on less than 5% of the time.
So considering that 95% of the time, the injectors are in off state, over heating of injectors would not happen at all.
GAF has also recommended MOSFETS that can handle at least 200V.
I tend to disagree with this recommendation.
Assuming the injectors has a inductive coil inside it, yes it will induce a high voltage when it is switched off.
But by having a free wheeling diode across each injector, the voltage build up should not exceed 24volts.
Based on this explanation and my experience, I would continue to recommend the IRL510 as the injector drivers.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.fd.com.my
www.mercedes.com.my
Regards
Chet
GAF,
Are there injectors that require more then 12 v?, ·significantly higher like 200v? , or
Can I drive a 12v injector, using 5v to power an Inductor that produces 12v for the injectors and 300 v for an ignition coil?
Also, have you written any papers that are pertinent to this discussion?
SAE's online search engine isn't so great. If so do you remember their #, If not I'm going to take a drive to Cal Poly Pomona and look all your material.
Bill
Post Edited (Capt. Quirk) : 6/7/2007 5:40:46 PM GMT
·· Low Z injectors are called "Peak and Hold" the injector is switched on high for the first portion of the signal to overcome the internal spring then it switches into PWM mode to keep the injectors from obtaining to much current. See my attachment to understand what I am saying more.
High Z on the other hand you can just turn them on and keep them on and they will not get to much current.
But like I said you can use series resistors to limit the current the treat Low Z injectors like High Z.
Also a motor does not use much less than 30% duty ever most that I know of use atleast 30% to idle and yes they do spray at 90% of the time at WOT.
Captain Quirck,
·· You can not open a Low Z injector with just 5V it is a peak and hold it takes 12v for a certain amount of time and the datasheets will tell you what the opening time is and then you use PWM to cut back on the current.
Guys I have not had time to put my Car 96 Rivi with Low Z injectors and my 91 Chevy truck with HIGH z injectors on a Oscope to show you the signals but I will try this weekend.
Post Edited (bennettdan) : 6/7/2007 4:55:22 PM GMT
· I dont think its so much art as someone having a very clear undestanding of everything that goes on in an internal combustion engine, as well as the capabilities of the electronics. To my understanding the idea behind a peak and hold injector is to allow you to use excessive amounts of current to produce a very fast opening time. The closer an injector pulsewidth is to a squarewave the more consistant and predictable, OR it could just be fuel pressure related.
Anyway, ECU design requires a very high level of skill in several disciplines, or a very well coordinated team of those disciplines.
Almost all gasoline engines in the U.S. are indirect injection, I'm sure there are some exotic DI's but dont know of them. Trust GAF, everything he's said has been spot on.
GAF Thanks, its been enlightneing.
RE: Eagle Text too Small
I think you set the text too small. Remember you can set the text to as small as .01 so even an ant would need glasses! I set mine at about 0.07.
Another thing to consider is the size of the schematic. If you put a lot of stuff on it, Eagle will size it to fit on the page and thus shrink everything.
Download my schematic and look at the font sizes and print it out. That way you can at least verify that Eagle can print a schematic and board layout.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
John J. Couture
San Diego Miramar College
What it comes down to, what is the amperage reqirments of a Low z and High z injector.
Post Edited (Capt. Quirk) : 6/7/2007 5:55:34 PM GMT
The low Z injectors only need about 2 amps to operate. High Z you dont have to current control them but they are probaly to big for what you want.
The smallest injector I know of it a 9lbs/hr injector, do you plan to run the plane with a bosch style injector? I dont know if you could get a low enough amount of fuel out of it and not flood the engine.
Hell we almost burn 9 lbs in 6 min.
Post Edited (bennettdan) : 6/7/2007 8:42:01 PM GMT
Just reading over the notes where we a talking injector flow rates etc.· How much thought is given to the fuel pump and the required fuel pressure to get these flow rates.· Most injector flow rates are specified at a nominal pressure·usually 40 psi but I gave seen some higher. I know this is·not a problem for the guys working·on existing vehicles, but trying to adapt an EFI system to a small engine presents serious design problems, though not impossible.
Capt. Quirk,
For Nitro Methane·the stoichiometric A/F is:· 1.7 lb air / 1 lb fuel.· It is interesting to note that Nirto Methane has only about 1/4 the heating value of gasoline. The high power levels achieved with this fuel are a result the large mass of the fuel that is required for combustion, almost hydro lock.
For my system with an injector,I am trying to do it without adding a gear pump to the crank. The airplanes run 4 psi max fuel pressure, so either I need to modified a TBI or make my own injector. That was part of todays diddling.
But in the near future I'll be building a system for a 2180cc VW (HairDryer, lmao) and then for a modified Olds 215ci aluminum block V8 w/ Land Rover heads and injectors.
I guess you have a point on the PWM thing.
Anyway, we can go ahead with the board design since PWM or no PWM, the driving circuit is the same.
GAF,
What is your opinion on Isuzu's DMAX 2.5 Direct Injection diesel engine which seems to blow all competition away, even the CDI engines.
They claim 1,400+ km on their 4x2 truck with just one tank of 76 litres of diesel.
Does this mean that Indirect Injection is grossly inefficient?
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.fd.com.my
www.mercedes.com.my
I liked it a lot better than my Dads Dodge with a Cummins engine.·
havent made use of the little eeprom that is on the board yet. not sure how i want to go around makeing use of it. maby eventualy use it to store the variables so they can be changed with out haveing to pull the crystal and used the sx-key. i think that ill just used the equation to get my VE, i think it would be faster then sending a comand to the eeprom then haveing it send back the info.
The IC's im useing to drive the injectors work fine for my application, did not lean out at high rpm and they just got a little warm while i was driving. i have a waterproof plastic box that the pcb board is designed to fit perfectly in. i think what i can do to keep it cool is do what they sometimes do with prossesors and heatpipes. i could just have 2 heat sinks on for the inside of the box and the other for the out side. and have them connect to each other with some copper and make sure that i seal the hole in the plastic. but right now everything runs fine with no heat sinks at all. but once its inclosed im sure it will start to warm up.
in the automotive industry, when building an engine and desigeing the fuel injection system for it, what is the basic proccess of getting the programing code tuned really good? do they used a dyno and get the proper variables (A/F, VE, ADVANCE) from trial and error? or is there a easer way to do it?
Thanks
To get the proper data to program the EEC many hours are spent on the dyno going through a process call Engine Mapping.· This is where at each speed load condition·all possible parameters are swept though there full range,·eg. spark is swept from full retard to full advance.··One of the main parameters measured during this process is fuel flow, so we can plot fuel flow vs spark advance, this determines the optimum spark setting for each speed load condition (the·A/F is held constant at Stoich for part throttle and around 12:1 for WOT or is EGT limited).··The Mapping process takes about a month, 2 shifts a day 6 days a week.· I am over simplifing this process but I think you·get the idea.