Discussion
Quite a lot of info on the Megasquirt site www.megasquirt.info/ go to injectors and fuel supply.
The links to www.geocities.com/MotorCity/Pit/9975/dataBySubject/Injectors.html and www.telusplanet.net/%7Echichm/tech/injectors.pdf give spec on injectors.
You can get all sorts of injectors from US a lot cheaper than UK, try www.fiveomotorsport.com or any of the speed shops stocking Accel injectors etc.
The links to www.geocities.com/MotorCity/Pit/9975/dataBySubject/Injectors.html and www.telusplanet.net/%7Echichm/tech/injectors.pdf give spec on injectors.
You can get all sorts of injectors from US a lot cheaper than UK, try www.fiveomotorsport.com or any of the speed shops stocking Accel injectors etc.
andygtt said:
anyone know of a site were I can get details and spec of injectors (flow rate Ohms by number etc) as I need to start thinking about weather my injectors can cope etc....
As far as im aware theres only 2 resistance ratings for injectors, the bosch type being 17-22 ohms and jap types (nippon denso etc) at a ballasted 4 ohms.
There are 2 ratings, low and high, but they do cover a wide range.
Generally, below 5 ohms are the peak and hold type, whereas above that, usually 10ohm+ are the saturated type, and most common.
The 2 types are not interchangeable, unless your ecu can support both types, which 99% of them cant.
Generally, below 5 ohms are the peak and hold type, whereas above that, usually 10ohm+ are the saturated type, and most common.
The 2 types are not interchangeable, unless your ecu can support both types, which 99% of them cant.
If you use Bosch units I put a spreadsheet together a bit back listing them.
www.f900.co.uk/ph/bosch.xls
If you need data for any others let me know
Matt
www.f900.co.uk/ph/bosch.xls
If you need data for any others let me know
Matt
If you were switching types e.g. low resistance to high resistance. you could theoretically use a resistor in parallel (across the injector terminals) to lower the impedance of the circuit. May need to cap balance it, but would watch out for filtering effects.
The high to low would be more complicated give the potential difference change with a resistor in series(approixmately 5x) so the intector would only see 3ish volts.
The high to low would be more complicated give the potential difference change with a resistor in series(approixmately 5x) so the intector would only see 3ish volts.
It isnt really as simple as the resistor method, although some people do use it, and you can buy devices to the same effect.
The resistance is one matter, but the actual control mehtod of the injector is different.
The peak and hold type draw a heavy current to initially open, say 4amp, but this is limited very quickly to 1amp, to hold it open. It gives much better response and control over the injector.
Simply adding a resistor would allow it to function, but I dont think it would function as well as it should.
It is something I'd like to know more about, as to get anything over 75lb, or 850cc, they simply arent available in saturated high impedance type. Probably as control would be very poor, which could cause fuelling issues low down, and injector overheating maybe.
I'd like to run low imp from my DTA, but to make the situation worse, I am using a group fire setup, which only uses 4 of the 8 outputs, and pairs the injectors ( in parallel ).
So fitting a high-low imp convertor box may not work at all in my case.
The resistance is one matter, but the actual control mehtod of the injector is different.
The peak and hold type draw a heavy current to initially open, say 4amp, but this is limited very quickly to 1amp, to hold it open. It gives much better response and control over the injector.
Simply adding a resistor would allow it to function, but I dont think it would function as well as it should.
It is something I'd like to know more about, as to get anything over 75lb, or 850cc, they simply arent available in saturated high impedance type. Probably as control would be very poor, which could cause fuelling issues low down, and injector overheating maybe.
I'd like to run low imp from my DTA, but to make the situation worse, I am using a group fire setup, which only uses 4 of the 8 outputs, and pairs the injectors ( in parallel ).
So fitting a high-low imp convertor box may not work at all in my case.
stevieturbo said:
It isnt really as simple as the resistor method, although some people do use it, and you can buy devices to the same effect.
The resistance is one matter, but the actual control mehtod of the injector is different.
The peak and hold type draw a heavy current to initially open, say 4amp, but this is limited very quickly to 1amp, to hold it open. It gives much better response and control over the injector.
Simply adding a resistor would allow it to function, but I dont think it would function as well as it should.
It is something I'd like to know more about, as to get anything over 75lb, or 850cc, they simply arent available in saturated high impedance type. Probably as control would be very poor, which could cause fuelling issues low down, and injector overheating maybe.
I'd like to run low imp from my DTA, but to make the situation worse, I am using a group fire setup, which only uses 4 of the 8 outputs, and pairs the injectors ( in parallel ).
So fitting a high-low imp convertor box may not work at all in my case.
So why not just go for a 2 injectors per cyl setup? Sounds like the ECU is more than capable of it.
Matt
>> Edited by matt_t16 on Friday 15th October 21:57
It would be if I was running sequential, which at the minute I'm not.
Not sure if I can use the other outputs for extra injectors using group fire again.
Either way, plumbing in an additional 8 injectors isnt very appealing, especially as the inlet manifold is plastic.
It will be a while before I need the big injectors anyway. I'll see how I get on with 600cc's, then move onto the 850's
They probably will be enough.
Not sure if I can use the other outputs for extra injectors using group fire again.
Either way, plumbing in an additional 8 injectors isnt very appealing, especially as the inlet manifold is plastic.
It will be a while before I need the big injectors anyway. I'll see how I get on with 600cc's, then move onto the 850's
They probably will be enough.
stevieturbo said:
The peak and hold type draw a heavy current to initially open, say 4amp, but this is limited very quickly to 1amp, to hold it open. It gives much better response and control over the injector.
This is just software, are there software modules available to install for different control methods?
Or do you have access to the code?
I know nothing about software, or codes.
But the low imp do draw a lot more current, so if the injector drivers within the ecu arent designed to cope with the load, then no amount of programming will sort it.
Motec etc can however control any type, but I would imagine their circuits within are designed for the higher current in the first place.
But the low imp do draw a lot more current, so if the injector drivers within the ecu arent designed to cope with the load, then no amount of programming will sort it.
Motec etc can however control any type, but I would imagine their circuits within are designed for the higher current in the first place.
Obviously as I=V/R,
Where I=Current, V=Voltage and R=Resistance.
(As resistance goes down, current goes up)
This is a problem when switching a high impedance ecu to run low impedance injectors, from the injector side. If the injector drivers (basically amplifiers) are not designed to handle the current loads.
With running high impedance on a low impedance unit, the issue may be that the current seen on the high impedance injectors may be higher than that which it is designed to accept.
If the strategy used in driving the different types of injectors is different, then the software used may also need to be changed.
Code is the written form of the software. E.g. 'C' Language, which is what is probably used.
The best thing to do may be to speak to the ecu designer/manufacturer directly to understand what sort of loading the ecu can handle and if their unit can support what you're suggesting, that way you'd get a direct answer from the people who would know.
Where I=Current, V=Voltage and R=Resistance.
(As resistance goes down, current goes up)
This is a problem when switching a high impedance ecu to run low impedance injectors, from the injector side. If the injector drivers (basically amplifiers) are not designed to handle the current loads.
With running high impedance on a low impedance unit, the issue may be that the current seen on the high impedance injectors may be higher than that which it is designed to accept.
If the strategy used in driving the different types of injectors is different, then the software used may also need to be changed.
Code is the written form of the software. E.g. 'C' Language, which is what is probably used.
The best thing to do may be to speak to the ecu designer/manufacturer directly to understand what sort of loading the ecu can handle and if their unit can support what you're suggesting, that way you'd get a direct answer from the people who would know.
Few sites to try :
www.robietherobot.com/storm/fuelinjectorguide.htm
www.powerpage.dk/dyser.htm
www.rceng.com/
As for high or low impedence injectors the low impedence will give the best responce with dedicated peak and hold driver circuitry (expensive) but even using just a ballast resistor are still quicker than high impedence (saturated) injectors. Most Honda's used this half-way house untill recently but now seem to be going down the high impedence route (apart from NSX and some R types)- maybe the saturated injectors are now getting better, maybe the slight performance advantage isn't worth the extra expense.
The other thing to think about is when you size your injectors for 80% duty cycle at peak power they will have to open when the engine is on its compression stroke and are therefore firing at the back of the closed inlet valves, will a couple of micro seconds make much difference in this situation ?
For the same reason sequential firing only makes a difference on part throtle - i.e. it is more of a benefit to fuel consumption than performance and can take lots of time on the rollers to refine.
Low impedence injectors with full sequential management is so much sexier though so thats what I've put on my engine.
www.robietherobot.com/storm/fuelinjectorguide.htm
www.powerpage.dk/dyser.htm
www.rceng.com/
As for high or low impedence injectors the low impedence will give the best responce with dedicated peak and hold driver circuitry (expensive) but even using just a ballast resistor are still quicker than high impedence (saturated) injectors. Most Honda's used this half-way house untill recently but now seem to be going down the high impedence route (apart from NSX and some R types)- maybe the saturated injectors are now getting better, maybe the slight performance advantage isn't worth the extra expense.
The other thing to think about is when you size your injectors for 80% duty cycle at peak power they will have to open when the engine is on its compression stroke and are therefore firing at the back of the closed inlet valves, will a couple of micro seconds make much difference in this situation ?
For the same reason sequential firing only makes a difference on part throtle - i.e. it is more of a benefit to fuel consumption than performance and can take lots of time on the rollers to refine.
Low impedence injectors with full sequential management is so much sexier though so thats what I've put on my engine.
The benefits are more at lower openings I think, where large injectors can be controlled much better, so emissions etc can still remain under control with good fuel atomisation.
Some large injectors can become very drippy if they cant be controlled properly, which I beleive was the case with Cossies running the greys which were only about 500cc.
Given that some modern cars can run injectors as large as 1000cc and still drive fine, means improvements have been made in that area.
Take a look at this convertor, and see what you make of it ?? It may do what I need.
http://fjoinc.com/
What you think ??
In fact this has answered my query, and is the sort of thing I was looking for...
www.acceleronics.com/instructions.htm
>> Edited by stevieturbo on Sunday 17th October 00:34
Some large injectors can become very drippy if they cant be controlled properly, which I beleive was the case with Cossies running the greys which were only about 500cc.
Given that some modern cars can run injectors as large as 1000cc and still drive fine, means improvements have been made in that area.
Take a look at this convertor, and see what you make of it ?? It may do what I need.
http://fjoinc.com/
What you think ??
In fact this has answered my query, and is the sort of thing I was looking for...
www.acceleronics.com/instructions.htm
>> Edited by stevieturbo on Sunday 17th October 00:34
I have cosworth greens which are Bosch 803's and are 5OHms.... I also have 36 std BMW V12 Bosch injectors that are 16Ohms.
The Motec M800 unit I have purchased can run either... but due to using 4 of the spare ignition outputs so that I can run fully sequential injection (as recomended by Motec) I can only use high Ohm injectors.
Now I've only just started to research the difference so really don't have a clue as to the pros and cons.... but I have been told by some of my electronic friends that high Ohm's means less current and faster electronically.
However from what you are saying there is less control on higher Ohm's injectors.....
Can you houmour me as I don't understand... why are low ones faster response?
BTW thanks for the links
The Motec M800 unit I have purchased can run either... but due to using 4 of the spare ignition outputs so that I can run fully sequential injection (as recomended by Motec) I can only use high Ohm injectors.
Now I've only just started to research the difference so really don't have a clue as to the pros and cons.... but I have been told by some of my electronic friends that high Ohm's means less current and faster electronically.
However from what you are saying there is less control on higher Ohm's injectors.....
Can you houmour me as I don't understand... why are low ones faster response?
BTW thanks for the links
I have cosworth greens which are Bosch 803's and are 5OHms.... I also have 36 std BMW V12 Bosch injectors that are 16Ohms.
The Motec M800 unit I have purchased can run either... but due to using 4 of the spare ignition outputs so that I can run fully sequential injection (as recomended by Motec) I can only use high Ohm injectors.
Now I've only just started to research the difference so really don't have a clue as to the pros and cons.... but I have been told by some of my electronic friends that high Ohm's means less current and faster electronically.
However from what you are saying there is less control on higher Ohm's injectors.....
Can you houmour me as I don't understand... why are low ones faster response?
BTW thanks for the links
The Motec M800 unit I have purchased can run either... but due to using 4 of the spare ignition outputs so that I can run fully sequential injection (as recomended by Motec) I can only use high Ohm injectors.
Now I've only just started to research the difference so really don't have a clue as to the pros and cons.... but I have been told by some of my electronic friends that high Ohm's means less current and faster electronically.
However from what you are saying there is less control on higher Ohm's injectors.....
Can you houmour me as I don't understand... why are low ones faster response?
BTW thanks for the links
I have cosworth greens which are Bosch 803's and are 5OHms.... I also have 36 std BMW V12 Bosch injectors that are 16Ohms.
The Motec M800 unit I have purchased can run either... but due to using 4 of the spare ignition outputs so that I can run fully sequential injection (as recomended by Motec) I can only use high Ohm injectors.
Now I've only just started to research the difference so really don't have a clue as to the pros and cons.... but I have been told by some of my electronic friends that high Ohm's means less current and faster electronically.
However from what you are saying there is less control on higher Ohm's injectors.....
Can you houmour me as I don't understand... why are low ones faster response?
BTW thanks for the links
The Motec M800 unit I have purchased can run either... but due to using 4 of the spare ignition outputs so that I can run fully sequential injection (as recomended by Motec) I can only use high Ohm injectors.
Now I've only just started to research the difference so really don't have a clue as to the pros and cons.... but I have been told by some of my electronic friends that high Ohm's means less current and faster electronically.
However from what you are saying there is less control on higher Ohm's injectors.....
Can you houmour me as I don't understand... why are low ones faster response?
BTW thanks for the links
Bosch/Ford Motorsport Greens, available from the US at reasonable money, are 434cc, and are high impedance, at approx 12ohm IIRC. I used 8 of them in my old engine.
The injector control, isnt just as simple as high imp, and low imp, v+i/r etc.
The control method is totally different.
The high imp use low current, as subsequently have low power to open and close the solenoid.
The low imp, use a lot more current to open ( makes it faster ) once open, the current then drops, so it doesnt overheat.
This makes it faster operating in general, and hence offers better control, which is why they are deemed better.
You will be very hard pushed to find an high impedance injector larger than 850cc as they become very sluggish after that. Low imp varietys go to around 1600cc I think.
Try shaking a brick back and forward in your hand.
Now do the same without the brick...
Which is easier to control ?? If you had more power available to push/pull the brick, then it would help.
Interesting you say that about the Motec. I wasnt aware than the low imp inj function was restricted.
But I really dont see many benefits of running sequential injection. Its more for emissions/economy than anything, and any actual improvements on economy would be very very small.
The injector control, isnt just as simple as high imp, and low imp, v+i/r etc.
The control method is totally different.
The high imp use low current, as subsequently have low power to open and close the solenoid.
The low imp, use a lot more current to open ( makes it faster ) once open, the current then drops, so it doesnt overheat.
This makes it faster operating in general, and hence offers better control, which is why they are deemed better.
You will be very hard pushed to find an high impedance injector larger than 850cc as they become very sluggish after that. Low imp varietys go to around 1600cc I think.
Try shaking a brick back and forward in your hand.
Now do the same without the brick...
Which is easier to control ?? If you had more power available to push/pull the brick, then it would help.
Interesting you say that about the Motec. I wasnt aware than the low imp inj function was restricted.
But I really dont see many benefits of running sequential injection. Its more for emissions/economy than anything, and any actual improvements on economy would be very very small.
I doubt I will need to go that large on the injectors as it is a V12.....
The cossie runs 360bhp on greens with a flow of 390cc at 3psi.....
by my reconing (which may be flawed) I would need to be packing 1100bhp to need anything bigger...
problem is the BMW ones I have are only 149cc @ 3psi.... so unless I can double the PSI safelly to make it flow twice as much (I don't know if this is how it works) there scrap (or ebay material!).
so I think I'm after 300cc @ 3psi high Ohm injectors??????
PS bet your gona tell me you can't compare flow of High to low flow ones.
The cossie runs 360bhp on greens with a flow of 390cc at 3psi.....
by my reconing (which may be flawed) I would need to be packing 1100bhp to need anything bigger...
problem is the BMW ones I have are only 149cc @ 3psi.... so unless I can double the PSI safelly to make it flow twice as much (I don't know if this is how it works) there scrap (or ebay material!).
so I think I'm after 300cc @ 3psi high Ohm injectors??????
PS bet your gona tell me you can't compare flow of High to low flow ones.
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff