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AJ4
Guest
What resistance ( in ohms ) are the standard 440 injectors ? What value are the resistors in the resistor pack ? Not near my car at the mo so I can't measure myself 
Cheers.
Cheers.
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AJ4
Guest
Cheers bud. Next question, know anyone that makes 4 ohm injectors round about 440's ?
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AJ4
Guest
440's in parallel ( 8 injectors )
I was thinking of doing similar using eight original 444cc @ 2 Ohm but got to thinking that this would lead to 3.5 A being consumed / going through injector drivers instead of 1.75 ( initially => peak n' hold ).... so thought about using a high power NPN similar to or the exact one used to power the ignition coil as it's 0.7 Ohm and applied with 14 V = 20A I was thinking that the ECU trigger for the injector for the injector could control the base of the NPN
didn't test try yet as I'm "still" installing / rebuilding engine ==> I'm slow !!!
Stu..
didn't test try yet as I'm "still" installing / rebuilding engine ==> I'm slow !!!
Stu..
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AJ4
Guest
Likewise, I thought about using a mosfet or something to drive the second bank, taking signals from the first bank. I've got a spare ECU that I can take the transistor block out of ( just an encapsulated circuit with all four transistors in it, doesnt even look that meaty ! ). Just one more thing to go wrong though
The other option is two 1's in series, but if one of the pair goes wrong it will kill the other one, at least with them in parallel there is still half the fuel going through.
The more complicated option is two 16's in parallel and change the firing circuit so it saturates a switch off the leading edge of the peak pulse.
Much easier just to find some 4 ohm jobs and run them in parallel, then everything is happy.
I'll let you know how I get on...
The other option is two 1's in series, but if one of the pair goes wrong it will kill the other one, at least with them in parallel there is still half the fuel going through.
The more complicated option is two 16's in parallel and change the firing circuit so it saturates a switch off the leading edge of the peak pulse.
Much easier just to find some 4 ohm jobs and run them in parallel, then everything is happy.
I'll let you know how I get on...
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AJ4
Guest
sypher - I've using a PFC
Jimmy - what resistance are they ? I need ones that are 4 Ohms ( the standard ones are only 2 Ohms )
Jimmy - what resistance are they ? I need ones that are 4 Ohms ( the standard ones are only 2 Ohms )
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AJ4
Guest
no problem, thanks anyway dude 8)
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AJ4
Guest
I did think about that, running two in parallel and using a bigger resistor but I'm not sure the injectors would still get enough current each to fire properly. Need to do a bit of measuring and research first though, but thats how I was originally going to do it until I thought about using two 4 Ohm ones.
Ross, I think that the best options are ( IMHO ) as you said two 4 Ohm in parallel & stock dropping resistor providing they are normally applied with 3 > 4 Volt thus keeping the circuit the same as far as the ECU is concerened
Failing that the two stock 444cc with a 3 Ohm dropping reistor and an NPN, but you are in the best position to select the correct NPN as my interest only takes me so far then I need to my friendly EE and explain what the circuit does..
Why go eight instead of 4 large? me I was looking at keeping cost down and the added WOW factor... L O L
been looking as well for 4 Ohms for you, but no success!!!
Stu..
Failing that the two stock 444cc with a 3 Ohm dropping reistor and an NPN, but you are in the best position to select the correct NPN as my interest only takes me so far then I need to my friendly EE and explain what the circuit does..
Why go eight instead of 4 large? me I was looking at keeping cost down and the added WOW factor... L O L
been looking as well for 4 Ohms for you, but no success!!!
Stu..
A
AJ4
Guest
The reason for 8 is because I dont like big injectors Without boring you all to death with another techie rant...
The same injector sprays fuel droplets in a variety of sizes, the smaller the injector the smaller the average droplet size. Not all of the droplets are of a small enough size to mix with the air properly and wont combust. Say a 440 injector sprays fuel that has droplets of which 80% of them are combustible, the other 20% dont get burnt because they are too big. With a 880 cc injector that ratio could drop to 60% combustible and 40% unburnt.
That means with a bigger injectors more fuel has to be injected just to get enough droplets that are combustible, so more fuel is wasted. Not only that, the combustion flame has to travel round the larger droplets that wont ignite and slows the combustion speed and maximum cylinder pressure drops, the same way that water injection works. Good for stopping detonation but not good for power Its common sense that a cylinder where 80% of the fuel volume combusts makes more power than a cylinder where only 60% of the fuel volume combusts. An ideal injector will spray droplets that are exactly the right size for combustion at all rates and none are wasted.
Thats why you always see the advice to use the absolutely smallest size injector you can get away with. People who buy 700 injectors but only really need 550's are just throwing money away, no matter how good it sounds down the pub
The right size injector has more of the right size droplets, combustion speed is faster causing more power, less fuel is wasted and less oil is borewashed off the liners by the unburnt fuel The reason people use bigger injectors is because its easy to swap them straight in rather than fabricating two fuel rails and the extra electronics etc but its not better for power or fuel economy, the only advantage is it helps to stop det and the extra wasted fuel helps to cool the pistons.
People on other cars ( not heard if it yet on a Pulsar ) move the injectors to the plenum chamber, so the larger fuel droplets smash into the throttle butterflies and break down into smaller more combustible particles. I'm kinda doing the same, with four in the standard position and four in the plenum chamber pointing straight down the bore.
I'm not saying there is anything wrong with bigger injectors, just that they aren't as efficient as smaller ones, and two smaller ones are always better than one single large one. More powerful engines with higher combustion speeds, higher combustion temps and higher intake velocities break down the fuel droplets better so wont make much difference, the only problem is people who fit huge injectors that dont really need them.
I'll just go and put my flame suit on now, for protection from the hundreds of owners who have fitted 700 injectors on their 1 bar Pulsars and swear they give more power
Without boring you all to death with another techie rant... The same injector sprays fuel droplets in a variety of sizes, the smaller the injector the smaller the average droplet size. Not all of the droplets are of a small enough size to mix with the air properly and wont combust. Say a 440 injector sprays fuel that has droplets of which 80% of them are combustible, the other 20% dont get burnt because they are too big. With a 880 cc injector that ratio could drop to 60% combustible and 40% unburnt.
That means with a bigger injectors more fuel has to be injected just to get enough droplets that are combustible, so more fuel is wasted. Not only that, the combustion flame has to travel round the larger droplets that wont ignite and slows the combustion speed and maximum cylinder pressure drops, the same way that water injection works. Good for stopping detonation but not good for power
Its common sense that a cylinder where 80% of the fuel volume combusts makes more power than a cylinder where only 60% of the fuel volume combusts. An ideal injector will spray droplets that are exactly the right size for combustion at all rates and none are wasted.Thats why you always see the advice to use the absolutely smallest size injector you can get away with. People who buy 700 injectors but only really need 550's are just throwing money away, no matter how good it sounds down the pub
The right size injector has more of the right size droplets, combustion speed is faster causing more power, less fuel is wasted and less oil is borewashed off the liners by the unburnt fuel
The reason people use bigger injectors is because its easy to swap them straight in rather than fabricating two fuel rails and the extra electronics etc but its not better for power or fuel economy, the only advantage is it helps to stop det and the extra wasted fuel helps to cool the pistons.People on other cars ( not heard if it yet on a Pulsar ) move the injectors to the plenum chamber, so the larger fuel droplets smash into the throttle butterflies and break down into smaller more combustible particles. I'm kinda doing the same, with four in the standard position and four in the plenum chamber pointing straight down the bore.
I'm not saying there is anything wrong with bigger injectors, just that they aren't as efficient as smaller ones, and two smaller ones are always better than one single large one. More powerful engines with higher combustion speeds, higher combustion temps and higher intake velocities break down the fuel droplets better so wont make much difference, the only problem is people who fit huge injectors that dont really need them.
I'll just go and put my flame suit on now, for protection from the hundreds of owners who have fitted 700 injectors on their 1 bar Pulsars and swear they give more power
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AJ4
Guest
Managed to find some Bosch injectors that will do at 4.7 ohms each. They are only 370cc though giving 740cc per cylinder but that should be enough for now.
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AJ4
Guest
I've been looking into this in a bit more detail, and I think I can get away with paralleling the standard ones and still stay in spec ( can someone check my figures ? )
Dropping resistor = 5 to 7 ohms
Injector = 1 to 3 Ohms
Assume V+ = 14 volts
Min possible resistance = 5 + 1 = 6 Ohms
Work out power required for each injector -
Lowest injector power required is when resistor = 7 ohm, injector = 1 ohm. This gives total resistance of 8 ohms and total current of V/R = 14/8 = 1.75 Amps.
Minimum power required to fire injector is therefore = I2R = 1.75 * 1.75 * 1 = 3 Watts.
Max power per channel is when resistor = 5 and injector =1 = 14*14/6 = 32.6 Watts
Two injectors per channel at 3 Watts = 6 Watts.
Dropping resistor has to dissipate 32.6 - 3 = 29.6 Watts.
If injector total resistance = 1 ohm and power dissipation is 6 watts, then the resistors must have 2.45 Amps running through them, 1.23 Amps each.
With 2.45 Amps flowing, and the dropping resistor must dissipate 29.6 Watts, then it must equal 4.93 Ohms.
So if I can keep the paralell injectors to more than 1 Ohm and the resistor to around 5 Ohms then I'm still within the spec of the ECU.
Better still would be to find some standard injectors that are just over 2 ohm to give a bit of margin.
)Dropping resistor = 5 to 7 ohms
Injector = 1 to 3 Ohms
Assume V+ = 14 volts
Min possible resistance = 5 + 1 = 6 Ohms
Work out power required for each injector -
Lowest injector power required is when resistor = 7 ohm, injector = 1 ohm. This gives total resistance of 8 ohms and total current of V/R = 14/8 = 1.75 Amps.
Minimum power required to fire injector is therefore = I2R = 1.75 * 1.75 * 1 = 3 Watts.
Max power per channel is when resistor = 5 and injector =1 = 14*14/6 = 32.6 Watts
Two injectors per channel at 3 Watts = 6 Watts.
Dropping resistor has to dissipate 32.6 - 3 = 29.6 Watts.
If injector total resistance = 1 ohm and power dissipation is 6 watts, then the resistors must have 2.45 Amps running through them, 1.23 Amps each.
With 2.45 Amps flowing, and the dropping resistor must dissipate 29.6 Watts, then it must equal 4.93 Ohms.
So if I can keep the paralell injectors to more than 1 Ohm and the resistor to around 5 Ohms then I'm still within the spec of the ECU.
Better still would be to find some standard injectors that are just over 2 ohm to give a bit of margin.
warringtonjack
Active Member
:shock:
I'm off back to the lounge where I obviously belong! :lol: :roll:
I'm off back to the lounge where I obviously belong! :lol: :roll: