EFI University

[injectordynamics]

Hey there,

We recently completed our test bench, and we are offering dynamic injector flowtesting.

The testing generates battery compensation values, minimum and maximum linear pulsewidths, optimum peak and hold currents, and just about any other important parameter that you can think of.

The details can be found on our website at

http://www.yawpower.com/injectordynamics.html

Thanks

Paul Yaw
Yaw Power Products

[MarcoV6T]

Hi, first I like to say it’s a nice spreadsheet with valuable information, if I lived a little closer I would let you test the injectors I have (I will test them in a Bosch Test Centre, here in Belgium).

One thing though I am not sure about in the spreadsheet, when I chose between batch and sequential injection, the max pulse with is doubled. Shouldn’t that be the same for both, as you only have one engine cycle (720°) to inject, be it batch or sequential? Or is the batch injection calculation based on one injection every revolution (360°), what also would explain why your max horse power numbers are lower with batch injection (2 x dead time + recovery time)?

I thought that at higher rpm, batch injection systems switches to one injection per engine cycle?

Maybe it’s something completely different, would like to know what the reason is.

Thanks,
Marc.

[injectordynamics]

Hi Marco,

Hopefully the terms batch and sequential do not cause any confusion. It seems that the ECU manufacturers have slightly different terminology for describing firing arrangements.

Here in the States, Motec sets the standard (In my opinion) and so I chose to use their terminology.

Using their terminology, sequential means that each injector fires once per engine cycle.

A complete engine cycle lasts 720 crank degrees for a four stroke engine, and 360 degrees for a two stroke engine, and so we get one firing per 720 crank degrees for a four stroke engine, and one firing per 360 degrees for a two stroke engine.

Batch fire means that each injector fires twice per engine cycle.

For a four stroke engine, we would have two firings per 720 crank degrees, equaling one firing per 360 degrees. For a two stroke engine we would have 2 firings per 360 degrees, equaling one firing per 180 crank degrees.

Keeping RPM constant for the comparison, the available time per event (The period) would be halved for a batch fired engine.

The horsepower potential for a given RPM will be slightly lower with a batch fire arrangement because as you suggest, the dead time, and recovery time will be applied twice per engine revolution.

For instance, a sequential fired four stroke engine running at 6000 RPM will fire the injectors at a frequency of 50 Hz, with a resulting period of 20 milliseconds. If the combined dead time, and recovery time equals 2 milliseconds, we are left with a possible 18 millisecond effective pulsewidth per engine revolution.

If we batch fire the same engine, the injectors will be fired at a frequency of 100Hz, with a resulting period of 10 milliseconds. Subtracting our combined dead time and recovery time of 2 milliseconds, we are left with a possible 8 millisecond effective pulsewidth. Since we are firing twice per engine revolution, we double this, and get an effective 16 milliseconds of fuel flow per engine revolution which is only 88.9% of our effective fuel flow with a sequential fired engine.

I hope that answers your question, and thanks for taking the time to download the sample.

PY

[MarcoV6T]

Ok, well that explains it.

I am not completely sure, but I think most or some batch fire ECU's (or the aftermarket ones who have the option to chose between sequential or batch) do fire once every engine cycle at higher rpm’s, as there is no reason to fire twice anymore.

Hopefully some of the EFI guy’s will chime in and could explain how there batch fire strategy is working.

Marc.

[Hugh]

Paul,

Please can you give us an update on any developments to your injector calibration system.

Does your output provide figures that I can directly plug into my Motec M600 to get the maximum benefit from your calibration.

I also use a resistor pack on my car in line with the injectors, please advise whether the injectors should be tested by you with or without the resistor pack.

If you test without, I wonder if there might be problems in applying the results you provide.

When I set up the injectors in the Motec software, the car seemed to run best with, from memory, an injector setting of 0. This was a pure guess, will you advise the correct setting for the Motec ECU?

Thanks

Hugh
_________________
R34 GTR Nissan Skyline + twin HKS 3037S
OS Giken 3 litre block + OS Giken sequential
M600 ECU - still learning after 3 years

[injectordynamics]

Hi Hugh,

[MarcoV6T]

Not so long ago I crossed a dead time calibration file for P&H injectors with and without resistor pack, the differences in dead time where rather significant, especially at lower voltages. So it's obvious, if you want a calibration file, the test must be done with the resistor pack. First, there is the tolerance of the injectors themselves, second, the tolerance of the individual resistors. Hence each injector should be matched with his proper resistor during the test.

Honestly, I would start with installing a P&H injector controller, and remap the low load and idling maps first.

My interest for the injector flow test is mainly the difference in flow between injectors at higher duty cycles near max VE, to trim the individual cylinders at that point, sure the difference is dynamic, but as Paul stated, with the newer generation of injectors the dynamic deviation between injectors is not that big anymore, so the risk to run lean on one cylinder at a different point in the map is small.

[Hugh]

Thanks guys,

I should have said I use Bosch 1600cc injectors and the spray pattern is more like spits rather than a spray at idle duty cycle.

Do you think it is possible for the M600 to drive these injectors directly, from memory they are about 3 ohms on their own and 9 ohms with the resistor pack?

Paul,

What is the turnaround time of the service?

Thanks

Hugh
_________________
R34 GTR Nissan Skyline + twin HKS 3037S
OS Giken 3 litre block + OS Giken sequential
M600 ECU - still learning after 3 years

[Hugh]

Paul,

Not sure if have posted this before, but I set up an injector tester to experiment with different duty cycles.

I weighed the bottle after 5minutes 2% duty cycle , 50% for two minutes etc.

It seemed to be OK but suffered greatly from battery voltage changes.

Don't fall off your seat laughing.

http://www.sol.co.uk/h/hugh/Injectors/50%20percent%20Duty%20cycle%20Flow%20Test.MPG
_________________
R34 GTR Nissan Skyline + twin HKS 3037S
OS Giken 3 litre block + OS Giken sequential
M600 ECU - still learning after 3 years

[injectordynamics]

[Hugh]

Paul,

From memory, the injectors are a standard 839 or similar, colour is a light grey.

I use a standard Motec M600.

I currently use 3 bar base pressure, but might want to raise that to 4 bar base as I am building a competition only car just now and like to keep duty cycle down and maximise atomisation.

I am using V3 software.

Cheers

Hugh
_________________
R34 GTR Nissan Skyline + twin HKS 3037S
OS Giken 3 litre block + OS Giken sequential
M600 ECU - still learning after 3 years

[injectordynamics]

Over here the 846's are off white, and the 839's are mint green. If you have the 846's, set the peak current to 2.1, and the hold current divider to 8.

Remove your resistors, and be prepared to lean out your entire map.

I don't have any data for the 839's at 3 Bar, but I do have some here, and could run them. It would not be the same as testing your injectors, but it would be better than nothing.

Sell the resistors to someone you don't like.
_________________
Paul Yaw
www.yawpower.com

[Hugh]

Paul,

I fully intend to send you my injectors to test, so will not bother trying any other settings just now.

I bought the injectors in the USA, but am in London just now so do not have access to the injectors or paperwork.

How long do you need the injectors to carry out your analysis?

Thanks

Hugh
_________________
R34 GTR Nissan Skyline + twin HKS 3037S
OS Giken 3 litre block + OS Giken sequential
M600 ECU - still learning after 3 years

[injectordynamics]

[Pantera EFI]

Would it be possible for you to post your standard results for the
Tan & Mint Green, and White injectors ?

Lance

[injectordynamics]

PM me Lance
_________________
Paul Yaw
www.yawpower.com