f4i injector opening time

[swazz]

Does anyone have information about the f4i's injector opening time vs voltage? I've tried contacting Keihin but they were less than helpful.

[swazz]

Does anyone have information about the f4i's injector opening time vs voltage? I've tried contacting Keihin but they were less than helpful.

[Chris Boyden]

I've never tested this, but
I'd expect ~2 ms to open the injector.
Keeping the injector pulse width above this number via fuel pressure settings will
help maintain a linear relationship between fuel delivered and pulse width. Pulse width times less than 2ms might cause you fuel metering quirks. Anybody test response time on the fuel injectors? You might try contacting RC engineering for help on this subject in general. They sell reworked bosch injectors.

[Ryan Schoffer]

on an injector test machine, the minimum stable p/w is around 1.6 - 1.8 ms, so the opening time will be less than that (obviously)

this should work for sequential or semi-sequential operation up to ~15000 RPM, but for full batch fire you might want ones with a slightly lower stable p/w

[Alexandre D.]

It depends of your ECU a lot....

[Ryan Schoffer]

??

these are times based on testing in an injector flow machine - the ECU type does not matter

as far as if you are running sequential, batch, etc. - well that definetly depends on ecu

[raska]

The ECU may matter to the extent of saturation or peak and hold type control, but other than that I would think each type of control is essentially the same for all manufacturers. 4 times the hold current is what the peak current is or something thereabouts. At the Claude Rouelle/Motec seminar last year Mr Clarke said to plan for a 1.5ms 'dead or unpredictable time' as a rule of thumb, but nothing more, or I didn't catch any more specifics of this.

[Alexandre D.]

ECU does matter. The control of the signal may differ. Don't forget that injectors are coils.

Some are current controlled other """pulse""" the signal while other send a constant signal.

By changing the peak value current, your rise time will change a lot. If you change your control method it may change even more! If your rise time change, it will change your whole fuel map.

[Ryan Schoffer]

like he said, the control signal only differs between low and high impedance injectors - differences in the voltage used or control signal other than that might make the mapping slightly different between ECUs, but no more than the different programming or operaion of 2 different units will

[Chris Boyden]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">on an injector test machine, the minimum stable p/w is around 1.6 - 1.8 ms, so the opening time will be less than that (obviously) </div></BLOCKQUOTE>

The opening time ,for all practical purposes, is the minimum time of 1.6 - 2 ms. The reason they are nonlinear below that time is because the solenoid plunger is still being drawn into the coil, i.e. still opening.

National semiconductor sells a peak and hold injector driver that explains the peak and hold operation pretty well as well as general solenoid LR model. L(inductance of the coil) changes as the plunger is drawn in. (L gets bigger as the magnetic circuit closes up.)

http://www.national.com/pf/LM/LM1949.html#datasheet-

[drivetrainUW-Platt]

what size injectors are stock say F4i? We are looking for some smaller ones, we have some 195cc RC performance ones right now.

[Chris Boyden]

I think the F4i's were 155cc/min ~ 15 lbs/hr.

The biggest problem with F4i injectors are the damn connectors....anybody know of a good NipponDenso aftermarket cross reference?
Maybe we can all join in on a FSAE NipponDenso Group Purchase of a pallet of CoilOnPlug connnectors and injector connectors http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif
I hate cut and splice, but you can buy the injector and coil harness from Honda dealers. I'd rather have the connectors by themselves.

[raska]

You can do the math to figure out how much benifit you'll get but you also eliminate the inductive current lag by controlling the current rather than the voltage.

Do F4i's have dual stage injection stock?

[Ryan Schoffer]

my measurement was around 120cc/min at 50 PSI rail pressure

the stock F4i is fully sequential injection

[Chris Boyden]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">You can do the math to figure out how much benifit you'll get but you also eliminate the inductive current lag by controlling the current rather than the voltage. </div></BLOCKQUOTE>

You can control the current, but you can't increase the current without increasing the voltage.....still have to overcome that pesky resistance of the coil. Unless the resistance is lower, like in an low impedance injector, good luck speeding things up even if you "control the current" without raising the voltage to say 24 volts.