Injector Duty Cycle, Pulse Width and Limits Related to RPM

[@Gun1Dwn]

As someone who recently graduated in mechanical engineering. I must say you explain these concepts better than any professor i have had!

[@AndyWhittle_HowEFIworks]

Thanks, I try to always keep things technically correct but easy to understand. It is a always a balance act.

[@christopherlamontnelson1729]

That was cool. Noticed that you mentioned 100% duty. Lol. Good laugh on that. I remember you telling me some one told you they were running 130 percent.

[@luiscarlospassarini1566]

Thank you Andy! Very good job! I loved the explanation.

[@AndyWhittle_HowEFIworks]

For a great source of info on lots of different injectors, They call Injector dead time "Injector Lag Times" I did not mention in the video is this time is very dependent on the voltage being supplied to the injector. See injector-rehab.com/shop/lag.html Injector dynamics is the source of the injector graph in the video. See injectordynamics.com/articles/ford-injector-characterization/

[@TeejtheDeej]

I would like to meet you in person Andy. Your videos are just so informational!

[@AndyWhittle_HowEFIworks]

See www.asnu.com/static-downloads/injectordata/ASNU%201500cc%20VC%203%20BAR.pdf This is an injector test run at several different voltages applied to the injectors. If you move the decimal over one on the horizontal scale (Pulse Width) by one, you have Duty Cycle along the bottom so 9ms = 90% DC. This injector is needing 1ms rest time at a rate of one spray every 10ms.

[@kern-sladeengineering1325]

Fabulous details and explanation Cheers Gilbert

[@jhtja]

Great video! I assume the formulas in the end apply only if injectors squirt sequentally and once per cycle? If theres more squirts per cycle (lets say two) and injectors squirt simultaneously to two runners (paired injectors) I need to multiply the injector reset time by four (because basically both runners get then 4 squirts per one engine cycle)?

[@aimless-drifter]

correct me if I'm wrong, from my understanding the time that intake port is open is no more than 25% of a Engine cycle (or 50% of Engine rev) time of intake stroke at 6000RPM would be about 0.005sec and the injector would be spraying for 0.017sec? So the injector at 85% Duty Cycle would be spraying fuel into a closed valves for 0.012sec?

[@paradiselost9946]

exactly. and fuel requires heat to evaporate, and evaporated fuel burns better than merely atomised mist... and as the heat comes from the valve it keeps cool, and as fuel is a solvent it gets cleaned...

[@NMrrado]

Hi Andy - love your videos and have been using MLVHD to post processes logs from my recently supercharged Lotus Elise with a Haltech ECU. Do you know of any way to create an integrator math channel using the custom channel interface tools? I have a fuel surge tank that has a high flow pump internal to the tank and is supplied fuel from the main tank with a lower flow lift pump. I wanted to create some channel logic to predict the fuel level in the surge tank given the fuel consumed by the engine and an estimate of the fuel supplied to the surge tank via the lift pump. Any tricks or tips to create this channel definition?

[@manitoublack]

The more you learn. the more you realise there is to learn :)

[@johnwolf1146]

is it normal for pulse width% to drop in higher rpm? does the computer calculate this and can it be manipulated for a longer pulse via a aftermarket ecu? my pulse drop 65% to 55% from 6000 to 7000 (redline) rpm. quote my tuner.

[@chippyjohn1]

If your engine struggles to breath after 6000 it will drop off. That is if your Volumetric efficiency declines as most engines do, the injector duty cycle will also decline to maintain a certain air fuel ratio. It may also reduce at higher rpm if fuel pressure increases. As the pressure increases for whatever reason, the duty cycle does not need to be as high.

[@Gun1Dwn]

Subbed btw

[@AndyWhittle_HowEFIworks]

Here is a site with some interesting plots showing how injectors flow at the limits. www.enginelabs.com/engine-tech/tuning-high-flowing-injectors-for-low-pulse-width-operation-with-fic/

[@rushweaver2807]

I just wanted to learn to calculate duty cycle from rpm. Instead I got a full college credit.

[@buder5116]

3:32 if its impossible get bigger injector hehehe