Jump to content
SAU Community

duty cycle defined

Doctor 30

By Doctor 30,
in Engines & Forced Induction

 Share

Recommended Posts

Sydneykid Grand Master

Sydneykid

Posted
Posted
What does duty cycle actually mean.  

If I am running at 2000rpm at 40% then that would be twice as rich as 4000rpm at 40% because the injector would be twice as long at 2000rpm when compared with 4000rpm.  Or does the computer allow for this?

RPM is irrelevant, 40% means it is open for 40% of the time, that can be 40% of 1 second, 40% of 1 minute, or 40% of one hour.:rofl:

Sydneykid Grand Master

Sydneykid

Posted
Posted
So realistically for a given manifold pressure it should read

1000 rpm 20%  

2000 rpm 25%

3000 rpm 35%

4000 rpm 45% etc

Is that correct?

Sorta. On a fuel map, rpm is one axis and load is the other axis. So you can have a lower duration at 3,000 rpm than at 2,000 rpm, if the load is lower. On a Skyline the load sensor is the AFM, manifold pressure is irrelevant. If it has no AFM, it is usually mapped for rpm against throttle position, again manifold pressure is sometimes irrelevant.

:rofl:

Doctor 30 Community Regular

Doctor 30

Posted
  • Author
Posted

Yeah, I was thinking other things being equal (IE load) Mine runs from RPM and MAP (I don't have an AFM. TPS is only used for extra enrichment which mine is set at 50% throttle.

So my car is probably running ridiculously rich down low and dangerously lean up top. Thanks for sorting that out for me.

I now need to find out what is a good duty cycle for varying loads and rpms for the RB20DET. Anyone that can help that would know would be very useful!!!

RB30-POWER Mentor

RB30-POWER

Posted
Posted

Ideally you want to go to about a maximum of 80% or so, at maximum power/boost for your motor.

Its not a good idea to run injectors close to 99% all the time as they weren't really intended to be pushed that far, and could shortern their life considerbly.

Therfore when choosing injectors for a certain motor, you want them to be at a maximum of 80%. This will allow safety margin, if you need a bit more injector on time, maybe when its a cold night or such.

Another thing, if you get massive injectors that you only run up to say 40% at full power, it makes it very difficult for the tuner to control them as acurately.

In fact microcraps and other cheap ecu arent the best for massive injectors if outright accuracy is wanted in the tune at low loads and light throttle. Autronic and Motecs are much better at controlling very large injectors at low duty cycle.

Sydneykid Grand Master

Sydneykid

Posted
Posted
hang on, who's hijacking this thread!  

I also have a MASTER FUEL section.  WTF is that about?!

Moves all the fuel load points on the map up or down. It makes changing from say 370 cc injectors to to 750 cc injectors real quick, just subtract 50% on the master fuel correction. Then fine tune the load points that need it. Much quicker than punching in every individual load point.:)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • 04-LOOX
      R34 GTR Vspec Garage Sale - All must go!

      By 04-LOOX · Posted

      Hi, is the HKS  Tower Bar still available ? negotiable ? 🤔
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
×
×
  • Create New...