IO540 Injector Tuning Frustrations

[RV10inOz]

I would like to hear what others have found with the IO540 being difficult to get the injectors tuned to peak under 0.5GPH.

We have found cylinder 1,3 &5 peak close together after our first round of adjustments, and although we have been taking cautious small steps, we still have 4=too much fuel and 2&6 too less.

Without plastering this thread with miles of data, and everyone wasting time on that, what I am looking at is the experiences and any frustrations in getting the Lycosaurus to function LOP smoothly.

We are getting LOP and down around 11GPH, however the spreads are still between 0.6 and 0.9 depending on the test, and its just a little bit rough, which is what you would expect. Not frighteningly so, but not smooth like it should be.

Any suggestions are welcome!

Cheers
DB

 

[Jesse]

Tuning Frustrations

In my working with Kyle at Airflow Performance, I have been able to get things pretty close. On one engine I have gotten 4 to peak at the same flow and 1 cylinder is .2gph rich and 1 is .2gph lean, so that's a spread of .4gph on that test on that engine. I know this can vary a little, but that made a huge difference running smoothly LOP compared to a 1.2gph spread originally on that engine.

On another engine I had an original spread of 1.6gph and the cylinders were all over the map. I have gotten that one quite close, but there is still one cylinder that doesn't seem to cooperate. With one restrictor it is a fair bit too rich and with the next size smaller it is a bit too lean. It is running smoothly now, though, so I'm pretty happy with it, with a total spread of now about .8gph, with 5 cylinders within .2gph of eachother.

One thing Kyle mentioned that seemed to make sense, was to completely change all of the nozzles with, for example, a .026" nozzle, run the test, and then work the individual cylinders up and down a little from there. I see that this really makes sense as you are really starting with a whole new playing field. Either way, on both of the engines mentioned above, I have gone at least 2-3 rounds of tweaking to get to where I am now. If you have one cylinder that is way low and one is way high, richen the lean one by .005" and lean the rich one by .005" and see where that gets you. One thing to remember is that if you lean one cylinder, all of the other cylinders will richen up a little bit in the system. On one engine I ended up buying 8-10 restrictors in the long run to get to where I am happy, but now I have the other restrictors to use in another plane if/when I do that.

Hope this helps.

 

[Kahuna]

I would like to hear what others have found with the IO540 being difficult to get the injectors tuned to peak under 0.5GPH.

We have found cylinder 1,3 &5 peak close together after our first round of adjustments, and although we have been taking cautious small steps, we still have 4=too much fuel and 2&6 too less.

Without plastering this thread with miles of data, and everyone wasting time on that, what I am looking at is the experiences and any frustrations in getting the Lycosaurus to function LOP smoothly.

We are getting LOP and down around 11GPH, however the spreads are still between 0.6 and 0.9 depending on the test, and its just a little bit rough, which is what you would expect. Not frighteningly so, but not smooth like it should be.

Any suggestions are welcome!

Cheers
DB

How many injector swaps have you made?
Go ahead and post up the data with the swaps and new data.
It should not take more than 4 iterations to get it right. 2 usually.
And no Ive not heard of anyone NOT being able to successfully get to w/i the desired .2gph at peak.

There are miles of discussions on LOP operations here. No sense in haggleing that all out. The very short answer to your question is yes, you should have no problem getting your 540 LOP and smooth when you get your peak spread in line.

 

[lmb118]

My experience has shown that the final .2 gal can be hard to balance. I have had 2 of the same size nozzels flow slightly diffrent. I might be helpful to swap the same size nozzels around and see what you get.

lynne

 

[Don at Airflow]

Flow Divider dividing flow

RV10inOZ

With your flow at 11 GPH if you are using the stock .028 nozzles as a starting point, the nozzle backpressure at that point is around 1.5 PSI. That means that the flow divider is influencing the division of fuel flow. So if you change nozzles and continue to take data at this flow range (10-12 GPH) you?ll be chasing your tail, as the flow divider is actually dividing the fuel flow. Then there?s a good possibility that at high power the flow distribution will be totally out of whack because you have been trying to change nozzle size based on incorrect data. The solution is increase the power to get the fuel flow above 12 GPH then take the data, or decrease the restrictor size on all cylinders to increase the nozzle back pressure thus driving the flow divider open so that it does not influence the division. Example: decreasing the nozzle size to all .024 restrictors will increase the nozzle backpressure to 2.9 PSI vs. the 1.5 PSI for the .028 restrictors.


Don