Onex107 wrote:Mike, I have been there with my AeroInjector also. I notice in your testing you don't consider air intake. I found my problem for not having full power at WOT to be restricted air, not fuel flow, due to an air filter I consider too small for that volume of air, especially if it has a little oil on it. Try it with the filter removed. Adjusting the needle won't change that. Also, the play in the needle holder was nearly 1/2 turn. The needle is free to move until you tighten that ball joint by bending or shims.
I hear you on the air intake.. the flights were done with the filter on but all of my ground adjustments were done with the filter off. I am using the same K&N filter that many people report good success with.
I don't think i quite had 1/2 turn worth of slop on mine.. but definitely agree that the slop-to-sensitivity ratio is a little higher than what i would like.
SonexN76ET wrote:1. The AeroInjector will not work properly with pressurized or ram air. As air pressure builds up the AeroInjector leans out erratically. Is the intake on the bottom of your cowling pressurizing the air to the AeroInjector?
Good eye.. I am running a custom cowl right now, but that scoop in the front is just an oil cooler and not a ram air intake. Air is fed to the AeroInjector the same way it would be with the stock cowl currently. The cowl i am running right now has a lot of areas where it can improved upon and I intend on developing a new cowl a bit later with what i learn from flying this one.
I am going to eventually try to feed the Rotec with a ram air intake in the cowl i am developing.. but i don't want to bring this thread too far off-topic. I will say this though, and it was the only point on which I found myself at odds with the good folks at Rotec when I talked with them at Oshkosh this year. They insisted that ram air not be done with the TBI. It is my opinion that it should be fine if done correctly - but the air needs to be properly recovered and/or straightened as it is fed into the inlet. I can see how air being directed into (instead of being sucked in), at some angle other than a perfectly parallel to the throttle body could do unpredictable things to the AeroInjector, and especially the Rotec with it's integral static port right at the inlet. That could screw with the fuel supply pretty bad. But if the ram air intake feeds a plenum where the ram pressure is recovered and the throttle body is just sipping from that pressure tank, it should theoretically be no different than just operating at a lower altitude. I get why Rotec would be defensive about this however, it is probably very easy to not do correctly and they are at risk of people badmouthing their TBI because it "doesn't work right", which would not be good for business.
SonexN76ET wrote:2. Sonex states you MUST have your wheel pants and gear leg fairings on when you are breaking in your engine. On the small Sonex airframe the un faired wheels and gear legs dramatically increase drag and thus cause high engine temperatures and reduced air speeds and reduced engine RPM. John Monnett made a big deal over this at the Builder's workshop I attended.
Interesting, thanks very much for this feedback. I had really wanted to get the wheel & leg fairings done before first flight, but i got pretty impatient towards the end of the build. I have some friends who told me the same thing - that i would probably get better RPM once the drag was cleaned up, but I don't remember hearing Sonex's stance on the issue. I totally agree that getting those fairings on there will help with some of the problems i was having. I am still confused, however, as to why my RPM was lower in the air straight and level than i got on the ground statically. I was blaming that on the AeroInjector's sensitivity to the ambient conditions of the day, but there may be more too it than that. Right now i have the wheel pants cut & trimmed and almost ready to be installed, but the parts that give the most bang for their buck, the gear leg fairings, are the two last parts of the airplane i still have to fabricate!