"zero" GAMI spread thanks to Don at AFP

scsmith · #1 09-07-2016, 02:31 PM

I've been flying with an IO-360-A1A straight out of the box, running LOP with a GAMI spread of about 0.3 gph. It has been fine, but looking at my data, I wondered if I could do better. Three of the four cylinders peak at essentially the same time, and one cylinder just lagged a bit. The upshot of that is by the time I get that one cylinder 30F or so LOP, the other three are more like 70F LOP.

So, I got to thinking, if I could just get a very slightly smaller injector nozzle for that one cylinder, they might all peak together.

After speaking with a different vendor and getting a lot of Bla-bla-bla for a while, I called Don at Air Flow Performance. Sure enough, he sells an 0.0275" restrictor (stock is 0.028"), for about $27. So I had him send me one and I gave it a try. PERFECT!
See the results before and after below:

Hmmm, picture doesn't post. Well, the url is http://hpaircraft.com/rv8/gami tests.pdf and if you type that in a browser, it will show the plots

Don was super easy to work with, listened to my plan, said 'sure, no problem'. No muss, no fuss. A far different experience from the bla-bla-bla I got from another vendor.

Raymo · #2 09-07-2016, 02:44 PM

I could get to the graph using this link.

EDIT: You figured it out while I was figuring it out

Randy · #3 09-07-2016, 03:11 PM

Thanks for the report. I have a very similar situation, seeing that it can get considerably better. I need to give Don a call and get er done...

Mark Dickens · #4 09-07-2016, 04:07 PM

While I plan to tune my injector nozzles with Don as well, I have to say that the "other vendor", which is no doubt GAMI, is outstanding. I've had 4 sets of Gamijectors on different planes, including a set of their turbo variety, I flew with them for years and would not hesitate to use them again. They are a lot more than "bla bla bla" in my experience.

TS Flightlines · #5 09-07-2016, 04:22 PM

Yep---Don has the injections covered. If you havent taken his FI course---I HIGHLY recommend it. Alot of us have, and its worth every penny.
Tom

Rupester · #6 09-07-2016, 05:29 PM

Quote:

Originally Posted by TS Flightlines

Yep---Don has the injections covered. If you havent taken his FI course---I HIGHLY recommend it. Alot of us have, and its worth every penny.
Tom

I'll second that.

miyu1975 · #7 09-07-2016, 05:44 PM

I got to do this soon. Haven't checked mr spread but it probably isn't terrible. But could be much better too. How,does one start the process with don?

Walt · #8 09-07-2016, 06:04 PM

Great job and definitely worthwhile, LOP ops are a good thing. However an actual "zero" spread is nearly impossible especially at various throttle settings, it's like trying to get a 0.000 ips prop balance, in reality it just ain't gonna happen, but depending on the equipment resolution, and if you're looking at only one specific "snap shot" in time, it may look close to "zero".

scsmith · #9 09-07-2016, 08:11 PM

Quote:

Originally Posted by Mark Dickens

While I plan to tune my injector nozzles with Don as well, I have to say that the "other vendor", which is no doubt GAMI, is outstanding. I've had 4 sets of Gamijectors on different planes, including a set of their turbo variety, I flew with them for years and would not hesitate to use them again. They are a lot more than "bla bla bla" in my experience.

NO I was not referring to GAMI. I have not spoken with them, but I hear of nothing but good things from them. I just didn't feel I needed to go the full GAMI service for an engine that was so close to perfect that tweaking one cylinder would do it. The other vendor was someone else.

scsmith · #10 09-07-2016, 08:14 PM

Quote:

Originally Posted by Walt

Great job and definitely worthwhile, LOP ops are a good thing. However an actual "zero" spread is nearly impossible especially at various throttle settings, it's like trying to get a 0.000 ips prop balance, in reality it just ain't gonna happen, but depending on the equipment resolution, and if you're looking at only one specific "snap shot" in time, it may look close to "zero".

I agree. Thats why I put it in quotes in the title. My fuel flow meter seems to be a bit g-sensitive, and otherwise not that consistent. Also this was at only one altitude -- 8200 ft, WOT. I will repeat the test at 11,000 next chance I get. But yes, settling time at each data point, altitude, turbulence, can all add uncertainty in the fuel flow measurement. What does seem to be pretty solid though are the temperature readings at a given throttle setting during a given test. So the peaks are the peaks, within the resolution of the 0.1 gph steps.