flow matched injectors

[rwayne]

So my GAMI spread is unacceptably high. I understand I need to flow match my fuel injectors so the cylinders EGT peak within a fuel flow of 0.2 gph. It may be an obvious question, but how do I flow match my injectors?

[BobTurner]

The guys at Airflow Performance can help you take the data, make recommendations, and sell you injector inserts.
Basically if you start rich and lean, the cylinder whose EGT peaks first is the leanest, you need a larger insert; last to peak is richest, needs a smaller insert. But make sure you still get rated fuel flow with full throttle.

[Kahuna]

http://mstewart.net/super8/nozzles/index.htm

[schristo@mac.com]

After you determine the EGT curves you change out the nozzle inserts as needed to shift the peaks closer together... you get a wee bit bigger one to flow more fuel to shift the peak earlier (shift the curve left on the graph) or use one that is a wee bit smaller to lean the the cylinder mix shift the peak later (shift the curve right).

The standard nozzle is 0.0280

Special nozzles are in increments of +/- 0.0005 (so a +1 is 0.0285)

Airflow Performance sells the special restrictors for 25 each.

[RV10inOz]

First of all, please post the data you collected for both the GAMI lean tests you did. One I assume at say 7500' and one at say 3000' at the same MP and RPM you had when at 7500'.

Then once we are sure you have no intake leaks, analyse the data.

What is your GAMI spread now and how did you determine it?

The reason for my cautious questioning and suspicious tone is that if you are asking these questions it is a sure sign that you may not really understand how and why you do the tests the way you should.

Happy to help.

[rwayne]

Thanks everyone. Great input. I'm going to go the Air Performance route. I've used Savvy's recommended flight profile and program (outstanding!) but think I'll leave the actual size determination and fitting of restrictors to the pros.