Installing turbo nozzle bodies on an RV-10 with a Lycoming IO-540

Based mostly on testing that Dan Horton (DanH on VAF) completed while working with Don at Airflow Performance, I decided to switch my stock Lycoming Fuel Injection Nozzle bodies for Turbo Nozzle Fuel Injection bodies. Most of my flights are 12k-16k and my objective was to improve LOP operations at altitude. Prior to this modification I have switched to 0.025″ nozzles at Don’s suggestion and I have completed the turning of my restrictors to achieve 0.2 GPH variation between cylinders.

How normally aspirated fuel injection nozzles work (Dan Horton post on VAF)
The nozzle body has a passage somewhat larger than the restrictor ID. There is an air bleed hole in the side of the body. The restrictor shoots a stream of solid fuel into the passage, where it mixes with air from the bleed. The result breaks up more readily in the intake port, in particular at part throttle.

The variables here are (a) pressure loss through the intake system and (b) upper cowl pressure recovery, i.e. how much of the available dynamic pressure was converted to increased static pressure in the upper cowl. An installation with great intake tract performance (ram, no filter, big throttle throat, etc) and lousy cooling pressure will have poor bleed air delta. A system with uneven upper cowl pressures will have unbalanced bleed air supply; the nozzles may flow different quantities of bleed air, and the proportions may change at different airspeeds.

Stock fuel injector nozzles can perform poorly due to the following:
1. Lack of pressure (could be due to cowling, plenum, or other obstructions affecting one or more injectors)
2. Running LOP while WOP at high altitude

I hoped to achieve better fuel atomization by replacing my stock Lycoming Fuel Injection Nozzle bodies for Turbo Nozzle Fuel Injection bodies

Costs: