to Inertia Ring or not to Inertia Ring - that is the question

[humptybump]

My RV-8 has an 0320-E2A (updated for 7/16 bolts) and a Catto 2-blade. A couple years ago I replaced the firewall mounted Odyssey 680 with an LiPeFO4 battery. Last year I pulled out the electric gyro based panel for simple VFR "glass".

All of his adds up (or doesn't add up) to a lighter nose. The RV-8 has the advantage of a forward baggage area so I use it when needed.

My airplane currently has a 15lbs inertia ring on the prop hub. Should I keep it or should I remove it and save the weight?

What benefits do I get from the inertia ring ?

[Kyle Boatright]

IMO, it comes down to the benefits you get from the inertia ring. Without it, will you be able to load up a passenger and bags and take a cross country without encountering aft CG issues? If so, I'd probably delete it. Otherwise, I'd keep it.

[humptybump]

I can load the forward baggage compartment with the heaviest items if CG is the only consideration.

Are there benefits beyond the inertia ring's effect on CG?

[rvator51]

I could set idle lower when I had the inertia ring on mine.

[humptybump]

I can idle pretty low (into the 500's) but it's rough so I advance the throttle a bit to idle at 650 (or what ever I need for it to not rock too much).

Are there considerations during engine start?

[crabandy]

There's been debates if it is indeed an inertia ring or just a CG ring.

Limited experience on my RV7 but I have about 1 hour or ground running without the ring (O-360/Catto/Dual EFII ignition) .1 at a time for carb tuning and leak checks. My original empty CG was 82.64 (1038lbs), decent but I wanted the full range of weight scenarios available. I added a used landoll inertia ring when re-torquing the prop before the first flight. After final assembly my empty weight was 1053 lbs and CG 80.787.
I've noticed no difference between before and after adding the inertia ring. Engine will idle very smoothly at 510-520 RPM(I believe the EFII helps a lot), it starts getting rough below 475 RPM. I will probably keep it because I don't have the front baggage option in the 7. If I were to do it again I would have Saber manufacture a crush plate around 8-9 lbs to put the CG right where I wanted it.

[humptybump]

Hi Andy, I've heard of inertia rings and harmonic balancers but no "CG rings".

I would guess the EFII is helping with your idle. I don't know of any O320 carb+mag engines than idle smoothly in the low 500's range.