I did some test recently with my G20 using different mufflers to check on the performance differences and list my findings. Prop used in all tests was a Xoar 16x8 and fuel was 90 octane pump gas mixed with MC-1 at 50:1. Tach used was a Cermark One Touch at and elevation of 3,000' ASL.

Open Exhaust 7,950 rpm .... extremely loud
Stock muffler 7,500 rpm .... very easy on the ears
SPE 26 muffler 7,800 rpm .... acceptable noise level
B&B muffler 7,850 rpm .... harsh bark almost as loud as open exhaust

Karol

G20 with stock muffler and C&H ignition running on 93 oct mixed 32:1 with Belray H1R and Zoar 17-6 = 8300 rpm. I am more than impressed. I will be looking for another.

I've never tried a Xoar 17x6 on the G20 but crunching some numbers using Pe thrust calculator chart with your rpm figure of 8,300 it is making 13.12 lbs. of thrust versus the 16x8 @ 7,800 giving 11.23 lbs. Even an APC 16x6 @ 9,000 is still way below at 11.91 lbs. I will certaintly have to give a 17x6 a try. FWIW all the above thrust figures were calculated with a datum of 100' AMSL.

Karol

Karolh,
The performance is way better than an APC 16-6. That is what I used to run. The plane (1/4 sscale Cub @ 15 lb will take off in 5 feet, into a slight breeze.

Xoar props...how many places handle them and what is average cost of a 17x6? Thanks Capt,n

I bought mine through Cheif, and it was like $14.00. It really puts all other props that I have ever used (and that is about every brand made). They are to pretty to fly. Mine was perfectly ballanced, and had a finish unlike I have ever seen on a model propeller. They make all the other wood props really look like paint mixing sticks, and in my opinion out perform a APC hands down, at half the weight.


http://www.chiefaircraft.com/rcmsec/...XOARProps.html

ALL the EXPERTS(?) just KNOW that ALL Zenoah engines are overweight, underpowered boat anchors....That's why modded GT80s are turning 12,000 rpm and STAYING TOGETHER in our USRA F1 race planes at 190 mph...4 lb G62 on a pipe turns 22-8s at 8400...STOCK G26s turn 18-6 Mejzlik props at 9000 with 17 lbs thrust...Most ALL the 45cc Chinese engines use a CLONE of the G45 cylinder...Conventional wisdom is neither conventional nor wisdom....Some of you people need to pull your head out and look around...