freakingfast

My Feedback: (3)

I’ve ran-in lots of ABC type engines with no problems however, only one ringed Webra 35 and it took a long time to shine.
This is a brand new Thunder Tiger 39 ringed and I wondered if it's a different procedures.
Any suggestions?

combatpigg

My Feedback: (3)

I would break it in with a 7x6 [cut down 8x6], 25% castor and run at as fast a 4 cycle until the exhaust residue is clear, then go for a few rich 2 cycle runs, looking for a steady needle setting. Check the torque on every bolt after the engine cools down. Don't play with the throttle until the engine is broke in. I haven't heard anything yet about this engine, hopefully it turns out to be a screamer. Is it the same weight as the .36?

Kmot

My Feedback: (24)

Who makes the cool looking engine test stand?

KC36330

ringed engines have to get hot in order for the ring to expand and wear to the proper fit to the liner. you need to peak them out for 30 seconds (let it warm up) and then richen them to a 4 cycle and let the excessive fuel/oil cool the ring/piston and repeat. after a few tanks, with the engine OFF, the engine will 'bounce' freely when the prop is given a quick flip toward compression (it'll ping/pong back and forth). at that point you can fly it on a rich 2 cycle setting till the exhaust residue is completely clear.

kc

EDIT: running it at a continuous 4 cycle setting (as previously suggested) before the ring is worn/fitted you'll overheat the piston. the ring is what transfers the heat from the piston to the sleeve with the continuous 4 cycle running the heat is ring doesn't wear to match the liner and the heat is NOT transfered efficiently.

freakingfast

My Feedback: (3)

It's a Thunder Tiger 39 pro Heli with the head's fins turned round/smaller and a prop dive plate added. Purchased it like this with the can exhaust from Diamond Dust a year ago.
Jeff told me it runs like a scalded ape on 30% with a 8X8. I asked how it compares to an OS 32 SX and he said "a lot more power and speed, Like night & day" It's in the 30 size/weight class case. By the way, the out put on the Webra 35(discontinued) is about the same as the OS 32.

I'm planing on putting the TT on my Outlaw. Thx for the break-in info!

KC36330

if you intend to run 30% you need to shim the head, most of the TT heli engines came with the shim, if you don't have one you should get one.

kc

freakingfast

My Feedback: (3)

The engine stand is made by Stan Hart (916) 383-4182. It's rather pricy at $140, but it's top quality, super adaptable and holds everything up to a Moki 2.1

combatpigg

My Feedback: (3)

There have been quite a few ringed engines that could really scream, even after ABCs took over. I remember the LHS owner getting all excited about his Webra helicopter-to-airplane engine conversion when competition fun flys were the rage around here. IIRC, the heli version came out a couple of years before they offered it for planes and there was a choice between ringed or ABC. Hopefully the TT .39 turns out as good as the Webra and OS .32s, but for less $$$.

freakingfast

My Feedback: (3)

Well, I took two new engines, a TT 39 and OS 32 to the field and mounted them to the test stand for break-in. After 48 oz of 15/18 Powermaster in each engine I started some testing. The OS broke-in nicely with great idle, transition and power. The TT will take a lot longer due to the ring and has not reached its peak yet; the engine gets noticeably better every run in all factors.
Both engines will reliably idle at 3,000 RPM. Both with an OS #8 plug, using the same Mac's pre-tuned header (cut 1/4" shorter than supplied) and Quiet pipe kit. RPM backed off 200 from peak. Here are some results.
OS 32 SX 15% nitro
16,500 with 9X6 APC
17,700 with 8X8 APC
TT 39 Pro heli 15% nitro
17,100 with 9X6 APC
18,200 with 8X8 APC
TT 39 on 30/20 Powermaster heli fuel
16,700 with 9X7 APC
17,500 with 9X6 APC
18,700 with 8X8 APC