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10-17-2016, 10:10 AM | #1 (permalink) |
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Join Date: Jul 2013
Location: Middle East
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OS Gt15HZ back into service
Hi, I'm going to put the Gt15HZ back into service and need some advice, confirmation that I'm going about it the right way please ?
It is going back into a Helix GT600 frame and I plan to use 600 - 620 blades. It is getting new internals and the WAR head (obviously spirals as before - looking forward to try and get it out .....). Accepting that the Trex cooling is not optimal, but it is what I have to work with. Previously I started losing compression after 20l and now have a lot of piston slop / play and little compression. No markings on sleeve or piston, just very loose. Is this wear a function of heat / high temps ? I will run it in as gentle as possible. Headspeed of about 1500 gets into a hover. Start directly with synthetic, or an initial period of dinosaur first ? How many liters / gallons before starting to ramp it up slowly ? What is the effective RPM range with a Hatori pipe ? Is there a confirmed not-to-exceed, before the wrist pin start elongating the piston holes - if this is still an issue ? Anything else I should be doing, not do and look out for please ? |
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10-22-2016, 09:42 PM | #2 (permalink) |
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Join Date: Mar 2005
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Hi there Dawiev.
You might be leading the knowledge base on the GT15HZ! And you may be the only one to get 20l through this engine without damage to engine or airframe. The mere fact that your post has gone unanswered for near a week probably says something about the remaining interest in the engine. But, like you, I'm still avid supporter For what it is worth my suggestion is to use a good full synthetic oil from the start. After 4l of fuel begin leaning it over another 4l to sneak up on an engine speed of 14,000rpm. If the model is happy there, then stop. Personally, I wouldn't strive for an "flying" engine speed over 14,500rpm. If this is not high enough for you, then it's not the right engine for the application. |
10-23-2016, 09:54 AM | #3 (permalink) | |
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Quote:
Hatori makes power between 14,5k to 16k. You don't get much more power spinning it faster. I flew mine all last year just under 16k.
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XL Power 700v2 Nitro NME - OS 105HZR - Power Tune - Rail 716/106 - Brain2 HD |
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10-23-2016, 10:07 AM | #4 (permalink) |
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Location: Middle East
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Thanks for the replies and help!
Parts will be here tomorrow, so I will be able to measure it all up to see where the compression went. ($ 130 from RCjapan including gaskets and wrist pin) I stretched the boom so I can run 626 blades and aim to be at low 15k motor RPM. That will be plenty for this purpose Ps. The WAR head is huge in comparison to stock! |
10-23-2016, 10:16 AM | #5 (permalink) |
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It reallys is. A lot more surface area.
What ratio will you be running? I ditched a lot of weight in my trex 600 conversion by dropping to an 8oz tank.
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XL Power 700v2 Nitro NME - OS 105HZR - Power Tune - Rail 716/106 - Brain2 HD |
10-23-2016, 10:20 AM | #6 (permalink) |
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It is 8:1. HelixHeli GT600 frame which uses the Trex 700 slant main gear and pinion from Infinity.
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10-23-2016, 10:26 AM | #7 (permalink) | |
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Quote:
I think a 600 at that headspeed is going to be pretty lethargic, might be hard to tune the bobbles and wobbles out of the head. I run my setup at 2150 with ~620mm blades. This is with a 7.34 ratio.
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XL Power 700v2 Nitro NME - OS 105HZR - Power Tune - Rail 716/106 - Brain2 HD |
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10-23-2016, 10:57 AM | #8 (permalink) |
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The hunt for a 15T pinion has started ............
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10-23-2016, 02:26 PM | #9 (permalink) |
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The WAR Head fits in the Helix 600 conversion, have an pictures?
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10-23-2016, 05:31 PM | #10 (permalink) |
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I found best life so far with my OS15HZ at 14500 or so... I tried higher and not much was gained in power. Luckily on the 570 conversion its simple and easy to get pulleys and belts for almost any gear ratio you want.
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10-23-2016, 07:02 PM | #11 (permalink) |
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The HelixHeli frame uses the Trex 700 fan and shroud. It is wider than the 600. Width is fine for the WAR head.
Seems 15T is not readily availabe. Found a 16T pinion gear which will put it at 7:1. |
10-23-2016, 10:54 PM | #12 (permalink) |
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14,5 @ 7:1 will put you around 2070, that is a good starting point.
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XL Power 700v2 Nitro NME - OS 105HZR - Power Tune - Rail 716/106 - Brain2 HD |
10-23-2016, 11:07 PM | #13 (permalink) |
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For the record, I found a selection from 14T to 17T.
14T is quite common from various sources. 15 & 16T are available from Century Heli. 16 & 17T are available from Helibug. The Century ones seems to be from a "soft" alloy and probably prone to wear, but at $15 a piece, no issue. The HB ones must be from rare earth metals at $70.... I will start the break-in with what I have and put the 16T in when it gets here. |
10-24-2016, 10:11 AM | #15 (permalink) |
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I opened the engine and the compression leak is at the exhaust port divider. Clear that the blow-by happened there.
Then........ Snap! Am I the first to break the head off the conrod retaining bolt? It is reverse thread! !!!! |
10-24-2016, 05:06 PM | #16 (permalink) |
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Trust me... You are not the first... Ask me how I know... LOL
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doug TRM Power - RC Racing Engines - - Blackout Mods Conversions - - VP Racing / Powermaster Fuels - - Gas-Powered-Helicopters.com |
10-30-2016, 04:52 PM | #17 (permalink) |
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I was very close to break that bolt.
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Suat Trex 700 Gasser FBL | HeliBug HB7-RC 17T | Silverline V-Bar| TRM VX290TT | SG | RJX Gas muffler (modded) Trex 600 Gasser FBL | HeliXHeli conv. | OS GT15HZ | iKon | Homemade onboard generator |
11-09-2016, 11:42 AM | #18 (permalink) |
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Test fit of the WAR head in the frame.
The new Axon arrived. I am in two minds to put an Ikon in and see if the vibs are tolerable (knowing the gov works well) or directly to the Axon and see what their new gov is like. |
11-09-2016, 01:33 PM | #19 (permalink) |
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I use an Icon on my helix 600. Works perfect.
Sent from my GT-I9300 using Tapatalk
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Suat Trex 700 Gasser FBL | HeliBug HB7-RC 17T | Silverline V-Bar| TRM VX290TT | SG | RJX Gas muffler (modded) Trex 600 Gasser FBL | HeliXHeli conv. | OS GT15HZ | iKon | Homemade onboard generator |
04-21-2017, 12:55 PM | #20 (permalink) |
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@dawiev
Did you find a drive gear that fits your HeliX conversion? How are the ones from century heli? The did you choose the gear for the 600 or 700 conversion? Eg 600 version Thanks! Manu Last edited by KO-Pilot; 04-21-2017 at 01:22 PM.. |
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