Build - OS Max Trex 600 Conversion for GT15-600

[Don S]

Subscribed.

[surferman]

"you'll also need the OS Max GT15-600 engine. If you have the original GT15-HZ it will not work out of the box because the crank size is different and won't fit the Trex 600 fan hub. "

Carey, what's the pro's and con's for someone looking to use either the GT15HZ or the GT15 600 engine for a Trex 600 DFC conversion. Looking to do basic to mild 3D (Not crazy stuff!)

[Don White]

Looks like you used the Align alum fan. Is that correct? Also the port in the power boast pipe is 5/16 shorter in height than the exhaust port on the motor. Did you port the pipe flange to match the motor? Also surferman I'm running DFC head on my 600 conversion and running 1680 head speed for the 1st 3 tanks. Heli is very stable with the DFC head.

[Dowquest]

Carey,
When will this kit be available? I didn't see it on your website. Also, how has it been flying?
Thanks, Jerry

[carey shurley]

hey Jerry

actually this kit is available from OS Max, as far as I know the only place you can get it is rcjapan.net

https://rcjapan.net/o-s-engine-parts...7voku2lm80pll5

[Dowquest]

Carey,
Thanks for the reply, How has this motor been working out?

[carey shurley]

having cooling issues at least here in the florida summer

the cooling system on the 570 conversion seems to be more effective

[Sowa]

How hot are the summers in Florida? I was flying this conversion in the San Fernando Valley (SoCal) last summer and it seemed to keep up with the motor. Temps would fluctuate between 90-100F.

[carey shurley]

"feels like" (temp/humidity) around 105 on worst days

engine would go north of 170C easily.

[msallua]

Carey ,I have the same Futaba temperature sensor, the sensor must be glued to the motor?

[HelisRock]

Carey, as always, very nicely documented build thread.

[carey shurley]

The loop sensor can be held in place by wedging in silicone fuel tube

The backplate sensor has to be glued on but will not be accurate because the backplate is too thick

[rcourtney671]

Carey,

Thanks for posting such an informative thread. Likewise, I have converted by Trex 600N to the OS. GT15HZ 600 frames and motor. However, I'm now having a problem with the ignition system that I can't seem to solve so thought I'd seek advise here. The engine ran great through one gallon of 25:1 gas/oil mix (Redline Synthetic) and I thoroughly enjoyed solid 25-30 minute flights (mostly hovering through break in). It seemed to have taken forever to get through that gallon but it gave me lots of time to practice slow stationary pirouettes. All of a sudden I can't get the engine to fire up any more. I used my RCexel testers to check and make sure I'm getting a signal from the hall sensor, which I am. I also used a tester to check the EI to make sure I'm getting current to fire spark the plug, again it was all good, strong spark; however, when I connect the hall sensor to the EI there's no longer any spark at the plug. Since the hall sensor is picking up the magnet and registering a signal to the EI, I thought maybe I have a defective switch so I bypassed the switch and connected a 2200mah, 2S lipo battery directly to the EI and tried to start the engine. Sadly I experienced the same problem, no spark at the plug. I'm baffled and can't understand why the hall sensor and EI test positive as working correctly separately but when I connect them there's no spark at the plug. I even changed the plug to a brand new NGK CM6, but still no spark from the ignition system when the hall sensor and EI are connected together. Do you have any idea what the problem could be? It's like the hall sensor and EI talk independently but no longer talk to each other when connected (if that makes sense). Or better yet, like a bad marriage; dating was fun but after the honeymoon the spark is gone and they no longer talk to each other . If you have any idea what the problem could be please, please, please advise. If anyone else reading this thread can tell me what the problem might be I'd love to hear from you too. Thanks guys.

Regards,

Rodney C.

[brw0513]

No expert here, but I have a few suggestions/comments.

I have two IG-05 ignition units and they both work (they run a GT15HZ600 just fine) but both behave a bit differently. One of the units happily drives a Hobby King mini tacho without a glitch, but the other unit doesn’t even when using the same Y-lead. When used with the “dodgy” ignition unit, the mini tacho doesn’t lose supply power at all, but it doesn’t display a valid rpm – it just cycles through displaying “8” in each LED segment. The odd thing is, the “dodgy” unit behaves itself when the plug is removed from the engine, still fitted within the plug cap, but is in “free air”. I mention this because I think testing for a spark at the plug electrode while the plug is under combustion chamber pressure is different than in free air i.e. around 10 atm compared to 1 atm makes it harder for a spark to jump across the gap between electrode and earth strap. I think it is possible you have a lazy ignition unit. Do you have access to another CDI unit to try? It could be an RCExl unit, not the genuine OS version.

Another possibility is a dodgy 3 pin connection between hall sensor lead and CDI unit. Is that known good?

If you attempt to start the engine at night in complete darkness do you see a stray electrical spark leaking anywhere?

I know others have had success with Redline oil, but I have not (admittedly that was with a Saito 4 stroke gas engine). That turned out to be a stuck piston ring. Is your piston ring stuck to affect your compression/fuel charge?

Just a final topic. I have a Revolution 10cc gas engine and its ignition unit has an RCExl sticker on it. With the exceptions of a rpm output lead and smaller plug cap, it’s outwardly identical to the OS IG-05. I suspect the majority of ignition units we are likely to use are made at the one factory in China. I also have a “genuine” RCExl ignition unit that I bought off FleaBay. When I use it to run my GT15HZ600, the engine sounds “duller” than when run with the IG-05. Maybe OS commissioned RCExl to make a limited run of ignition units with some minor requirements included? Perhaps those changes are not as well tested? I still wonder if some of the “blown” engines that were reported early were part ignition related where the ignition unit failed in a way to help temps runaway very quickly.

[rcourtney671]

Thanks for the input but my frustration level reached the point I said "screw it" and I simply ordered a new engine with all new components. The aluminum fan I initially installed did not have gov sensor magnets so I ordered a new one of those too. Once the new fan arrives I'll install all and with any luck be in the air soon going through the break in process.

I have GT15HZ installed on my Trex 700N, flybarred and concerned because I'm getting temps waaay over 175 Celsius. I stopped the break in process on that one until I can figure out how to bring the temp down. Our average daily temp outside is 85 - 95 degrees Fahrenheit. I'm running the Trex 700 at a head speed of 1450 rpm with the motor rich on a 25:1 fuel mix, so I can't understand why it's running so hot. Anyone else having this type overheating problem?

[msallua]

Originally Posted by carey shurley

The loop sensor can be held in place by wedging in silicone fuel tube

The backplate sensor has to be glued on but will not be accurate because the backplate is too thick

Ok, the sensor must be place in the exhaust side or in the opposite?
Thanks

[Stevendavis]

Any one know if the 600 conversion kit is still available anyware?

[rcourtney671]

Got mine from RCJapan.net. Delivery took about 10 days.

[SlezY83]

What is the clearance on the osmax conversion between pinion and main gear?
Would it fit 23t pinion there? There should be 0,28mm difference (22t vs. 23t):


Or would be necessary to little cut the frames and use 0,3mm spacers on the engine mounting?

From discussion here, it seems that the 170/23 (7,39) gear ratio would be better than 170/22 (7,73), is not so?

[phrygia]

Hello,

Which fbl unit is most stable for hz600?

I plan to work it with gy701 governer. Also plan to use motul 800 2T and I would like to hear your opinions.

Sorry for my poor English.