This brief article is about fitting the OS MAX GT15HZII to a Pantera P6. We are providing guidance on how this gets done, but whether you attempt to accomplish it is on you. This is showing you how to do this safely as possible but with no guarantees it works, is safe, or suited for your purpose and how you use it and or what may happen is on you, not us. You’ve been warned!
Background
Once folks realized you can fit a P6 with a big block, we had a hit on our hands because guys could source 61SX-H and 70SZ-H on the cheap because 91 and 105 had superceded them in the minds of many. However, the 61 and 70 were perfect to stuff into a Pantera P6, thus creating a 600-class model with balls . . . on the cheap.
Meanwhile, those with deeper pockets opted for the 91SX-H and 105HZ. And in the world of big blocks, the 105HZ-R pretty much reigns supreme!
Lerch conversion
However, instead of stock gears, these engines needed taller gears (lower numerically). Enter the Lerch-conversion whereby fitting Raptor gears to a Pantera P6 changes the gear ratio from 8.7:1 to 7.08:1 and thus, creates a rocket ship!
The BBC mount was also the foundation for fitting big thumpers, like the FZ115S four–stroke, within a Pantera P6, also. This helped the model earn the title of world’s most versatile model helicopter. Why? Simple, because it can be a hoot with a 55, a 61-105 2-stroke, a four-stroke, as well as with a baby gasser.
These engines all share the same bolt pattern and the BBC conversion kit is what opens a whole new avenue of fun!
GT15HZII installation
Now to the question as it relates to the OS MAX GT15HZII, and the answer is, yes, this works, also! And as easy as that, compact performance helis using inexpensive gas/oil premix – without – the outsized mass of the Zenoah gasser engines is at hand.
At last, a crash doesn’t also mean a heavy ass lump like a Zenoah gasser tearing loose of the air frame and destroying everything in its path. So now, when your desires call for a gasser, you can opt for a lightweight powerhouse instead. The new engine of choice in compact models is the OS MAX GT15HZII, model number 38156.
Note; the GT15HZII 38156 is what you want versus 38150, the original GT15HZ.
Installation
If you’ve poked around any length of time on the website you know about the BBC conversion. This conversion is a foundational piece in allowing you to outfit a Pantera P6 with a big block engine from the range of OS MAX 61SX-H through 105HZ.
Cooling
As do 'all' hot rodding endeavors, this one soon begins to take you down issues to sort. For example, we deleted the cooling fan because the ginormous Walbro carburetor blocks airflow. Instead, we follow the path of the electric cooling fans just like we showed in the Four-strokes, article. If this is news to you, go check it out.
Note; up to a 60mm computer fan fits, and running this off a 10A BEC on its own channel with a program mix slaved to throttle is the way. Basically, as you open the throttle, the faster the fan turns, the more airflow and this equals more cooling. But in the interest of keeping it simple, if all you do with a P-mix is turn the cooling fan on-and-off . . . that works, also!
Caveat
That said, just because you can do something, doesn't mean you should. Like, doesn't it strike you as more than a little silly to pony up north of $650 for an engine (plus another $200 for an exhaust) and then trot out the argument about saving money on fuel? Pull the other one!
However, if you just say it's for the fun of it, then we're with you, 100%.
Further resources
Anyway, while installing the OS baby gasser is doable with our conversion parts, whether it’s best for you is your call, not ours. Videos linking to various gasoline conversions (using weedwhacker-based engines like the Zenoah products) are within the video section of Resources, so have at it if one of these is your heart's desire. Especially because it's a hobby and it's supposed to be about enjoying yourself!
Exhaust
Is it insane to shoehorn a GT15HZII into a P6? Maybe, but we don’t think so. But as usual the answer to this is . . . it depends! What doesn’t depend is the matter of an exhaust. You’ll need one. We opted for the OS MAX Pro. Pricey? Yes. Can’t be helped.
And just in case you’re wondering, we were also curious how the PowerBoost Pipe GT15HZ compared to the PowerBoost Pipe 105 (the one for the 105HZ engine). The exhaust system for the 105HZ is significantly larger!
Loading
So now it's time to discuss blade loading in greater detail. As with the big block conversions, you've got to update the gear ratio. The Lerch-conversion allows this in a straightforward manner.
Note; we don’t guide you to our 700-stretch kit for a GT15HZ-family equipped Pantera P6 because the head remains a 600-class. It's our opinion, the mass and typical RPM regimen of a 700-class model will overload the head and lead to failure. Thus, loading the model with 700-class blades and turning them into the range which the engine is capable of, is a very bad idea.
Why is it OK to use a stretch kit with the big thumpers? Simple, because you don’t get up to the same level of head speed with the big thumpers as easily you may with 2-stroke big blocks. So let's be clear, the RPM limit for the P6 main rotor head when fitted with 700mm blades is 1650RPM. Consider yourself warned about not using a stretch kit with the GT15HZ family of engines along with 700mm main rotor blades.
Anyway, it’s our opinion the best way to load the OS MAX GT15HZII is with the Quattro rotor head . . . yep, the 4-blade main rotor blade setup!
Wrap up
Recapping, fitting the OS MAX GT15HZII is doable with a BBC conversion kit. Cooling needs to be addressed and we recommend leaving the engine-fan off and substituting a 60mm computer type pancake fan using a 10A BEC to drive it along with a P-mix. Loading the engine requires re-gearing the model via Lerch-conversion plus a Quattro four blade running a maximum of 620mm blades. This last because fitting the model with 700mm blades within the 600-class blade grips and then operating in excess of 1650RPM is prohibited. Trust us, doing this is a bad idea due to concern for failure.
Disclaimer: you have to be true to yourself and have the discipline to recognize these stated RPM limitations whilst operating the product or you may injure yourself, or others. We’re warning you about it, and stating unequivocally, if you decide to build one, it’s not our responsibility what you do with it just because we have zero control over the quality of the build, or of its operation. Playing with this toy is on you, and you only. We’re asking you to be reasonable in your approach and if you can’t abide by the RPM limitations, then don’t buy our product or endeavor to attempt this GT15HZ-family of engine conversion. And if you have already bought the components from us, then return same under our terms for product returns. Please, this is not really a toy and you don't need the trouble you can bring on yourself by skirting the spirit of what we're saying.
