heres the skinny on the vmax 6 engine. Ive been through it all and then some. the Vmax 6 engine loves to be tightly sealed in order to run correctly for the LMH helicopter. As the heli engine heats up, something is expanding and is causing a leak somewhere. Ive done it and others also, we put a little blue locktite on the threads of the heatsink and what did ya know.... Ive found out that its ususlly a leak somewhere that will cause a power loss. Things to check: Check screws for tightness on cylinder, check backplate, check muffler, check Heatsink. If your engine is tight as it can be and it still dont produce power then there is the compression (adding and reducing copper rings). It actually takes a while to wear out one of these engines. I run my engines both V6 and V7 with 15% fuel with no probs at all. My personal opinion on the V6: Its a headache to tune but once you find the right settings for the engine, they run fine. As far a for the LMH Heli, I think the V6 is borderline sufficient power for the heli. Now, The V7 engine It opens up another world for the LMH Helicopter. It has ample power for the LMH Heli. when descending and you get caught in that down wash from the rotor wash and you are falling like a rock, you can actually throttle up out of the down wash, even at low altitudes. You'll have good power to loop (Its not just pulling back on the sticks) It a technique you will have to learn with the fixed pitch light litemachines heli. hopes this will be of a help to you.