Hi Dave,

I have a dingo which seems to be down on power. I am running it on Coolpower 30% heli fuel and without the restrictor in place it is turning a 16x12 apc prop at around 8.2k rpm. It has the hatori header and the hatori 698 pipe, pretty standard equipment. It's not overheating as running it without the cowling on makes no change.

In every other respect it runs beautifully, it idles smoothly at 2.2k and the throttling is instantaneous, and it will burn through a tankful without missing a beat. It's just the top end power that seems lower than I would expect, given other people's reported performance.

Does this seem to you to be lower than would be expected? I would have though somewhere above 8.5k would be about right. Any ideas as to why I could be down on power? It currently does not seem to out-performing my 140L.

thanks for your help,

James

How is the hot compression? If it's not really snappy, that might be the cause.
Have you checked the valves? They like to be set fairly tight on the DZ, we use about .002" or a bit less.

Dave,

seems reasonable when turning it over, but I will check the integrity of the head bolts before I fly it again. I have re-set the valves once since new but have not looked at them recently, again I will check them before next session.

thanks for the advice,

James

The secret is how the engines feels when it's really hot. Run it at full throttle on the ground for 2 minutes and shut it down. Then see how it feels.

Let me know.

Dave,

I tightened the valve tolerance to the 2 thou you suggested, and it gave me an extra 200rpm. I also removed the CFE air filter which gave me another 200rpm, and now the engine seems to be up to where I feel it should be, about 8.5-8.6k on a 16x12 and coolpower 30.

Quite surprising what a difference making these changes had.

Thanks for your help and suggestions.

James

Good to hear.

Happy Flying!

What could be the reason to have a Dingo "down on power", ( from normal APC 16x12 - 8600 rpm CP 30% Heli to 7600 rpm ). I've noted that the disc valve ( piece 29 )came loose time to time because the retainer screw ( piece 31 ) unscrew itself. Than i adjust the clearence between disc valve and back plate and screw again the Retainer screw, and the motor goes ok. But after 2 or 3 flights came again the same problem.
What could be the major reason for that?

Possible a bad rear housing. Difficult to tell without seeing the engine.

The motor now have 316 minutes of running. That problem start to hapen when he have 200 Min. Till there it has not this problem.
By the Minute 75th of running I've have a small crash with other plane where this motor was mounted. The crash was on "soft sand". I've take the motor out and cleaned it, and mounted in the actual plane.
Is there any possibility the "Cranckshaft" be slightly bended, and cause some vibration on the backplate to unscrew the "retainer screw" ?

Maybe, but I cannot tell without seeing the engine.