30% Nitro

[jschief]

When running higher nitro fuel do you lean out the carb or do you richen it up a little bit. Just curious, I have a OS50 hyper.

[flyinfool]

Usually you will need to richen the needles since the higher nitro fuels generally have more oil and less fuel per given volume.

As a general rule when changing any thing to do with the engine, I will richen the main needle 1/2 turn for safety and then retune from there.

[WayneBrown]

What Jeff said. :noteworthy

[Mark J]

I wish I had seen this post BEFORE I tested out some 20% fuel over the 10% I had been running before!

I hadnt even ran half a tank through my 50 hyper of the 20% and it suddenly bogged down loads, then as I was bringing it back down, there was a loud *POP* and the engine died, so I had to auto it down (luckily over a corn field so that helped cushion the landing)

Took the backplate off and removed the the glow plug I and I could see light from the bottom of the engine THROUGH the piston :(

A picture of the damage (sorry for poor quality as used my mobile phone)

[WayneBrown]

that sucks!

[mplourde]

WOW!!!! some hole!!!! :shock:

[Mark J]

reading the thread about the OS 50 hyper blowout, it seems it could have been a mixture of not only the higher nitro content, but also as I found when I removed the head, that the bolts holding the head were ALL loose in that it took NO effort to remove them.

So basically, the head had come slightly loose allowing fuel to be forced out which made the engine even leaner which is what I believe led to the blow out and the rather nice (not!) hole!

So I would suggest checking on your head bolts regularly on the hypers as in the other thread is seems to be quite common.

[SteveL]

It is very common for an engine that has run hot to have a loose head. That being said this is not the first time I have heard of a hyper having a loose head. You should see a dramatic loss in power if it is leaking. When it leaks you loose fuel and air so your ratio (mixture) should remain constant.

[flyinfool]

My rule of thumb still stands.
If you change anything related to the engine, be it fuel, muffler, filter, fuel lines, glow plug type, or anything else, open the main needle 1/2 turn and retune from there.

Last week I switched to a Hatori SB-50 muffler and the needle needed to be opened more than 1/2 turn from what my old muffler needed.

[Mark J]

I did notice a rather rapid dropoff of power in a short space of time during my last flight, and as I was bringing the heli back in to land, thats when it went 'pop' and stopped the engine (what a way to experience your first forced auto from about 20 - 30 foot up! :shock: ) Luckily id been practicing my auto's on the sim, so that helped me a lot with not just pulling the throttle stick down and burying the heli into the floor!

[Mark J]

Flyinfool:

I wish I had read your rule of thumb before I tried the other fuel! I know for definate from now on, any changes will also include the richening of the needle.
Will be right at the top of my list whenever anything changes regarding the engine etc.

[marcelo_sp]

should a higher nitro and oil fuel help my engine to get cooler??

[jschief]

I far as I understand it the 30% nitro add more air to the fuel mix. This is why you have to richen the mixture which intern also keeps the engine cooler.

[DebianDog]

should a higher nitro and oil fuel help my engine to get cooler??

Yep that or richen it up.

[Fuelman]

When going up in nitro, the needles must be richened, generally both hish speed and low speed.

When going down in nitro, leave it alone and lean into the lower nitro fuel.

Adjust the mid range as necessary