Yak13

My Feedback: (17)

For experienced Zenoah GT80 and G62 users only, please.

I am running a GT80 and a G62 in hot weather, above 105 F (42 C). Using Klotz oil 50:1 now.

Would raising the oil content in high temperatures help keep them cooler? Possible negative effects?

Please comment if you have experience in this topic.

Thanks!

tschuy

My Feedback: (1)

I've read somewhere that increasing the oil quantity in the mix will only raise the operating temperature. if anything enrichen the engine slightly or increase the octane of the fuel. Don't mess with the recommended oil to fuel mixture...

1QwkSport2.5r

Engine cooling is paramount compared to the oil type and quantity. Have the engine setup so its got baffling to direct the air across the engine to keep it as cool as possible and be done with it.

Gasoline doesn't behave anywhere like glow fuel where if you richen the mixture way up it cools the engine way down. There's a little of that effect with gas, but nowhere near as much as glow fuel.

countilaw

I agree with 10wksport, arrange baffles that direct the air through the fins of the cylinder. If the head is not out in the air stream direct fresh air to pass through the fins of it.

Also be sure you have twice the size air exit hole as you do the air inlet . And I would leave the 50:1 mix alone.

Frank

pe reivers

Twice the size does not matter; it's a myth that need not work. Yak cowls have HUGE air entries, yet are known for bad cooling without proper air ducting.
Be sure to have LOW PRESSURE at the cooling air exit. Block all air entry holes that do not direct air to the engine. You want none of that precious cooling medium to bypass the engine cooling fins.

Yak13

My Feedback: (17)

Pe, Guys,

The engine is properly cooled wth adequate airflow. My question is if raising the oil content to 45:1 actually helps cooling as many experienced pilots assure, or if will not do anything in this respect.

Thanks

Turk1

Or to add some minor castor oil into oil content? Can it help to prevent ( damage) from lack of adequate cooling? Any idea?

MTK

If I understood your question right, increasing the oil content from 1 part to 50 (50:1 ratio) to 1.1 parts to 50 (45:1 ratio) will not change the cooling ability of the fuel. It increases the oil content and that helps lubricate more, but that's it.... Improved lubrication may help overall engine operation tho. Slight richening of needles may also help.

This isn't a glow situation where one may add several ounces of oil per gallon fuel to possibly improve cooling from more fuel volume through put

Put another way, it takes 12.8 ozs oil in 5 gallons gasoline to get 50:1 gasil mix. Increasing the oil 10% to 14.1 ozs per 5 gallons gas is what you are talking about (45:1 ratio).....That's a scant 1/4 oz per gallon increase which isn'tmuch added oil

captinjohn

pe reivers, How about profile airplanes where the engine has about total exposure to air. Is there a bad thing we should know about whats happens with them? Should a small air scoop be used to cool back-side of the cyl? Capt,n

closetguy

My Feedback: (13)

don't you want to go with a higher oil content like 32-1 to get the most cooling?

pe reivers

The central part of the propeller is a very lousy fan design. Unless you fly and get a lot of wind over those very small cooling fins cooling WILL suffer and shrouding will improve it.
I noticed a 30°C temperature drop in a fully exposed cylinder just by adding a cooling jacket.

Regarding oil content.
The oil very often burns off, and adds NOTHING to the cooling. In case the oil does not burn, there is about one ounce of oil going through the engine for half an hour of operation. Be sensible: how much heat will this thimble full of oil carry away???? The advantage is, that more oil lubricates better, and thus there is less friction to generate extra heat. This lack of friction (better=less friction) will make the engine run cooler.

Yak13

My Feedback: (17)

I'm going to try the additional oil while monitoring and recording engine temp.

Will let you know

Ed

TimBle

Increasing the oil content in the fuel will do nothing for your engine temperatures. The percentage oil is small and the contact time is also very small meaning there is negligable additional heat transfer taking place due to oil. In total loss systems the biggest cooling factor is the air flow, secondly the stoichiometry of the engine and lastly the viscosity of the fluid in contact with the hot surface. If anything, adding more oil will result in more residdue build up on the piston and ring groove resulting in higher temperatures.

Changing the octane of the fuel will do nothing for your engine temperatures since octane is not heating value

You need to look at;

1) proper cooling baffles as mentioned above

2) ensure the engine is tuned correctly for the exhaust fitted

3) is not overloaded with too large a prop.

closetguy

My Feedback: (13)

here we go again.about the more oil and build up on the piston,not true in my case.i use redline at 32-1 and the top and sides of the piston are shinny new.