1948 Ragwing Engine cooling

[KenyaSkies]

I have been reading up on all the posts relating to high oil temperatures and have some questions that I have not found an answer to. My 170 is running in the 215 degree range. I am flying in outside air temps of around 80 in Kenya - hot and high most of the time.

Questions 1: What purpose are the two panels covering the engine - the aluminum panels that are secured with three butterfly screws? My thought is that in hot climate operation that they are aiding in the hot running temperatures. Can I remove them and what effect will this have on other aspects of cooling and airflow in flight? If I do remove them will it make a difference?

Question 2: I am running on 93 octane Mogas - with six newly installed cylinders. Is there a difference in cooling between Avgas and Mogas and will my six new modern cylinders prefer Avgas or does the original STC still apply?

Thanks and looking forward to feedback. Nick in Kenya.

[Dallas170]

It sounds like you are flying with the winterization block off plates installed. The ones covering the holes to the sides of the prop should be removed if ambient temp is 30F or warmer. The one below the prop, centered in the cowl should be removed at 60F.

http://www.cessna170.org/forums/viewtop ... 25&t=13838

It sounds like he is describing the baffles over the cylinders. I don't know the answer to the question, but my understanding is that the baffles are to keep air flowing over the engine to aid cooling.

[sfarringer]

Absolutely do NOT remove the "two panels covering the engine"!
Without them you do not have a pressure box to feed air down through the cylinder fins!

[Poncho73]

I have been reading up on all the posts relating to high oil temperatures and have some questions that I have not found an answer to. My 170 is running in the 215 degree range. I am flying in outside air temps of around 80 in Kenya - hot and high most of the time.

Questions 1: What purpose are the two panels covering the engine - the aluminum panels that are secured with three butterfly screws? My thought is that in hot climate operation that they are aiding in the hot running temperatures. Can I remove them and what effect will this have on other aspects of cooling and airflow in flight? If I do remove them will it make a difference?

Question 2: I am running on 93 octane Mogas - with six newly installed cylinders. Is there a difference in cooling between Avgas and Mogas and will my six new modern cylinders prefer Avgas or does the original STC still apply?

Thanks and looking forward to feedback. Nick in Kenya.

Those two panels are part of the cooling and baffling system for that engine and must remain in place..do not remove. Is the high temperatures the result of the cylinder change? What were the temps prior to installing the new cylinders, same or lower? Also you should have the larger lower cowl lip.

I have no comment on the 93 Octane mogas STC. Perhaps George or Bruce could chime in.

[GAHorn]

Most warnings I've seen by cylinder manufacturers insist that new cylinders must be "broken in" using aviation gasoline... not to use mogas (auto gas).
The air "box" installed over the cylinders within the outer cowling are necessary for proper engine (especially cylinder) cooling. New cylinders WILL run hotter while they "break in". This is normal.
The 215-F temperature is not excessive. If you use straight SAE50 wt aviation oil the temperature is allowed to go up to 240-F in accordance with the Continental type certificate. YOur early airplane has an oil temperature gauge which will not accommodate / indicate that allowable increase. I suggest you not be too concerned about 215-F if using SAE50 oil.

[hilltop170]

Also, the cowling baffles may not have been installed properly after the cylinder change. Make sure there are no holes between the baffle seals and air box (the air box is what traps the high pressure air coming in thru the front air intakes and forces it down thru the cylinder cooling fins) that are bigger than about 1/2"/1.25cm in diameter. Look down between the cylinders and make sure the inner-cylinder baffles are there, they help direct air thru the lower cooling fins.

There are two blast tubes that run from the rear air box bulkhead left and right that direct cooling air down to the oil strainer housing. Make sure those blast tubes were replaced at cylinder change and they aim at the strainer housing.

Good luck!

You might think about joining the club and you will have access to more information. We always welcome new members.

[Bruce Fenstermacher]

Curious, the lip under the cowl at the cowl exit. How deep is yours? As a '48, it should be 3" from the top edge to the bottom.. If you have a 3/4" lip, you have the wrong lip for a '48. You have a lip for a '51 and '52. It would not be unusuall to see the oil temperatures your seeing if you have the 3/4" lip.

Make sure you have all the inner cylinder engine baffles installed and improve the seal of the inner pressure cowl (the parts you can NOT remove) and make sure those cooling air tubes which run out of the back of the baffling down to about the nose of your generator, are actually pointing at the accessory case in the area of the oil temp gauge bulb. They are to cool that area to bring the oil an the oil temp into the range Cessna specifies. Often these tubes get mistakenly misdirect cause their purpose in not understood.

Remember pictures of your airplane and parts you have questions about are invaluable helping us give you good info. There is a big difference in the winterization plates someone first thought you might be talking about and the inner pressure cowl doors. Posting pictures here is not the most intuitive process, but anyone should be able to do it.

As for cylinder break in on MOGAS. There have been millions and millions of piston rings and cylinders broken in with MOGAS. The only reason I'd use 100LL over MOGAS is if the cylinder warranty was riding on it.

[KenyaSkies]

Thank you all for your most valuable comments and advice. I was a member - somehow fallen off the membership. Will get myself back on. I'll take a look at all the factors and get back. Presently the plane is sitting in a tropical download in Mwanza, Tanzania, being admired during the day by Caravan pilots who have never seen a 170! Heading back to Nairobi Friday across the Serengeti - what an awesome flight! Thanks all!

[DaveF]

Rejoin the association so you can post some pictures!