The International Cessna^® 170 Association

Hi
First time on this board. Someone from POA sent me here, it is a nice board. I have some questions.
First one is I missed spelled my user name it should read Skyhawk ....anyone know how I can change it????

I am a 1st cousin, I have a 1957 C-172 with a O-300 in it. It runs good and is at 1600 +/- smoh. I really like the smooth 6 but would like more power. I have been thinking of the Continental IO-360,any toughts on this would be much appreciated. I would like to find a complete run out one that I could overhaul under supervision or (2) have had some thoughts about finding a C-170 project that I could redo with a IO360. I love building things. I have overhauled several tractors and have done a restoration on a 1947 KB-1 pickup so rebuilding is not new to me.

The T-41 had a IO360 in it you would think this should be such a difficult thing to do?????

Thanks for your input.

HI! And Welcome! (And what's your real name?)
The simplest method us to just re-register under a new username. The misspelled username will become inactive.

There are many O-300-powered C-172 owners who are Members here. The two airplanes are essentially the same until the mid sixties (except for the gear, of course.)

The TCM IO-360 is an ideal engine for the conversion you suggest, and for the very good reasons. The T-41 certainly is worthy from a proof-of-concept point of view, but unfortunately one cannot simply get a T-41 from the firewall-forward and bolt it on, due to the different firewalls of the aircraft. (The T-41 has a firewall that is "stepped" similar to the C-175, so the engine mount will not simply bolt onto a 170 or 172 which has a flat firewall.) It is that engine mount that is the most difficult-to-obtain commodity when making the conversion.
The IO-360 also has plenty of power and is a six-cylinder engine like the O-300 it replaces, and therefore fits well within the original cowling and runs very smoothly.

Unfortunately the holder of the most popular STC, XP Mods, Inc. (who also had the approval to produce the engine mount) has slipped into difficulty over the divorce of the principals and, at last notice, is not available. This makes the conversion somewhat problematical purely from the paper-work standpoint. You'll have to find another basis of approval.

There are other engines which may be installed under other STC's, of course. The Lycoming O-360 is the most popular. It requires considerable cowling changes due to it's width, however, and since it's a 4-banger it makes a bit more vibration than the six cylinder engines.
Then there is the Franklin engines, but their difficulty is lack of availability and lack of factory support.

Occasionally someone considers the TCM O-470 which was used in the 182 but that engine is considerably heavier and magnifies a C.G. problem with the conversion.

Hope this helps. Best regards
George

Hey George

Thanks for the reply. Guess I have to sit and wait. I had heard about the xpmods guy...hope he gets his stuff together and gets back at it.

Thanks again

Willie

Our internet has been down for 2 days just got back on.

I just want to amplify some of what George had to say. The Cont IO360 is a nearly ideal upgrade for the 170. There are few cowl changes necessary and the finished product is somewhat difficult to distinguish from the original. The main clue is the larger spinner to accomodate the c/s prop. Mine was done using a one time STC. We changed the engine mount. The mechanic used a modified T41 mount the first time, but changed to a modified Piper Seneca mount for my installation. The Seneca mount fit the 170 better and the exhaust system was much easier to install. One problem is that the induction system is on top of the engine. If you mount the engine in the same position as the O300, the top cowl will not fit. We put in a 2.5 degree downthrust partly to solve the clearance problem and partly to help relieve back pressure on the control wheel during an aborted landing.

I would not recommend trying to install the IO360 without an STC in today's FAA climate. It seems to be almost impossible to get an engine swap approved now. I have a friend who owns a C172 with the stepped firewall. The T41 mount fits the 172 so he put his installation together using all Cessna parts with part numbers. He had to use a T41 cowl because of the top mounted induction system. He has been finagling with the FAA for 10 years now, but still does not have it approved. They give him an experimental certificate every once in a while so he gets to fly it a little bit. He thought it would be easy since he basically converted it to a T41, but that turned out to be wrong. The T41 is on a different type certificate than the 172 so he doesn't exactly have a 172 or T41. They keep leading him on. Every so often they tell him of some additional thing to do and then it will be approved. He does that additional thing, but nothing comes of it. The latest is that the paper work must all be in owners name, not the mechanics. He has recopied all the paper work with his name on it. It will be interesting to see what the next nonsensical requirement is.

jamyat wrote:I just want to amplify some of what George had to say. The Cont IO360 is a nearly ideal upgrade for the 170. There are few cowl changes necessary and the finished product is somewhat difficult to distinguish from the original. The main clue is the larger spinner to accomodate the c/s prop. Mine was done using a one time STC. We changed the engine mount. The mechanic used a modified T41 mount the first time, but changed to a modified Piper Seneca mount for my installation. The Seneca mount fit the 170 better and the exhaust system was much easier to install. One problem is that the induction system is on top of the engine. If you mount the engine in the same position as the O300, the top cowl will not fit. We put in a 2.5 degree downthrust partly to solve the clearance problem and partly to help relieve back pressure on the control wheel during an aborted landing.

I would not recommend trying to install the IO360 without an STC in today's FAA climate. It seems to be almost impossible to get an engine swap approved now. I have a friend who owns a C172 with the stepped firewall. The T41 mount fits the 172 so he put his installation together using all Cessna parts with part numbers. He had to use a T41 cowl because of the top mounted induction system. He has been finagling with the FAA for 10 years now, but still does not have it approved. They give him an experimental certificate every once in a while so he gets to fly it a little bit. He thought it would be easy since he basically converted it to a T41, but that turned out to be wrong. The T41 is on a different type certificate than the 172 so he doesn't exactly have a 172 or T41. They keep leading him on. Every so often they tell him of some additional thing to do and then it will be approved. He does that additional thing, but nothing comes of it. The latest is that the paper work must all be in owners name, not the mechanics. He has recopied all the paper work with his name on it. It will be interesting to see what the next nonsensical requirement is.

Thanks for the reply.
I understand the safty thing and FAA but it'e too bad, it almost is getting too restricktive. Years ago when I was a year teenager I had a chance to spend a day with Mr Pietenpol in his Cherry Grove shop. I still marvel at some of the things he invented and would like to think G.A. is farther ahead for it. Hope your freind gets what he needs to fly, cause that's what it's all about.

Willie

jamyat, I am curious about your friends conversion of the 172. When converting a B model 170 to the C-IO360, the ones I have seen converted were the early B models without the pressure cowling. I am wondering if that engine will fit under the pressure cowling as easily as the non pressure cowling. It would seem that there would be no difference since both cowlings have the same upper profile--only difference being the pressure cowling having just one or two oil doors vs having the hinged cowling. This is assuming one used the T-41 or Piper engine mount to which you refer. I think it unusual that of all the C-170's I have seen with the IO-360 conversion, none of them have been the later B models with a pressure cowling?

Frank, here is one with Pressure Cowling:

If memory serves, the IO360 conversion we saw at the Tehachapi convention (at the airport we had lunch and the helicopter demo) was a polished-and-red '53 model, and it was only after I walked up to it and stood in front of it that I realized it wasn't simply a O300 because it had a fixed-pitch McCauley prop with the standard '53 spinner. It had fit very tightly, but it fit, under the standard 53 pressure cowl. I wish I could find the owner to discuss it further. He was only there that one day.
He also had a gorgeous interior and a bag door mod.

Yea, John, I remember seeing your plane at Petit Jean a few yrs ago. Had forgotten it had the pressure cowling. That is one really nice plane; I liked the extra fuel capacity you have and the way the filler caps were out on the outboard end of the tanks.

And yes George, I had forgotten about that pretty red C-170 when we were in Tehachapi. I didn't manage to get any photo's of it over at that airport we had gone to and I never did see it back at Tehachapi either. That one just might have been one of the nicest 170's I have seen, although there are a bunch of them like John's that would be award winners at our conventions. If I had one of those I0-360's & a cs prop on ole pokey, I might be able to keep you guys in sight when we fly together

170C wrote:jamyat, I am curious about your friends conversion of the 172. When converting a B model 170 to the C-IO360, the ones I have seen converted were the early B models without the pressure cowling. I am wondering if that engine will fit under the pressure cowling as easily as the non pressure cowling. It would seem that there would be no difference since both cowlings have the same upper profile--only difference being the pressure cowling having just one or two oil doors vs having the hinged cowling. This is assuming one used the T-41 or Piper engine mount to which you refer. I think it unusual that of all the C-170's I have seen with the IO-360 conversion, none of them have been the later B models with a pressure cowling?

The previous posts show that there are some 170B conversions with the pressure cowl. I think the 170B pressure cowl would be somewhat easier than the older cowl. With the older cowl you have to convert a non-pressure cowl to a pressure cowl. The old inside box can't be used because of the induction system on top of the engine. Because of the hinges and the support angle braces it is hard to get a good seal for the baffle. You also have leakage through the long piano hinges. The Swift guys have the same problem with the hinges when putting the IO360 into a Swift. One Swift owner said he glued buckskin to the inside of the hinge to seal it. I have not had any heating problems with mine, about the highest it seems to run on 100 degree days is 190 - 200 in cruise, but I spent a lot of time with the rear seal. It gets higher than that in a climb.

The older cowl is very nice when doing the preflight.