different engines in 170,s

[ghostflyer]

I have just been reading in Plane and Pilot that a 1962 cessna 175 skyhawk has been fitted with a Continental O-470R engine . However saying all that about 6 months ago a friend of mine who purchased a RV-8 from Alaska informed me he had seen in Alaska[Fairbanks] a Cessna 170b fitted with a Continental O-470 also. He thought the transplant was from a Bird Dog .
No he didn’t take photos etc It was in a hangar where it was being serviced. Can any body throw any more light on this .

[GAHorn]

I once inquired into the idea of converting a B-model to an O-470…. but discovered the engine weighs 140 lbs more than an O-300 ….. which, sitting forward of the firewall…. made for some CG compromises that were untenable. The IO-360 only weighs about 35 lbs more than the O-300…but produces similar HP as the O-470…. so……..

When 80/87 octane was readily available it might have seemed possible….but since the near-complete conversion of AvGas to 100 Octane…. the
IO-360 is the one that makes the best conversion…if you want to stay with 6 cyls.

[mit]

Well, I don't know every 170 owner in Fairbanks, but I have not heard anything about an O-470 install. I will start asking.

[falco]

Don't forget the added weight of a constant speed propeller...

[n2582d]

Ghostflyer mentioned that the engine came from an L-19. The L-19 came with two versions of the O-470. The O-470-11 or -11B used a fix pitch prop. The O-470-15 used the constant speed prop. 391 lbs. and 408 lbs. dry weight respectively according to the TCDS.

Researching the FAA database for the C-170 series doesn't show one with an O-470. Not too surprising as engine changes often don't get recorded there. The most unusual engine on a C-170 that I found in the database was a Wright J-5. The TCDS says the dry weight for this is 520 lbs.-- 252 lbs. heaver than the O-300 dry weight which is listed as 268 lbs. How is that even possible?

[johneeb]

............................ How is that even possible?

Engine in the baggage compartment and a shaft out through the firewall

[GAHorn]

Ghostflyer mentioned that the engine came from an L-19. The L-19 came with two versions of the O-470. The O-470-11 or -11B used a fix pitch prop. The O-470-15 used the constant speed prop. 391 lbs. and 408 lbs. dry weight respectively according to the TCDS.

Researching the FAA database for the C-170 series doesn't show one with an O-470. Not too surprising as engine changes often don't get recorded there. The most unusual engine on a C-170 that I found in the database was a Wright J-5. The TCDS says the dry weight for this is 520 lbs.-- 252 lbs. heaver than the O-300 dry weight which is listed as 268 lbs. How is that even possible?

It’s possible because of the many other errors in FAA data…. Before I spent two weeks convincing them otherwise….. I owned a 1971 170-B….(with an ORIGINAL O-300-C engine.

[ghostflyer]

The bird dog design is similar to the cessna 170 series . I have looked at both aircraft side by side and I simply do not know how Cessna engineered that bigger engine up front in the bird dog. The wing design is very similar ,plus we have a bird dog that has not the original flaps fitted . It has 170 flaps and attach points . I think it has 170 wings fitted. The owner goes very quiet when I ask questions.

[hilltop170]

It’s scary to look at the motor mount structure behind the firewall of a C180 or 185 with the O-470 and IO-520.

There isn’t much metal there to carry the weight and thrust combination of the larger engines, just a hat-channel stringer riveted to the skin in 4 places with a bracket for the motor mount bolt, but I’ve never heard of those structures failing either. (The 5 bolts hold the ski bracket on the outside of the skin, another significant load on the motor mount structure!)

Those Cessna engineers knew what they were doing!

C180 Upper engine mount support structure