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different engines in 170,s
Posted: Sun Apr 21, 2024 10:24 pm
by 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 .
Re: different engines in 170,s
Posted: Mon Apr 22, 2024 1:51 pm
by 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.
Re: different engines in 170,s
Posted: Sun Apr 28, 2024 4:12 am
by 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.
Re: different engines in 170,s
Posted: Mon Apr 29, 2024 2:35 pm
by falco
Don't forget the added weight of a constant speed propeller...
Re: different engines in 170's
Posted: Mon Apr 29, 2024 10:28 pm
by 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?
Re: different engines in 170's
Posted: Tue Apr 30, 2024 12:39 am
by johneeb
n2582d wrote: ↑Mon Apr 29, 2024 10:28 pm
............................ How is that even possible?
Engine in the baggage compartment and a shaft out through the firewall
Re: different engines in 170's
Posted: Tue Apr 30, 2024 4:08 pm
by GAHorn
n2582d wrote: ↑Mon Apr 29, 2024 10:28 pm
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.
Re: different engines in 170,s
Posted: Sun May 26, 2024 12:41 am
by 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.
Re: different engines in 170,s
Posted: Sun May 26, 2024 1:19 am
by 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
Re: different engines in 170,s
Posted: Mon May 27, 2024 12:14 am
by ghostflyer
There is a AD [in australia ] on that very part of the airframe to check for cracks . To check of cracking all switches are checked off and some one moves the prop forward and aft . A stethoscope can be used to listen for a crackling noise on the outside of the airframe where this fitting joins the fire wall . We found a near new cessna 172 with cracking in this area. This aircraft had a history of landing on rough strips and being at all max weight . Smoking rivets on the outside of the area concerned is also a good indicator ,that there are issues.