The International Cessna 170 Association

For those who have modified their C170Bs from the stock engines to O360s or IO360s, how much additional weight did the mod add? And/or what is your useful load now?

We are considering doing an upgrade.

Thanks!

I asked for weights and C of G in a previous thread called

viewtopic.php?f=24&t=14934#p139544

I just weighed my conversion at 1440, 37.2”. 66 lbs from my old weight. A composite prop would help, and a modern panel.

My O-360powered aircraft is 1432lbs and 37.9 ins with a moment of 624977. BUT, I have many STC,s fitted which weigh heaps extra. But my baggage compartment was incorrectly marked for many years and we were way under weight thinking we were at max weight or a “little” over. This one of the main reasons why I went for a fixed pitch prop. But after talking to “knowledgable “ people in the industry ,I have ben informed it could lift the same as a modern 172 . But “I “ wouldn’t do anything like that . LOL.
Maybe this should be in the Humour area.

Same airfoil and same area... but just because it can “lift” it.... doesn’t equate to having the same structural strength required by regs...or the same performance requirements, for example, the balked-landing-climb requirements.

You know that, of course, ... I’m not telling anyone anything new. I’m also aware that the list of owners who’ve never operated over-weight is a very short list. Just bringing reality back into focus....

My 170B and my 172C have essentially the same airframe and same engine with only a landing gear change... So why does the 172 have a gross wt 50 lbs MORE than the 170B?

Ans: For one, the tail is different and the horiz stab spar has a doubler on it that added considerble strength to it which the 170B does not have.... the 172C can withstand higher vertical gust loading, both positive and negative. That’s just one minor example of how airplanes can LOOK the same... but they are not.

I would hope that someone would have actually weighed their airplane before/after a conversion for a better comparison.

Actually I did have all the original paper work [weight and balance and about 30 years of maintenance records for the aircraft] but helpers have thrown away the original paper work.[accidentally ] . We were changing hangars and had a big clean out and some helpers tossed a lot of paper work out .
They still got their beer for their help.
But using my memory [it’s a bit shaky ] I do recall the converted aircraft was about 30 lbs heavier, that’s when I changed the carpet,and tossed a heap of junk out of the locker and under the back seat and properly drained the fuel tanks for the final weighing. My attitude then was if you always carried that junk it was part of the aircraft .