Looking for 170B engine conversion STC's

[Treetopflyer]

I am new to this forum and trying to find an existing STC to convert from the 0-300A to an O-320 Lycoming with a fiixed pitch prop and tuned exhaust. I believe it would provide almost 180hp performance with better fuel economy and weight and maintainance savings

[170C]

You may get the results desired with this conversion, but you will be giving up a smooth running engine for one not nearly so smooth. IMHO

[Bruce Fenstermacher]

What your looking for is a Doyn (sp) conversion and I'm pretty sure it's not available anymore as one or two others who have it have been looking for info for their records. It does not have a tuned exhaust.

The 0320 is a 150 or 160 horse engine at 2700 rpm depending on the version. Your installation will never see 2700 rpm on takeoff unless you have a very flat pitch prop.

So for all the work and expense you will get 5 to 15 more hp over the C-145/0-300. You can just put the flat pitch prop on the C-145/0-300 and nearly achieve the same thing.

No if you are really serious about this don't waste your time and money on a 0-320 when you can do the 0-360 for the same money after engine purchase and depending on the prop get 180 hp at 2700 rpm.

Maybe the 0-360 is what you meant from the beginning. In any case most of the engine swap STCs are not really available today as I understand it with the notable exception of those held by Del-Air

Here is a thread with more on the subject: http://www.cessna170.org/phpBB2/viewtop ... ight=harry

[53B]

I was curious about the O-320 as well. Would it fit in the original cowl? I know that it is narrower than the O-360 but not sure if it will fit without the bumps. My O-300A is at TBO but currently runs very well. The high OAT climb performance is somewhat less than impressive however. The Continental IO-360 is just too expensive and too much for my needs. I understand that you don't get 160 HP on take-off but you also don't get 145 HP on take off with the O-300A so you would still see a 15 HP increase over the O-300A and the way I see it that would stlll be helpful.

[Bruce Fenstermacher]

Mark before I considered the matter much I thought the same thing. Find a cheaper 0-320. But after considering the work and expense would be the same for the 150 or the 180 you can understand why you don't see any 0-320 converted 170s. OK in 10 years I've seen one.

As for the bumps yes I seem to remember the one I saw had some sort of modification to the cowl but it may not have been bumps.

[53B]

I hear what you're saying Bruce. The issue for me personally is that I don't care for the bumps and honestly I don't need the extra power 98% of the time. As for the costs, since I can do all of the work myself I tend to think about only what I want the end result to be, not how much financial sense it makes. I guess I'll just keep dreaming about the IO-360 and not taking full fuel on hot days.

[Treetopflyer]

After reading all the replies to my search for existing STC's ,some questions have been answered but a few more have been raised.
Such as cowling mods engine mounts baffling etc etc.
In regard to actual hp realized with a Lycoming O-320 Powerflow Exhaust systems seem to provide a very real increase in performance, fuel economy, engine cooling etc., as reported by owners who are presently using them. Whether or not Powerflow has an STC for the 170 is ofcourse another matter
What has taken me down this path is an interest in a '53 170B for sale with a timed out engine...
Also the cost of overhaul on 6 cylinder versus 4, and a few 172's in our area have O-320 D2G engines that seem to be bullet proof with some going double their TBO

[Bruce Fenstermacher]

All of the engine mods will require a different motor mount and some require at least cowl mods if not a whole new cowl. Since it is a different engine you will need new or different baffles as well as a new prop and spinner.

As for the Powerflow, they will not have a STC for the 170 because their pipe won't fit a Continental and the market for 170 with Lycomings is to small to bother with.

As for the extra power they might provide that is debatable. I happen to believe it they may provide more power but if you search here you'll find a thread or several threads with people who don't believe under the limitations of aircraft setup that it can provide more power.

Bottom line most of us would never stick that ugly pipe on our 170s unless it doubled the power and then there are lots that still wouldn't.

As or rebuild cost comparisons I believe you will find the Lycoming and the Continental to be about the same as long as your major components, crank and case are usable.

Will the Lycoming go beyond TBO, sure will. Double TBO? Maybe on the bottom end if flown daily but not the cylinders. Same can be said for the c-145/0300.

[Treetopflyer]

Well Bruce you make some very good points regarding gain for cost , both money wise and from a mechanical perspective. I guess the question that comes to mind first and formost if it aint broke why do you want to fix it. Talking to people who have either owned or flown a 170 it would appear that the 170 is a great airplane, but the O-300 is a little underpowered and a bit thirsty.

I guess there is always some trade off in flying

Thanks for your input
Brian

[Bruce Fenstermacher]

You can easily run the 0-300 at 7-8 gal an hour. That is exactly what the Lycoming 0-320 burns.

As for underpowered? Well that is sure in the eyes of the beholder. The 170 is no more underpowered than most other planes. I think a Cherokee 140 is underpowered with the 0-320. That is why Piper made a 180 model. Cessna eventually put a 180 in the 172.

There are few stock overpowered airplanes.

[Jr.CubBuilder]

Another consideration is that the cowl inlets may need to move out some with the O320. I have the O360 conversion in mine and that is the reason it has a different nose bowl. The O320 is a lighter motor, that's another consideration.

I to would also advise against the O320 conversion unless you can do one with a constant speed prop THAT would be worth the effort.

An even cooler way to go (in my humble opinion) would be to rebuild the O300 and create an STC for the MT electric constant speed prop. If I could have done my own work or worked with a mechanic at the local field (which wasn't an option then) I should have gone this route in hind sight. Of course that might have been a nightmare of red tape and who knows what technical hurdles but we don't see those things when we are dreaming.

I had a float plane prop on my plane when I first got it, till I discovered that was technically not legal, and I got real tired of the dismal cruise performance 85-90mph flat out at redline. However, the climb performance was great and it got off the ground quick. If the C170 had a constant speed prop it wouldn't have it's undeserved reputation for being a dog in performance. That C145/O300 is a good motor it just needs to make redline on takeoff and the C170 will get off the ground in short order, a constant speed prop is all it needs. The other good thing would be the ability to run auto gas still. I don't think you can do that with a 160hp O320 and I can't do it now with my O360. The extra cost of 100LL and the 2gph more fuel burn has made a bigger dent in the amount of flying that I do than I thought it would.

Another thought that I had after having spent the money for my new O360 motor was that I could have looked into the Aeromatic F200 prop a little more. There is a fellow manufacturing them, but they were an unknown and I was blinded by glittering hp numbers. That F200, if it worked as advertised might be the perfect ticket for getting the climb and cruise the 170 is capable of without the expense of an engine conversion, weight issues, etc. and it's already in the TCDs.

[Bruce Fenstermacher]

I second Jr's thoughts. If I was to consider an 0320 it would be with the constant speed prop for all the reasons he mentioned.

And he's also right all the 0-300 really needs is a constant speed prop and the MT electric prop because of it's control design seem like it would be the perfect answer. I'm sure if MT had an STC the cost would be prohibitive for most unless of course your planning on springing for a 180 conversion. Then the cost comparison would make the prop look cheap.

You wouldn't be able to LEGALLY burn auto fuel in a -0320 powered 170 because no one has an STC for the engine airframe combination It's once again a paperwork issue.

The Aeromatic F200 is also an interest of mine. Jr is correct in that it is already in the TCDS but only IF you have the correct engine, a C-145-2H and NOTHING else. This of course makes no sense because the H engine has the provision for the prop control which isn't used with the Aeromatic but none the less that is what the TCDS says. Once again paperwork stops us.

[Treetopflyer]

You folks have brought up some more interesting points re; constant speed props, however, its back to more weight more maintainance and STC's that may or may not be available. Plus add in the some what intractable nature of Transport Canada regarding some of these ideas and you have to wonder is the gain worth the cost. Especially when the whole idea is about enjoying the ride.
You folks have been exceptionally helpfull to me as I work thru this stuff and the more I learn the more it makes sense to keep the classical 170B classical.
The airplane that I am interested in does have a Horton Stol kit and a pretty good panel so maybe a 0 time O-300A may just be the ticket given that for the most part I would use the aircraft mainly as a 2 place airplane grass strips etc.
The other question I do have, is the O-300A more or less superior to the O300D
Also the thought of a mogas STC would provide some operating expense savings but it does kind of spook a person out given the ethanol. Here in Canada I believe maybe only Shell hightest might be etanol free.
Any thoughts on that??

[cessna170bdriver]

The other question I do have, is the O-300A more or less superior to the O300D

The power sections of the O-300A and O-300D are identical other than the 8-bolt and 6-bolt prop flanges, respectively. The 6-bolt cranks (O-300C and D) seem to be easier to come by if you happen to need one.

Other than that, it mainly depends on whether you want a vacuum pump or not. The venturi system seems to be adequate for most folks. The O-300D also has an all-electric starter, but you can retrofit a B&C (my personal preference ) or Skytec starter to an O-300A.

Miles

[Bruce Fenstermacher]

Expanding on Miles comments. By all electrical starter Miles means that on the 0-300D you push a button that energizes a solenoid that engages the starter. On the other models and originally you pull a cable that does the job of the solenoid. So the early starters are simpler.

The 0300 has a vacuum pad that the others don't so you could use a more complicated vacuum pump instead of the simple venturi that is stock on the plane.

As for mogas you are right in that it might be difficult to find mogas without ethanol. Ethanol is easy to test for so being able to us mogas when you find a suitable supply could be an advantage. Also I believe if GA is to survive there will be STCs to use ethanol and they won't likely be available for none stock configurations just like mogas STCs are today.