My 520 is just about finished from Lycon. All the goodies, Millenium cylinder, hc pistons, porting, etc... Im wondering if you guys had also changed out engine mount and exhaust when putting on the new engine?

It seems like you would be restricting the engine by keeping the with same stock o470 exhaust, no? I know the Acorn bumps up the diameter a bit and is really well made. Also have read really good things about Leading Edge on here. After doing all this to get this perfect engine, should i just bite the bullet on exhaust too?

Now engine mounts I really know nothing about but I just want to give this engine a solid foundation to operate. Any help would be greatly appreciated.

My 520 had an original type 0470 exhaust on it, but it was definitely not in good shape. I replaced it with a Knisely. I have the 1953 dual muffler setup. I noticed an increase in power going from the old exhaust which I think had 1.25" down pipes to the new ones at 1.5".

Thanks for the info. Looks like the Acorn and LEES both increase to 1.75".

We went to a float kit so required the new engine mount. And the exhaust was pretty bent from the previous nosegear collapse so yes we did both.
The SPW mount is considerably more robust than stock.
As to the exhaust, the SPW seems very well made. I would think it worthwhile to upgrade both for the PPONK. But I do understand they are not cheap.

In your post I assume hc means high compression pistons. I thought you wanted Pponk to be able to use car gas???????

Yeah I originally did but a few things changed in my life so only having access to Mogas isnt an issue anymore.

I kept my original mount when I changed the engine in 2008. I upgraded to the Knisley Exhaust in 2009. I had no issues until 2018 when cracks developed in my mount. I put the Texas Skyways heavy duty mount and Acorn exhaust in at that time (I have a TS O520). It wasn't cheap both in materials and labor. It also added some weight and forward CG. It certainly is a lot stronger now and an improvement. I know another C180 pilot who had a similar problem but elected to fix it with an overhauled mount at considerably less cost. I think there are some other structural reasons for going with the SPW or TS Skyways mounts especially on an early C180. Overall I am very happy with it now, but as many have said - it costs a lot of money to turn a 180 into a 185.



Josh

Having owned a SPW mount in the past I think its a very well worth while upgrade. If I had to do it over again I would. Don't skimp on the exhaust system, just too much potential for issues, issues than can leave you stranded or even worse yet kill you. Have fun!

Kurt

Great advice. Thank you. I just wanted to make sure I wasn't going down a mod rabbit hole since Im doing the engine. If you guys think it is worth doing now, while the engine is put on, I should just go for it. I plan on owning this plane for a very long time and I dont mind putting the money in up front to know I have a strong and reliable bird.

I did both the mount and exhaust. The mount is worth every penny. I had been trying to get the 0-470R to run smoother prior to the conversion and had changed the mounts, overhauled the carb, rebuilt the mags, Overhauled the prop and no matter what it was still rough running. So after a PPonk engine, Mac 401 and SPW mount it feels like a turbine. Really amazing!

Did you do Acorn exhaust too?

I went with new Knisely dual exhaust and had my mount overhauled which I think basically gives you a new one(not that much extra money in scheme of things, if it's 20+ years old, not a bad idea to have I checked out)..

I did the clampless Knisley dual exhaust with bonus girth. It’s really nice. I went with a K Mount (used AWI) and beefier gussets for my Pponk (8.5:1) with MT. So far so good, but I’m only at a couple hundred hours. Happy with it so far.

Not a pponker but a Norlander. Did Knisely dual exhaust and the old Kosola overhauled the mount. No SPW for me as way too pricey and cannot use dual exhaust. no thanks.

I really only hear about SPW but is there another brand that does work with the LEES or dual exhaust systems?

I sent my mount and exhaust to AWI. Mount was a complete rebuild using the original attach points so it can be called a "repair" and the stacks were exchanged out for the clampless type. Glad I bit the bullet and did both. There is plenty of down time while waiting on the engine and hopefully the mount will be on the plane for another 25 years. I would have gone with Knisley exhaust, but there was close to a $500 difference (plus shipping) to go that route. My project had already exceeded my intended budget enough at that point....

C180_guy wrote:Not a pponker but a Norlander. Did Knisely dual exhaust and the old Kosola overhauled the mount. No SPW for me as way too pricey and cannot use dual exhaust. no thanks.

I've recently come into a Norland as well, any way to tell which exhaust I have?