0320 up grade

ak49flyer said:

We’ve all heard of bootleg 8.5 pistons in a ND 320 with no banana plates, and I’ve always wondered, say a guy is running a 82x42 or 41 borer, are his cylinder pressures any higher with the 8.5’s than they would be with the 7.0’s and a 74x56 or 58 cruise prop? I’ve always wanted a transducer to measure it... maybe some of the engineers/mathmeticiams here can give us a rough idea

Click to expand...

Which prop has the lower static rpm on the same engine might be one question. Lower = higher load BMEP at that static rpm - maybe? Then in flight same deal...which produces the higher load or requires more manifold pressure (install a MP gauge to discovert) to achieve the same rpm....the cruise prop I suspect loads the engine while the Borer produces less BMEP.

Gary

scottsville said:

I have a narrow deck 0320 a2b and I have heard you can not put high compression pistons on that motor legally. I do not think its a B model. Is there away to do this?

Thank you for any advice. I bought a prop for a 160 so I am kind of in a pickle!

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What prop do you have? Make, model, diameter and pitch? You may find that it works just fine on 150 hp. Many are using a pitch on their long props that is less than optimum with their 150 engines. This just to get full rpm on take off.

To really notice the 10 HP, your going to need upgrade the carborator nozzle, and probably will want to investigate a modern
muffler with better tuned flow characteristics? Everyone was slapping in HC pistons back in the late 80s/90s and honestly just pistons, certainly never felt like a factory 160hp engine. Never heard of a cly base cracking on a ND clyinder without clips, and there were lots of guys running HC pistons with no clips; However Lycoming put banana clips on them, on 'all' factory ND 160hp engines, to spread that load over a larger surface area so they obviously should be added. I had a 160 ND,
in a PA 12 in the 90's; that came out of an Apache, spinning a Borer 82/42 it would turn it better than 3 other 0320s running that same prop on 3 Cubs we had in camp: ALL running just HC pistons. Another thing to question; is the lobe angle exactly the same on a factory 160 cam as a factory 150 ???? Lots of times guys would need a top on their tired 0320's and would slap in HC pistons and claim a 'noticeable difference' which I am sure was true. However the real true comparison would have been how much difference would those pistons have been over a set of new
Standard pistons ??????

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scottsville said:

I have a narrow deck 0320 a2b and I have heard you can not put high compression pistons on that motor legally. I do not think its a B model. Is there away to do this?

Thank you for any advice. I bought a prop for a 160 so I am kind of in a pickle!

Click to expand...

If you stay with legal pistons,repitch the prop


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Thought:
I noticed Grand Forks has a -1500 density altitude right now... whats the lowest da ya’ll ( channeling SP) have seen???
....and what horsepower would a 150 hp ND be making??


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On the creek ice in front of my cabin at -38* the DA was about -7000'. That's my personal low.

If you get cold enough you are going to need carb heat for the fuel to atomize properly. -30 at McGrath with the long runway I had time to play with the carb heat. When you pulled it out you got a nice power boost just as if you had it out and pushed it back in on a 70 degree day.
DENNY

Today in Fairbanks Ak. at 8:40am it was -34.6 F, Dew point -77.8 F, and local pressure 29.63 for a DA of -6625 ft. Not bad, but when it gets cold we're near the Earth's core for DA.

https://www.weather.gov/epz/wxcalc_densityaltitude

Gary

Denny, I'd bet it had more to do with enriching a lean mixture. Most of us with big carbureted Continentals don't have adequate fuel flow for those temps.

With every 1000’ increase in density altitude you supposedly lose 3.5% hp

Sooo... with each 1000’ decrease hp should increase to a certain extent with limiting factors, as Denny mentioned
I guess at what point do 150 horse ND engines start blowing jugs
Interesting to know if the AD for banana plates was a result of some mistorqued cylinders or if lycoming did test stand studies?


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