O-320 tweaks

[n5lp]

If one was overhauling a 150 HP O-320 and considering performance mods up to around 180 HP, what would people think would be the best bang-for-the-buck mods and tweaks that would retain reliability?

[BikePilot]

I've no personal experience with it, but this article from the April kitplanes was really interesting (its about porting)
http://www.kitplanes.com/issues/26_4...t_8623-1.phtml

I've read elsewhere that 180-185hp can be expected from a 320 with 10:1 pistons and properly ported heads.

Edit, thought I remembered a hot 320 posted here before
http://www.vansairforce.com/communit...ad.php?t=48320

[Mel]

I went with 9.5:1 pistons, roller rockers and ended up with around 177 hp. If I had it to do over, I would not go beyond 9:1. I have about 750 hrs since overhaul and still have the same oil burn and compression as just after overhaul.

8.5:1 will get you 160 hp.

[Ironflight]

Years and years ago, I put an O-320 on my Yankee to replace the stock O-235 that had run out....bought a core and had it rebuilt. The overhauler asked if I wanted a 150 or a 160. I asked what the price difference was, and he said there wasn't one!

No brainer - 160 HP at least....

Paul

[mannanj]

Originally Posted by n5lp

If one was overhauling a 150 HP O-320 and considering performance mods up to around 180 HP, what would people think would be the best bang-for-the-buck mods and tweaks that would retain reliability?

Larry:

Check with Barrett Performance Engines in Tulsa. Doesn't get any better.
Their shop is No. 1 in my opinion. They can get you 170-180hp out of an old narrow deck with no problems or reduced engine life.

Class act and nice folks to talk to.

[LifeofReiley]

Piece of cake experimental build 320, built better than Lycoming Specs ever thought of... Got one flying. Flowed, balanced, ported, polished, cam etc... Makes for a fast, SMOOOOTH running engine available up to 190 HP to my knowledge. These engines perform at high RPM's and love it!

Whatcha Building???

[N941WR]

Larry,

At OSH this past summer I spoke to Bob Honig at Eagle engines and he said adding dual electronic ignition to any engine will increase your HP by 6%. (They recommend the P-mags, BTW, just to start that war again.)

He also said adding ported cylinders will get an O-320 well over the 180 mark. If you do this, mark your cylinders (#1, #2, etc.) and send in your exhaust and intake tubes and ask them to match the cylinders to them. That will keep the air flowing smoothly, in and out of the cylinders.

Remember, an engine is nothing but an air pump. The easier you can get the air to flow in and out, the more power it will make.

One other thing Bob told me, when done properly, these changes will not impact your TBO.

[chaskuss]

Originally Posted by BikePilot

I've no personal experience with it, but this article from the April kitplanes was really interesting (its about porting)
http://www.kitplanes.com/issues/26_4...t_8623-1.phtml

snipped

I'm to cheap to spend $7.50 to read one article out of KITPLANE. Light Plane Maintenance recently had a good article regarding port and polish work on aircraft engines. I'll happily email it to anyone who requests it. Contact me via email or private message. When responding via private message, include your email address.
Charlie Kuss

[jrs14855]

There are some shops, I will only say in the Western part of the US, that make absurd claims about horsepower enhancements. Unless you want to fly a hand grenade, a reasonable horsepower for the 0 320 is in the 170-175 range. More than that and you won't get much time out of it. Study the REAL FACTS about Barrett and Mattituck and you will find that they generally agree with the above and do not recommend radical mods for every day use and longevity.
Barrett, as of a few years ago, did not like electronic ignition. They will tell you exactly how much they think high compression pistons will reduce TBO. The number that Monty gave me years ago was that 10-1 pistons on an acro airplane that is flown hard will go 700 hours and the bearings will be worn out.
The 0 320 H pistons are a good compromise. They will not reduce TBO significantly. They run about $120 each vs $250 plus for the 10-1. Flowing the cylinders is a huge waste of money unless you want to run 3000 r/m to race at Reno. A forward facing fuel injection vs carb will give a noticeable increase in power. Balancing does not necessarily increase power but is cost effective just to have a smoother running engine. A cam can be a very expensive experiment when you have to tear the engine down to put the stock cam back in. Barrett, as of a few years ago, did not offer special cams. Mattituck does cams only for the likes of Bohannon.
Unless you have special considerations, such as racing in a certain class, it is far more cost effective to hang a parallel valve IO 360 on the front and forget about the hand grenade. I have hopes of doing some racing so I am building an 0 320 with the H pistons, balanced and not much else.If my checking balance was something north of 500k I would do the full treatment except for the cam, but that is not going to happen. (It would be Barrett or Mattutuck, I wouldn't even consider any one else) I strongly urge you to talk to Barrett and Mattituck and treat all the other hype as you would a promise from a politician.

[n5lp]

I appreciate the opinions expressed, both here, and via e-mail and PM.