150 to 160 hp piston upgrade

S64eman

Hello,

I have a 1974 Warrior with an O-320-E3D 150 hp engine. I would like to replace the pistons with the higher compression 160 hp pistons. I know I need an STC for the airframe for this, but do I actually need one for the engine. My research comes up with conflicting results. Some people say no, because all O-320's are under the same TCDS, therefore you can mix and match parts without an STC. Others say yes you need an STC. I know there are a couple STC's out there that cover this.

I am looking for input from folks that have done this conversion, and how they accomplished it, including where they obtained the parts, and STC's.

Thanks in advance

Erik

Scott Sherer

Here is an STC for this: https://www.pennyanaero.com/penn-yan-aero-stcs

Johnjetman

Hi Erik,

I did this upgrade on my 74 Warrior using RAM. You will need an airframe and an engine STC. It made a big difference in performance. RAM will have all the parts you need or they will direct you to them.

Also consider repitching your prop.

S64eman

Thanks for the replies fellas. I will look into both of those.

Erik

S64eman

Update,

I spoke with RAM and they have both the eng upgrade STC and the airframe STC. 350.00 each. They have two "Kits", A and B. Kit A is 9,444.00, and includes new cylinders, along with pistons, pins, rings, carburetor, and both STC's. Kit B is 3884.00 and it has everything in kit A except new cylinders...

I have not heard back from Lycon or Penn-Yan.

Erik

empannin

Erik,

$10k + labor for more HP and a top overhaul does not seem bad at all. How close are you to TBO? Might make sense to fully overhaul it and complete the STC at the same time.

S64eman

Eric,

I am only at 1550 hrs TT on the engine. So hopefully it will be many years before I need to overhaul it. I was just looking to add some more power in the meantime. I am leaning toward just going with RAM kit B and not install new cylinders. I would just do an IRAN on the existing cylinders if they are suitable candidates. , (clean and lap valves, ream the guides, hone the cylinder, and replace the rotator caps on the exhaust valves for good measure) I really think if I was at overhaul, I would just get the STC's and put an O-360 180 hp in it.

Erik

Unit74

https://piperowner.org/talk/discussion/comment/1443666#Comment_1443666

I get the need for more horses. But a mesoscale opinion is that doing it with 1500 hrs on the current power plant is not the best idea. If you are gonna spend $10k in parts, doing it at OH will really be the most intelligent thing to do because your OH shop will sub in the STC parts offsetting the total cost for the performance increase. On top of that, you have a lot of labor involved and again, that labor would also be wrapped into an OH vs paying now vs later.

My advice is that if you’re really set on doing this, just OH the entire power plant and start with a fresh engine WITH a warranty. I just don’t see it as a wise decision to top the engine with an STC so close to TBO.

BillCorbett

Not sure if anyone has put an electronic ignition engine on a dyno. I put in a Sure Fly ignitionin my Arrow and i think the performance gain might be equal to the Ram kit??? The ignition if i remeber correctly is good for 2500 hours, so would last this engine and your next OH. It would be interesting to see the dyno results especially under 24"mp as it can advance the timing substantially 14-16° producing more power.

I also agree with Unit 74, do the over haul at the same time, and send the new cylinders to Lycon to have them ported. You will pick up another maybe 16hp= 176.

Bill

jacobsja

IIRC, the electronic ignition gets about the same power at WOT as magnetos. If this is correct, it will not meet what looks like the goal as few people want more power for cruise speed.

When cruising at lower power settings, the electronic ignition gets its benefit by squeezing more burn out of the fuel. One way to look at this is more power, where the actual effect is less loss from greater efficiency.