thinking ahead to engines -----

[fairchild1934]

I have switched horses-- but not in mid-stream. ordered Patrol plans. I came upon a nice older maybe overhauled o-320. Thought that would be a bit wimpy for the 4 place but maybe less so for a patrol. The engine is a narrow deck 57 model before they started using the banana plates.

I am thinking what I might do to it (to add some HP ) that would not affect reliability or overtax the components.

one thought would be a tuned exhaust. Is there more than one brand of those ? Has anyone made their own ?

another might be a polish job of the intakes. I have heard that tuned exhausts give 20 extra HP when the airspeed is below 40----
and the intakes couid give 5 extra. (?)

I dont think I will mess with the pistons since they are new. I wouldn't think a turbo would be good on an early engine like this--

Any thought on perking up a little---

Im thinking 150 would be adequate on a patrol. Probably slightly better climb than an older 172 ????

But thinking that another 20 might be could if it was "free".....

Tim

[Viking]

I hate to be the bearer of bad news, but I doubt very seriously you could get 20-25 hp out of exhaust and intake alone. Assuming you had a hypothetical perfectly designed exhaust, and a perfectly designed intake, and added ported heads and a 5 angle valve job, you might get an extra 10-15hp, MAYBE. An ideal intake setup might get you a 3” boost in manifold pressure at cruise speed due to ram effect, but you won’t see much increase at low speed or on takeoff. The Power Flow exhaust people claim “Up to 23hp increase over stock exhaust” for a Piper Cherokee. I think the “up to” is a key part of their claim.

Assuming a fixed pitch prop, you’re going to have to pitch your prop for aggressive climb to get rpm and power out of your engine at low speed, which is going to significantly hurt your cruise speed and efficiency. You could install a ground adjustable prop and adjust pitch depending on your flight profile, but that takes time.

It is absolutely possible to get more power out of a 320, but there’s not a whole lot on the table, maybe 10% without increasing compression ratio, which I wouldn’t really want to do on an old engine with light cylinder flanges. I think you should look at a realistic maximum of about 160-165hp out of that engine. Is that enough for a patrol? Yea, as long as you aren’t trying to get in and out of the shortest backcountry strips.

As a data point, last summer I finished up an O-320 build for a customer with a C172. We did the 160hp STC (different pistons) power flow exhaust, and surefly electronic ignition. We removed the original McCauley 7553 prop and installed a 7557(4 more inches of pitch diameter) and still saw about a 250rpm increase in static rpm. I estimate with everything we did, that engine is making around 175hp.

[fairchild1934]

another thing I wondered about was maybe an electric prop like an Ivo..... lighter than a oil pressure CS prop and probably cheaper too.
But I dont know if anyone uses them on engines bigger than a rotax........

[rodsmith]

You might talk to Lycon. They do CNC porting on O-360/540 cylinders, don't know about O-320. They gain 5hp/cylinder, verified on a dyno.

[500AGL]

Power is the most important attribute an airplane can have, aside from less weight.
A Patrol with less than 180 hp will never be a great airplane. It’s too heavy and needs good thrust to keep the wing on step for cruise. Don’t sell yourself short on the flying experience. Buy the torque it needs.

[Paul Johnston]

I second this

[fairchild1934]

Maybe I can upgrade to an IO-360 (200 + hp) down the road----

[Hewko]

Upgrading to something better down the road will cost a lot more money, kind of like upgrading a wife

[Franky139]

Hewko

It's not the cost of upgrading a wife that will kill you, it's the price of getting rid of the previous one.

[Utah-Jay]

I was not going to originally comment as I did not think you would like what I had to say, but others have so I will chime in….

Dude, that is not enough power for a Patrol. The beauty of all BH’s is the wide flight envelope, super slow and VERY fast, you are essentially eliminating the fast side. if you are going with an underpowered BH, why not just buy a J3?

Yes the J3 comment is a bit of a hyperbole, but you get my point. IF you ever plan to fly in the mountain west, you need a minimum of 180HP, and maybe more.

I reckon airplanes are like houses, #1 a commodity, and #2 all about resale. Gonna be hard to sell a obviously underpowered plane.

Good luck with your decision

[Bissetg]

Fairchild 1934, If I were you I’d talk to someone who has an 0320 in a Patrol regarding performance etc.

[Pbruce]

How about marketing your 0-320 to the crowd who need one for their RV-9, Rans, Rebel or Zenair? Could you sell and keep looking for an 0-360? I realize you might have to put up more cash for an equivalent 0-360, but maybe not that much more, since you are already considering engine mods. And you have time to look if you are just starting now. Hopefully an opportunity will present itself. Good luck.

[gregc]

Yes, more power is better but it's not the only factor. Weight and mission are big elements as well. It may be better to consider where you would be in terms of power loading with respect to your mission and environment. You can't really argue with the resale value issue though. I suspect you would be competing almost exclusively with O-360 Patrols.

1909p_pf_performance5.jpg

[kestrel]

Bissetg seems to feel that an O360 works well in a 4 place. I'm not sure how much power he has, but there are a whole lot of O360 powered 4 place Bearhawks out there and people love them. Given that, I don't see why a light, O320 powered Patrol wouldn't be a good airplane for some missions.

However, I like 6 cylinders better than 4.

[Bissetg]

IO360 with tuned exhaust and tickled intakes to be fair, it produces more static pull than a Maule M5 with an O540. Weight and running cost are the positives, lack of climb performance above 8000 ft the negative.

[Nev]

I was lucky to go flying in Graham Johnson's beautifully built NZ Patrol with an O320 engine, a lightweight build, and delightful handling characteristics. With 2 of us on board the Patrol was airborne in a very short distance - it sort of levitated into the air. As a result of building light, it has a very good Power to Weight Ratio, combined with a low Total Weight - a combination that gives very favourable takeoff and landing speeds. I think my own 4-place (IO540) would probably need a longer takeoff roll.

[NZfarmer]

This is my first post on the forum. The Patrol Nev refers to is mine. I used a quick build wing kit and built the rest off plans with the intention to use a lycoming 0-360, however a 0-320 came up at a price that was hard to pass up. The intention then changed to using the 0-320 until I got a titan 0-340 that would slot straight into my mounts and cowling. Price, delivery time and 70 hrs flying the 0-320 now leaves me questioning if I will ever change given that high DA or high altitude is seldom an issue for my flying and although cruise speed is back on what some might like cruising at 110knts at 2350 rpm is fine for me. I also feel the cost difference in NZ for my engines choices would not be recouped in sale value.

[Pbruce]

This is pure gold: A guy that actually has one and has experience flying it. NZ farmer, can you tell us how you equipped your Patrol and what your empty weight is? Thanks.