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Originally Posted by RV7ator
Oh, Most Knowledgeable Ones,
ECi's Classic Cast AD (2005-26-10) bit my O-320-E2D in the empennage. Installing four new jugs opens some possibilities: flow balancing and 8.5:1 compression.
I'll probably bump to higher compression. No more $ than 7:1 and there are STCs for it in a 172M (pay no attention to the spam can behind the green curtain). The front bearing was modified last overhaul to accommodate higher compression. Any hidden issues other than the usual associated with more horsepower?
The definite maybe is whether or not to port, polish, and flow balance the cylinders. The engine is carbed, but does have a Power Flow Systems exhaust installed with salubrious effect. It might induce greater benefits than usual from the cylinder procedure, optimistically speaking. I'd spring for it if the prospects were good for ~5 or more horsepower and smoother operation. Is it worth upwards of $1000 for this service, or does it rank in there with chrome valve covers as a power enhancement?
John Siebold
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"Salubrious" lol lol ha ha ha ha. Was that the word for the day. I LOVE IT.
Yea sure, go for the 8.5 to one. That will give you 160HP and more efficiency. I know there may be some issues with differnt engines I think you alluded to like bearings. Than there is the choke of the jug, but it all very doable and the timming (cost) is right.
The compression will give you the most bang for the buck and we know it is salubrious because there are a few 160 HP O320's out there.
The argument for staying with 150HP is for MOGAS or auto-gas. I looked at the real world savings of Mogas and it is peanuts, unless you pump your own car gas into your plane and only fly local. NOT A FAN of MOGAS or CAR GAS in planes. Besides the **** they put in car gas may kill your plane and you if you are not careful. Pump gas in other words is fast becoming a NON-option, and MOGAS is not always cheaper or as available as 100LL.
As far as port and polish I don't buy that is makes no difference for Carb, but agree the gain is small compared to other things that you can do: compression, EI, exhaust (which you have)? However for a Cessna, port and polish is NOT an option from a legal standpoint as far as I know.
The reason port&polish is not as good for carbs vs. FI, is the polish part, where the induction surfaces are "cleaned up". On a carb engine, this is not all goodness, as the rough surface keeps the gas / air mixture mixed on its way from the carb to the cylinder. This is not an issue with FI. I agree, P&P is not worth it to you. You do want mass & volume balanced well, at least as good or better than Lycomings max tolerance. However combustion chamber volumn and mass balance should be routine not a $1000 option. The port part where they open up areas will help ( a little) but I don't like removing material. As I said I don't think it is allowed for a factory plane engine. This is a Cessna not a Reno racer. Lean towards salubrious-ness and pass on the P&P.
Power Flow Systems exhaust- That is a cool exhaust for a Cessna. May be you could find a LASAR cheap on eBay to top it all off
The last thing I would say to any RV'er wanting more HP in their RV. Your 10 hp is only going to get you 2.5 kts more top speed. You could get that with a cool after market aerodynamic mod they sell for the airframe (don't know any but guess there are some gap seals or something). Of course you will always get better climb wiht more HP, and a C172 needs all it can get.
The higher efficiency will increase your economy. Sounds like a salubrious no brainer decision, considering the cost is the same. If you sell the plane it will add value. Of course you have to buy the STC. What does that cost?
G
Rodding a 320
Linear Mode
