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  #1  
Old 12-30-2017, 07:04 PM
punkin punkin is offline
 
Join Date: Jan 2016
Location: Northern Colorado
Posts: 211
Default Best plan for 160hp upgrade... o-320

I have an o-320 E2A with about 1950 hours total and 540 since it was majored with NuChrome cylinders and 7:1 pistons. Oil use is very low, not scary low, but pretty minimal...about a quart every 30 hours depending on how hard I run it XC. Based on the timeframe it was majored, I dont think it was chromed due to problems, it because at that time it was the thing to do.

So I could...:

1.) pull my cylinders, send to engine shop to inspect and hone, and install 8.5:1 pistons and the upgraded wrist pins (if not equipped) and reassemble. Id get 160hp and cylinders and lower end with about 540hrs on them. This assumes nothing is wrong and the engine shop can put a surface on the Nuchrome walls. (Likely well Under $2k)

2.) pull and replace with Superior Millennium complete cylinders and pistons and have new cylinders and a lower with about 540hrs. (Around $4300?)

3.) pull and replace with Lycoming factory nitrided cylinders (a little more, maybe closer to $4800)

What would the folks who know better do?

Im looking to eek every last bit of takeoff performance out of my airplane, and constant speed is not an option. A little more power cant hurt, right?
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  #2  
Old 12-30-2017, 08:01 PM
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Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
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1 quart per 30 hrs. is very low consumption. Chances are VERY good that oil consumption would be worse after an overhaul.

150-160 hp? Look at a ruler that is divided into 1/16".
Look at the 1" mark. That is 16 or 160.
Look at the 15/16". That 1/16 mark is what you would be gaining.

Not hardly worth it unless you need an overhaul anyway, which, in my opinion, you do not.
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<rvmel(at)icloud.com>
North Texas (8TA5)
RV-6 Flying since 1993, 172hp O-320, 3-Blade Catto (since 2003)
Legend Cub purchased 12/2017
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Last edited by Mel : 12-30-2017 at 08:03 PM.
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  #3  
Old 12-30-2017, 08:20 PM
punkin punkin is offline
 
Join Date: Jan 2016
Location: Northern Colorado
Posts: 211
Default No fair!

But Mel, you’re making 175! I am really enjoying offairport stuff in my -6, but lack some of the oomph that I’d like to have for getting in the air quickly. If I repitch my GA prop to super climb, I have to be super careful to throttle back and not over speed.

I know I don’t NEEEEEEED it, but I’ve pretty much made this plane into a keeper, and I will fly the value out of the change eventually.

What if I went to 9:1...? Then I’d be at what, 165? Then I’m at what, like 12% instead of 8%?
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  #4  
Old 12-31-2017, 10:14 AM
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Mel Mel is offline
 
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Quote:
Originally Posted by punkin View Post
But Mel, you’re making 175! I am really enjoying offairport stuff in my -6, but lack some of the oomph that I’d like to have for getting in the air quickly. If I repitch my GA prop to super climb, I have to be super careful to throttle back and not over speed.
I know I don’t NEEEEEEED it, but I’ve pretty much made this plane into a keeper, and I will fly the value out of the change eventually.
What if I went to 9:1...? Then I’d be at what, 165? Then I’m at what, like 12% instead of 8%?
My point is: I was due for an overhaul anyway. My engine was at 2800 hrs. I would never had done anything on a 540 hr. OH burning a quart of oil every 30 hrs!
Of course it's your engine and your money. It's a free country. Just expressing MY opinion. Your opinion is the only one that really counts.
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Mel Asberry..DAR since last century
A&P/EAA Tech Counselor/Flight Advisor
Specializing in Amateur-Built and Light-Sport Aircraft
<rvmel(at)icloud.com>
North Texas (8TA5)
RV-6 Flying since 1993, 172hp O-320, 3-Blade Catto (since 2003)
Legend Cub purchased 12/2017
FRIEND of the RV-1
Eagle's Nest Mentor

Last edited by Mel : 12-31-2017 at 11:15 AM.
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  #5  
Old 12-31-2017, 10:34 AM
punkin punkin is offline
 
Join Date: Jan 2016
Location: Northern Colorado
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Default Thanks Mel...

The problem is, I really value your opinion, and the knowledge and experience you bring to the forum...so it would be much easier if you would tell me Id be thrilled with 10 more horsepower and how much Id be glad I spent the time and money to change it.
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  #6  
Old 12-31-2017, 10:58 AM
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RONSIM RONSIM is offline
 
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Location: Largo, FL
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Default Spend the money on a constant speed prop?

Just my opinion, but would certainly give you the extra push (pull) you are looking for.

Ron
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  #7  
Old 12-31-2017, 11:04 AM
William William is offline
 
Join Date: Nov 2006
Location: Sarasota,Florida
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Scott, though I see Mel’s point, I went from 8.5:1 compression pistons on my o320 with dual mags to 10:1 compression pistons with dual sds electronic ignition and noticed a good improvement. Picked up at least 300ft/minute climb and 4 knots. I did the piston swap with only 100 hours smoh on the engine. It is a fairly in depth job but is not hard just time consuming. Plan on around 30 hours from start to finish plus machining time. My current project is a rv10 and I plan on using the high compression pistons/electronic ignition/electronic fuel injection from the start.

Bill
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Last edited by William : 12-31-2017 at 11:06 AM.
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  #8  
Old 12-31-2017, 11:07 AM
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Ironflight Ironflight is offline
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Location: Dayton, NV
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Quote:
Originally Posted by punkin View Post
The problem is, I really value your opinion, and the knowledge and experience you bring to the forum...so it would be much easier if you would tell me Id be thrilled with 10 more horsepower and how much Id be glad I spent the time and money to change it.
The thing that Mel forgot is that rate of climb is proportional to EXCESS horsepower- not total horsepower. So if it takes (for example) 75 HP to maintain level fight, you have 75 HP that can be converted into climb. 10 added to 75 is a much bigger percentage than 10 added to 150....... feel better - 10 HP is noticeable!
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  #9  
Old 12-31-2017, 11:10 AM
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flytoboat flytoboat is offline
 
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I have an RV6A with a 160HP 0-320, and Sensenich fixed pitch prop that has a 2600 RPM red line (I don't remember the pitch off hand.) It has a solid crank, so no option for a hydraulic operated constant speed prop. I typically see 2250 RPM and 10.3 GPH on take off roll. I'm guessing I'm making only 130 HP or so. I am not complaining about my performance, but it sure does hurt to leave unusable horsepower under the cowling. I operate in the Midwest (500 feet elevation), so it has plenty of performance for my operations. I have only 600 hours on this fine running engine and will keep it as is, but will certainly look at a constant speed prop option with any engine replacement.
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  #10  
Old 12-31-2017, 11:12 AM
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humptybump humptybump is offline
 
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Quote:
Originally Posted by Mel View Post
150-160 hp? Not hardly worth it unless you need an overhaul anyway, which, in my opinion, you do not.
While a change from 150hp to 160hp represents about 7%, the difference is not linear. Based on the performance charts, the power gain at lower RPMs is about 15%. For fixed pitch propeller configurations, the low end gains are significant at take-off RPMs.
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Last edited by humptybump : 12-31-2017 at 11:24 AM.
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