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sailvi767

Well Known Member
I asked this question about a year ago however no one had the answers I was looking for. I thought I might revisit it again. I am running a ECI IO360 with 10 to 1 compression. Is there anyone out there with some long term experience running LOP with higher compression pistons. I have searched the internet with no real results. I have spoken with ECI, Lycon and PennYan about the issue and they all said they really don't know but would not do it if it was there engine. I emailed John Deakin and he felt it would be OK but does not have any direct experience. Is there anyone out there with some direct operating experience with LOP operations and high compression. The engine appears to operate very happily LOP, I am just not sure if there might be long term issues.

George
 
I can't see why it would be a problem..Now I don't KNOW for sure, but it would seem the engine is less likely to detonate if it has less fuel in there than the point hwere it is most likely to detonate i.e about 50F ROP.

I guess the question is..How much ROP do you need to run to avoid detonation?.. The answer would probably not much more than 80 to 100F ROP.. becuause if you need to burn more than that then it will be running pretty darned rich.

If thats the case, then in theory the opposite, i.e LOP is true and it should be perfectly happy.

I would just use it for cruise an run it very lean..then over time up the mixture to say 7GPh at 24*24. (i'm assuming 100LL here)..all the time keep an eye on the cy hed temp.

maybe after 50 hours get the engine borescoped..if no signs of distress your good to go.
 
I kind of assumed the same thing. One interesting thing is that Lycon and ECI recommend running the engine at Peak. Seems like 50 LOP would be better.

George
 
LOP has worked for me

I have an RV-8 with an IO-360 M1B with 9.2 to 1 pistons and one Lightspeed ignition. I have been running LOP for 1100 hours with no problems. I did balance my fuel injection nozzles so that all cylinders peak at the same fuel flow. I never cruise at more than 70% power. I normally run 35 to 50 degrees LOP. Engine runs well and compressions are good. LOP saves me about 2.7 gallons/hour at a cost of about 10 knots.

Dan Miller
RV-8 N3TU
 
Think about the higher compression a bit like a turbo engine at 40+ inches of MP, now I have never botherd to do the numbers and you could but the extra pressure or the higher compression ratio is going to yield a similar trend.

So I reckon you should take up a pre-Oshkosh training school..... http://www.advancedpilot.com/
 
cdmiller said:
I have an RV-8 with an IO-360 M1B with 9.2 to 1 pistons and one Lightspeed ignition. I have been running LOP for 1100 hours with no problems. I did balance my fuel injection nozzles so that all cylinders peak at the same fuel flow. I never cruise at more than 70% power. I normally run 35 to 50 degrees LOP. Engine runs well and compressions are good. LOP saves me about 2.7 gallons/hour at a cost of about 10 knots.

Dan Miller
RV-8 N3TU
Click to expand...

Dan - 100LL for fuel? Or something else?
 
cdmiller said:
I have an RV-8 with an IO-360 M1B with 9.2 to 1 pistons and one Lightspeed ignition. I have been running LOP for 1100 hours with no problems. I did balance my fuel injection nozzles so that all cylinders peak at the same fuel flow. I never cruise at more than 70% power. I normally run 35 to 50 degrees LOP. Engine runs well and compressions are good. LOP saves me about 2.7 gallons/hour at a cost of about 10 knots.

Dan Miller
RV-8 N3TU
Click to expand...
This is almost identical to how I am running my ECI IO-340. I have 9.0 to 1 pistons and one Lightspeed Plasma III. cruise around 70% to 75% power and see 35 to 50 deg LOP burning around 7-7.5 GPH. The CHT's in cruise run around 300-325, EGT's around 1365-1385 when fully leaned out in cruise. This gives my 9A a cruise speed around 150-160 MPH TAS. I have 150 hours on the engine so no long term effects known but everything is purring like a kitten so far.

Oh, forgot to add, I only run 100LL as per ECI specs.
 
10:1 lop

A company in Colorado has an STC to put 10:1 pistons into Mooneys. I called him a fews years ago about my engine and he was very pleasent. I can't find his web site. You might give him a call and see if he can advise on LOP operations.

Brian

Firewall Forward Aircraft Engines Inc
(970) 669-6185
5212 Cessna Drive
Loveland, CO 80538
 
N3TU details

Greg, I only use 100LL fuel.

When 30 to 50 degrees LOP, my CHT's and EGT's are similar to Steve's, 300-325 and 1365-1385 degrees. At 8500', 2350 rpm, and WOT, I normally see 170 knots TAS and a fuel flow of 7.2 GPH.

My engine is a Superior IO-360 M1B built by AeroSport Power, and I have a WW 200RV prop.

Dan Miller
RV-8
Battle Ground, WA
 
cdmiller said:
Greg, I only use 100LL fuel.

When 30 to 50 degrees LOP, my CHT's and EGT's are similar to Steve's, 300-325 and 1365-1385 degrees. At 8500', 2350 rpm, and WOT, I normally see 170 knots TAS and a fuel flow of 7.2 GPH.

My engine is a Superior IO-360 M1B built by AeroSport Power, and I have a WW 200RV prop.

Dan Miller
RV-8
Battle Ground, WA
Click to expand...
Is your RV8 really flying 35 knots faster than my RV9A? Quite a difference in speeds for the same amount of fuel! Sometimes I don't even think about how much faster other RV models are than the 9 until posts like this. I spend most of my time flying with friends who have spam cans. This perspective makes my plane seem fast until I hear about other RV flyers speeds. :eek:
 
Is your RV8 really flying 35 knots faster than my RV9A? Quite a difference in speeds for the same amount of fuel! Sometimes I don't even think about how much faster other RV models are than the 9 until posts like this. I spend most of my time flying with friends who have spam cans. This perspective makes my plane seem fast until I hear about other RV flyers speeds.
Click to expand...

He may have a static error and is not actually that fast.

You may have a static error and not be flying that slow.

He is running at around 60% power LOP, so what engine settings are you using for that same fuel flow? Well by my guess reading your post above, you are burning 7.5GPH and LOP, thus 111HP and about 63% power for a 175HP engine.

Oddly enough cranking the same HP the -9 should be slower. But we have all seen the speed threads, you need to have a known good static before you can compare numbers. You may have a static error.

By the way I have been testing an RV9A with the 8 cylinder Jab in it, not that I would do this myself, but it seems to work well so far. With 180 ponies up front she goes all right, but it is not meant for that many and you have to be careful. I still think when it is flown at 75% power it is slower than a -6,-7,-8 and so it should. Look at the wing.
 
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