Like so many others I am having problems with high CHTs. My engine is broken in and I've confirmed minimal baffling leakage. Interestingly oil temps are doing fine (185 to 205F). I've read of others using louvers with great success but have not heard much about them lately. Anyone with a similar problem find them helpful; or another idea? Thanks.
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Louvers and CHT
- Thread starter rwayne
- Start date
ReidVaitor
Well Known Member
high CHT
What power setting and what altitude? I had 400f plus on my 1,2,5 and 6 cylinders. But this is at 75% or more.
I cut the front plates from cylinder 1 and 2 about .30 or so and that brought my temps down 10F.
What power setting and what altitude? I had 400f plus on my 1,2,5 and 6 cylinders. But this is at 75% or more.
I cut the front plates from cylinder 1 and 2 about .30 or so and that brought my temps down 10F.
Temps
I'm getting above 400 until I hit cruise and power back to 23.5" and 2450rpm, then get 390 or so. I usually climb at 26" and 2500rpm but often back off as CHTs climb. By "front plates" do you mean the metal baffle at the bottom of the air intakes? Thanks for the help.
I'm getting above 400 until I hit cruise and power back to 23.5" and 2450rpm, then get 390 or so. I usually climb at 26" and 2500rpm but often back off as CHTs climb. By "front plates" do you mean the metal baffle at the bottom of the air intakes? Thanks for the help.
MauiLvrs
Well Known Member
We opened the cowl exit 5/8 inch.
MauleDriver
Well Known Member
I'm topping out at 380F - WOT during initial climb out
That's 380F on Cyl 2 which is now my hot cylinder.
I first sealed up everything I could with hi temp silicone. The baffle holes for the engine mount bolts are sealed with cups (big gaps there).
Then, noticing that Cylinder 1 and 2 were my hot cylinders, I cut down the dams at the air intakes. An improvement was noted but #1 was still hottest so I removed the entire dam. Now #2 is the hottest so I'm going to completely remove that dam as well (as others have suggested). If everything else stays the same, I'll be running 365 to 376 during the climb. It may be hotter in summer - these temps were seen on a 55F day.
I wish my oil access door didn't leak so much cooling air.
Bill "at the tuning everything up stage" Watson
That's 380F on Cyl 2 which is now my hot cylinder.
I first sealed up everything I could with hi temp silicone. The baffle holes for the engine mount bolts are sealed with cups (big gaps there).
Then, noticing that Cylinder 1 and 2 were my hot cylinders, I cut down the dams at the air intakes. An improvement was noted but #1 was still hottest so I removed the entire dam. Now #2 is the hottest so I'm going to completely remove that dam as well (as others have suggested). If everything else stays the same, I'll be running 365 to 376 during the climb. It may be hotter in summer - these temps were seen on a 55F day.
I wish my oil access door didn't leak so much cooling air.
Bill "at the tuning everything up stage" Watson
Space Cadet
Well Known Member
Seal
Bill- you tried putting a gasket seal on that door? You can just put a bead of RTV or similar on one side, clear tape on the matching flange, close it and let it dry. Should seal it right up. Course, I haven't done it to mine yet, on the list of finishing items...
Dwight
Bill- you tried putting a gasket seal on that door? You can just put a bead of RTV or similar on one side, clear tape on the matching flange, close it and let it dry. Should seal it right up. Course, I haven't done it to mine yet, on the list of finishing items...
Dwight
My temps started really high during flight test (400+) in cruise. I did the following in order of effectiveness.
1. Installed wheel pants and fairings
2. Cut down the blocker plates in front of cylinders 1 and 2
3. Added a fiberglass baffle to the top cover that provides a close fit around the prop governor
4. Sealed every little baffle leak i could find with rtv
After all of this, my hottest runs around 360 in cruise on an 80 degree day. Climbs on this same day are around 400 at Vy but i like to climb out at 125 knots where temps stay around 180. When i go lean of peak the 360 cruise temp on the hottest drops to around 320, with the coldest around 295.
My next step would have been to add baffles, but with the temps above, i didn't see the need.
Aaron
1. Installed wheel pants and fairings
2. Cut down the blocker plates in front of cylinders 1 and 2
3. Added a fiberglass baffle to the top cover that provides a close fit around the prop governor
4. Sealed every little baffle leak i could find with rtv
After all of this, my hottest runs around 360 in cruise on an 80 degree day. Climbs on this same day are around 400 at Vy but i like to climb out at 125 knots where temps stay around 180. When i go lean of peak the 360 cruise temp on the hottest drops to around 320, with the coldest around 295.
My next step would have been to add baffles, but with the temps above, i didn't see the need.
Aaron
rleffler
Well Known Member
MauleDriver
Well Known Member
sealing oil door
I have a pretty good fit on the door. The problem is more about door flexing. There's enough pressure to flex the door along 3 of the 4 edges. Tried embedding some carbon fiber strands but that didn't work at all.
I'm thinking if I put a flexible seal in that will stay sealed despite the flexing, it won't flex and leak so much. But I'm not so sure..... just too vexing so it's on my punch list...
I have a pretty good fit on the door. The problem is more about door flexing. There's enough pressure to flex the door along 3 of the 4 edges. Tried embedding some carbon fiber strands but that didn't work at all.
I'm thinking if I put a flexible seal in that will stay sealed despite the flexing, it won't flex and leak so much. But I'm not so sure..... just too vexing so it's on my punch list...
Barnstormer
Member
CHT's
All this conversation and I'm still not convinced 400 deg is a bad thing. How many planes out there don't even have CHT gauges?
Pat
RV6 flying phase 1
All this conversation and I'm still not convinced 400 deg is a bad thing. How many planes out there don't even have CHT gauges?
Pat
RV6 flying phase 1
RV10inOz
Well Known Member
Why is it a good thing?
If you have 400 in the cruise, what is it in the climb? 460?
Ignorance is not bliss in aviation.
In the long run, the life of the engine components is affected by stress and heat, keep them to as low a value as you can.
But hey, it's your engine!
If you have 400 in the cruise, what is it in the climb? 460?
Ignorance is not bliss in aviation.
In the long run, the life of the engine components is affected by stress and heat, keep them to as low a value as you can.
But hey, it's your engine!
Barnstormer
Member
CHT's
Lately I've been delivering new Cessna singles to Turkey. After about 25 hours on new IO-360's the CHT's go from ~425-430 in cruise to ~390 with OAT at O to -2C In climb before break-in they are seldom above 430 with slight increase in FF. Cruise EGT= peak+50 rich. If I saw them running 350-360 cruise, I'd be a little concerned.
Nothing bothers Lycoming below 450. Just sayin.
Pat
Lately I've been delivering new Cessna singles to Turkey. After about 25 hours on new IO-360's the CHT's go from ~425-430 in cruise to ~390 with OAT at O to -2C In climb before break-in they are seldom above 430 with slight increase in FF. Cruise EGT= peak+50 rich. If I saw them running 350-360 cruise, I'd be a little concerned.
Nothing bothers Lycoming below 450. Just sayin.
Pat
So the dimensions you gave me a few months ago, I can ignore?
I can't remember what I gave you
What did I tell you?
Scott's front plates are taken off all the way and his temps are good.
RV10inOz
Well Known Member
What on earth makes you say that?
So are you running them in at 50ROP?
A better method of running an engine it would be to set a power setting of say 80% while 60-80 LOP.
Unfortunately most Lycomings injector balance is that poor out of the factory you may have to tune them first, in the first hour or so.
Before anyone hits the keyboards with all sorts of waffle, stop and think very carefully about why I have said what I said
Because I know it will go against all you were once taught.Remember the art of science is to test a hypothisis and despite a hundred claims all agreeing, it only takes one to disprove it.
Barnstormer
Member
CHT's
A better method of running an engine it would be to set a power setting of say 80% while 60-80 LOP.
LOP? Really?
A better method of running an engine it would be to set a power setting of say 80% while 60-80 LOP.
LOP? Really?
Revodriver
I'm New Here
If you are using electronic ignition check the timing. I am using the Electroair ignition system with the Mag pickup on my IO-540. After checking the timing with an automotive timing light, I found the timing advanced, reset the timing and my temp problems went away. Even if you are using mags, check the timing before spending a lot of time putting mods on the baffles or cowling.
MauiLvrs
Well Known Member
But... That's not what the folk that desgned it have to say...
RV10inOz
Well Known Member
Are you sure? Have you asked them??
They are all dead now, so that might be a bit hard then. Trouble is for a long long time people never had the instrumentation, the knowledge and we never had the internet even 25 years ago let alone 40. Some folk back 50 - 60 years ago knew this stuff. It just never made it into the recent past.
The folk at TCM and LYC are only just waking up to the fact that for many long years they have had their head buried in the sand.
Use some science or just some basic logic and you an work it out for yourself.
Let me ask a few mental questions for you to ponder.
What is happening in the break in period? or What are you trying to achieve
What is actually doing that work?
Why is as much power as possible good for this? ie 75 or more if you can?
Once you have answered that ask yourself is there any good reason why the same "conditions" can't be achieved either ROP or LOP? Provided it will run happily LOP.
The best way is down low, highest power, if you have cowl flaps(non RV's i.e.210/A36 etc) keep them open and either FULL RICH or 90F LOP.
Most people will run around a bit higher and take a lot longer, so say 80% power and 60-80 LOP.
Which one is cleaner on your engine and has cooler CHT's?
They are all dead now, so that might be a bit hard then. Trouble is for a long long time people never had the instrumentation, the knowledge and we never had the internet even 25 years ago let alone 40. Some folk back 50 - 60 years ago knew this stuff. It just never made it into the recent past.
The folk at TCM and LYC are only just waking up to the fact that for many long years they have had their head buried in the sand.
Use some science or just some basic logic and you an work it out for yourself.
Let me ask a few mental questions for you to ponder.
What is happening in the break in period? or What are you trying to achieve
What is actually doing that work?
Why is as much power as possible good for this? ie 75 or more if you can?
Once you have answered that ask yourself is there any good reason why the same "conditions" can't be achieved either ROP or LOP? Provided it will run happily LOP.
The best way is down low, highest power, if you have cowl flaps(non RV's i.e.210/A36 etc) keep them open and either FULL RICH or 90F LOP.
Most people will run around a bit higher and take a lot longer, so say 80% power and 60-80 LOP.
Which one is cleaner on your engine and has cooler CHT's?
rocketman1988
Well Known Member
Ran a Cessna 421 for many years. Talked to the guy at the factory that designed the engine. He told me that the engine he designed was meant to be run at better than 65% power AND LOP. We ran it that way for over 800 hours. Sold the plane to an A&P, and he ran it the same way to 700 hours past tbo. When they tore the engine down for overhaul, it looked great...
Just FYI...
Just FYI...
RV10inOz
Well Known Member
A C421, ohh no with those hand grenades that need to be handled with kid gloves you speak with forked tongue for sure!
I bet he is kicking himself for pulling it down so soon too.
Recently, I showed a chap with a new RV10 how to run high power LOP while running in his engine. He was horrified......horrified that what I said was actually true, and he could see the results in the instrumentation. It's just hard for people to accept something at odds to what has been repeated over and over for years, often from folk they respect.
If I asked you what color are Swans. Most people still say white. All swans are white. And two hundred years ago the accepted science was exactly that. It was a settled science, a bit like the greenies and their man made CO2= global warming story.
Anyway all it took was for botanists to find some birds where Perth WA is now, and bugger me if they were not Swans...... And jet black Accepted Science busted!
you speak with forked tongue for sure!I bet he is kicking himself for pulling it down so soon too.
Recently, I showed a chap with a new RV10 how to run high power LOP while running in his engine. He was horrified......horrified that what I said was actually true, and he could see the results in the instrumentation. It's just hard for people to accept something at odds to what has been repeated over and over for years, often from folk they respect.
If I asked you what color are Swans. Most people still say white. All swans are white. And two hundred years ago the accepted science was exactly that. It was a settled science, a bit like the greenies and their man made CO2= global warming story.
Anyway all it took was for botanists to find some birds where Perth WA is now, and bugger me if they were not Swans...... And jet black
Accepted Science busted!Wayne Gillispie
Well Known Member
Lycoming SL 1427B
That was included with my new engine works for me.
No louvers anywhere presently. Air dams per plans. After 50+ hrs and some warmer weather flying I will decide whether I want to cut the air dams down, add louvers to bottom/sides or balance injectors. OAT's will be below 60F here for next three months. I bought everything new so that I would know my engines history. No more renting. I buy the fuel. I stay within Lycomings recommended limits.
That was included with my new engine works for me.
No louvers anywhere presently. Air dams per plans. After 50+ hrs and some warmer weather flying I will decide whether I want to cut the air dams down, add louvers to bottom/sides or balance injectors. OAT's will be below 60F here for next three months. I bought everything new so that I would know my engines history. No more renting. I buy the fuel. I stay within Lycomings recommended limits.
LOP
David,
Can you elaborate a little more on your LOP for engine breakin procedure?
Having broken in 3 engines so far I have always been admonished to be sure
and keep a rich mixture for break in procedure.
My understanding was the extra fuel was needed to keep the cylinders cool.
On my newly finished 10 I made several modifications to the cooling system, louvers among other things and saw no more than 330F on CHT followed by a significant drop less than 10 minutes into the flight where I believe the rings had been seated. In fact my oil temps hovered around 175F when I decided to close the oil cooler butterfly valve bringing it up to 220F.
I have flown my 8 LOP for many hours and will do so again but doing it for break in is new to me.
What say you?
David,
Can you elaborate a little more on your LOP for engine breakin procedure?
Having broken in 3 engines so far I have always been admonished to be sure
and keep a rich mixture for break in procedure.
My understanding was the extra fuel was needed to keep the cylinders cool.
On my newly finished 10 I made several modifications to the cooling system, louvers among other things and saw no more than 330F on CHT followed by a significant drop less than 10 minutes into the flight where I believe the rings had been seated. In fact my oil temps hovered around 175F when I decided to close the oil cooler butterfly valve bringing it up to 220F.
I have flown my 8 LOP for many hours and will do so again but doing it for break in is new to me.
What say you?
RV10inOz
Well Known Member
Ernst,
The mention of this will drag out all sorts of opposition purely based on lack of understanding of what is actually going on inside their engines.
I would be more than happy at some time to chat on skype so it is easier for Q&A's and to be able to share info quickly.
Bottom line is, you are seating in the piston rings. They do not know about ROP or LOP, all they care about is the pressure in the cylinder expanding the rings and bedding in against the cylinder walls.
Now do not for one minute think that I could trust all and sundry to do this. It takes a good understanding and a well matched intake system. But that is what you want anyway right?
So Running in can be ROP full rich, down low, say 80-85% power. But equally it could be done around 80-90F LOP. Same % HP, same BMEP and generally kinder on the engine so far as deposits and the peak pressure pulse will be less, CHT less, but the average pressure equal.
And one more thing....Fuel does not cool your engine Fuel is the source of all the heat. Over rich mixture retards the ignition of the fuel charge, delaying the Peak Pressure Pulse, and thereby lowering the CHT. Coincidently on the lean side of peak egt, the leaner the mixture the same things happen One just wastes more fuel.
The mention of this will drag out all sorts of opposition purely based on lack of understanding of what is actually going on inside their engines.
I would be more than happy at some time to chat on skype so it is easier for Q&A's and to be able to share info quickly.
Bottom line is, you are seating in the piston rings. They do not know about ROP or LOP, all they care about is the pressure in the cylinder expanding the rings and bedding in against the cylinder walls.
Now do not for one minute think that I could trust all and sundry to do this. It takes a good understanding and a well matched intake system. But that is what you want anyway right?
So Running in can be ROP full rich, down low, say 80-85% power. But equally it could be done around 80-90F LOP. Same % HP, same BMEP and generally kinder on the engine so far as deposits and the peak pressure pulse will be less, CHT less, but the average pressure equal.
And one more thing....Fuel does not cool your engine
Fuel is the source of all the heat. Over rich mixture retards the ignition of the fuel charge, delaying the Peak Pressure Pulse, and thereby lowering the CHT. Coincidently on the lean side of peak egt, the leaner the mixture the same things happen One just wastes more fuel.Lycoming recommends full rich at full power for detonation protection. For powers of 75% or less, they supposedly promise no detonation regardless of mixture setting. But not necessarily at full power.
Now, the IO-540D4A5 has a pretty high detonation margin when run on 100LL. It was originally certified for a lower octane (91/96?) avgas. So if it doesn't detonate when run lean of peak at high powers, fine. If it does, you won't have an engine very long.
Now, the IO-540D4A5 has a pretty high detonation margin when run on 100LL. It was originally certified for a lower octane (91/96?) avgas. So if it doesn't detonate when run lean of peak at high powers, fine. If it does, you won't have an engine very long.
I don't worry about opposition and disagreement, it is an important part of
any forum and discussions.
I understand and I am familiar with the slight change in combustion sequence
when fuel/air mixture is changed from rich of peak to lean of peak.
More precisely, a lean of peak mixture will burn more completely before
the exhaust stroke forces gases out and past the EGT probes.
The LOP condition also produces lower pressures and less heat and I can't see how this condition helps in setting the piston rings.
LOP operation is generally acceptable below 75% power settings and the
concern about detonation is valid.
Since most rings are seated in the first hour of engine operation I can't see much reason not to fly lean of peak after the oil consumption has stabilized,
indicating fully seated piston rings. We are talking about 10 hours of flying ROP or LOP. I am still looking for a little more insight into LOP operation
during the break in period.
any forum and discussions.
I understand and I am familiar with the slight change in combustion sequence
when fuel/air mixture is changed from rich of peak to lean of peak.
More precisely, a lean of peak mixture will burn more completely before
the exhaust stroke forces gases out and past the EGT probes.
The LOP condition also produces lower pressures and less heat and I can't see how this condition helps in setting the piston rings.
LOP operation is generally acceptable below 75% power settings and the
concern about detonation is valid.
Since most rings are seated in the first hour of engine operation I can't see much reason not to fly lean of peak after the oil consumption has stabilized,
indicating fully seated piston rings. We are talking about 10 hours of flying ROP or LOP. I am still looking for a little more insight into LOP operation
during the break in period.
RV10inOz
Well Known Member
Bob I was lead to believe this too, however having seen what the Vans cables do to your mixture when the engine pulls forward and the cable is not long enough
I would say the detonation margin may not be as high as you think.I am curious to hear about the 91/96 rating. Where is that noted?
At high power settings as we are discussing 80-90 LOP is plenty of detonation margin
and if it gets a bit leaner from here.....no harm, conversely this is not the case!
RV10inOz
Well Known Member
Ernst
That is why with a new engine, you might as well run it hard full rich down low and get the job done with. Of course you could do a few GAMI spread tests while you are out tooling around.
Up to you, our engine was that bad we had trouble doing the tests. Another Identical factory Lyc I flew recently was damned near perfect out of the box, so it could have been run in LOP.
That is why with a new engine, you might as well run it hard full rich down low and get the job done with. Of course you could do a few GAMI spread tests while you are out tooling around.
Up to you, our engine was that bad we had trouble doing the tests. Another Identical factory Lyc I flew recently was damned near perfect out of the box, so it could have been run in LOP.
Wayne Gillispie
Well Known Member
For recommended fuels see:
http://www.lycoming.com/support/publications/service-instructions/pdfs/SI1070Q.pdf
There are not any black swans around my test flight area, so I am following Lycoming's recommendations as much as possible. Lean per POH is what Lycoming says. Well "my poh" has me maintaining takeoff egt which is 1310F during the wot climb to a safe altitude. Once at altitude I vary throttle/prop settings to stay between 65-85% power. Cht's running well under limits from the start...330-380.
Most new engines won't run more than 20F lop including mine. I will decide months down the road if I want to balance injectors or not. Possibly after it is out of warranty. If one has a warranty issue with their "improved fuel metering", I am sure Lycoming would not be happy. Compared to the cost of my engine, I think I will just buy a little more fuel for now.
Yes, you get more heat and pressure from rop than lop. Good for seating rings.
http://www.lycoming.com/support/publications/service-instructions/pdfs/SI1070Q.pdf
There are not any black swans around my test flight area, so I am following Lycoming's recommendations as much as possible. Lean per POH is what Lycoming says. Well "my poh" has me maintaining takeoff egt which is 1310F during the wot climb to a safe altitude. Once at altitude I vary throttle/prop settings to stay between 65-85% power. Cht's running well under limits from the start...330-380.
Most new engines won't run more than 20F lop including mine. I will decide months down the road if I want to balance injectors or not. Possibly after it is out of warranty. If one has a warranty issue with their "improved fuel metering", I am sure Lycoming would not be happy. Compared to the cost of my engine, I think I will just buy a little more fuel for now.
Yes, you get more heat and pressure from rop than lop. Good for seating rings.
