IO550A Missile 65% Power Why HOT Cylinders?

[Missile=Awesome]

Guesses are welcome.  I generally fly between 6k and 10k and run 2550RPM/Full Throttle and 20 degrees LOP.  On way home Sunday I had a direct headwind at that setting (6500’) and decided to do the Rocket Engineering printed data for 7500’ (65%) to see if speed would pick up.  The setting is supposed to yield 180knots and 195HP.  22”MP/2350RPM/15.7GPH Fuel Flow

When I plugged that in (I understand I was 1000’ lower) I immediately had cylinder temps climb up to 400 and change.  Immediately said to myself “self, the engine does NOT like that, knock it off” and went back to my previous/normal power setting.

Why were temps so high there?

Thanks for replies.

Edited September 23, 2020 by Missile=Awesome
Wrongly stated 20% vs degrees

[Missile=Awesome]

Mooney brain trust has no thoughts?  O.K.  Mystery will remain unsolved I guess.

[1980Mooney]

4 hours ago, Missile=Awesome said:

Guesses are welcome.  I generally fly between 6k and 10k and run 2550RPM/Full Throttle and 20% LOP.  On way home Sunday I had a direct headwind at that setting (6500’) and decided to do the Rocket Engineering printed data for 7500’ (65%) to see if speed would pick up.  The setting is supposed to yield 180knots and 195HP.  22”MP/2350RPM/15.7GPH Fuel Flow

When I plugged that in (I understand I was 1000’ lower) I immediately had cylinder temps climb up to 400 and change.  Immediately said to myself “self, the engine does NOT like that, knock it off” and went back to my previous/normal power setting.

Why were temps so high there?

Thanks for replies.

When you say you “plugged in” 22”MP/2350RPM/15.7GPH FuelFlow are you saying that you adjusted mixture to achieve that fuel flow rather than adjusting for temperature either LOP or ROP?

[Missile=Awesome]

43 minutes ago, 1980Mooney said:

When you say you “plugged in” 22”MP/2350RPM/15.7GPH FuelFlow are you saying that you adjusted mixture to achieve that fuel flow rather than adjusting for temperature either LOP or ROP?

Yes.

[Missile=Awesome]

44 minutes ago, 1980Mooney said:

When you say you “plugged in” 22”MP/2350RPM/15.7GPH FuelFlow are you saying that you adjusted mixture to achieve that fuel flow rather than adjusting for temperature either LOP or ROP?

THAT is definitely NOT LOP...

[1980Mooney]

You don't mention the what happened to your EGT when you dialed in that fuelflow.  I assume that EGT spiked to about 1525 F before the CHT rose to over 400.  

[Jeff_S]

I know nothing about what Rocket Engineering did to test and certify their configuration.  But I know that even though we generally prefer to keep CHTs below 400 for cylinder longevity, the actual Continental redline is much higher than that, I think 450.  If your engine is running how you like it in all other respects, I would suggest this is probably normal for your setup.  You already know what you need to do to get lower temps.

As you say, you were at a lower altitude than the book spec, and what about outside temperature? Was it standard, high, low?  That would have an impact as well.  And of course, your actual fuel flow may be different than what the meter is showing, so unless you know it's calibrated perfectly that would be a factor. It's probably been quite some time since that airplane rolled off the "factory" floor (I admit, I don't know the process for how those Rocket planes are first configured) so time has assuredly moved your plane away from true book specifications, as it has with all our planes.

[Missile=Awesome]

7 minutes ago, 1980Mooney said:

You don't mention the what happened to your EGT when you dialed in that fuelflow.  I assume that EGT spiked to about 1525 F before the CHT rose to over 400.  

My EGT’s have been over 1450 when LOP.  I don’t think our totalizer is off much on fuel flow...BUT (shrug)

[Missile=Awesome]

2 hours ago, Jeff_S said:

I know nothing about what Rocket Engineering did to test and certify their configuration.  But I know that even though we generally prefer to keep CHTs below 400 for cylinder longevity, the actual Continental redline is much higher than that, I think 450.  If your engine is running how you like it in all other respects, I would suggest this is probably normal for your setup.  You already know what you need to do to get lower temps.

As you say, you were at a lower altitude than the book spec, and what about outside temperature? Was it standard, high, low?  That would have an impact as well.  And of course, your actual fuel flow may be different than what the meter is showing, so unless you know it's calibrated perfectly that would be a factor. It's probably been quite some time since that airplane rolled off the "factory" floor (I admit, I don't know the process for how those Rocket planes are first configured) so time has assuredly moved your plane away from true book specifications, as it has with all our planes.

Yes, 450 redline, but I have no desire to have cruise cylinder temps above 380.  I would question my totalizer reading except fuel on board after flight is matching up with “used” total.  Appreciate your input as well as 1980.  Just trying to better understand the engine and proper operation.  Bush and Deakon are not higher rpm guys.  I like the performance running 2550 and this matches up with an Ovation/Eagle post here on Mooneyspace some years ago.

[Missile=Awesome]

Found these online for Beech.  This is the kind of data I was looking for.

[Missile=Awesome]

Are there such charts for Ovation and Eagle?  Please POST THEM.

[Niko182]

ill post the 310hp Chart. should be very similar. Do you have the GEEBEE baffles?

[Missile=Awesome]

56 minutes ago, Niko182 said:

ill post the 310hp Chart. should be very similar. Do you have the GEEBEE baffles?

Thanks much!  I do not have GEEBEE baffles. Where to obtain?  I have a j/Missile. Does he have them?  Contact?

[Niko182]

6 minutes ago, Missile=Awesome said:

Thanks much!  I do not have GEEBEE baffles. Where to obtain?  I have a j/Missile. Does he have them?  Contact?

When they were installed on Edward, the temps came down about 20 to 30 degrees F on each cylinder. yesterday I was flying 7500, 184 knots, 2500RPM / 22MP, at 15.1 GPH which I believe is about 20 to 50 degrees ROP, or the mixture settings that yield the hottest CHT's and the hottest one was 350 degrees.

In my opinion, probably the best modification along with the PMA450B for the money spent. The baffles were like 300 to 400 bucks and the labour was 4 hours.

his name is Guy Gibney. @GEE-BEE . He should be here within the next couple hours.

[Missile=Awesome]

17 minutes ago, Niko182 said:

When they were installed on Edward, the temps came down about 20 to 30 degrees F on each cylinder. yesterday I was flying 7500, 184 knots, 2500RPM / 22MP, at 15.1 GPH which I believe is about 20 to 50 degrees ROP, or the mixture settings that yield the hottest CHT's and the hottest one was 350 degrees.

In my opinion, probably the best modification along with the PMA450B for the money spent. The baffles were like 300 to 400 bucks and the labour was 4 hours.

his name is Guy Gibney. @GEE-BEE . He should be here within the next couple hours.

Thanks for info. We are going into annual next week. I will discuss with our A&P. Scott 

[Missile=Awesome]

21 minutes ago, Niko182 said:

When they were installed on Edward, the temps came down about 20 to 30 degrees F on each cylinder. yesterday I was flying 7500, 184 knots, 2500RPM / 22MP, at 15.1 GPH which I believe is about 20 to 50 degrees ROP, or the mixture settings that yield the hottest CHT's and the hottest one was 350 degrees.

In my opinion, probably the best modification along with the PMA450B for the money spent. The baffles were like 300 to 400 bucks and the labour was 4 hours.

his name is Guy Gibney. @GEE-BEE . He should be here within the next couple hours.

We have older PS audio panel with plug on panel for phone and music. Working well so not tempted

 

[carusoam]

Niko’s chart is pretty good... but...

It is data for running ROP, says the note... 50°F ROP...

The Brand B has both ROP and LOP, but is given in °C...

It would be helpful to have the 310hp LOP chart... looking briefly, it doesn’t look like Rocket Engineering included a power chart for LOP.... In their 310hp STC...

Hmmmm.... drop back a step... use the O1 Data...

Note the words Best Econ on the chart... and 50°F LOP...  Continental and Mooney both agreed that LOP was a great way to fly....  the O1 also got performance data for T/O from grass surfaces....   

Notice all the detail given Including the OAT....  Go back to the OP, and fill in all the data to make a comparison remotely possible...

Best regards,

-a-

Niko, Is that awesome Eagle named after the great Ski Jumper from England?   (I must have asked this before....)  https://en.wikipedia.org/wiki/Eddie_the_Eagle

[carusoam]

When chasing high CHTs in most Mooney engines...

We have a few choices...

Either run more FF.... or more AF... or less power...

When ROP, full rich should give excess FF, so leaning back toward 100°F ROP should net some cooler CHTs, if not try 150° or 200°F...

The OP mentions leaning to 20% LOP...?  I’m not familiar with this reference... that will seriously cause a challenge when comparing to all the charts above...

Best regards,

-a-

[Missile=Awesome]

1 hour ago, carusoam said:

When chasing high CHTs in most Mooney engines...

We have a few choices...

Either run more FF.... or more AF... or less power...

When ROP, full rich should give excess FF, so leaning back toward 100°F ROP should net some cooler CHTs, if not try 150° or 200°F...

The OP mentions leaning to 20% LOP...?  I’m not familiar with this reference... that will seriously cause a challenge when comparing to all the charts above...

Best regards,

-a-

Thank you for the chart -a- as the “original poster” it is both helpful and baffling.  The “baffling” part is that the Rocket Engineering suggested power settings are “OFF THE CHART” i.e. NOT recommended. (Either at 6k’ and 7 isn’t listed)  It was an “experiment”...Understand pouring more fuel and reducing power to address, but NEITHER would of done what I wanted for an acceptable return on the investment (fuel=neg$) (less power=neg speed).  Your chart is the best example of guidance for operating the engine I have found thus far.  Much appreciated.

[carusoam]

Have you gotten anywhere with your max FF situation? (Also unrelated to original post)

Most of the power charts are still using 50°F ROP...

Acceptable to some... with enough cylinders in reserve...

Oddly, Mooney gave performance numbers at 50°F LOP... by the time you go that deep LOP, you are wondering why you have an IO550...  

What did you mean by 20% LOP?

Best regards,

-a-

[Missile=Awesome]

12 minutes ago, carusoam said:

Have you gotten anywhere with your max FF situation? (Also unrelated to original post)

Most of the power charts are still using 50°F ROP...

Acceptable to some... with enough cylinders in reserve...

Oddly, Mooney gave performance numbers at 50°F LOP... by the time you go that deep LOP, you are wondering why you have an IO550...  

What did you mean by 20% LOP?

Best regards,

-a-

20 degrees LOP -a-

Max Fuel Flow adjustment next week at annual.  (I have checked and totalizer is reading accurately (k factor)

Would prefer to keep six I have for a good long time

That is primary reason for this thread.

[carusoam]

Capture as much before and after data for post annual comparisons...

a couple of GPH is pretty magical at lowering CHTs as desired...

Mostly in the climb, when airflow through the cowl isn’t ideal... And HP is close to max....
 

Most of my memorized data sets are at higher altitudes... Where 65%bhp is less available... and running closer to peak at WOT works pretty well... CHTs 380 or less depending on OAT...
 

Best regards,

-a-

[Missile=Awesome]

22 minutes ago, GEE-BEE said:

AMS3320-.093

 

ROYAL BLUE

CHAMPION RED

BLACK

POP RIVETS

WHITE-SILVER-BLACK

 

N77GB@MSN.COM

GB

Forgive my ignorance, but this reads like “code” to me.  What do these mean?  I punched in the address and it gives a list of google sites with you talking about three product groups...The seal baffles are NOT listed?  Other stuff is FAA saying not approved...which I thought you HAD gained approval so why are these searches coming up at top when GEEBEE is searched?  Interested in process to order and pricing...but coming up empty.  Do you need to have the baffles in hand to produce as this is a custom design/unique cowling/baffling through Rocket Engineering vs. a stock Mooney application?  Lot’s of questions...Not seeing answers.  Please clarify in “layman” terms.  I will be having an A&P do install.

[Missile=Awesome]

15 hours ago, carusoam said:

Niko’s chart is pretty good... but...

It is data for running ROP, says the note... 50°F ROP...

The Brand B has both ROP and LOP, but is given in °C...

It would be helpful to have the 310hp LOP chart... looking briefly, it doesn’t look like Rocket Engineering included a power chart for LOP.... In their 310hp STC...

Hmmmm.... drop back a step... use the O1 Data...

Note the words Best Econ on the chart... and 50°F LOP...  Continental and Mooney both agreed that LOP was a great way to fly....  the O1 also got performance data for T/O from grass surfaces....   

Notice all the detail given Including the OAT....  Go back to the OP, and fill in all the data to make a comparison remotely possible...

Best regards,

-a-

Niko, Is that awesome Eagle named after the great Ski Jumper from England?   (I must have asked this before....)  https://en.wikipedia.org/wiki/Eddie_the_Eagle

Bottom line: In using the M20R Cruise Power Settings the 22.0MP and 2400RPM (65% Power) suggests a fuel flow of 12.3GPH...Rocket Engineering was at 15.7GPH.  That 15.7 suggestion at 7500’ is OFF the chart you provided -a-  The 15.7 approaches a Max recommended fuel flow setting in chart (16.4gph).  What I am learning (and I believe is where you operate) peak is a fine place to be and a good balance between economy and Max/75% for operation.  This was a good exercise for me.  Is it any wonder people are challenged to attain “safe” power settings when Bushe and Deakon don’t provide detailed settings and in my case Rocket was recommending adverse settings for operation.  I guess it is “good” for cylinder business as you say -a-...(Have some extra’s around) if you want to fly at 75% to Max...Scott

[Niko182]

8 minutes ago, Missile=Awesome said:

Bottom line: In using the M20R Cruise Power Settings the 22.0MP and 2400RPM (65% Power) suggests a fuel flow of 12.3GPH...Rocket Engineering was at 15.7GPH.  That 15.7 suggestion at 7500’ is OFF the chart you provided -a-  The 15.7 approaches a Max recommended fuel flow setting in chart (16.4gph).  What I am learning (and I believe is where you operate) peak is a fine place to be and a good balance between economy and Max/75% for operation.  This was a good exercise for me.  Is it any wonder people are challenged to attain “safe” power settings when Bushe and Deakon don’t provide detailed settings and in my case Rocket was recommending adverse settings for operation.  I guess it is “good” for cylinder business as you say -a-...(Have some extra’s around) if you want to fly at 75% to Max...Scott

The power setting I provided along with rocket engineering are ROP. The chart anthony provided is LOP. The Chart anthony posted has an ROP chart too. IMO peak is a great place to be if you can control the CHT's. If they start getting above 400, I would not fly peak.