CHT Gauge Limit Settings

How to keep the Cessna 170 flying and airworthy.

Moderators: GAHorn, Karl Towle, Bruce Fenstermacher

CHT Gauge Limit Settings

Postby brian.olson » Fri Jul 31, 2020 3:51 pm

My A&P will be installing a new Aerospace 6-cylinder CHT gauge in 62C early next week. It is PMO'd as a primary engine gauge and will slide in as a replacement for the current single-cylinder needle gauge on the panel. With new cylinders on the engine I prefer to keep an eye on the temps of all six cylinders. This gauge allows the user to select temp limits for "green", "yellow" and "red" bands. I understand the top limit for the C-145 is 525 degrees, which we will set for the "red" limit. To anyone else running an engine monitor ... what have you typically used for the limit setting between "green" and "yellow"?

Thanks for your input -
Brian
1950 170A
N5762C s/n 19716
User avatar
brian.olson
 
Posts: 175
Joined: Mon Aug 14, 2017 12:04 pm
Location: Fayetteville, GA

Re: CHT Gauge Limit Settings

Postby GAHorn » Fri Jul 31, 2020 4:15 pm

My CHT normally runs around 350, so IF I were to do this I’d place the green from 250-450 and 450-524 yellow.

Edit: I have what I believe is original to the airplane, an old WW2 type analog gauge of unknown accuracy. (I’ve never had it checked for calibration but it’s believable. It reads only the spark-plug-gasket probe on Cyl #2, as per the OEM recommendation. The main value I place on that gauge is “repeatability”. If I ever noticed a drastic difference than usual it would give me cause to take immediate action and subsequently investigate.

59D48C1A-270F-4ADC-9EB4-95FA2FF9817A.jpeg
A sharp eye will see this is a Centigrade Gauge 175C ~ 350F

96A21CE3-A04F-418B-B3FE-DE3702C63ACF.jpeg
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight.
An originality nut (mostly) for the right reasons. ;)
User avatar
GAHorn
 
Posts: 19057
Joined: Fri Apr 12, 2002 8:45 pm
Location: Spicewood (Austin), Texas

Re: CHT Gauge Limit Settings

Postby cessna170bdriver » Sat Aug 01, 2020 1:57 am

You didn’t say what brand of cylinders, or what style probes you’ll have, but the instructions for my ECI’s with bayonet style thermocouples say to lower the published limits by 25 degrees over the spark plug gasket style.
Miles
User avatar
cessna170bdriver
 
Posts: 3749
Joined: Mon Apr 22, 2002 5:13 pm
Location: 45G, SE Michigan

Re: CHT Gauge Limit Settings

Postby n2582d » Sat Aug 01, 2020 5:27 am

To add to what Miles writes ECI says, in Service Instruction 04-3,
5.0 NEW MAXIMUM CYLINDER TEMPERATURES: Because the probe type thermocouples measure between 20 and 25 °F lower temperatures than temperatures measured at the lower spark plug, ECi recommends that the maximum operating temperature when using thermocouples installed in this location should be maintained below 500 °F. ECi further recommends that cruise temperatures be maintained below 415 °F for longer cylinder life.
Mike Busch recommends even lower top of the green numbers in this article.
Gary
User avatar
n2582d
 
Posts: 2288
Joined: Mon Apr 29, 2002 4:58 am
Location: Mariposa, CA

Re: CHT Gauge Limit Settings

Postby brian.olson » Sat Aug 01, 2020 10:22 am

Sorry, Miles - I have new Superior Millennium cylinders and will be using bayonet probes with the gauge. Thanks for the suggestion of "25-degrees lower".
Brian
1950 170A
N5762C s/n 19716
User avatar
brian.olson
 
Posts: 175
Joined: Mon Aug 14, 2017 12:04 pm
Location: Fayetteville, GA

Re: CHT Gauge Limit Settings

Postby brian.olson » Sat Aug 01, 2020 10:25 am

Gary - thanks for the link to the Mike Busch article ... that's exactly what I was looking for (and exactly the rationale behind getting the new gauge, btw).
Brian
1950 170A
N5762C s/n 19716
User avatar
brian.olson
 
Posts: 175
Joined: Mon Aug 14, 2017 12:04 pm
Location: Fayetteville, GA

Re: CHT Gauge Limit Settings

Postby n2582d » Sat Aug 01, 2020 1:45 pm

How much of an issue has high CHT temps been on O-300 powered 170’s? Over the years it seems like most of the conversation here has been concern over high oil temperatures rather than high CHTs. On a recent YouTube video posted here N2962D, a Lycoming-powered 170, is seen sporting what appears to me to be Beech Bonanza cowling gill vents.
FDF386F8-DC56-483D-A7CC-3042ACACAA52.jpeg
BCP discusses adding C-206 gill vents to 180’s. Is this a solution looking for a problem on an O-300 powered 170?
Gary
User avatar
n2582d
 
Posts: 2288
Joined: Mon Apr 29, 2002 4:58 am
Location: Mariposa, CA

Re: CHT Gauge Limit Settings

Postby eskflyer » Sat Aug 01, 2020 9:55 pm

On my 170 with o300D have high cht on the back 2 cylinders.# 2 IS USUALLY THE HGIHEST HOTTEST, this is what i have done so far to manage the high cht . check baffling and close up any and all air gaps around intake and around the front of the engine crankshaft behind spinner. Place dams in front of both front cylinders by playing with aluminum tape to get the size correct. Use a oil filter and a diffuzer around the oil filter to expel heat. Remember you want your oil higher than 180 degrees .
I try and never exceed 405 cht on #2 in climb out . Normal straight level cruise i see 325-328 on #2
Last edited by eskflyer on Sat Aug 01, 2020 10:16 pm, edited 1 time in total.
AA16, SHORTWING and SPAMCAN FLYER, JP
User avatar
eskflyer
 
Posts: 38
Joined: Sat Feb 02, 2019 1:48 pm

Re: CHT Gauge Limit Settings

Postby GAHorn » Sat Aug 01, 2020 10:12 pm

At risk of furthering my reputation as bizarre.... I have to say I think there’s some foolishness being promoted in the Busch article.

He wrote: “ A second factor identified by ECi studies, and a surprising one, is that junc- tion strength is adversely affected by high blow-by past the compression rings, partic- ularly if the new cylinder is not properly broken in, and the barrel becomes glazed before break-in is complete. High blow-by appears to weaken the head-to-barrel junc- tion because the associated hot gases heat up the junction and impair the interference fit without being reflected on the CHT gauge. The gauge measures cylinder head temperature at a location quite distant from the junction. Thus, a high-blow-by cylinder will have a hotter junction tem- perature, and thus a weaker junction, than a low-blow-by cylinder with the same indi- cated CHT.

He then concludes with the revelation that high CHTs are bad for cylinders. (Is that some sort of new revelation to anyone?)

Since he did not offer any “new” definition of “blow by” I can only presume he means gases that escape from the combustion-chamber past the rings and down into the crankcase. It is unclear to me how and why that would adversely affect the “sealing ring” on the outside of the head/barrel joint, especially as blow-by occurs in a rapidly-downward-moving piston. I don’t see it.

His article is supposed to prove how CHTs lower than OEM are causative of failures... then goes on to give an example of how CHT had nothing to do with the examples given per his subsequent comment in that paragraph which implies CHT has nothing to do with the failure :?: as he states CHT in failed cyls are the same as a non-failure cylinder. (”Thus a high blow-by cylinder.... will have... a weaker junction, than a ... cylinder with the same indicated CHT”.). If that is true because of sensor-location as he states... then how can he offer a qualified change in operating temp guidelines;... since it makes no difference?
Still not understood by me is how “blow-by” affects anything at all other than higher sump pressures, which are vented overboard anyway. I don’t think that has anything to do with head-seperation. I believe CYCLES have a lot to do with it however. You can only bend a paperclip so many times before it fails. And certainly exceeding OEM CHT limits is bad. I suffered a blown cyl head on takeoff late at night over a congested area and I can tell you it grabs your attention. But that was on a TCM IO-520...an engine which has mixed reputation with regard to cylinder manufacturer. That cyl was genuine TCM and of unknown service history.
Gotta wonder how aftermarket cyls are given PMA status if they cannot conform to OEM specs on CHT. :? Seems like they should not enjoy PMA status...but should be STCs instead, with different operating limitations.

n2582d wrote:How much of an issue has high CHT temps been on O-300 powered 170’s? Over the years it seems like most of the conversation here has been concern over high oil temperatures rather than high CHTs. On a recent YouTube video posted here N2962D, a Lycoming-powered 170, is seen sporting what appears to me to be Beech Bonanza cowling gill vents.
FDF386F8-DC56-483D-A7CC-3042ACACAA52.jpeg
BCP discusses adding C-206 gill vents to 180’s. Is this a solution looking for a problem on an O-300 powered 170?


Gary, I don’t follow your implied question. What has a non-problem with O-300 engines got to do with cowling/cooling modifications applied to Lycoming-converted aircraft? And how do those converted aircraft translate to address a non-existent O300 problem?
Not being argumentive... just not following your thoughts on those gills... :?:
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight.
An originality nut (mostly) for the right reasons. ;)
User avatar
GAHorn
 
Posts: 19057
Joined: Fri Apr 12, 2002 8:45 pm
Location: Spicewood (Austin), Texas

Re: CHT Gauge Limit Settings

Postby n2582d » Sun Aug 02, 2020 1:03 am

George,
There was no implied question. It was a straight-forward question. I don’t know if high CHTs are an issue with O-300s on 170s. Apparently not by your response. There has been talk of using the seaplane cowling lip on 170s on wheels but - if I recall correctly- that was to help control high oil temperatures. That lip was required when using the Aeromatic prop. I just thought that if high CHT was an issue the cowling gill vents might be something to look into although approval might be an issue.
Last edited by n2582d on Sun Aug 02, 2020 3:54 am, edited 1 time in total.
Gary
User avatar
n2582d
 
Posts: 2288
Joined: Mon Apr 29, 2002 4:58 am
Location: Mariposa, CA

Re: CHT Gauge Limit Settings

Postby TFA170 » Sun Aug 02, 2020 2:41 am

GAHorn wrote: It is unclear to me how and why that would adversely affect the “sealing ring” on the outside of the head/barrel joint, especially as blow-by occurs in a rapidly-downward-moving piston. I don’t see it.


He talks about improperly broken in cylinders with glazed walls. Higher blow-by absolutely will increase the temperature at the location of highest blow-by compared to any other location. Higher pressure combustion gasses leaking past glazed rings/cylinders than normal will score cylinders and increase temperature as the score worsens. This is true in every combustion engine.

GAHorn wrote:His article is supposed to prove how CHTs lower than OEM are causative of failures...

You should read his whole book on engines. It's very good and he gets more in depth on some of these issues, as well as the science behind his recommendations for CHT limits. His company has literally thousands and thousands of hours of EMS data to pull from that back up his claim.

GAHorn wrote: Still not understood by me is how “blow-by” affects anything at all other than higher sump pressures, which are vented overboard anyway. I don’t think that has anything to do with head-seperation.

See above. Temps will always be higher at the location of blowby.

GAHorn wrote: I believe CYCLES have a lot to do with it however.

Not disputing, but define what you mean by cycles as used here.

GAHorn wrote: But that was on a TCM IO-520...an engine which has mixed reputation with regard to cylinder manufacturer.

I believe Mike Busch operates a pair of IO-520s (might be 540s) and has gone well past 3500 hours with them.

GAHorn wrote: Gotta wonder how aftermarket cyls are given PMA status if they cannot conform to OEM specs on CHT.

And I believe there have been some recalls and ADs on aftermarket cylinders.
User avatar
TFA170
 
Posts: 91
Joined: Tue Jan 26, 2016 3:18 am
Location: 74FL

Re: CHT Gauge Limit Settings

Postby GAHorn » Sun Aug 02, 2020 2:28 pm

TFA170 wrote:
GAHorn wrote: It is unclear to me how and why that would adversely affect the “sealing ring” on the outside of the head/barrel joint, especially as blow-by occurs in a rapidly-downward-moving piston. I don’t see it.


He talks about improperly broken in cylinders with glazed walls. Higher blow-by absolutely will increase the temperature at the location of highest blow-by compared to any other location. Higher pressure combustion gasses leaking past glazed rings/cylinders than normal will score cylinders and increase temperature as the score worsens. This is true in every combustion engine.

GAHorn wrote:His article is supposed to prove how CHTs lower than OEM are causative of failures...

You should read his whole book on engines. It's very good and he gets more in depth on some of these issues, as well as the science behind his recommendations for CHT limits. His company has literally thousands and thousands of hours of EMS data to pull from that back up his claim.

TFA170 wrote:
GAHorn wrote: Still not understood by me is how “blow-by” affects anything at all other than higher sump pressures, which are vented overboard anyway. I don’t think that has anything to do with head-seperation.

See above. Temps will always be higher at the location of blowby.


Blow-by (as I understand the implied definition of gasses escaping past rings during a combustion-event)... if “blow-by” occurs.... it occurs throughout the power-cycle, ...all along the piston’s travel....which is while pressure from the combustion is higher above the piston than below. Why would damage occur to the head at a point below TDC but not above or below that point? The article doesn’t present that well.
But if he is suggesting that the damage occurs at the point of contact between head and barrel is...at the point of greatest contact/sealing area.... what is the revelation in the article? We already knew that.
I suspect the attention given to “blow by” as a causative agent is merely a distraction. It’s not “blow-by” that “blows” the head off a barrel. It’s high pressure inside the barrel looking for the weakest-link in order to escape. The different expansion/contraction rates of aluminum vs steel ...and how many time that paper-clip can be bent.... is the real root-cause of the problem.

The bottom line of the article seems to be that CHT instrumentation does not measure CHT at a point of highest cylinder temperature..that cooler cylinders are better cylinders....and we already knew that.

This thread was initiated in order for the OP to gauge a quantifiable green/normal and yellow/cautionary range indication for an instrument that does not offer sufficient information to accomplish that. Mr. Busch’s article leaves us with no more information than what we already had. O-300 engines do not suffer from high CHT or frequent head-separation. So my contribution to this thread is simply to note that the issue with Titan cylinders and Mr. Busch’s personal choice of CHT-gauge temperature-ranges for his bog-bore Continentals are not helpful as for our C145/O300 engines.

TFA170 wrote:
GAHorn wrote:
GAHorn wrote: I believe CYCLES have a lot to do with it however.

Not disputing, but define what you mean by cycles as used here.


Say “please”. :lol:

Oh...OK.. I mean it in the traditional-sense of flight cycles. Cold engine, start-up, take-off (huge stresses from temp-rise), cruise, let-down (large temp-reduction), landing and shut-dn.

I forgot until just now that I’ve actually had TWO cyl-head separations in my 13K+ hours. The one already mentioned in my C-206, but another discovered during an ordinary compression-test on a cylinder which had just-passed annual inspection 6 hours earlier and was being tested again during a buyer’s pre-buy of my IO-470-powered Baron. The inspector claimed he could hear hissing from a cylinder which was indicating 70/80 compression. 8O
(Really good ears on that young inspector because the test was being conducted in an open hangar at AUS while SWA B737’s were taking off just outside the hangar.).
Of course we didn’t believe him ... so he sprayed some soap-solution on that cylinder and it instantly looked like a washing-machine blowing bubbles exactly AT the head-to-barrel joint of that cylinder. 8O
That was on a 900-hr Reman engine so, being a “zeroed” reman, the cylinder-history was unknown. I replaced it with a chromed/ovhl cylinder, the history of which was also unknown (because I was selling that airplane and wanted to meet the buyer’s satisfaction.). Personally, when I replace a cylinder on MY airplane I only install NEW cylinders to avoid the unknowns of numbers of “cycles”.

My bottom line is to operate all piston engines well-below CHT limits as published by the OEM. Mr Busch’s article indicates he does the same.

There’s an interesting Aviation Consumer article on this subject as it pertains to Titan cyls: https://www.aviationconsumer.com/uncate ... em-or-not/
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight.
An originality nut (mostly) for the right reasons. ;)
User avatar
GAHorn
 
Posts: 19057
Joined: Fri Apr 12, 2002 8:45 pm
Location: Spicewood (Austin), Texas

Re: CHT Gauge Limit Settings

Postby TFA170 » Mon Aug 03, 2020 3:08 am

GAHorn wrote:Blow-by (as I understand the implied definition of gasses escaping past rings during a combustion-event)... if “blow-by” occurs.... it occurs throughout the power-cycle, ...all along the piston’s travel....which is while pressure from the combustion is higher above the piston than below. Why would damage occur to the head at a point below TDC but not above or below that point? The article doesn’t present that well.
But if he is suggesting that the damage occurs at the point of contact between head and barrel is...at the point of greatest contact/sealing area.... what is the revelation in the article? We already knew that.
I suspect the attention given to “blow by” as a causative agent is merely a distraction. It’s not “blow-by” that “blows” the head off a barrel. It’s high pressure inside the barrel looking for the weakest-link in order to escape. The different expansion/contraction rates of aluminum vs steel ...and how many time that paper-clip can be bent.... is the real root-cause of the problem.


Blow-by can occur all along and at any point of piston travel, however, the area where the rings "live", which is a smaller area than the total cylinder depth, will become egg shaped and out of round with time. This can be "induced" with improper break-in. In either case, this can cause blow-by to become localized and because it isn't uniform around the circumference of the cylinder anyway, a localized hot spot can create scoring, increase blow-by, and further damage to the cylinder wall - all of this creates hot spots and uneven heating/cooling of the cylinder (Which may actually interplay with your cycles theory) and the cyl/head junction. If you unevenly heat a circle or ring of metal, it will bulge as the tension in the cooler areas pushes/pulls the hot area out of shape - the same holds true in a cylinder - and in this case, the movement is most likely between the two dissimilar metals at the cyl/head junction - hence why blow-by may contribute to failures here. It's not the blow-by itself, it's the uneven heating and hot spots in the cylinder that causes the actual failure, but the root cause of the uneven heating is the blow-by. Now, there's always some uneven heating and this is why engine warm-up is important, but there are a lot of contributors to uneven heating - blow-by caused by improper break-in should be preventable. Is he overstating the case? I don't have the data to say one way or the other (he probably does), but it's clear to me that blow-by can absolutely lead to uneven heating and subsequent failures related to that uneven heating...even if it's just scored cylinders.

GAHorn wrote: The bottom line of the article seems to be that CHT instrumentation does not measure CHT at a point of highest cylinder temperature..that cooler cylinders are better cylinders....and we already knew that.

Yes, but you really should read his book. It goes into quite a bit of depth regarding cylinder pressure and that neither CHT nor EGT alone are perfect indicators of what's going on inside the cylinder and since internal pressure is all but impossible to read (affordably), CHT & EGT are good approximations, but he's a strong believer in both.

GAHorn wrote: Mr. Busch’s article leaves us with no more information than what we already had. O-300 engines do not suffer from high CHT or frequent head-separation. So my contribution to this thread is simply to note that the issue with Titan cylinders and Mr. Busch’s personal choice of CHT-gauge temperature-ranges for his bog-bore Continentals are not helpful as for our C145/O300 engines.

Again, if you read his book, you'll find Continental as his source for many of his recommendations. A fair bit of personal interaction with engineers at Continental, along with some "reading between the lines" within the manuals themselves as well as his thousands of hours of EMS data lead him to the conclusions he comes to. The article is a little bit of an oversimplification or concise synopsis of information in his book and this article is looking specifically at the Titan cylinder issues...

...regardless, what the original poster requested was guidance/opinions on where to set his alarms. Using Mike Busch's parameters meets both your and his recommendation of lower is better. :D Perhaps you find it too conservative - that's OK.

GAHorn wrote:Oh...OK.. I mean it in the traditional-sense of flight cycles. Cold engine, start-up, take-off (huge stresses from temp-rise), cruise, let-down (large temp-reduction), landing and shut-dn.


So, your theory is that high cycles lead to cylinder head separation - or at least could contribute to it? I think that is more than just plausible, it is likely, however, it would likely take a number of cycles well beyond the normal life of an engine to reach. Regardless, it would seem that temperatures involved likely play a larger role depending on longevity of the cylinders - in other words, operate at lower CHTs and eventually fatigue/cycles will get you, but operate at higher temps, and you may induce the failure sooner. I think that's the key point of the Busch article; failures are induced prior to fatigue by temperature. I think that is a reasonable conclusion.
User avatar
TFA170
 
Posts: 91
Joined: Tue Jan 26, 2016 3:18 am
Location: 74FL

Re: CHT Gauge Limit Settings

Postby GAHorn » Mon Aug 03, 2020 3:02 pm

(OK...being troublesome here now..but the virus is adding to boredom...). Soo... I have to buy his book to understand what we already know?

It’s my opinion the differences of heat dissipation and expansion-rates between aluminum and steel is the root cause for this failure .... blow by is a red herring. And it stands to reason these differences will be more exaggerated in large bores than in small bores... probably the major reason small bore engines suffer this failure less frequently than the big bores.

(If blow-by is a problem due to improper break-in and cylinder-glazing we’d fix that early in the engine’s life, right? I mean, who wants to keep low compressions and high oil consumption? Is it being suggested by Mr. Busch that since we discovered we had blow-by that we should discard those heat-damaged new cylinders and start over? I think not. Most, if not all operators would de-glaze them and go thru break-in again. Does that mean we will have some head blow off in the future because of latent damage caused by that blow by?)

Even if the imagined Or real intricacies of blow-by inside a cylinder contributes to the problem, it cannot be managed by any tool or gauge we have in the cockpit (except perhaps by closing the throttle, which is exactly what I did when my IO-520 #4 cyl blew it’s top on takeoff.) I doubt there is any information in his book that would have prevented that failure. (We know how he makes his money.)

Technicalities are fun and entertaining, but I don’t have to know how to alloy brass to make a gear to build a clock just to know what time it is.
If you have read his book, what Busch-recommended operational changes have you undertaken to avoid this particular problem? ... and how can you quantify that those changes, if any, have resulted in fewer cylinder-head failures for you?
Or did we simply go out and buy some expensive monitoring equipment he promoted so as to feel better about things?

(Boy, I must have gotten up on the wrong side of the bed...)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight.
An originality nut (mostly) for the right reasons. ;)
User avatar
GAHorn
 
Posts: 19057
Joined: Fri Apr 12, 2002 8:45 pm
Location: Spicewood (Austin), Texas

Re: CHT Gauge Limit Settings

Postby TFA170 » Tue Aug 04, 2020 2:34 am

GAHorn wrote:(OK...being troublesome here now..but the virus is adding to boredom...). Soo... I have to buy his book to understand what we already know?

Clearly you didn't know that blow-by increases temperatures and hot spots and adds to problems within the cylinders. :lol: :D

GAHorn wrote:It’s my opinion the differences of heat dissipation and expansion-rates between aluminum and steel is the root cause for this failure .... blow by is a red herring.

You can lead a horse to water, but it's still a horse. Blow-by increases hot spots. Hot spots, increases out of round conditions. Out of round conditions are problematic at the head/cylinder junction and any sealing. That's engine 101 and not unique to aircraft engines.

GAHorn wrote: And it stands to reason these differences will be more exaggerated in large bores than in small bores... probably the major reason small bore engines suffer this failure less frequently than the big bores.

Perhaps. Irrelevant to original post and question.

GAHorn wrote: (If blow-by is a problem due to improper break-in and cylinder-glazing we’d fix that early in the engine’s life, right? I mean, who wants to keep low compressions and high oil consumption? Is it being suggested by Mr. Busch that since we discovered we had blow-by that we should discard those heat-damaged new cylinders and start over? I think not. Most, if not all operators would de-glaze them and go thru break-in again. Does that mean we will have some head blow off in the future because of latent damage caused by that blow by?)

OK, this is a strawman argument. Nobody claimed anything about what should be done. However, if you read the book, you'd learn nothing new as Mr. Busch does indeed recommend deglazing and re-ringing rather than replacing where appropriate.
It's also a red herring argument as it's got nothing to do with the original post.

GAHorn wrote:Even if the imagined Or real intricacies of blow-by inside a cylinder contributes to the problem, it cannot be managed by any tool or gauge we have in the cockpit (except perhaps by closing the throttle, which is exactly what I did when my IO-520 #4 cyl blew it’s top on takeoff.) I doubt there is any information in his book that would have prevented that failure. (We know how he makes his money.)

Another strawman. Your obsession with blow-by is problematic in our discussion and in the original post.

GAHorn wrote:Technicalities are fun and entertaining, but I don’t have to know how to alloy brass to make a gear to build a clock just to know what time it is.


GAHorn wrote:If you have read his book, what Busch-recommended operational changes have you undertaken to avoid this particular problem?

Run cooler than the book recommends.

GAHorn wrote:... and how can you quantify that those changes, if any, have resulted in fewer cylinder-head failures for you?
Or did we simply go out and buy some expensive monitoring equipment he promoted so as to feel better about things?

I've done nothing other than try to keep my cyl head temps lower. I do not have a full EMS, but when I upgrade to an O360, I will likely install one at that time. Further, it is all but impossible to prove something that doesn't happen, but I will defer to Mr. Busch's thousands of hours of EMS data. You do you.

GAHorn wrote:(Boy, I must have gotten up on the wrong side of the bed...)

I think you do that most days on here. :lol: :lol: :D

That's all fine, really, but the original poster asked for a recommendation for an alarm on his EMS. You made a recommendation of 250-450 for the green arc because yours runs at 350. You based this on what data precisely? Mike Busch, on the other hand, runs a company that analyzes engine data from thousands of planes with thousands of hours of data and monitors trends on a variety of factors - based on all of this, he recommends 380 as an alarm point. It seems you've latched onto this blow-by comment by Busch, and because you don't "buy into it", you have dismissed his entire argument based on a single data point when you have nothing but anecdotal evidence to contradict.

Now, that doesn't mean you're wrong, merely that attacking Busch and dismissing a recommendation based on a single comment you disagree with sounds a lot like grandstanding when he has reams of data to back up his position. His, like yours, is a recommendation - the difference is, this is what he does for a living; monitor engines for customers.

At the end of the day, you don't have to read his book, you don't have to take his recommendation, you don't even have to agree with anything that's posted on here (you often don't), but just because you don't understand how blow-by increases temps and hot spots leading to out of round conditions on cylinders and exacerbating issues related to those cylinders and specifically the cylinder/head junction doesn't make him wrong or you right...just more of what you usually are. :mrgreen: :wink:
User avatar
TFA170
 
Posts: 91
Joined: Tue Jan 26, 2016 3:18 am
Location: 74FL

Next

Return to The Hangar

Who is online

Users browsing this forum: Bing [Bot], daedaluscan, DaveF and 18 guests