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CHT vents

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bobbyhester(at)charter.ne
Guest

Posted: Mon May 28, 2007 4:52 am Post subject: CHT vents

Ron, I saw an old post about your cowl louvers. Are they what made the 

big differance? My CHT's are getting up to 455 by about 2500 ft on climb 

out and then I level off til they come down to about 430 then I climb 

some more. At cruise I am seeing 410-420. I would really like to see 

them more like 350 at cruise. This is at about 87 degree F OAT on the 

ground. Any other suggestions? Were did you get you louvers?



-- 

Surfing the web with my laptop from Hopkinsville, KY

Visit my RV7A website: http://webpages.charter.net/bobbyhester/MyFlyingRV7A.htm

ronlee(at)pcisys.net
Guest

Posted: Mon May 28, 2007 5:38 am Post subject: CHT vents

I did three things.



1)  Remove the extra tubing that went with a dual cabin heat system (tubes 

all over in the back of the engine area).



2)  Opened up the bottom of the cowl around the exhaust.



3)  Added louvers made by a friend of a friend.



I don't know where my flight test numbers are but my recollection is that I 

got about equal

improvement from all three.  This was after ensuring that the baffling and 

associated sealing

was in good order.



Ron Lee

---

khorton01(at)rogers.com
Guest

Posted: Mon May 28, 2007 5:48 am Post subject: CHT vents

On Mon, 28 May 2007 07:50:47 -0500

Bobby Hester <bobbyhester(at)charter.net> wrote:



 	  Quote: 	
		   

 

 Ron, I saw an old post about your cowl louvers. Are they what made the 

 big differance? My CHT's are getting up to 455 by about 2500 ft on climb 

 out and then I level off til they come down to about 430 then I climb 

 some more. At cruise I am seeing 410-420. I would really like to see 

 them more like 350 at cruise. This is at about 87 degree F OAT on the 

 ground. Any other suggestions? Were did you get you louvers?

 


	


Bobby - If I understand properly, you have a 180 hp engine.  There are many, many RV-7/7As flying with this engine without CHT problems.  While adding cowl louvers might bring your CHTs down, I fear that you would simply be curing the symptom, without really fixing the basic problem.  This could lead to greater grief down the road, if the basic problem is significant.  For example, some people have high CHTs due to a too lean mixture, caused by the wrong carb.  If this were the problem, it would be far better to find it and fix it now.



Kevin Horton

Ottawa, Canada

n616tb(at)btsapps.com
Guest

Posted: Tue May 29, 2007 5:19 am Post subject: CHT vents

Bobby,



My plane was essentially self grounded till I could fix the high CHT

problem.  I tightened up the cowl, sealed around the front intake ramps, put

a door across the back of my oil cooler (cooler temps around 160-170) and

absolutely no joy.  Finally I added louvers I got from Alex De Dominicis in

Texas.  I think you can reach him through his website at

http://www.RVtraining.com  After this my plane was flying again.  My CHT

will still climb to near 450 on climb out sometimes but will be under 400

for cruise.  They do make a difference.  I cannot say this is the cure all

as Kevin mentioned there is a reason mine runs hot and so many others don't.

I just don't know what it is.



My next step is to remove some more of the lower cowling around the exhaust

area as mine is particularly smaller since my scoop portion actually hangs

back over the airframe about 2 inches.  I am going to remove all of that

this week before I fly this coming weekend.  If you haven't done that, it

would be advisable.  I am still trying to get mine down quite a bit more.



My plane is an RV-6 with 0-360A1A and constant speed prop.  I am flying

without wheel pants or leg fairings.

Tim



[quote] --

Doug Gray

Joined: 10 Jan 2006
Posts: 112
Location: Sydney, Australia

Posted: Tue May 29, 2007 6:30 am Post subject: CHT vents

There has been discussion about two issues that may be a factor for you,

first was casting flash obstructing airflow and the second was adding

some spacers (washers only) between baffles and cylinders at the

mounting bolts. 



Sorry I cannot be more specific I not familiar with the specifics,

others may be able to add detail.



Doug Gray



On Tue, 2007-05-29 at 08:18 -0500, Tim Bryan wrote:

[quote] 

 

 Bobby,

 

 My plane was essentially self grounded till I could fix the high CHT

 problem.  I tightened up the cowl, sealed around the front intake ramps, put

 a door across the back of my oil cooler (cooler temps around 160-170) and

 absolutely no joy.  Finally I added louvers I got from Alex De Dominicis in

 Texas.  I think you can reach him through his website at

 http://www.RVtraining.com  After this my plane was flying again.  My CHT

 will still climb to near 450 on climb out sometimes but will be under 400

 for cruise.  They do make a difference.  I cannot say this is the cure all

 as Kevin mentioned there is a reason mine runs hot and so many others don't.

 I just don't know what it is.

 

 My next step is to remove some more of the lower cowling around the exhaust

 area as mine is particularly smaller since my scoop portion actually hangs

 back over the airframe about 2 inches.  I am going to remove all of that

 this week before I fly this coming weekend.  If you haven't done that, it

 would be advisable.  I am still trying to get mine down quite a bit more.

 

 My plane is an RV-6 with 0-360A1A and constant speed prop.  I am flying

 without wheel pants or leg fairings.

 Tim

 

 > --

n616tb(at)btsapps.com
Guest

Posted: Tue May 29, 2007 6:38 am Post subject: CHT vents

I should have mentioned; I did check for casting flash and did not see

anything significant.  I may not have looked in the right place or something

however.  I also did add washers to the rear of the baffles where they

typically would restrict the airflow around the rear cylinders.  I saw no

difference in my application but others have so Bobby may want to check this

on his. Thanks for bringing these points up.



Tim



[quote] --

ronlee(at)pcisys.net
Guest

Posted: Tue May 29, 2007 6:41 am Post subject: CHT vents

 	  Quote: 	
		   My plane is an RV-6 with 0-360A1A and constant speed prop.  I am flying

 without wheel pants or leg fairings.

 Tim




	


Adding wheel pants and leg fairings will add 10-15 knots at ZERO additional

power.  That means additional cooling with no changes.  Seems like that 

should

be a priority.



Ron Lee

pitts_pilot(at)bellsouth.
Guest

Posted: Tue May 29, 2007 8:22 am Post subject: CHT vents

Tim, place a lightbulb below the cylinder and look down through the fins around the spark plug.  There should be about 1/8" (maybe less) between the fins.  With the light, it will be apparent if the flashing is there.  I see it on almost every Lycoming cylinder I look at.

 Linn

 

 Tim Bryan wrote:

 [quote]   [quote]--> RV-List message posted by: "Tim Bryan" <n616tb(at)btsapps.com> (n616tb(at)btsapps.com)



I should have mentioned; I did check for casting flash and did not see

anything significant.  I may not have looked in the right place or something

however.  I also did add washers to the rear of the baffles where they

typically would restrict the airflow around the rear cylinders.  I saw no

difference in my application but others have so Bobby may want to check this

on his. Thanks for bringing these points up.



Tim



       [quote]--

n616tb(at)btsapps.com
Guest

Posted: Tue May 29, 2007 8:33 am Post subject: CHT vents

 	  Quote: 	
		   

 

 > My plane is an RV-6 with 0-360A1A and constant speed prop.  I am flying

 > without wheel pants or leg fairings.

 > Tim

 >

 

 Adding wheel pants and leg fairings will add 10-15 knots at ZERO

 additional

 power.  That means additional cooling with no changes.  Seems like that

 should

 be a priority.

 

 Ron Lee


	


[Tim] You are right Ron.  I wish I could stop flying long enough to put them

on.  Actually we moved to Texas and are still living in our 5th wheel trying

to get a house built.  The wife thinks it is a bigger priority.  I wonder if

it would make my plane cooler thought? Hmmm.



Do Not Archive

bobbyhester(at)charter.ne
Guest

Posted: Tue May 29, 2007 5:37 pm Post subject: CHT vents

My engine is a Superior XP-0360

 There is no casting flashing on the cylinders

 I added a washer at the rear screw/bolt on the #3 cylinder to help cool that cylinder.

 I've sealed all holes that I can find.

 Baffling seems to be sealing farely well.

 The cowl exit is cut off even, all the way across.

 

  	  Quote: 	
		  Surfing the web with my laptop from Hopkinsville, KY

Visit my RV7A website: http://webpages.charter.net/bobbyhester/MyFlyingRV7A.htm 	
 

 

 Doug Gray wrote: [quote]   [quote]--> RV-List message posted by: Doug Gray <dgra1233(at)bigpond.net.au> (dgra1233(at)bigpond.net.au)



There has been discussion about two issues that may be a factor for you,

first was casting flash obstructing airflow and the second was adding

some spacers (washers only) between baffles and cylinders at the

mounting bolts. 



Sorry I cannot be more specific I not familiar with the specifics,

others may be able to add detail.



Doug Gray



On Tue, 2007-05-29 at 08:18 -0500, Tim Bryan wrote:

       [quote]--> RV-List message posted by: "Tim Bryan" <n616tb(at)btsapps.com> (n616tb(at)btsapps.com)



Bobby,



My plane was essentially self grounded till I could fix the high CHT

problem.  I tightened up the cowl, sealed around the front intake ramps, put

a door across the back of my oil cooler (cooler temps around 160-170) and

absolutely no joy.  Finally I added louvers I got from Alex De Dominicis in

Texas.  I think you can reach him through his website at

http://www.RVtraining.com  After this my plane was flying again.  My CHT

will still climb to near 450 on climb out sometimes but will be under 400

for cruise.  They do make a difference.  I cannot say this is the cure all

as Kevin mentioned there is a reason mine runs hot and so many others don't.

I just don't know what it is.



My next step is to remove some more of the lower cowling around the exhaust

area as mine is particularly smaller since my scoop portion actually hangs

back over the airframe about 2 inches.  I am going to remove all of that

this week before I fly this coming weekend.  If you haven't done that, it

would be advisable.  I am still trying to get mine down quite a bit more.



My plane is an RV-6 with 0-360A1A and constant speed prop.  I am flying

without wheel pants or leg fairings.

Tim



           [quote]--

rv8tor(at)lazy8.net
Guest

Posted: Tue May 29, 2007 7:06 pm Post subject: CHT vents

Bobby, have you checked the mag timing? Not using LASAR are you?

 

 The other common problem is too lean a mixture...do you have the usual 50 rpm rise when you pull the mixture to idle cutoff when shutting down?

 

 The baffles that come with the engine, that go in between the cylinders often have some pretty big holes where they go up against the case.

 

 I think Kevin is right, the basic design of the cowl has worked on many similar engines...I wouldn't cut it up unless I had tried every other possibility.

 

 Good luck, John

 

 

 Bobby Hester wrote: [quote]       My engine is a Superior XP-0360

 There is no casting flashing on the cylinders

 I added a washer at the rear screw/bolt on the #3 cylinder to help cool that cylinder.

 I've sealed all holes that I can find.

 Baffling seems to be sealing farely well.

 The cowl exit is cut off even, all the way across.

   

    	  Quote: 	
		  Surfing the web with my laptop from Hopkinsville, KY

Visit my RV7A website: http://webpages.charter.net/bobbyhester/MyFlyingRV7A.htm 	
   

   

 Doug Gray wrote:   [quote]     [quote]--> RV-List message posted by: Doug Gray <dgra1233(at)bigpond.net.au>



There has been discussion about two issues that may be a factor for you,

first was casting flash obstructing airflow and the second was adding

some spacers (washers only) between baffles and cylinders at the

mounting bolts. 



Sorry I cannot be more specific I not familiar with the specifics,

others may be able to add detail.



Doug Gray



On Tue, 2007-05-29 at 08:18 -0500, Tim Bryan wrote:

         [quote]--> RV-List message posted by: "Tim Bryan" <n616tb(at)btsapps.com>



Bobby,



My plane was essentially self grounded till I could fix the high CHT

problem.  I tightened up the cowl, sealed around the front intake ramps, put

a door across the back of my oil cooler (cooler temps around 160-170) and

absolutely no joy.  Finally I added louvers I got from Alex De Dominicis in

Texas.  I think you can reach him through his website at

http://www.RVtraining.com  After this my plane was flying again.  My CHT

will still climb to near 450 on climb out sometimes but will be under 400

for cruise.  They do make a difference.  I cannot say this is the cure all

as Kevin mentioned there is a reason mine runs hot and so many others don't.

I just don't know what it is.



My next step is to remove some more of the lower cowling around the exhaust

area as mine is particularly smaller since my scoop portion actually hangs

back over the airframe about 2 inches.  I am going to remove all of that

this week before I fly this coming weekend.  If you haven't done that, it

would be advisable.  I am still trying to get mine down quite a bit more.



My plane is an RV-6 with 0-360A1A and constant speed prop.  I am flying

without wheel pants or leg fairings.

Tim



             [quote]--

dale1rv6(at)comcast.net
Guest

Posted: Tue May 29, 2007 11:13 pm Post subject: CHT vents

The point about rpm rise at shut down has no bearing on the mixture at power settings well above idle.  Has the accuracy of the CHT gauge been verified twice?  I noticed on your website the sealing around the inlets. Can you rig up a couple tape strips to determine if that seal is fluttering during flight? The tape needs to be placed so that engine rock during startup and shutdown will not tear it loose.  

Good luck,  

Dale  

         

  

From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of John Huft

 Sent: Tuesday, May 29, 2007 11:04 PM

 To: rv-list(at)matronics.com

 Subject: Re: CHT vents  

  

   

Bobby, have you checked the mag timing? Not using LASAR are you?

 

 The other common problem is too lean a mixture...do you have the usual 50 rpm rise when you pull the mixture to idle cutoff when shutting down?

 

 The baffles that come with the engine, that go in between the cylinders often have some pretty big holes where they go up against the case.

 

 I think Kevin is right, the basic design of the cowl has worked on many similar engines...I wouldn't cut it up unless I had tried every other possibility.

 

 Good luck, John

 

 

 

   [quote] [b]

PGLong

Joined: 10 Jan 2006
Posts: 37

Posted: Wed May 30, 2007 1:50 am Post subject: CHT Vents

Bobby, I had kind of a reverse problem, but also may work for you. My RV-4  couldn't warm the oil up enough. I closed by about 40-5-%, the lower  cowling area where the exhaust and air exit from cooling the engine. This  brought up my oil temps to normal.  I just put a baffle plate of  sorts to throttle the air leaving. I would think that if you opened your up to  allow more air to exit, you would also get more air in and hence do more  cooling. Wish you the best.   

 Pat  Long

PGLong(at)aol.com

N120PL

RV 4

Bay City,  Michigan

3CM



 





See what's free at AOL.com. 

  [quote][b]

_________________
Pat Long
RV-4, N120PL
Bay City, MI

bobbyhester(at)charter.ne
Guest

Posted: Wed May 30, 2007 7:38 pm Post subject: CHT vents

I just double checked the timing on my Lightspeed Ign.. The timing was just slightly off. I adjusted it and it is perfect now.  Test flight did not show any change in my CHT's. What I did find out is that I can tell if the timing is correct by looking at the RPM drop on the Electronic Ign. Before makeing the adjustment I had about a drop of about 20 RPM. The first adjustment I made was not right and I got about a 200 RPM drop. I found my mistake and made the correct adjustment and now I only have a 10 RPM drop. When checking the timing on the lightspeed, with a automotive type timing light, you disconnect the Manifold pressure hose to retard the timing, The engine run quite a bit rougher like that, which I beleive is how it would be running with two mags. When the line is connected back it advances the timing and runs much smoother, all this at about 850 RPM. This is some good info to find out. Now I've got to get to work on those wheel pants and leg farings.

 

 Superior XP-0360  65hrs and counting 

  	  Quote: 	
		  Surfing the web with my laptop from Hopkinsville, KY

Visit my RV7A website: http://webpages.charter.net/bobbyhester/MyFlyingRV7A.htm 	
 

 

 Bobby Hester wrote: [quote]       My engine is a Superior XP-0360

 There is no casting flashing on the cylinders

 I added a washer at the rear screw/bolt on the #3 cylinder to help cool that cylinder.

 I've sealed all holes that I can find.

 Baffling seems to be sealing farely well.

 The cowl exit is cut off even, all the way across.

   

    	  Quote: 	
		  Surfing the web with my laptop from Hopkinsville, KY

Visit my RV7A website: http://webpages.charter.net/bobbyhester/MyFlyingRV7A.htm 	
   

   

 Doug Gray wrote:   [quote]     [quote]--> RV-List message posted by: Doug Gray <dgra1233(at)bigpond.net.au>



There has been discussion about two issues that may be a factor for you,

first was casting flash obstructing airflow and the second was adding

some spacers (washers only) between baffles and cylinders at the

mounting bolts. 



Sorry I cannot be more specific I not familiar with the specifics,

others may be able to add detail.



Doug Gray



On Tue, 2007-05-29 at 08:18 -0500, Tim Bryan wrote:

         [quote]--> RV-List message posted by: "Tim Bryan" <n616tb(at)btsapps.com>



Bobby,



My plane was essentially self grounded till I could fix the high CHT

problem.  I tightened up the cowl, sealed around the front intake ramps, put

a door across the back of my oil cooler (cooler temps around 160-170) and

absolutely no joy.  Finally I added louvers I got from Alex De Dominicis in

Texas.  I think you can reach him through his website at

http://www.RVtraining.com  After this my plane was flying again.  My CHT

will still climb to near 450 on climb out sometimes but will be under 400

for cruise.  They do make a difference.  I cannot say this is the cure all

as Kevin mentioned there is a reason mine runs hot and so many others don't.

I just don't know what it is.



My next step is to remove some more of the lower cowling around the exhaust

area as mine is particularly smaller since my scoop portion actually hangs

back over the airframe about 2 inches.  I am going to remove all of that

this week before I fly this coming weekend.  If you haven't done that, it

would be advisable.  I am still trying to get mine down quite a bit more.



My plane is an RV-6 with 0-360A1A and constant speed prop.  I am flying

without wheel pants or leg fairings.

Tim



             [quote]--

martin(at)gbonline.com
Guest

Posted: Fri Jun 01, 2007 7:00 pm Post subject: CHT vents

Tim,

8 years ago when I finished my RV8, I encountered similar problems with 

temps.  After trying a lot of different fixes, it was suggested that my 

electronic ignition was set to far advanced.  I reset the ignition timing 

(with more care and also reread the instructions) and have had no problems 

since.  Also loose fitting of engine baffles etc will also cause your 

problems.  Good luck.

Dick Martin

RV8 N233M

the fast one

---

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