COZY: Hi CHT with 0.0 gami spread


Andrew Anunson
 

So I posted back in May that I had near perfect fuel injector balance but had a high CHT (#4, which is closest to the firewall and on the right side of the plane).  Since that time, I programmed my Garmin G3X to alert me when the CHT got to 410 and then again at 425.  That alert and use of the mixture lever are the tools I use to keep that #4 cylinder at acceptable temperatures.

I prefer to run at best power (or at least better power) instead of my rich cooling mixture, so this week I finally followed most of the groups advice and installed a ramp to blow air at my #4 cylinder and it works very well!  Thank You!!!!  

I wanted a temporary ramp to see if it worked and I built it from a leftover 0.032" thick aluminum (see photos).


Now my #4 is the same temperature as #1 and #3... but #2 is hot (right behind #4 on the Cozy)d.   I will trim off some of the ramp, perhaps from 2.5" wide down to 2.25" or 2" and see if it balances #4 with #2. 

Question:  Once I get the ramp so that #4 and #2 are at closer temps, should I replace this ramp with a fiberglass one?  Does anyone see any structural dangers with this temporary ramp in the lower cowl?

Thanks!
Andrew Anunson
Cozy MKVI #1273 (30 hours)
Pound, VA

On Wednesday, May 18, 2022 at 02:53:28 PM EDT, 'Andrew Anunson' via COZY Builders Mailing List <cozy_builders@...> wrote:


My Bendix injected Lycoming O-360 (COZY MKIV, built to plans, 1 LSE EI, 1 mag) is running hi CHT's on the #4 cylinder (see CHT and OIL TEMP image).

On the ground, not moving, the CHT's are all pretty close (see GROUND CHT image).
During taxi and climbout, the #4 leaves 1, 2, and 3 in the dust (see TAXI and CLIMB image)

The GAMI lean testing shows a spread of 0.0 to 0.5 gph (see images GAMI 1 and GAMI 2 images)

It appears to be an airflow balance issue.
What are the first steps to take?

Open up baffling for #4 cylinder?
Tighten baffling for #1, 2, and 3?

Air deflectors?

Thanks,
Andrew Anunson
Cozy MKIV #1273
Pound, VA

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Marc J. Zeitlin
 

Andrew Anunson wrote:

I prefer to run at best power (or at least better power) instead of my rich cooling mixture...

If you're under 75% power (above 8K DA, basically) you can run at any mixture level you like and are very unlikely to damage the engine. However, if you're at 75% or above, you should be running rich of best power setting, which is 50 DegF ROP.

If you're under 75% power, you'll get lower CHT's by running LOP - 20F - 30F LOP, up to 150F LOP, if you can get there and the engine still runs smoothly.

Question:  Once I get the ramp so that #4 and #2 are at closer temps, should I replace this ramp with a fiberglass one?

Only if the metal one bothers you somehow.
 
Does anyone see any structural dangers with this temporary ramp in the lower cowl?

Not in the least, if it's attached well to the fiberglass baffles, which it looks like it is. I have something similar in 0.032" AL that's been there for 20 years or so.

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Del Schier
 

Andrew,

I ended up with more aggressive ramps to get more air on 3 and 4.  Final tweaking I found that, closing up the opening on the baffles that wrap the bottom of the cylinders by 1/4 “ brought my cold #1 up almost 50 deg. If you have baffles wrapping the cylinder bottoms you might try opening up #4.

The glass ramps I made were not doing enough so I added silicon rubber strips on top to bring them up closer to the front cylinders. If your metal falls loose it probably wouldn’t get out of the cowl into something bad.

Del Schier

Cozy IV N197DL

Cannon Creek Airpark 15FL

 

 

 

From: 'Andrew Anunson' via COZY Builders Mailing List <cozy_builders@...>
Sent: Saturday, November 12, 2022 9:41 PM
To: Cozy Builder Google List <cozy_builders@...>; Canard Aviators List <canard-aviators@canardzone.groups.io>
Subject: Re: COZY: Hi CHT with 0.0 gami spread

 

So I posted back in May that I had near perfect fuel injector balance but had a high CHT (#4, which is closest to the firewall and on the right side of the plane).  Since that time, I programmed my Garmin G3X to alert me when the CHT got to 410 and then again at 425.  That alert and use of the mixture lever are the tools I use to keep that #4 cylinder at acceptable temperatures.

 

I prefer to run at best power (or at least better power) instead of my rich cooling mixture, so this week I finally followed most of the groups advice and installed a ramp to blow air at my #4 cylinder and it works very well!  Thank You!!!!  

 

I wanted a temporary ramp to see if it worked and I built it from a leftover 0.032" thick aluminum (see photos).

 

 

Now my #4 is the same temperature as #1 and #3... but #2 is hot (right behind #4 on the Cozy)d.   I will trim off some of the ramp, perhaps from 2.5" wide down to 2.25" or 2" and see if it balances #4 with #2. 

 

Question:  Once I get the ramp so that #4 and #2 are at closer temps, should I replace this ramp with a fiberglass one?  Does anyone see any structural dangers with this temporary ramp in the lower cowl?

 

Thanks!

Andrew Anunson

Cozy MKVI #1273 (30 hours)

Pound, VA

 

On Wednesday, May 18, 2022 at 02:53:28 PM EDT, 'Andrew Anunson' via COZY Builders Mailing List <cozy_builders@...> wrote:

 

 

My Bendix injected Lycoming O-360 (COZY MKIV, built to plans, 1 LSE EI, 1 mag) is running hi CHT's on the #4 cylinder (see CHT and OIL TEMP image).

 

On the ground, not moving, the CHT's are all pretty close (see GROUND CHT image).

During taxi and climbout, the #4 leaves 1, 2, and 3 in the dust (see TAXI and CLIMB image)

 

The GAMI lean testing shows a spread of 0.0 to 0.5 gph (see images GAMI 1 and GAMI 2 images)

 

It appears to be an airflow balance issue.

What are the first steps to take?

 

Open up baffling for #4 cylinder?

Tighten baffling for #1, 2, and 3?

 

Air deflectors?

 

Thanks,

Andrew Anunson

Cozy MKIV #1273

Pound, VA

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skovbjerg
 

Sitting here “armchairing” it, I do think that there is room for lots of improvements here.
First, those fore to aft vertical wall, are they really called for? In my eye ball judgement they are too far inboard if they have to be there at all ( for structural integretity?) The guide in the pic does not lead air to the cylinder heads but seem to aim at the barrel, at best?
IMHO, the verticals should be aligned with the valve covers and the flow ramps be wide, like 3” and attached to them. On my C3 the flow ramps are installed directly on the side of the cowl which off course is narrower.

image

On Nov 12, 2022, at 18:44, Andrew Anunson via groups.io <macleodm3@...> wrote:


So I posted back in May that I had near perfect fuel injector balance but had a high CHT (#4, which is closest to the firewall and on the right side of the plane).  Since that time, I programmed my Garmin G3X to alert me when the CHT got to 410 and then again at 425.  That alert and use of the mixture lever are the tools I use to keep that #4 cylinder at acceptable temperatures.

I prefer to run at best power (or at least better power) instead of my rich cooling mixture, so this week I finally followed most of the groups advice and installed a ramp to blow air at my #4 cylinder and it works very well!  Thank You!!!!  

I wanted a temporary ramp to see if it worked and I built it from a leftover 0.032" thick aluminum (see photos).


Now my #4 is the same temperature as #1 and #3... but #2 is hot (right behind #4 on the Cozy)d.   I will trim off some of the ramp, perhaps from 2.5" wide down to 2.25" or 2" and see if it balances #4 with #2. 

Question:  Once I get the ramp so that #4 and #2 are at closer temps, should I replace this ramp with a fiberglass one?  Does anyone see any structural dangers with this temporary ramp in the lower cowl?

Thanks!
Andrew Anunson
Cozy MKVI #1273 (30 hours)
Pound, VA

On Wednesday, May 18, 2022 at 02:53:28 PM EDT, 'Andrew Anunson' via COZY Builders Mailing List <cozy_builders@...> wrote:


My Bendix injected Lycoming O-360 (COZY MKIV, built to plans, 1 LSE EI, 1 mag) is running hi CHT's on the #4 cylinder (see CHT and OIL TEMP image).

On the ground, not moving, the CHT's are all pretty close (see GROUND CHT image).
During taxi and climbout, the #4 leaves 1, 2, and 3 in the dust (see TAXI and CLIMB image)

The GAMI lean testing shows a spread of 0.0 to 0.5 gph (see images GAMI 1 and GAMI 2 images)

It appears to be an airflow balance issue.
What are the first steps to take?

Open up baffling for #4 cylinder?
Tighten baffling for #1, 2, and 3?

Air deflectors?

Thanks,
Andrew Anunson
Cozy MKIV #1273
Pound, VA

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IMG_5277.JPGIMG_5278.JPG


Andrew Anunson
 

Jay wrote:
First, those fore to aft vertical wall, are they really called for?

Well actually, yes, those vertical walls are called for in the Cozy MKIV plans and my cowls are built to plans.


Jay wrote:
In my eye ball judgement they are too far inboard if they have to be there at all ( for structural integretity?)The guide in the pic does not lead air to the cylinder heads but seem to aim at the barrel, at best?

The vertical walls start at, and match (tie into), the NACA duct and they are outboard of the cylinder heads (they angle outwards and spread apart towards the rear of the plane.  The MKIV has a BIG NACA duct.  The aluminum ramp I built is directly in line with the head.... I'd say the #4 CHT probe kinda lines up with the middle of the ramp.  


Jay wrote:
IMHO, the verticals should be aligned with the valve covers and the flow ramps be wide, like 3” and attached to them. 

Well, believe it or not.... thats pretty much exactly how the cowls are built.  My ramp started out as 3" wide, but I trimmed it to 2.5" wide to keep it safely away from one of my fuel lines.  


Here is a photo looking into the NACA duct.... you can see the verical walls and the ramp in there.  You can also see how I have some fuel components (fuel lines, red cube) that likely interfere with cooling airflow.  I may relocate those components if needed The MKIV evidently has much more room inside the lower cowl than the EZ's or the Cozy 3.