REFLECTOR: CHT's

Mon Oct 19 09:28:37 CDT 2009

I have diverters on my IO-360 but I have updraft cooling and the cowl is modified with two inlet scoops on the bottom. The diverters split the air and run from the inlet up in between the cylinders. It is very effective and I can easily control my temps by adjusting the height of the diverters. Just another note, a friend of mine who is a Red Bull air race mechanic said 360F is optimum on the lycoming for internal clearances. My cylinders run under 400F on T/O and 340-360F cruise. 

Dean Unterreiner

> From: reflector-request at tvbf.org
> Subject: Reflector Digest, Vol 65, Issue 85
> To: reflector at tvbf.org
> Date: Mon, 19 Oct 2009 09:06:19 -0500
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> Today's Topics:
> 
> 1. CHT's (Scott Derrick)
> 2. Re: CHT's (aminetech at bluefrog.com)
> 3. Re: CHT's (Scott Derrick)
> 4. Re: CHT's (aminetech at bluefrog.com)
> 5. Re: CHT's (Douglas Holub)
> 6. Re: servo speed control (Andrew Ellzey)
> 7. Re: CHT's (Scott Derrick)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Sun, 18 Oct 2009 14:09:58 -0600
> From: Scott Derrick <scott at tnstaafl.net>
> Subject: REFLECTOR: CHT's
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Message-ID: <4ADB7616.1060901 at tnstaafl.net>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> Flew this morning after plugging holes in the TCM/Cessna supplied
> "between cylinder baffles". I should have made my own, because the
> stock baffles have huge holes in them. They also don't wrap up around
> the sides of the cylinders for optimal cooling flow. I may try to
> tighten things up a bit more but it will require me to remove all the
> injection plumbing, spark plug wiring and some other stuff.. 
> 
> Also adjusted the fuel map and smoothed out a few bumps in the oil
> cooler exit duct.
> 
> The CHT's are really coming into a comfortable range. Cruising at 165
> KTAS(low power setting) they all stay below 360, but increasing power 
> to above 200 KTAS and #2 climbed to 395, #1was about 365, the rest
> were all below 330. I'm mostly concerned with #2 but would like to see
> #1 more inline with the other 4 as well.
> 
> I'm debating installing some kind of diverter(s) inside the plenum to
> direct more air onto #1 & #2. Anybody do that to lower CHT's with
> success? How did you do it? Got pictures? Controlling air movement is
> such a funny thing, sometimes what seems logical or intuitive is exactly
> the wrong thing to do! 
> 
> The fuel map is as good as I will be able to get it, until I get the new
> prop. At least I am not running at peak EGT in RPMs above 2200 now. 
> That helped the temps a whole lot.
> 
> Now to getting the oil temp down some more. Right now I am not running
> the fan on the secondary cooler as I see it as a summer time auxiliary
> cooler. With OAT in the 60's I shouldn't need it. The oil temps were
> OK, but a bit on the high side at a low power cruise speed of 165KTAS.
> about 210F, but as soon as I fire-walled the throttle it started to come
> up and seemed to stabilize at around 230, though I didn't stay at that
> power setting more than a couple of minutes. With the IO360 my current
> oil cooler was good enough but marginal. On hot days I had to step
> climb. I don't have an exit scoop or air dam on the exit duct. The
> duct opening is flush with the fuselage. I'm really intrigued with Don's
> idea of an Oil cooler flap that can be adjusted from the cockpit. When
> flying with the IO360 I had too much cooling in the winter and marginal
> in the summer. I would tape some of the cooler face in the winter so my
> temps were hot enough to get a bit of warm air in the cabin. With a
> hinged controllable flap I could set it for whatever the conditions
> were. It would probably work out to 3 or 4 settings that covered all
> scenarios.
> 
> Scott
> 
> 
> 
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> ------------------------------
> 
> Message: 2
> Date: Sun, 18 Oct 2009 15:20:52 -0700
> From: <aminetech at bluefrog.com>
> Subject: Re: REFLECTOR: CHT's
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Message-ID: <20091018152052.A676C0A4 at resin09.mta.everyone.net>
> Content-Type: text/plain; charset="UTF-8"
> 
> 
> 
> --- scott at tnstaafl.net wrote:
> 
> 
> 
> The CHT's are really coming into a comfortable range. Cruising at 165
> KTAS(low power setting) they all stay below 360, but increasing power 
> to above 200 KTAS and #2 climbed to 395, #1was about 365, the rest
> were all below 330. I'm mostly concerned with #2 but would like to see
> #1 more inline with the other 4 as well.
> 
> I'm debating installing some kind of diverter(s) inside the plenum to
> direct more air onto #1 & #2. Anybody do that to lower CHT's with
> success? How did you do it? Got pictures? Controlling air movement is
> such a funny thing, sometimes what seems logical or intuitive is exactly
> the wrong thing to do! 
> 
> That's what I found with my Franklin. First of all, where are your #1 and 2? Front or back? My back cylinders (#5 & #6) ran hotter than the rest. Baffling didn't help. I think the air will take the least path of resistance in spite of where you try to send it. What worked for me was putting spacers between the plenum and back cylinders to allow more air to pass by. It helped a lot. I also made a cut out in the bottom cowl just aft of the oil pan because there is a gap between the cowl and the intake scoop and I felt that ingressing air was combining with the exiting engine cooling air and congesting at that point. Sometimes my CHTs read identical and sometimes there's a 10-20 degree difference. No idea why it changes, but close enough I think.
> 
> John
> 
> 
> ------------------------------
> 
> Message: 3
> Date: Sun, 18 Oct 2009 17:30:50 -0600
> From: Scott Derrick <scott at tnstaafl.net>
> Subject: Re: REFLECTOR: CHT's
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Message-ID: <4ADBA52A.2050809 at tnstaafl.net>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> John,
> 
> 1&2 are the farthest from the propeller, or closest to the firewall. 
> 
> And I agree, trying to direct the air is like trying to push on a rope. 
> Pulling works better which is what your additional cut out in the lower
> cowl does. Thats whats weird because 1&2 are right below the duct from
> the NACA and has the largest space between the lower cowl and the cylinders?
> 
> I would think opening up a space between the plenum and some of the
> cylinders would allow more air to not go through the fins and thus raise
> your overall cylinder temps?
> 
> Anybody with a IO550 have hotter 1&2 cylinders?
> 
> Scott
> 
> aminetech at bluefrog.com wrote:
> > --- scott at tnstaafl.net wrote:
> >
> >
> >
> > The CHT's are really coming into a comfortable range. Cruising at 165
> > KTAS(low power setting) they all stay below 360, but increasing power 
> > to above 200 KTAS and #2 climbed to 395, #1was about 365, the rest
> > were all below 330. I'm mostly concerned with #2 but would like to see
> > #1 more inline with the other 4 as well.
> >
> > I'm debating installing some kind of diverter(s) inside the plenum to
> > direct more air onto #1 & #2. Anybody do that to lower CHT's with
> > success? How did you do it? Got pictures? Controlling air movement is
> > such a funny thing, sometimes what seems logical or intuitive is exactly
> > the wrong thing to do! 
> >
> > That's what I found with my Franklin. First of all, where are your #1 and 2? Front or back? My back cylinders (#5 & #6) ran hotter than the rest. Baffling didn't help. I think the air will take the least path of resistance in spite of where you try to send it. What worked for me was putting spacers between the plenum and back cylinders to allow more air to pass by. It helped a lot. I also made a cut out in the bottom cowl just aft of the oil pan because there is a gap between the cowl and the intake scoop and I felt that ingressing air was combining with the exiting engine cooling air and congesting at that point. Sometimes my CHTs read identical and sometimes there's a 10-20 degree difference. No idea why it changes, but close enough I think.
> >
> > John
> > _______________________________________________
> > To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector
> >
> > Visit the gallery! www.tvbf.org/gallery
> > user:pw = tvbf:jamaicangoose
> > Check new archives: www.tvbf.org/pipermail
> > Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
> >
> > 
> 
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> ------------------------------
> 
> Message: 4
> Date: Sun, 18 Oct 2009 18:24:50 -0700
> From: <aminetech at bluefrog.com>
> Subject: Re: REFLECTOR: CHT's
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Message-ID: <20091018182450.A676EE75 at resin09.mta.everyone.net>
> Content-Type: text/plain; charset="UTF-8"
> 
> 
> 
> --- scott at tnstaafl.net wrote:
> 
> 
> 
> 
> 
> I would think opening up a space between the plenum and some of the
> cylinders would allow more air to not go through the fins and thus raise
> your overall cylinder temps?
> 
> In my case, probably a little, but that's what you want, balanced CHTs. The cooler ones increase a little while the hot ones decrease. I believe that the air escaping in the plenum/cylinder gap is still providing cooling (air has to travel over the cylinder top to get to the gap. It's simple enough to try.
> 
> John
> 
> 
> 
> ------------------------------
> 
> Message: 5
> Date: Sun, 18 Oct 2009 22:01:22 -0500
> From: "Douglas Holub" <douglas.holub at gmail.com>
> Subject: Re: REFLECTOR: CHT's
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Message-ID: <76ED5A2887B34AC88E60913CE86C0B22 at Workshop>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
> 
> "Baffling didn't help. I think the air will take the least path of 
> resistance in spite of where you try to send it."
> -------------------------------------------------------------------------------
> That's what I found, too. I tried to direct the air where needed, but in the 
> end got my hot cylinder cool by opening up the baffles around it.
> 
> Doug Holub
> ----- Original Message ----- 
> From: <aminetech at bluefrog.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Sunday, October 18, 2009 5:20 PM
> Subject: Re: REFLECTOR: CHT's
> 
> 
> >
> >
> > --- scott at tnstaafl.net wrote:
> >
> >
> >
> > The CHT's are really coming into a comfortable range. Cruising at 165
> > KTAS(low power setting) they all stay below 360, but increasing power
> > to above 200 KTAS and #2 climbed to 395, #1was about 365, the rest
> > were all below 330. I'm mostly concerned with #2 but would like to see
> > #1 more inline with the other 4 as well.
> >
> > I'm debating installing some kind of diverter(s) inside the plenum to
> > direct more air onto #1 & #2. Anybody do that to lower CHT's with
> > success? How did you do it? Got pictures? Controlling air movement is
> > such a funny thing, sometimes what seems logical or intuitive is exactly
> > the wrong thing to do!
> >
> > That's what I found with my Franklin. First of all, where are your #1 and 
> > 2? Front or back? My back cylinders (#5 & #6) ran hotter than the rest. 
> > Baffling didn't help. I think the air will take the least path of 
> > resistance in spite of where you try to send it. What worked for me was 
> > putting spacers between the plenum and back cylinders to allow more air to 
> > pass by. It helped a lot. I also made a cut out in the bottom cowl just 
> > aft of the oil pan because there is a gap between the cowl and the intake 
> > scoop and I felt that ingressing air was combining with the exiting engine 
> > cooling air and congesting at that point. Sometimes my CHTs read 
> > identical and sometimes there's a 10-20 degree difference. No idea why it 
> > changes, but close enough I think.
> >
> > John
> > _______________________________________________
> > To change your email address, visit 
> > http://www.tvbf.org/mailman/listinfo/reflector
> >
> > Visit the gallery! www.tvbf.org/gallery
> > user:pw = tvbf:jamaicangoose
> > Check new archives: www.tvbf.org/pipermail
> > Check old archives: http://www.tvbf.org/archives/velocity/maillist.html 
> 
> 
> 
> ------------------------------
> 
> Message: 6
> Date: Mon, 19 Oct 2009 06:34:04 -0700 (PDT)
> From: Andrew Ellzey <ajlz72756 at yahoo.com>
> Subject: Re: REFLECTOR: servo speed control
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Message-ID: <397227.55212.qm at web50802.mail.re2.yahoo.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> Lou,
> 
> Have you checked the voltage?that you are getting out of the SPD-1? I designed my own speed controller and found that it took an output of around 4VDC to see a change in speed of the standard Velocity elevator trim actuator. I'm not flying yet so this is in an unloaded condition. 
> 
> Andy Ellzey
> 
> 
> 
> 
> ________________________________
> From: Lou Stedman <stedmanlou at roadrunner.com>
> To: Canard Aviators <canard-aviators at yahoogroups.com>; Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Sent: Sat, October 17, 2009 9:41:05 AM
> Subject: REFLECTOR: servo speed control
> 
> 
> I recently installed a SPD-1 Servo Speed Control which I purchased from ACS. The unit has three wires . One for power from 1 amp fuse, one to feed power from control to the DPDT switch on my control stick, and one to ground. I am very sure that I connected it correctly but it made no difference in the speed of my?liner actuator?speed. After adjusting I found that in the lowest setting, my liner actuator would not move. In all other settings the speed was the same. Has anyone else installed this or something similar?
> Lou Stedman
> Velocity SEFG
> N7044Q
> Olean, NY
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> ------------------------------
> 
> Message: 7
> Date: Mon, 19 Oct 2009 08:07:31 -0600
> From: Scott Derrick <scott at tnstaafl.net>
> Subject: Re: REFLECTOR: CHT's
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Message-ID: <4ADC72A3.3070101 at tnstaafl.net>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> OK. I'll give it a shot..
> 
> Scott
> 
> aminetech at bluefrog.com wrote:
> > --- scott at tnstaafl.net wrote:
> >
> >
> >
> >
> >
> > I would think opening up a space between the plenum and some of the
> > cylinders would allow more air to not go through the fins and thus raise
> > your overall cylinder temps?
> >
> > In my case, probably a little, but that's what you want, balanced CHTs. The cooler ones increase a little while the hot ones decrease. I believe that the air escaping in the plenum/cylinder gap is still providing cooling (air has to travel over the cylinder top to get to the gap. It's simple enough to try.
> >
> > John
> >
> > _______________________________________________
> > To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector
> >
> > Visit the gallery! www.tvbf.org/gallery
> > user:pw = tvbf:jamaicangoose
> > Check new archives: www.tvbf.org/pipermail
> > Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
> >
> > 
> 
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> ------------------------------
> 
> _______________________________________________
> Visit the gallery! tvbf:jamaicangoose
> 
> End of Reflector Digest, Vol 65, Issue 85
> *****************************************

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