REFLECTOR: High Temps
Brian Michalk
michalk at awpi.com
Wed Jan 12 10:23:32 CST 2005
A very rapid increase in CHT could be an indication of detonation.
Is this accompanied by a reduction in EGT?
Does this cylinder run hotter while not leaned? If so, detonation may not
be your problem. What do the spark plugs look like?
I sound like a broken record, but retarding the timing may fix this hot
cylinder.
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> Behalf Of Gary Ciampa
> Sent: Wednesday, January 12, 2005 9:30 AM
> To: reflector at tvbf.org
> Subject: REFLECTOR: High Temps
>
>
> NOTE: First Time Post,Happy to be Here! <G>
>
> Jim,
>
> I'm flying a 173 FG, IO-360-C1D6 and have *recently* experienced
> the same high temperatures as you observe on Number 4. Running
> above 75% power and/or any attempt to lean, shoots the number 4
> cylinder up to 450F pretty quickly. A short bit of history, not
> to bore anyone but to provide a bit of context.
>
> I purchased the airplane in May of 2004 and had need to replace
> the exhaust stack. The original configuration was updraft
> cooling, rear exit exhaust, cylinder wraps around each cylinder
> head/barrel, fore and aft with a reverse scoop in the top cowling
> above Number 4, I also have two VG's in front of the NACA scoop
> on the right side only. In reviewing the logs and in discussions
> with the former owner, cooling number 4 has always been watched closely.
>
> In replacing the exhaust stack I made the decision to switch to
> the forward facing exhaust (at this point, I'm not sure if this
> was the correct decision, I'll know when the cowling work and
> temperature problems are corrected). In any case, with the new
> exhaust in place the temps on Number 4 are high, once again.
>
> The changes to the cowling included cutting holes near the NACA
> scoops for the forward exhaust exit, cutting out the fiberglass
> shrouds for rear exit exhaust and six layers of BID layed in to
> cover the holes for the old exhaust scheme. Also, fabricated a
> scoop in the cowling under the exhaust for Number 1, as this bend
> in the exhaust pipe extends below the cowling about three-fourths
> of an inch.
>
> Our current *theory* on how to correct the temperatures on number
> 4 include:
>
> 1. Remove the inner cylinder baffles that wrap between Number 2
> and Number 4, with a stock Lycoming Intercylinder Baffle. This
> will allow more air to flow up through the cylinder heads (I will
> note that other posts seem to indicate no problems with having
> these baffles between number 2/4.)
>
> 2. Experiment with deflectors along the inside bottom of the
> lower cowling, perpendicular to the longitudinal axis, in the
> vicinity of Number 2. The theory being that we can buffer the
> cooling air in front of Number 2, creating additional pressure so
> that air will be forced through Number 4.
>
> NOTE: Number 1 and 2 are running cold. Number 3 is within
> limits(I suspect that fact that Number 3 temperatures are
> acceptable may be a result of the scoop under Number 1 forcing
> more air up through Number 3)
>
> 3. Finally: replace updraft with downdraft cooling (least
> attractive alternative, but recommended by our friends at Velocity).
>
> Of course, the information above is subject to the vagaries of
> the author and may not be reliable, time will tell.
>
> Warm regards,
>
> Gary
>
> ----- Original Message -----
> From: "Jim & Sharon Beck" <jsbeck at charter.net>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Tuesday, January 11, 2005 10:28 PM
> Subject: REFLECTOR: High temps
>
>
>
> I have a 173 RG that was completed in 2001 and then not flown
> until recently and since I did not build it my questions may seem
> simple to you more experienced builders & pilots. It has a newly
> rebuild IO 360 A1B6 that now has about 10 hours on it. The 2
> front cylinders are running about 425 to 450 and the oil tem is
> running about 225 at cruise. Should I be considering a second
> oil cooler or might these temps come down as it breaks in. These
> a winter time temperatures so it seems when summer comes I'll be
> over redline. Anyone help on this or thoughts would be appreciated.
> Jim
>
> _______________________________________________
> 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
More information about the Reflector
mailing list