Mailing List lml@lancaironline.net Message #70540
From: Colyn Case <colyncase@earthlink.net>
Subject: Re: [LML] TSIO 550 Climb profile
Date: Mon, 11 Aug 2014 07:14:04 -0400
To: Lancair Mailing List <lml@lancaironline.net>
no.  Part of what you may be seeing is that there's a mixture boost near the high end of the throttle setting.   So, ironically, reducing the throttle for cruise climb can actually be harder on the engine.

Colyn

On Aug 10, 2014, at 4:57 PM, Jay Phillips wrote:

I'm going to have to take back what I said about climb speeds, at least
conditionally.

For comparison, the general take-off and climb profile I use is as follows:

Take-off: 2700 RPM, full-rich mixture, WOT, yields 38.5" MP, and about 42
gph fuel flow. I stay with this until I reach 1500' AGL, then reduce RPM to
2500 and Throttle to 31.5" MAP. I then climb using these settings and 165
IAS until I reach cruise altitude. I struggle to keep the hottest cylinders
(#3 & #4) below 400F. Total flight time from lift-off to 17,500' MSL
(starting at 5,100' AGL field elevation) is typically 20-22 minutes at an
average burn rate of about 25 gph.

This morning I performed a test: at 1500' AGL I reduced RPM to 2500, but
left WOT and full-rich mixture. I set the AP for 145 IAS climb to 17,500 MSL
(starting at 5100' field elevation). Total flight time was 11:05.  Fuel burn
average was around 35 gph. The best part? Hottest cylinder (#3) never went
over 380F.

25 gph for 20 minutes = 8.3 gallons.
35 gph for 11 minutes = 6.4 gallons.

So the WOT climb profile is faster, burns less fuel, and keeps the cylinders
cooler. Anyone see anything wrong with this?

Jay Phillips

-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Jay
Phillips
Sent: Thursday, August 07, 2014 4:28 AM
To: Lancair Mailing List
Subject: [LML] Re: High CHTs on #2, TSIO 550

Thomas,

I had a similar problem when I first bought my IV-P - #2 ran hot during
climb, and I could alleviate it a bit by partially closing the oil cooler
door.

The back side of the #2 cylinder is right up against the forward side of the
oil cooler. It doesn't leave much room for airflow. I had a modification
installed (don't know what it is called, but any shop knowledgeable on
IV-P's should know what it is) that added some concavity to the front side
of the oil cooler, providing more room for airflow around the back of the #2
cylinder.

In my case, at the same time we discovered I had a burned exhaust valve on
the #2 cylinder. Whether that was related or not I'll leave to the engine
experts. We also changed the baffling around the prop hub to better control
the airflow. After all was said and done (including an engine overhaul -
different problem) my #2 CHT now behaves and #'s 1,2, 5, and 6 are pretty
close in CHT. #'s 3 and 4 are now my warmest. I still don't have it where I
want it but it is a lot better.

I think your IAS during climb is too low. Try using 165 or 175 IAS for climb
speed and see how that affects things. Using 165 I used to have to level off
at about 13,000' to allow the airspeed to climb and provide cooling air and
time to bring my CHT back down. Once it was trending downwards I would
continue the climb.

You don't mention your MP during climb. I used to (and still do sometimes)
used 31.5" during climb. One suggestion I received was to continue climbing
at WOT. That helped a lot although it uses a lot of fuel. I've also tried
lowering power to somewhere between 27.5" - 29.5" - that also helps.

If you haven't already you should check compression and put a borescope into
#2 to make sure something else isn't going on.

Jay Phillips

-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of
Thomas Whalen
Sent: Wednesday, August 06, 2014 1:20 PM
To: Lancair Mailing List
Subject: [LML] High CHTs on #2, TSIO 550

I have been fighting for over a year to try to keep the #2 CHT below 400 dg
on the climb. It has hit as high as 430. I leave it full rich and climb at
140kts. When I level off, I then LOP and then #1 cools off. I have the
Lancair baffles and RTV the gaps with the engine and have a good baffle
seal. I even covered my 3rd intercooler and that only helped a little.
Behind the prop the baffle seals up to the top cowl but not down to the
bottom. I have seen it the reverse of that as well. If close the oil cooler
door the CHT will drop 5dg at times.
This was a factory new engine.
Any suggestions?

Thomas Whalen
N444TW
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