CHT questions again - Page 3

JDA_BTR · #21 09-09-2019, 07:39 PM

Question: at the inboard side of the inlets is the rubber from the ramp put inboard of the lower cowl rubber? Or outboard sticking into the inlet. I’ve always had it inboard seems to lie better that way. ?

DanH · #22 09-09-2019, 07:47 PM

Quote:

Originally Posted by JDA_BTR

Dan maybe I should fly over Saturday and get some help or advice if you are willing.

Gotta be at a ribbon cutting on Saturday. Maybe Sunday? Glad to help.

JDA_BTR · #23 09-11-2019, 08:28 PM

So I investigated the top cowling carefully. At the outboard sides of the ramps the ramps didn't quite seal to the top and there were about 3 inches of slightly open space there (1/8-1/4 gap). On the right I don't think it mattered much. On the left it would mean that air going up the governor hole could go across and down the gap next to the #2 cylinder.

So I floxed the gaps. I played with the lower baffles some. I sealed the sides of the baffles better. I made sure as much of the inlets as possible were sealed with gasket material even though it made the seals a little weird looking the way they laid down.

The OAT at 3500 ft this evening was 72 degrees (S. Louisiana...). The max temp I got on the climb was 389 (on number 2), and cruising around 25MAP, 2400RPM and fully leaned #2 temp got up to 382. It would have been more before my changes. #1 is next in the 355 range and #3/4 very cool 310/315.

So I made things better OVERALL, but haven't made #2 cooler compared to the others. On the other hand it isn't crowding 400 when I lean it hard either....

So maybe it is time again to just sit back and see what the temps do over the next 40 hours. I'm at 60 now.

gereed75 · #24 09-12-2019, 07:35 AM

Where is the oil cooler air vented from?

On my James Plenum 6 with an outlet to the oil cooler behind the left rear cylinder, that cylinder runs 25-30 degrees hotter than others. I have an oil cooler door that I can use to close flow to the cooler. When that door is closed, the back left cylinder temp goes down about 20 degrees

The cooler vent “robs” enough air from that cylinder to make a difference.

Tom Martin · #25 09-12-2019, 08:08 AM

regarding the governor seal. I am not sure what you meant by floxing the gap? Making gap smaller will help but air will still take the easiest way out of the plenum.
To seal this area I made a small plenum for the governor. Take a soup can that is larger than the governor and lay two or three layers of glass around it. When set, pop it off the can and then glass this piece into the governor cut out. This will ensure a complete seal in this area.
I had forgotten that the 14 baffles had incorporated the improved cooling on the forward part of number 2 and the aft of number 3. Take a look at this area again and see if you, by chance, plugged the gap with sealant? This gap is on the forward out board part of the cylinder and lets the air go down and cool the hot forward top of the cylinder.

Not all engines are the same and not all cylinders are the same. It is possible that you have a hotter number 2 cylinder. Take a flashlight and look down the cooling fins from the top and make sure that there is nothing blocking airflow. A few years ago, quality control had gone for a **** and I found a bunch of casting sand and slag in the fins of a brand new cylinder. A little competition from ECI and Superior greatly improved Lycoming quality.

Bavafa · #26 09-12-2019, 08:43 AM

Quote:

Originally Posted by JDA_BTR

So I investigated the top cowling carefully. At the outboard sides of the ramps the ramps didn't quite seal to the top and there were about 3 inches of slightly open space there (1/8-1/4 gap). On the right I don't think it mattered much. On the left it would mean that air going up the governor hole could go across and down the gap next to the #2 cylinder.

So I floxed the gaps. I played with the lower baffles some. I sealed the sides of the baffles better. I made sure as much of the inlets as possible were sealed with gasket material even though it made the seals a little weird looking the way they laid down.

So maybe it is time again to just sit back and see what the temps do over the next 40 hours. I'm at 60 now.

Tweaking baffles are often incremental and we all take those as they are gained so great job there.

One other area that is worth checking? the foam/dam that we create and install under the left upper ramp inlet need to seal well. This is the foam that goes right above the governor which you just worked on. If that is not sealing, you could have air scape on the opposite side that you just fixed.

JDA_BTR · #27 09-12-2019, 10:38 AM

Tom I will look and see. I didn?t put sealant on the front of number 2 because the piece has to come off for the filter. I?m not sure exactly where this designer gap is supposed to be in relation to old baffles.

The oil cooler is no factor it is low right behind number 3 which is very happy.

Tom Martin · #28 09-12-2019, 12:00 PM

The cowling and inlets are much better then RVs in the past. That does not mean that there are not some improvements possible.
Note the following picture

http://halie.com/o5v.jpg

Ideally the inlets should run parallel to the direction of flight or slightly diverge. You can see in the picture that the top of the plenum is correct but the outboard edges actually converge. This causes both turbulence and a decrease in the size of the inlet. I cut the offending corner off and then clamped the proposed rubber baffle in place. After waxing a new edge was formed that solved the problem of turbulence and at the same time making a perfect seal with the baffle material.

Here is the modified lower corner. After it is done you can do the upper inlet corners to make a perfect inlet. It really is about an hour a day for two or three days to get it done.

http://halie.com/o5W.jpg

Here is the final inlet picture

Note I have also cleaned up the inboard corners as well, this provides both a better seal and at the same time a better flow of air.

http://halie.com/o51.jpg

JHartline · #29 09-12-2019, 12:16 PM

Tom, yours is one of the first RV-14?s flying. How many hours and any unexpected surprises?

Tom Martin · #30 09-12-2019, 12:20 PM

The RV14 is a wonderful airplane and is a great cross country machine. I had to chose between the RV14 and the Rocket and I decided to stay with my rocket. The RV14 sold with about 60 hours on it and the new owner has been flying for quite a will now and is very happy with the plane.
I would certainly recommend the RV14 to new builders. Van's has done a great job with this aircraft.