O-320-E2D RV-9A CHT, TEMP, BAFFLES

Hello Everyone.

Sometimes things just work out by chance. Owner is happy!

A friend has a beautiful -9A that is about 11 years old and he recently put a brand new Lyc O320E2D from the factory in.
(150HP, FP Sense pitched for climb @75% she will do 145-150kts indicated at 2000 ft)

We had some problems with the carb running lean due to the RVs speed. But we have that mostly under control by now.

Engine running strong at just over 50 hours and break in should be complete.
The only real problem was that the #1 CHT was about 40F colder than the rest.

Well better cold than hot... So we went out and put a little bit of aluminum in front of the front cylinder fins. We opted to use bolts instead of rivets here for now because we thought we may have to trim and adjust and will do final pretty version with rivets once we found the right size. BTW: the only reason I assisted here was that I had to drill the 3 rivets out where the bolts are now... He is a buyer not a builder.

Here is the first try


And here is the result at cruise...WELL DAAANG!


I think that is pretty good! I kind of would have like the metal to go all the way outward and cover the fins there as well. But hard to argue with those numbers.

At Full power climb at 90kts indicated #3 will go up to 405F the others will stay below 400F. In cruise they look just about perfect. There are a few inter-cylinder areas that may need improvements but its a good start.

Couldn't get her LOP at 75% PWR but the owner is not a fan of LOP anyway.
#2 peaks about 20F before the others = Rough engine at -20F on #2. The others are at peak at that mixture.

Ideas how to fix this? Partial Carb HT maybe?

What do you guys think?

I think for a carb engine that's an impressive EGT spread. CHTs seem right in line too and the numbers look good. Watch them at higher OATs and make sure they're still OK, but I'd be very happy with this performance.

My EGT spread (RV9A, carb Titan O-340) is WAY worse than this, but CHTs are roughly in line and manageable...

RV74me said: "What do you guys think?

Taking the temp of an assembly that is so "varied" in conformation can be problematical.

Understand that I speak from the perspective of having read a NACA report that took temp readings from 30+ positions on the downstream side of the cylinder.

What you're seeing or reading is the temperature at the sensor, but what is the temperature in the areas affected by the "dam"?

My "read" of the NACA report is the "temperature map" on the backside determined a spot that was the most consistent over the range of operations, not the "absolute" temperature.

FWIW

Thanks.

krw5927 said:

I think for a carb engine that's an impressive EGT spread. CHTs seem right in line too and the numbers look good. Watch them at higher OATs and make sure they're still OK, but I'd be very happy with this performance.

My EGT spread (RV9A, carb Titan O-340) is WAY worse than this, but CHTs are roughly in line and manageable...

Click to expand...

Thanks for you input. Yes We will have too watch the temps once the summer is here. Could always climb with a little more speed.

Marc Bourget said:

RV74me said: "What do you guys think?

Taking the temp of an assembly that is so "varied" in conformation can be problematical.

Understand that I speak from the perspective of having read a NACA report that took temp readings from 30+ positions on the downstream side of the cylinder.

What you're seeing or reading is the temperature at the sensor, but what is the temperature in the areas affected by the "dam"?

My "read" of the NACA report is the "temperature map" on the backside determined a spot that was the most consistent over the range of operations, not the "absolute" temperature.

FWIW

Click to expand...

Ok. I understand that the CHT only measures one point. But from a practical standpoint that is all we have for these engines, correct? Based on your knowledge how would you improve the "dam" or come to an even better solution? I am all ears.