How high are your front cylinder air dams?

[DCBrown198]

i'm trying to get the #1 and #2 cylinder head temps down a bit compared to the remaining 4 cylinders. Need to achieve a 25 degree drop if possible - particularly in climb modes. Other cylinders are OK.

I'm trying to wrap my head around imagining air flow at those front two cylinders. Does lowering the height of that air dam enhance front cylinder cooling or the opposite? For those of you with good front cylinder cooling, how high are your dams / plates?

Thanks!

David

 

[lr172]

i'm trying to get the #1 and #2 cylinder head temps down a bit compared to the remaining 4 cylinders. Need to achieve a 25 degree drop if possible - particularly in climb modes. Other cylinders are OK.

I'm trying to wrap my head around imagining air flow at those front two cylinders. Does lowering the height of that air dam enhance front cylinder cooling or the opposite? For those of you with good front cylinder cooling, how high are your dams / plates?

Thanks!

David

Yes, cutting down the dam will send more air to front cyl and less to rear cylinder. One of my dams is completely gone (2,4,6, iirc) and the other is about half its original size.

 

[soloff]

I removed both, which reduced the CHT’s about 30 degrees in the summer. I think it added more cooling drag and reduced the airspeed slightly, but I didn’t do an exact comparison before and after.
I’m planning to install nut plates so I can easily swap out air dams of different sizes for the summer and winter months.

 

[Jesse23]

Both are gone. Most new 10 builders do not install them. I am in FL. I do not see any temps over 385 climbing @120 to 10K. 350-365 in cruise.

 

[rocketman1988]

I never installed them; cylinder 2 is still the hottest one but within acceptable range.

 

[DaveN]

I removed both before Phase I was finished; all cylinders within 10 degrees of each other in almost all phases of flight and no cooling issues once I diligently worked to resolve all air leaks.

 

[Strikhedonia]

I have about 1/3" of high temp foil tape over cylinder 1 and no dam on cylinder 2, not as good as DaveN but I have about 17 degree spread (#1 hottest and #6 coolest).

 

[bjdecker]

RV-7, IO-360-A1B6 ("Angle Valve"), with a tight - custom plenum cover & baffle.

The temp riser in front of #1 is about 3/4 (75%) of the original riser height. The #2 riser was replaced with the version from the RV-14 baffle kit.

OAT: 29.7°C / 85.5°F
CHTs at top of climb from 800MSL to 6500MSL are : 343, 332, 334, 308

OAT: 18°C / 64.4°F
CHT's In cruise, 40°F LOP/ 10GPH, 6500MSL : 298, 304, 301, 279

At some point, I am going to trim the #1 riser another 1/2" -- the hopes being that #1 will run a bit cooler in climb, and #4 will be a bit warmer in cruise...

 

[[email protected]]

RV-7, IO-360-A1B6 ("Angle Valve"), with a tight - custom plenum cover & baffle.

The temp riser in front of #1 is about 3/4 (75%) of the original riser height. The #2 riser was replaced with the version from the RV-14 baffle kit.

OAT: 29.7°C / 85.5°F
CHTs at top of climb from 800MSL to 6500MSL are : 343, 332, 334, 308

OAT: 18°C / 64.4°F
CHT's In cruise, 40°F LOP/ 10GPH, 6500MSL : 298, 304, 301, 279

At some point, I am going to trim the #1 riser another 1/2" -- the hopes being that #1 will run a bit cooler in climb, and #4 will be a bit warmer in cruise...

I used Velcro to attach mine till I go it right. easy to take out and reinstall if needed. No need for nut plates, But, they would work also. Haven't had any baffles come loose in five years either.
But my luck varies FIXIT

 

[Auburntsts]

My right dam (cyl 1-3-5) is the stock height. I originally had a hot #5 but did the baffle washer trick which solved that issue. I could have probably removed the dam altogether a long time ago but have never bothered. The left one, on the other hand, I’ve removed altogether.

 

[Kyle Boatright]

I don't have dams on either 1 or 2. #2 is one of my hotter cylinders (along with #6). It might be that a short dam on #1 would be beneficial for me.

 

[Papa]

I don't have dams on either 1 or 2. #2 is one of my hotter cylinders (along with #6). It might be that a short dam on #1 would be beneficial for me.

Recommend that you try some aluminum tape first…easy to experiment around to find the optimal size. I did that “temporarily” 15 years ago and it’s still there!

 

[Webb]

I removed #1 and on #2, cut it in half and cut a deflector to push the air down as well as pried the mount away from the cylinder. Like #3, the casting doesn’t allow air to the lower fins unless there is a space. There is a lengthy thread on cooling #3 so you can read about it. All mine run within 5 degrees of each other in cruise now.

As I understand the design the deflectors were designed to direct more air to the rear cylinders. Without, the fronts get more air for cooling and the rear less. Someone can verify this bit all I know is what I did narrowed the spread.

 

[amckeen]

I removed #1 and on #2, cut it in half and cut a deflector to push the air down as well as pried the mount away from the cylinder. Like #3, the casting doesn’t allow air to the lower fins unless there is a space. There is a lengthy thread on cooling #3 so you can read about it. All mine run within 5 degrees of each other in cruise now.

As I understand the design the deflectors were designed to direct more air to the rear cylinders. Without, the fronts get more air for cooling and the rear less. Someone can verify this bit all I know is what I did narrowed the spread.

Is it possible that #2 could benefit from a similar baffle spacer that helps #3/6 cylinders ? My O-320 #2 with no air dam is my hottest CHT too.

 

[lr172]

Is it possible that #2 could benefit from a similar baffle spacer that helps #3/6 cylinders ? My O-320 #2 with no air dam is my hottest CHT too.

Yes. I have done that modification on my 10 and #2 is pretty much the same temp as #1 and I may still have half a dam in front of #2. I just can't remember which side the dam is on. Did the same on my 6 (320) and have half a dam in front of #2 and it is my coolest cyl.

 

[Webb]

Is it possible that #2 could benefit from a similar baffle spacer that helps #3/6 cylinders ? My O-320 #2 with no air dam is my hottest CHT too.

.

Most definitely. That side of the jug doesn’t allow air to get to lower fins.

 

[Webb]

Not sure if the deflector contributes much over pulling the baffling away from #2 cylinder but I’m not going to question the success.

For the curious about the FIRE 1&2, that’s the air temp exiting the cowl. 2 thermocouples mounted on the firewall. And if one show high heat, I’m not worried about. If both show, I know I have a problem. I used the TIT and renamed it since I don’t have turbines.

 

[Tweetr]

I trimmed 1/2" off of the height of the #1 cylinder air dam, retaining its profile shape. My #1 cylinder had been always hotter than #2. With that modification and the #2 air dam unchanged, the CHTs on all 6 cylinders stay very close to each other in all phases of flight. Seems to be about right.