Cylinder 5 and 6 front baffles

[hilltop170]

Since I can't post pictures to a PM, I was asked to post some pictures of the front baffles on cylinders #5 and #6. Here are the baffles provided by Airforms as installed on my O-300-D.

Click on picture to enlarge, then click again to enlarge again

Cylinder #5 front baffle

Cylinder #6 front baffle

[blueldr]

Looks like the majority of the bugs go for the left bank.

[170C]

Richard, I noticed that your baffles each have an opening in them as opposed to some owner produced baffles and those I have observed on some 172's that are solid. Wondering if those folks at Airform did any engineering and found the openings were necessary for proper cylinder cooling ? I have considered making some myself and attaching them to the existing baffle areas.

[hilltop170]

These baffles would be very easy to fabricate but Airforms will probably sell a set if they were asked.

Yesterday, flying at 5500', all of the cylinders were between 315 and 330 CHT except #5 which was 285. I think I will tape over the hole and see if that helps on #5.

The hole in #6 is there for clearance for the exhaust flange because it sticks out a little past the edge of the cooling fins. The hole does not seem to effect the CHT of #6 like it does #5 CHT.

[hilltop170]

I really need to get my hands on a set of these. If anyone knows where I can get them used or new, please send me a PM!

#5 & 6 consistently run cooler CHTs for me and I think this is the solution to even out the airflow. Thanks for posting these pics.

Very interesting!!! I just looked at the Airforms website and they don't show the front baffles on the exploded parts picture. I had the s/n 1 set of their baffles for the 170A With the air box baffle system and I specified front baffles so I don't know what happened.

Again, they would be very easy to fabricate if Airforms won't sell them. If anyone calls Airforms to ask about them, talk to Levi if he is still there, he is the CNC guy that made them and should still have the data to make them.

[GAHorn]

These baffles would be very easy to fabricate but Airforms will probably sell a set if they were asked.

Yesterday, flying at 5500', all of the cylinders were between 315 and 330 CHT except #5 which was 285. I think I will tape over the hole and see if that helps on #5.

The hole in #6 is there for clearance for the exhaust flange because it sticks out a little past the edge of the cooling fins. The hole does not seem to effect the CHT of #6 like it does #5 CHT.

The "hot spot" created at the #6 exhaust flange needs additional cooling to service that valve. The #5 square opening is not necessary and I wonder why they have it at all unless for head-fin clearance as it will cause a cool spot.

The later 172 used the front baffles, as generally depicted.

[hilltop170]

Cessnas have had this problem since day one but nobody knew what was going on until 6-position CHTs came along. I installed a 6-probe CHT on my 180 in 1996 when it was upgraded to the O-520. The plane is in Alaska and when I saw what was happening with front cylinder CHT, I called Steve Knopp who had STC'd the engine installation and asked him about it. He told me to make a set of front baffles similar to the ones pictured. The CHTs immediately levelled out and run that way to this day usually within 25-30 degrees of each other. That has to be better for engine life.

The 170 has the same problem and the front baffles will have the same effect to even out the CHTs. The bottom line is front baffles don't hurt anything, they make the front cylinder cooling more like the other four cylinders. There is no reason not to install them if you want them. I would install them again even if I had to make a set. I would not put the hole in #5 though.

[GAHorn]

...

George, when you mention "later 172s", I'm assuming you mean the Lycoming powered ones? If Cessna never put these on Continental engined 170/172s, then that solves my dilemma on what to do very quickly.

No.....I mean the Continental models, thru the mid-60s.

[blueldr]

Richard Pulley,
In your above message you mentioned that you upgraded your C-180 to the 520 engine. Did you also change the fuel system to injected or did you maintain the 470 induction system? If your engine is carbureted, what is the estimated horsepower ?

[hilltop170]

Richard Pulley,
In your above message you mentioned that you upgraded your C-180 to the 520 engine. Did you also change the fuel system to injected or did you maintain the 470 induction system? If your engine is carbureted, what is the estimated horsepower ?

Dick-
The PPonk O-470-50 conversion (470+50=520) can use the stock C-180 induction system, exhaust, motor mount, etc. The only things that had to change was the main jet in the carb and the cylinders. I chose to use an actual 520 but Steve Knopp (PPonk spelled backwards) will machine out the 470 case to accept 520 jugs if you choose to go that way. 520 cylinders have 1/4" larger bore, same stroke.

The O-470-50 engine only turns 2700rpm instead of the 2850rpm for the IO-520-D on the 185, so you don't get 300hp any longer. PPonk claims 250hp but it's probably more like 270. Anyway, I have never felt like I needed any more hp than that in the 180. I have competed at the Valdez STOL competition several times and average 300' for landing and take-off. My 180 is very heavy with all the stuff on it but it still performs good enough for me. I regularly operate out of an 800' strip at my cabin with plenty of room to spare. It's at sea level with no obstacles.

PPonk also has an injected 520 conversion STC'd for the 180/182 but that gets complicated with fuel pumps, header tanks, plumbing, etc that I didn't want to deal with but you end up with an honest 300hp.

[rusty]

View of front baffles on my 64 Skyhawk.
Rusty

[rusty]

Thanks for the complement, its a lot of work but everyone likes how they look

[hilltop170]

Yesterday, I covered the hole in #5 cylinder front baffle with aluminum tape then went flying to see what happened to #5 CHT. It looks like a success, #5 cylinder CHT above 300F and all cylinders match up with their respective opposite sides (the dark bars on the UBG-16).

#5 cylinder front baffle with cooling hole

CHTs after covering hole in #5 cylinder baffle

[johneeb]

Richard, is the ADF 910 frequency Country and (or) Western?

[Bruce Fenstermacher]

BTW Richard, that scoop for the heat air intake is nice looking but not stock.