Thor McIlrath RV-10 Engine Cooling

We are getting the temps a little warm on number 2 and 5 CHT and thinking about putting cowl flaps in. We really dont see any downside but wondering if anyone out there has any experience. Thanks in advance.

Our cooling louvers have been used with a lot of success for those who have cylinder cooling issues. The standard size ones will fit on an RV-10.

http://www.aircraftspecialty.com/rvall1.html

That might be an easier mod than installing cowl flaps. If your temps end up too cool in the winter, you could always fabricate a plate to cover the inside for winter flying.

Take care and let us know if you have any questions,
Steve

Your first step should be to balance all six fuel/air ratios by swapping out injectors as needed.
Then adjust baffles, air dams, etc, to even out CHTs.
Then decide if you need more cooling.

BobTurner said:

Your first step should be to balance all six fuel/air ratios by swapping out injectors as needed.
Then adjust baffles, air dams, etc, to even out CHTs.
Then decide if you need more cooling.

Click to expand...

Wise words here. I too experienced high CHTs during Phase 1, most notably on 5 and 6. I tried several things:

* Removed the air dams from the front of 1 & 2. (This helped 1&2)
* Drilling out the crud in the fins left over from the casting process. (No noticeable effect)
* Putting a washer behind #5 cylinder to give a little space between the baffle and the back of the cylinder. (This helped some)
* Went to Airflow Performance, had my injectors balanced. (This made a HUGE difference, and pretty much put me right where I wanted to be).

The only time I see north of 400 on CHTs is when climbing out at Vx for several minutes.

I experienced the same issue with the front cylinders and #5. I cut my front air dams down to about 1/3 of the original size, and I modified the rear baffle behind #5 to allow for more air flow by removing some of the bend. I have around 1/16" airflow now between the baffle and the cylinder. In addition, I flow matched my injectors. The flow matching did not help to any great degree as they were pretty close to start with. I can climb at Vx for about 3 or 4 minutes before I hit 400 degrees. I normally climb out at 120 kts, and never see more than 380.

Thor McLirath RV10 Engine Cooling

Some over here have had good cooling results with "letterbox" vents outboard of the main bottom cowl, exhaust vent. Easily done and not visible from the side of the aircraft. Three sided cut on both sides of cowl (about 4 1/4" wide 6" long) push up about inch and a half, then fill in the sides. ( best to take out top skin and honeycomb down to the bottom layer so nice curve can be achieved) No apparent speed penalty and no ongoing maintenance. Another plus is a handy hand hole/grip when fitting bottom cowl. Cheers from Western Australia

Thor RV10 said:

We are getting the temps a little warm on number 2 and 5 CHT and thinking about putting cowl flaps in. We really dont see any downside but wondering if anyone out there has any experience. Thanks in advance.

Click to expand...

Two and five are the cylinders with baffle tin hard against the head where there is no fin depth. You can crutch it with a washer or two under the screw that holds the tin against the cylinder, or fix it with a variety of bypass passages to allow air to the fins in the lower quarter of the cylinder head.

Read these:

http://www.vansairforce.com/community/showthread.php?t=37835

http://www.vansairforce.com/community/showthread.php?t=113134

http://www.vansairforce.com/community/showthread.php?p=1054640

Cowl flaps

You asked about cowl flaps- these are really nice-http://antisplataero.com/EZ_Cool_Flap.html

I would balance the jets first, as many recommended, it will make for a better leaning engine and with that will come the cooler CHT's. Airflow will work with you over the phone, they are a good group of folks. I did mine on my own and get about .1-.3 usually, My temps go down below 400F quickly when I pull back and lean, if I dont lean temps dont drop much.
#2 cut that dam a little more, #5, my #3 was the coolest so I took the advice of my mentor and put a dam over the #3, that brought my temps lower for #5 and alittle hotter for #3 and pretty close from coolest to hottest- range about 40F.

Pascal

dam at #3

Could you provide a photo and more information about your "dam at #3"?

Thanks!

Jerry