oil cooler spacing

I have less than a 1/2" of space between the oil cooler and muffler. I haven't epoxied the duct to lower cowl. Anyone have an average measurement for this.
I have seen a photo of the duct cut out. Does anyone have better photos and possibly instructions or dimension to do the job? Need help as fiberglass repair is not one of my strong points. Thanks for your help!

Rod

cooling

If you have not fixed its position yet, change it so that you can get 1" at least. I had about a 1/3rd of an inch and lots of hot oil readings. I moved it about 1 inch forward and solved all of the cooling problems. Sorry I don't have pictures but if you search for oil cooler mod you will find them.

Richard

Concur, you need more space

I had major oil temperature problems in our Texas summer heat. Not being able to directly measure my spacing I took several measurements from the firewall and determined that I only had 1/8 inch spacing between the oilcooler and muffler. I moved the oil cooler 1inch further forward with the lower cowling mod and have had no more oil temperature problems in our 100 f + days. IMHO you need at least 1inch between the oil cooler and muffler if you fly in The Texas summer heat. In the 90's today.
"2BK" 165 hrs

Me too, also

I moved the cooler forward also and solved my high oil temp problems. It should be MUCH easier to do this during the build than later. Search for Cowl Duct Modification-- good photos and a source for drawings that work.

Wayne 120241/143WM (205 hours)

08FATBOY said:

I have less than a 1/2" of space between the oil cooler and muffler. I haven't epoxied the duct to lower cowl. Anyone have an average measurement for this.
I have seen a photo of the duct cut out. Does anyone have better photos and possibly instructions or dimension to do the job? Need help as fiberglass repair is not one of my strong points. Thanks for your help!

Rod

Click to expand...

Rod,

living in Tucson, AZ I did not wait to discover cooling problems and I modified the oil cooler position during the build:
http://torstensrv-12.blogspot.com/2012/11/modifying-cooling-duct.html

This gave me a good enough clearance to the muffler when the oil cooler was mounted:

Everything you ever wanted to know, but was afraid to ask about the cowl mod.
http://www.vansairforce.com/community/showthread.php?t=89532&highlight=Rotax+likes+hot

Hi Macpara,

I'm in Tucson also at Ryan Airfield hangar C22 on the east side of Ryan. I have an SLSA RV12 that will be here Wed. morning (Oct.10th).

Hi Roger,

you helped me sell my RANS S-12S in 7/2011 doing the Rotax pre-sale inspection on it. Good to see you are joining the RV-12 crowd . I'll be coming by for a visit when mine is certified or I'll step by after work during the week, as I'm working close to TUS and RYN is not really much of a detour on my way home. I'm hangared at AVQ now.
I am curious what temps you will see with the SLSA but it's cooling down now pretty quickly, so we might have to see what it does next summer.

I live in the Phoenix area, and did not modify the oil cooler spacing. In summer I end up climbing in about 2000 FT steps pausing to cool down a bit at4800 RPM.

Unwanted heat.

None of us here at Ryan airfield are having any over heat issues and we see some hot OAT's in the summer, but we are all propped regardless of the prop type to 5600-5650 rpm at WOT flat and level. That said some people with their aircraft have air flow issues across the coolers and or engine.


Prop pitch can play a huge part in the engine cooling. Over pitching causes excess heat and stresses the engine. In the older Rotax crankcases (pre mid 2006) setting a prop pitch to only see about 5200 rpm at WOT (wide open throttle) was cracking some cases, hence the later SB from Rotax. The cases that came after that are different, but you still shouldn't over pitch. It hurts climb, cruise, fuel economy and causes unwanted heat. A sweet spot for many LSA with the 912ULS or UL is right around 5600-5650 rpm for a WOT flat and level pitch setting. This is a good balance since we don't have an in flight adjustable prop. That of course would be the best. Setting this at your average flight altitude makes a difference too. As an example if you live down at sea level and never get more than 1000' AGL then set it for that altitude. If you fly at 8000' most of the time set it for that average altitude. We just have to find that balance to make us and the engine happy at the same time. people always ask what the static should be. Static is really only good to use when you have an unknown prop and setting. You will always need to fly it to double check it and fine tune it after your first setting. Plus if you go from 5200 rpm WOT to 5650 rpm WOT you'll think someone just turboed your engine. There is a difference. I have change at least 100 LSA prop pitchs over the last several years and not a single person ever wanted to go back to something like 5200 rpm WOT.

Roger,

Looking at the torque and horsepower curves it looks like the optimum for the high DA locations would be 5200 RPM at Vy. I'm in PHX and run about 5050 at best rate of climb. I cruise about 116 KTAS. That seems to be the best of all worlds for me.

Rich.

Although Roger's info on prop pitching is spot-on, many 12 owners have had no choice but to modify the cowl duct. With the oil cooler as close to the muffler as many are (were), re-pitching the prop did not help. At this point there are enough success stories with this procedure, we know it will solve the problem. Bottom Line-you need at least 1 inch of clearance.

Buzz J

Rod, beautiful job! I've just installed my RV-12 engine, including oil cooler, and I've glassed the shroud to the lower cowl and I'm ready to order the avionics kit and complete the 12. However, I notice, as others have that there is only about a 3/8 inch gap between the oil cooler and the muffler! I, too, live in a hot climate...many days each year near/over 100 degrees. I, now, see yours and other threads on the web concerning this same issue. Wish I had known of this problem before glassing the shroud to the lower cowling. Has Vans engineering given any recommendations? If I need to cut & reglass part of the schroud as you have done so expertly, I would like to do it before painting. what are your thoughts? Thx!

Buzz

Oil cooler spacing input requested

Does anyone have input/recommendations for me? I'm ready to primer the cowling and continue wit the next steps...

Buzz

With the temps in Calafornia I would do the "mod".
I also modified the cowl after glassing in the shroud like in the link mentioned before ; modify cowl
No big deal, couple of hours work. My test flight was at a temperature off 77*F, the oil temp at the end of the climb was just 200*F, during cruise dropped to 185*F. Flying now with a strip off 2" to block the radiator to get the temps up.