[C-FAH Q]

In the search for a little more speed, I have embarked on the mythical world(to me anyway) of exit air flow modification, as it relates to the flow of air from the back of the oil cooler. I decided to make a plenum for the back of my oil cooler and, in seperate test stages, will find out what works and what does not for my current configuration. I have a IO-360 A1B6 with hartzell contstant speed and superior cold air sump with a Rod Bower Ram Air induction. I installed a 9 row oil cooler , which was the largest I could fit on the back of the baffles behind the number 4 cylinder. My current oil temps run around 197 degrees at 23 square, leaned to best power and on a fairly wam and humid day. I am happy with that oil temp but want to see if i can increase efficiency of airflow.
First step was to make a plenum to fit on the back of the cooler and leave room for clearance for the engine mount.

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I did this by taking a foam block and started to hack, chop and file to get the shape I wanted. Next step was to glass over the shape, cure, remove the plug and attatch it to the back of the cooler and then seal up any gaps with RTV.
I will test fly this soon and see if my temps are affected for the better or worse. After that, I plan to attatch a 4 inch skeet tube to the bottom of the outlet I made and direct the airflow down to the lower cowl, near the exhaust pipes. Hopefuly this works, if not, other mods are in the works with regards to smoothing airflow to more gently guide the airflow out the lower cowl and possibly directing the oil cooler airflow out the side of the cowling if other mods dont work. The three pics are of the part that was made and the last is a last resort of airflow redirection.

Hopefully some of this ends up giving me better airflow and some better speed. If it dosnt....oh well, it was fun doing it anyway.

 

[burgundyja]

louvers

I was thinking about this also. What if you flipped that Upside-down and trim the length then put louvers on the top cowl. I think the top is low pressure and the bottom is high. If it works then you could. Block some of the bottom exit air.

 

[rvmills]

Gary,

Looks good, and this is on my list of wanna-try mods too. My cooler is in the same location, so the thought is similar. Did you look at John Huft's site on how he did this? He might have some additional ideas on the ducting path out of the plenum.

Some thoughts, ideas and questions (for you and other readers):

I was thinking of using a smaller, convergent plenum that necked down to a 2" scat tube, then running that tube down to above the exit opening, pointed down and back. Since the air from on top of the engine is hi pressure, low velocity as it hits the oil cooler, I thought perhaps re-accelrating the air coming out of the cooler by using the convergent plenum and 2" scat, then directing it down and aft might help accelerate the exit of the engine cooling air out of the exit...especially if the exit area itself necks down into a venturi-like shape (as shown in Speed With Economy). My only concern would be that the convergent plenum might somehow cause backpressure of sorts at the oil cooler itself, and degrade oil cooler airflow and performance. Have you guys at the Fairlea Skunk Works talked about that? Interested in how you came up with the plenum shape and the 4" sceet sizing. Thoughts? (John H?, Dan H?)

I recently modded my fresh air/heater air mixer to direct the overflow air from it down to the exit in much the same way. My plan is to direct as much air (oil cooler outlet and heater overflow) to the exit to act as little "flow augmenters", and then try to somehow fair the cooling air from the back of the cylinders towards the exit, so it doesn't bash into the firewall and all the "stuff" on it. That "stuff" is the hard part to work around. Not original thinking on my part...I think Dan H built his 8 with that concept in place, and Tom's had some good ideas...just need to play with them a bit (perhaps a winter project or two!)

Really interested to see your results...and if its a bust, you could vent it over the wing like that last picture, and get some really cool warbird-like "exhaust" stains running up and over your wing!

Nice job! See you in OSH?

Cheers,
Bob

 

[C-FAH Q]

Bob,
Osh is nothing more than a mythical place I will never get to untill I retire. The less I think about going, the less depressed I get about not going...if that makes any sense?
Time will tell if the mods work or not, lots of options and tweaking to do along the way.
See ya at the Great Canadian Air Rally
http://www.sportairrace.org/id335.html
This will be a good time with a BBQ'ed animal of some kind, live music and lots of great people. Hopefully some of you will make the trip.( i know Bob is!)

 

[kentb]

Gary, it looks like this should be a winner.

I'll be following you post on this.
If it works out for you, than I want to copy you mode.

Kent

 

[rvmills]

Bob,
Osh is nothing more than a mythical place I will never get to untill I retire. The less I think about going, the less depressed I get about not going...if that makes any sense?
Time will tell if the mods work or not, lots of options and tweaking to do along the way.
See ya at the Great Canadian Air Rally
http://www.sportairrace.org/id335.html
This will be a good time with a BBQ'ed animal of some kind, live music and lots of great people. Hopefully some of you will make the trip.( i know Bob is!)

Gary...OSH and the height of golf season coincide...thought it might make it hard. Someday we'll get Bill Murray to come up and mind the courses to get you some OSH time ("to win, you must think like the gopher...and whenever possible...to look like one"...Caddy Shack paraphrase).

Good luck with the mod, and C-Ya in August!!

Cheers,
Bob

 

[C-FAH Q]

Bill Murray has been here on a number of occasions. He is not far off the caddy-shack character. He is a very nice fella and one heck of a golfer. I picked him up at the airport one day and he was wearing a plaid shirt, striped shorts and two different colour ankle socks and a Tilley hat...... exactly what i expected.