SonexBuilders.net

Stupid question time...

I'm almost done rebuilding my aerovee engine for my waiex and have started contemplating moving from the bottom mounted oil cooler to the top. I see in posts that folks see marginally (if any) hotter temps when they make this conversion.

My question is essentially this: I already have everything setup for a bottom mounted system, what harm (I.E. why shouldn't I) just add the top cooler to the system and keep the old bottom one too, presumably since much of the cooling on this motor comes from the oil there should be a good gain from doing this. I imagine that the adapter from Sonex and the top cooler can't be more than 1/2 a pound right? I could drink one less Mountain Dew to make up for that :D

Thoughts, comments?

-jordan

jfuerst wrote:Stupid question time...

I'm almost done rebuilding my aerovee engine for my waiex and have started contemplating moving from the bottom mounted oil cooler to the top. I see in posts that folks see marginally (if any) hotter temps when they make this conversion.

My question is essentially this: I already have everything setup for a bottom mounted system, what harm (I.E. why shouldn't I) just add the top cooler to the system and keep the old bottom one too, presumably since much of the cooling on this motor comes from the oil there should be a good gain from doing this. I imagine that the adapter from Sonex and the top cooler can't be more than 1/2 a pound right? I could drink one less Mountain Dew to make up for that :D

Thoughts, comments?

-jordan

I understand hat's what's they do in (race) cars, they never replace the std top mounted oil cooler with an external cooler, they only use the external cooler in addition to the standard cooler to get extra cooling.

One important question though, is it required?
Is your AeroVee running particularly hot? You don't want too much cooling either.
I remember on the vwaircraftengines forum someone had a 24 row bottom mounted external cooler installed (as opposed to smaller the 12 row one on the Aerovee) and he ended up having to deflect some airflow away from the cooler as he could not get the oil to warm up enough.

Another point to note, don't just count the weight of the cooler & adapter, you also need to count the weight of the additional oil in your system (although probably not significant either).

I had wondered about the possibility of the oil not getting hot enough.

I remember reading somewhere (ThaSamba) that the oil pressure relief plungers at startup function in a way that does not send oil up to the point that the top oil cooler is located until the oil heats up. If this is true it would seem that a larger bottom cooler could prevent the oil from heating up as the oil is always circulated through, even if it is not hot. If those plungers do indeed only "turn on" and move oil up to the top filter once hot, then worst case is that the use of the top cooler would be cycled on and off in conjunction with whatever temperature these plungers cycle on.

I do not believe that I have a heat problem, but I'll soon have all the hardware, and dangit, if I paid for it all, shouldn't I use it :?:

jfuerst wrote:I remember reading somewhere (ThaSamba) that the oil pressure relief plungers at startup function in a way that does not send oil up to the point that the top oil cooler is located until the oil heats up.

Correct, you can find a good explanation on how this works here:
http://www.shoptalkforums.com/viewtopic.php?t=118923

You made me look. The one I was thinking of is here http://www.thesamba.com/vw/forum/viewtopic.php?t=280293

Has pretty pictures that I remembered seeing...

I hardly ever hear of AeroVee oil temps getting too hot. In fact, it's normally the opposite, especially during the winter months. I have the top mounted cooler and during the winter here in Ohio even when I have the whole cooler taped off, I still struggle to get my oil much over 150 degrees. On the hottest days I've flown, I don't think oil has ever got over 200-205. So yes my worry is that you would have way too much oil cooler and never get your oil very hot. Ideally the best case scenario is to have oil in the 190-210 range to help boil the water out of the oil.

Plus it's just one more possible failure point, added weight, etc. My advice is just decide on a single cooler and go with it!