> This is Dave's current system. He is not entirely happy
> with the water cooling.
> Air flows through the inter cooler on the left side and the oil
> cooler on the right side and then through the 2 inch thick rad
> mounted below the engine and out the exit below the cowl.
> The air is also heated by passing over the turbo charger
> and exhaust manifold before it flows through the rad.
>
> Does anybody have any suggestions what Dave could to to improve
> the water cooling?
>
> Oil cooling and inter cooling are fine.
Leave the oil cooler and intercooler ducted & positioned as-is. Leave
the radiator positioned as-is, but add a chin scoop and duct to the
current backside of the radiator. Let the airflow through the radiator
be reversed from the current pathway. Add vents on the top of the cowl
slightly ahead of the firewall. If the windscreen is near the
firewall,
that area of the cowl should be a lower pressure area (compared to the
rest of the cowl; it's still high relative to the static port).
Russell Kent
Russel,
I like that Idea best so far, as it would be the easiest to implement
and would leave the cleanest looking cowl..
There is little doubt that the other suggestions could be made to work
as well. Some would be impossible because of limited space.
However, I would like to now throw out some other points for
consideration:
1) The point of improving my cooling system is all about going faster.
After all, it works perfectly fine (em... recent incident excluded) to
get average performance for an RV.
2) up above 200 mph. (the speed I now travel at) reduction in drag
becomes more important than increases in power
3) Cooling drag is 10% of overall drag - give or take.
4) Therefore, maintaining low cooling drag, or decreasing it, should
take priority in any planned improvements - for reasons of both speed
and economy. After all, we want to disprove the rotary's reputation as
a gas gussler.
So given the 'minimize cooling drag' premise, I submit that:
1) All air used for cooling must be heated to the maximum extent -
otherwise it is waisted cooling drag.
And I know from measuring temperatures in my cowl that:
1) The intercooler and oil cooler add very little temperature rise to
the incoming air, about 10-20 deg. There is plenty more cooling to be
had from it (as is proved by the relative success of my current system).
So, until convinced otherwise, I am more or less committed to the
minimization of cooling drag and the re-use of my intercooler and oil
cooler air for at least some of the water cooling.
That being said, improvement is needed. Clearly, more air is part of
that solution. The other part of the solution appears to be more
radiator volume - used to obtain more cooling from each bit of air.
Weight penalty yes, but still more efficient IMHO.
Paul is a big proponent of a cowl flap, and I agree. As soon as things
are cooling so well that I need to warm things up in cruise, it will be
a simple matter to add a cowl flap to close down the air outlet.
A spray system is still an excellent addition for augmenting climb
cooling without adding drag. Used mostly for bragging rights etc. but I
have not ruled that out yet.
And that's all I know. (well, pretty sure of anyway :-)
BTW, I have also come to accept the wisdom that the rotary does not
tolerate temperatures above 180 very well. My previous red-line was
230 and I would not start reducing power until it hit 210. In the
future, my "reduce power" limit will be 190 and redline (dramatically
reduce power) will be 210. The goal is to not get there very often.
Unfortunately, that is the big problem with the turbo. I can always make
more power. And BHP is like money: not matter how much I have, I
always would like a little more.
--
Dave Leonard
Turbo Rotary RV-6 N4VY
http://members.aol.com/_ht_a/rotaryroster/index.html
http://members.aol.com/_ht_a/vp4skydoc/index.html
Dave,
Bearing in mind the rule of thumb that a Paul uses about the effect
higher temperatures decreasing the available cooling I think you would be
better off not preheating the air for your coolant. You are right though
about about making the air going into your intercooler and oil cooler do
more work. Why not use less air into these, idealy to the point where the
outcoming air is at some maximum desirable level. Use the remaining unused
air and possibly a little more to cool the coolant using properly designed
ducts. This way your radiator is seeing cooler air thus allowing the use of
less air overall.
John
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