>
> > 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/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
Actually, I think Dave needs to figure out how to split off just enough
air for the intercooler/oil cooler, diffuse it properly, and get it out
of the cowl. The rest of the air needs to go to the water heat
exchanger. Rotating the oil cooler and intercooler might allow for
installation of a more efficient diffuser - wedge. It sounds like the
flow speed through these items must not be optimum, since the delta-T
across them isn't very high.
Matt-
Here is the way I would do it Dave.
I would move the rad you have now up and forward as far as it
will go.
I would get rid of the
lump on the bottom of the cowl and cut a big square hole
the size of the rad. Then I would fab a K&L wedge diffuser
and scoop that looked something like this. You can fair it
in around the edges and on top of the scoop up
to the bottom of the cowl surface. Cover that with one
layer of glass.
I would add a sheet metal radius on the lower edge of
the firewall and a simple wide cowl flap.
All the hot air goes out the slot behind the rad and
past the cowl flap.
You could add some small louvers on the top
of the cowl to handle heat soak.
As it is now your cowl must be perfectly sealed everwhere at every
joint as it is acting as a huge plenum above the rad. It probably is
not perfectly sealed so you are losing a lot of cowl pressure along
with the extra heat problem. In other words you are pumping air into the cowl
through the inter cooler and oil radiator scoops and it is leaking
out before it goes through the rad.
This design obviatates that as all you have to do is
seal the K&L diffuser to the rad core.
Let the hot air leak out of the joints in the cowl where ever
it wants to. It now matters not.
Paul Lamar ...No rotor no motor.
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