Paul,

  Check out pages 9-11 in this issue of the RVator:
  http://www.vansaircraft.com/RVator/2010/1-2010-RVator.pdf
  Look at the [intake]  manifold and the muffler.

  Steve Brazil

 That intake manifold is called a dynamic chamber. It was invented by
 Mazda to increase torque at 3000 RPM. Very important in a car engine
 but kind of useless for a aircraft engine that cruises at 4500 to 6500
 RPM.
 In effect it doubles the length of the runners.

 The early "standard" intake system mentioned in some of the illustrations
 was pretty bad as it had runners of different lengths fed by a 4 barrel
 carb so just about anything tuned properly would be a improvement.

 This was a point many  people over looked when dynamic chambers
 were all the rage. It was like comparing apples with oranges.
 Mazda PR did a good job of selling it :) Just about all modern
 engines use simple tunned intake manifolds with equal length
 runners.

 You want the torque to peak at the cruise RPM as that gives
 the best BSFC or lowest fuel burn per HP.

 The very complicated stock RX8 intake manifold is the same thing
 except it has more stages as it goes all the way up to 9000 RPM.

 Tracy was the first to build one for an aircraft engine but then
 he gave up on the idea when he went to the RX8 engine and used
 simple equal length runners. That is when he went 217 MPH in
 the 100 mile Sun n Fun X country race.

 I suspect most people have given up on the idea for aircraft
 use but there still could be some die hards out there:)

 Paul Lamar

In the article you pointed to, I see a Griffin oil radiator.  I tried a
Griffin in my glass goose,  it was a waste of my time and money, it does not
work.I had to reinstall the RX 7 oil radistor I had before.

The Griffin [one pass] crossflow radiator was a: CX-27256-01
core: 22" x 7.5" x 2.75",area 135, volume 371

The [two pass] Mazda radiator core is: 17.5" x 4.5" x 2,  area 87, volume 157

The Griffin water radiator I have works fine, it is a GR1-2-58185-X
It is a crossflow, core 18" x 13" x 2.75 dual row  1.25" tubes
area 234, volume 643

Rino Lacombe
Renesis powered Glass Goose

Thanks Rino. Good work.

Cooling is relative to one's engine HP.
My guess is Rino's engine may be generating more HP than
the RV7 in the article. I think Rino could get even more
HP by putting the intake plenum on the other side of the
oil filler and shortening the runners.

On the other hand Rino lives in Canada which is a bit
cooler than the southern U.S.There are of course many
other factors.

All that does not mean I endorse Griffin anything :)


The best way to compare cooling systems is measure the
water temp in and out of the rad and the air pressure
on front and back of the rad with 4 to 10 pressure taps
equally distributed over the face of the core at a given
air speed.

BTW Rino, do you have a picture of your latest rad set up.
I don't think this one is current.


Paul Lamar