http://www.cafr.ebay.ca/itm/311012094845?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT


Hello Paul,

Just to say hello and pick your brain

 At this point, I basically need to reduce drags:

I have a list of several items: a cover for my belly rads to shoot the air back instead of underneath, wheel pants, paint etc…


Second, I need more power, I can tell from my take off run, and climb rate, I am probably around 150 hp at max.

My large alternator, the powerful water pump and the PSRU are certainly sucking a 6-8 hp.


I am not equipped to go p-port and would like to avoid opening up the engine; making my runners longer let say from 11 inches now to 19 inches would bring me to 165hp, 170hp at best and only if I do it perfectly.


Turbo is way to complex for me therefore the supercharger seems a relatively easy way to boost from 14.7 to 20psi for takeoff an altitude compensation, while not doing much at cruise and this without having to redo the intake again.


PS.: If you enlarge the photo I joined it is possible to see the wave heat under the rads


Prop: Dia: 69in; pitch 3/4R = 85in; Static rpm = 6300 @ 75F;

Take off run on rough grass about 800ft; climb rate a little over 1000fpm @ 75F;

Max speed  at wot = 6000ft, 6800rpm, 140mph IAS


Thanks for commenting


Jean-Pierre Ducharme

Congratulation on flying. A few years ago we would have heard first flight horror stories on cooling
problems :)

You will pay a little fuel burn penalty with a super charger  over a turbo charger because the turbo
uses some of the 50% waste energy in the exhaust to compress the air.


That picture is very interesting. Obviously the quick and simple cooling system is working well.

What gear ratio are you using? 6000 RPM is low on the top speed.
Sounds like one of Tracy's early 2.12 GB's with the prop rotating in the wrong direction.

The only way to get significantly more power from a side port is up the gear ratio to at least 2.85 and
even 3.12. Then of course the intake runners should be adjusted.

Perhaps 2 inches off the prop diameter would help.

The intake runners are too short even for 6000 RPM.

For lower cooling drag move the rad to the cool side of the engine and mount it
vertically. Adding a exit duct will not help much as it must be several inches deep
on the front part. Otherwise it will block the flow through the front part of the
rad. All that adds to the over all  frontal area.

Paul Lamar

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