X-Mozilla-Keys:
Wschertz@aol.com wrote:
One thing I noticed at Oshkosh about Tracy's installation, was that he did
not have any bug-splatters or carcasses on his radiators. None! I think this
is trying to tell us something about the flow through the openings and the
radiators. There were splattered bugs on the rims of the openings of the cowl.
1. Tracy uses a substantial pressure to force the air through the thick
cores, and a resultant low velocity.
2. The bugs must be being deflected to the side as they approach the opening.
Any other thoughts?
Bill
Wow Bill! I am impressed. That never occurred to me. Very interesting.
A sure fire way to tell if you have substantial external diffusion.
This is a quote from this web site http://www.sdsefi.com/air10.html
The guy placed a stock Mazda car radiator on his flow bench and
compared it to a evaporator core like Tracy uses.
Quote:
"Pressure Drop
I also did pressure drop tests on the cores using my cylinder head flow
bench. The thicker the core, the more resistance to airflow
through it. With the cores mounted over the exhaust port of the bench
flowing 160 SCFM (area was 9.6 square inches), the thin
Mazda core only showed a drop of 1 inch of water [.04 psi] across it.
The GM core showed 5.5 inches [.2 psi] across it. It would appear that
pressure drop is fairly proportional to core depth with the GM core
having
about 5.8 times the depth of the Mazda rad. For
comparison, I also flowed my 3.5 inch thick Spearco intercooler core. It
showed a drop of 7.5 inches across it."
End of quote.
We all owe this guy a huge debt of gratitude for performing
this simple test.
As a matter of interest I will repeat the sea level dynamic pressure
chart
and let everybody draw their own conclusions. With a perfect
duct and no flow through the radiator the max pressure you can get
is dynamic pressure.
MPH PSI Inches of H2O
60 0.065 1.80
65 0.076 2.11
70 0.088 2.44
75 0.102 2.81
80 0.116 3.19
85 0.130 3.60
90 0.146 4.04
95 0.163 4.50
100 0.181 4.99
105 0.199 5.50
110 0.218 6.04
115 0.239 6.60
120 0.260 7.18
125 0.282 7.79
130 0.305 8.43
135 0.329 9.09
140 0.354 9.78
145 0.380 10.49
150 0.406 11.22
155 0.434 11.98
160 0.462 12.77
165 0.492 13.58
170 0.522 14.41
175 0.553 15.27
180 0.585 16.16
185 0.618 17.07
190 0.652 18.01
195 0.687 18.97
200 0.722 19.95
Paul Lamar
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