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Originally Posted by Bisimoto
...Jim, I fail to understand why you feel this test is not factual. I duplicated both results, twice, as stated on page 1. As an engineer, who takes pride in being meticulous, I understand the value of repeating experiments to ensure validity. Such attention to detail has allowed me success in my present field of racing. In addition, I even invested in the most accurate and repeatable chassis dynamometer...no skimping there either.
I am here to share my experience, not to blow hot smoke. Feel free to perform the same tests...I am confident that you will perceive similar results.
In regard to the NACA ducts..at least we agree on that...
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Hi,
Sorry, but we do not share the same confidence. In my years at the Naval Flight Test Center at Pax River MD, we spent about 5 times the effort on defining the methodology than we did in actual testing, to insure the results we got were valid, and even then, with virtually unlimited time and expenditures, we sometimes got it wrong. I was trained at MIT and Pax River to distrust all testing results until no other plausible explanation could be found to invalidate them.
Your
results, IMHO, lie within the degree of error of the testing methodology as you describe it (or even within the HP variation between individual cars and engines), which automatically makes them suspect, if not altogether invalid.
You insinuate that this is
the definitive test, but I remain skeptical for the reasons already stated. Did you even monitor Alternator Output? This variable alone could make your runs
Doo-Doo.
I'm glad you shared your experience, but I'm concerned that many less-knowledgeable people will take it as Gospel, which I don't believe is the case. Judging from some of the
Pied Piper responses already, of people believing what they want to hear without question, this seems to be the case.
A $61k Chassis Dyno, isn't any better than a $25k Inertial Dyno if the methodology is flawed. I'm not impressed by the cost of the gauges. An inertial Dyno can be just as good a tool, if used properly.
I spoke personally with a Porsche Engineer (an invited Guest Speaker at a Tech Session) in 2005 and asked him specifically about the Snorkel. His response was that it was solely a Noise Abatement device, aimed specifically at the Swiss Market (but with an eye toward increasing Noise Abatement regulations in other countries as well). He said that several prototypes were rejected for various reasons, including a power reduction, and Porsche, rather than mute the exhaust note - a Marketing Decision, chose to meet the overall madated Noise Levels, by reducing the Intake noise instead, so long as it didn't interfere with creating power. He said that this gen of Snorkel showed no change to the power/torque curves at all, which is why it was approved for production.
While I'm inclined to support his arguments, I am nonetheless prepared to change my mind in the face of definitive testing. I just don't think you have done any. You may in fact be on to something, but I don't believe you've proved it - yet. Improve your methodology, and you may just win me over.
It isn't a matter of Snorkel vs De-snorkel to me, I removed my snorkel well over a year ago - but for the sound enhancement, not to try and
eek another 1-2% from the motor. Good Luck...
Happy Motoring!... Jim'99