pressure gauges are an absolutely useful tool in monitoring a turbo/supercharged engine, not just an add-on toy for amusement.....
mule didn't get what I was saying either, but what the heck?
this discussion of atmospheres has gotten pretty much into the argument of semantics, until Sniper chimed in.
However, Sniper was off when he claimed tunnel ram intakes create forced induction. Having operated numerous tunnel ram equipped engines, both cast manifolds and fabbed sheetmetal t-rams, I have never found that the intake charge was under pressure. It was always under some amount of vacuum, even in the high-end ProStock engines I was privileged to run. I have never seen any tunnel ram create positive pressure (atmospheres as this discussion calls them) in any rpm range, regardless of load or not on the engine.
as for the issues of percentage of improvements, to be blown or not to be blown, the comment that 10% improvement is unattainable is false.
if you supercharge (or turbo for that matter) a given engine at an overdrive percentage, you can overcome the 100% increase in HP. My diesel engine example in my earlier comments demonstrate this example.
My diesel won't hardly run without the turbo, but makes 600 plus HP at only 2100 rpms. Take the turbo off, and you'll be lucky to get 100 HP at the same rpms.
this same example should be applicable to gas engines as well, although I have no actual number to back up this up. it is just a common sense approach to the question at hand.
Herr is on track with some very good numbers as well, but I have found holes in his R&D as well. His latest clutch issues will skew his dyno numbers, because there may have been slippage on the old clutch (before turbo), and now that he's got a non-slipping clutch (after turbo) the numbers may be skewed. His addition of bigger stickier tires will skew the numbers as well.....
Your discussion of facts and figures as they relate to dyno this and dyno that...... are dependent upon consistent conditions for comparison. ambient temps, barometric pressures, engine components, etc., all have bearing on hp and torque claims.
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