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Old 07-26-2005, 11:00 AM   #19
Element Tuning
Former Vendor
Member#: 54918
Join Date: Feb 2004
Chapter/Region: MAIC
Location: Gaithersburg, MD
673 WHP Element
Tuning Pro Comp Engine


There really isn't any argument as I agree with what I believe you are trying to say but I've never claimed pre-turbocharger IAT was better.

“While they may not be major issues, I am sure that having the IAT's measured pre-turbo does not lend towards an accurate mapping of air into the motor. Any type of differing airflow over the intercooler and the true IAT's (in the manifold) can be all over the place compared to the temps at the air filter.”

What I'm saying it that it hardly makes a difference in AFR and this is where we disagree. My point has been that the AFR will not stray with a pre-turbocharger IAT reading because once the air enters the turbocharger there will be no miraculous way to increase oxygen. Without more 02 the AFR will hold true regardless of where you r IAT sensor is unless you tell it to do otherwise. I believe the temperature of the air entering the turbocharger is more indicative of its 02 content then variable and heated reading post turbocharger.

There are instances where an inferior IC will heat up during a very long pull and a post IC IAT will allow you to increase the AFR to prevent detonation. I believe this is your point and I agree but there are other ways to provide adequate protection such as the coolant temp fuel and spark corrections along with proper mapping.

Without getting into all the nuances of tuning, a static AFR is not used at all boost and rpm ranges. Maps are tuned with a margin of error and will always be but more importantly they are tuned with a specific set of modification in mind. The AFR run at a turbocharger’s peak efficiency will be much leaner than when run at very high boost pressures. Each map is designed for a specific turbocharger’s characteristics and tuned under extreme conditions, not for ideal conditions so they are setup with heat soak in mind.

“….but the joe blow on the street tuning his own car would likely go up to the point of detonation, and pull back a hair, basically creating an "on the edge" map that would very likely have problems of detonation if tuned for non-heatsoaked situations.”

We all know joe blow is capable and has blown up his car but that’s why we provide great base maps along with tech support and of course excellent knock protection. As a company we have our customers best interests at heart and since joe blow doesn’t really know how to tune the IAT map I’m suggesting they use what we’ve developed and consider appropriate for even our own use.

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