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There's a relatively cheap way to solve the issue and it appeals to my German technology background.
Filterminder makes a nice ratcheting vacuum sensor...it normally indicates when the pressure drop across the engine air filter is so high that the filter needs to be replaced.
By the same token you can remove the air filter and test the intake system for restriction...the sensor is essentially a piston with a ratchet on it and the piston moves as vacuum gets higher and stays where it moves to...kind of handy when you're in the car and the sensor is in the engine compartment!!
Anyway, it used to be about $25 or so (I've only found it on the internet although some Ford Duramax diesels and Army trucks now run it from the factory) and you install the tap between the air filter and the throttle.
FWIW, the stock OG900 air filter system (well, on my 18psi 87 900T anyway)is an inherent restriction above 4K rpm wot. So even without an air filter the filterminder on my car would go red and indicate I needed to replace the filter. I went to an aftermarket (SPG9?) K&N-type system that did NOT trigger the filterminder so I probably gained some horsepower above 4K but OTOH I was still pulling 18psi boost so the tradeoff with the aftermarket air filter was less restriction, same boost, so it was probably just lower temp air to the engine. The car seemed to run ok with just the stock air filter system so I put it back. Cooler air too since it wasn't feeding off the air from the intercooler. One day I might put a fan on the intercooler and relocate the air intake to the battery side but too much work for an OG900 with an automatic....
posted by 140.185.5...
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