Quote:
Originally Posted by Atomic Ed
A couple of new data points.
First, the limiting orifice in the vacuum line did seem to eliminate the minor surging when at a steady speed on the highway. It was hardly noticeable to begin with, but this mod got rid of it completely with no reduction in boost response. However, it did not reduce the upper rpm/boost fluctuations.
Secondly, I had the hood up on the car, thinking about how to tackle the heat soaking. It suddenly struck me that the intercooler "bricks" in the supercharger body are the high point in the intercooling system.
I jacked up the front end of the car and just started the intercooler pump without starting the car. Sure enough, I got about 3/4 of a filler neck of air out. Filled the neck back up to the full mark and repeated this process about a dozen times until the system quit burping air. In the end, I was able to get about a pint of displaced air out of the system. Pretty clear to me that I had air trapped in the intercooler "bricks". I didn't get a chance to log IATs on a hard pull, but around town, the IATs look to be running about 15-20* F cooler!
May try to get some logs tomorrow if I can.
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That's good news. Air is no bueno.
That timing table you posted looks right to me. Most tunes start to pull timing when IATs cross the 150° mark, especially on stock pistons. The typical weak point I've seen is the rings and ring lands. As the cylinder temps rise, the rings expand, and if they get too hot they'll touch end to end. With no where to go they start to deflect and will snap off the edge of the piston. On the HEMI we almost always see this on the intake side if memory serves. Then you got a 1/2 long 3/16th inch thick piece (or pieces) of piston flying around in the cylinder tearing up the heads and valves. Definitely better safe than sorry.