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Question for engine builders. On a Chrysler RB engine do cylinders 8 and 6 run leaner or hotter than the others? I have experienced problems with a few of my engines where these cylinders seemed to get heat/detonation damaged but the other six cylinders were fine. Just wondering.

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How are you measuring this problem.. are you running
EGTs on the pipes or just looking at the plugs...
I'm curious also.. I always thought it was the center
cyl on each bank that got hotter

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We didn't measure EGT's. I just have an O2 sensor but it is located after all exhaust has merged together. We were tuning based on the a/f ratio as measured by that O2 sensor. So I don't really have any data on what happened in those two cylinders individually but I do know they got damaged during a dyno session last Saturday because before the dyno session I had done both compression and leak down tests on the engine and all eight cylinders were healthy. Then immediately after the dyno session I did compression and leakdown tests and discovered that cylinders 6 and 8 were both significantly down on compression and leaking badly. Before the dyno session all eight cylinders had compression readings in the 180 to 190 psi range (most of them 185 psi). Before the dyno session the leakdown was between 6% and 8% leakage on all eight cylinders (the engine is brand new freshly built). After the dyno session the compression and leakdown readings were unchanged on all but two cylinders (6 and 8). After the dyno session cylinder 6 had 150 psi compression and cylinder 8 had 145 psi compression. After the dyno session cylinder 6 had 25% leakage and cylinder 8 had a whopping 60% leakage. The leakage was NOT coming past the valves but rather past the piston/rings into the crankcase. Next thing I did was put a video probe in through the spark plug holes to visually inspect both cylinders. In cylinder 6 the piston is missing a chunk of it's perimeter probably about 1.5 inches long. In cylinder 8 it looks like a bomb exploded... there is so much damage I can hardly make out the piston on the video image. We think the damage happened on the final dyno pull, which we only put 7 lbs of boost in the engine. Air/Fuel ratio was in the 11.5 range, but again that was measured for all eight cylinders. For all I know cylinder 8 could have been in the 14's a/f ratio on that pull.

My plan moving forward is to use the EGT bungs that I have in each header tube and the O2 bungs I also have in individual header tubes (especially 8 and 6) and then monitor those two cylinders individually for a/f and egt then trim ignition and fuel as necessary. Don't ask me why we weren't using the individual EGT and O2 bungs.... that was a mistake on my part which I won't repeat.

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Its nice if you can run all 8 O2s but the EGT will
tell you alot... if you see it going up past 1500 and
the rest are still holding 1280 or so then you know
you have a issue... but yes 8 O2s sure would be nice
but that sure cost some coin
EDIT
I run ALL of the EGTs at 1" from the head surface
(and I mean 1") so you can compare the temps