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They definitely run hotter as they get the poorest cooling. In any V engine the rear cylinders always run hotter IMHO.

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If you have the individual cylinder controll on the EFI. You can pull timing out.

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Is this on a roots blown motor?If so maybe it is the intake manifold distribution I seem to remember that the roots blown motors do that, load up the rear cylinders on the passneger side bank

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Is this on a roots blown motor?If so maybe it is the intake manifold distribution I seem to remember that the roots blown motors do that, load up the rear cylinders on the passneger side bank

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No, this is a turbo engine running electronic fuel injection. The manifold is dry. Each cylinder has a fuel injector that sprays fuel directly into the intake port at the back of the valve.

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I think I would try rotating those two injectors to the other side and see if the problems follow those injectors or not

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Is this on a roots blown motor?If so maybe it is the intake manifold distribution I seem to remember that the roots blown motors do that, load up the rear cylinders on the passneger side bank

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No, this is a turbo engine running electronic fuel injection. The manifold is dry. Each cylinder has a fuel injector that sprays fuel directly into the intake port at the back of the valve.

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I think I would try rotating those two injectors to the other side and see if the problems follow those injectors or not

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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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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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I would not trim fuel at first. It's prolly lean now. Unless the plug shows otherwise, just pull some timing. I'd pull four degrees and sneek back up on it.
It's an air distribution problem. You have a pic of the intake plumbed up?

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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

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Just a thought, but what is the fuel plumbing situation? I can't tell allot from the pics you posted, but it looks like 6 and 8 are the farthest away from the regulator. How much pressure? I can't see but assume you have a crossover in the back? How much is the pressure rising with boost?

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I would definetly have those two injectors look at, maybe have all eight flowed by the same company

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I would definetly have those two injectors look at, maybe have all eight flowed by the same company

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There is a history of this problem with this engine. Last year I had the same thing happen; burned number 8 piston. I was using Bosch 160 lb/hr injectors and I sent them out and had them tested... they tested good and flowed within 1% of each other. Even so, I replaced all eight injectors when I rebuilt the engine. I now have a brand new set of Injector Dynamics 225 lb/hr injectors and that's what I ran on the dyno. I could have them tested but I'll bet there's nothing wrong with them, just as there was nothing wrong with the Bosch 160's. Given that I have had the same thing happen twice with two entirely different set of injectors, I am inclined to look elsewhere.

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This is proving to be a challenge, how about something in the heads, maybe a thin spot in the combustion chambers I've burnt up pistons on the dyno also, due to unequal fuel distribution on a tunnel ram My bad, I had a loose power valve plug Good LUCK some of these things(problems) can be very frustrating and maddening, but you can find it

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I would definetly have those two injectors look at, maybe have all eight flowed by the same company

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There is a history of this problem with this engine. Last year I had the same thing happen; burned number 8 piston. I was using Bosch 160 lb/hr injectors and I sent them out and had them tested... they tested good and flowed within 1% of each other. Even so, I replaced all eight injectors when I rebuilt the engine. I now have a brand new set of Injector Dynamics 225 lb/hr injectors and that's what I ran on the dyno. I could have them tested but I'll bet there's nothing wrong with them, just as there was nothing wrong with the Bosch 160's. Given that I have had the same thing happen twice with two entirely different set of injectors, I am inclined to look elsewhere.

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This is proving to be a challenge, how about something in the heads, maybe a thin spot in the combustion chambers I've burnt up pistons on the dyno also, due to unequal fuel distribution on a tunnel ram My bad, I had a loose power valve plug Good LUCK some of these things(problems) can be very frustrating and maddening, but you can find it

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Thanks Cab. I appreciate all the feedback you guys are giving me. You guys are asking all the right questions. Unfortunately the answer to this one is elusive. I will keep plugging away and I know I will figure it out eventually. Maybe I should have a priest come over and sprinkle some holy water on it!

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Is this a siamese bore block? If so, was the deck/gasket/head drilled for steam bleed off?
Ringland issues can be caused by a few different things. Blown/ turbo motors with ringland issues are almost always to rich. Liquid fuel gets into the space (usually close to the intake valve) and burns or breaks the piston. Nitrous motors will do this to, but oil control is usually involved.
I would suggest making sure the deck area is drilled as I mentioned before, knock your A/F ratios back into the mid to high 12s and keep your timing in a realistic zone. To much breaks things, not enough melts things.
Another poster asked about sparkplugs. Use the coldest plug you can get away with. Trim back the electrode strap. The shorter the strap the cooler the strap will be. Keep your plug gaps tight(.020- .025). If you blow out the spark under boost, fuel will puddle in the lower portion of the piston and the ringlands will be damaged at the 6:00 position of the piston.

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This is a Keith Black block and I believe it has the steam bleed off holes. Before I hurt the engine on the dyno I had the cylinder heads off and took a pic (passenger side), you can see the little steam holes between the cylinders. I have cometic head gaskets and they have slits where those holes are. A/f ratio on the last dyno pull when we hurt the pistons was 11.7 and ignition timing was 25 degrees on that pull with 7 lbs of boost. Spark plug I was running was NGK R5671-A9 which is a pretty cold plug.

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Prior to the damage, what have past plug readings had to say about the mixture? Do they look leaner than the others? Does the ECU you are using have individual cylinder fuel trims?

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How in the world does water get into the heads?.....

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How in the world does water get into the heads?.....

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There are two main water passages, one at each end of the block. The water enters the head from rear passage, flows through the head, then back into the block through the front passage. In the pic I posted you can tell the main water passages (see the holes that have traces of black sealer around them).

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How do you figure the water enters the head at the
rear and goes back into the block at the front....
coolant enters the total block and goes up into the
heads then out the front of the heads to the thermostats
hose... it dont go back into the block

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Actually, thats not right. A big block has two waterpump holes at each side of the block(r&l). Water does flow into the block from the lower hole, around the cylinders,(and normally thru holes in the deck to the heads in small quantities) to the back of the block, where it enters the head and than flows back to the front water passage, into the front of the block. The front water passage in the block is separate/divided from the inlet waterflow. Remember, a big block has the t-stat housing on the pump, not the intake.
The picure shows the upper small holes in the deck, but on a siamese block, air gets trapped in the hourglass shape on the lower deck because the air cant escape between the cylinder bores. Your gaskets will have holes in them, and my guess would be that your heads have holes there also. It may be as simple as drilling a few 1/4"holes in the deck to get rid of this problem.
The timing you report seems awfully low. Do you have a real small cam?

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Your correct on the 4 holes in the block...my error

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Actually, thats not right. A big block has two waterpump holes at each side of the block(r&l). Water does flow into the block from the lower hole, around the cylinders,(and normally thru holes in the deck to the heads in small quantities) to the back of the block, where it enters the head and than flows back to the front water passage, into the front of the block. The front water passage in the block is separate/divided from the inlet waterflow. Remember, a big block has the t-stat housing on the pump, not the intake.
The picure shows the upper small holes in the deck, but on a siamese block, air gets trapped in the hourglass shape on the lower deck because the air cant escape between the cylinder bores. Your gaskets will have holes in them, and my guess would be that your heads have holes there also. It may be as simple as drilling a few 1/4"holes in the deck to get rid of this problem.
The timing you report seems awfully low. Do you have a real small cam?

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My heads are Indy 440-1's and yes they do have the lower holes (see pic, see the two lower holes shaped like arrows).

My cam is very small. Intake duration is 224 degrees at .050 and lift is .541 and Lobe Sep Angle is 116. The ignition timing is so low because this was the first time we put boost in the motor and we wanted to start very conservative on the timing and a/f and then creep up on the tune to make more power. On that pull we only put 7 lbs of boost in the engine and it only made 707 hp at the wheels. Figure it would have gotten closer to 800 whp on that boost if we could have run more timing and leaner a/f... but as I said we only got the one pull in on boost and burned those two pistons.