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Cylinders 8 and 6 run leaner, hotter, more prone to det #1244470 06/02/12 08:59 PM 06/02/12 08:59 PM
Joined: Feb 2004 Posts: 1,417 Chicago, IL blownEFI OP pro stock
blownEFI OP pro stock Joined: Feb 2004 Posts: 1,417 Chicago, IL	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. "These go to eleven", Nigel Tufnel

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: blownEFI] #1244471 06/02/12 09:08 PM 06/02/12 09:08 PM
Joined: Mar 2003 Posts: 4,848 Memphis HemiRick master
HemiRick master Joined: Mar 2003 Posts: 4,848 Memphis	They definitely run hotter as they get the poorest cooling. In any V engine the rear cylinders always run hotter IMHO. Take care, Rick 68 Coronet R/T 440 & 68 Charger 528 Hemi,and 5 Challengers! 6 cyl, 318, 360, 383, 451

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: HemiRick] #1244472 06/02/12 10:13 PM 06/02/12 10:13 PM
Joined: May 2005 Posts: 1,030 ohio 6 67mprfan super stock
67mprfan super stock 6 Joined: May 2005 Posts: 1,030 ohio	Quote: They definitely run hotter as they get the poorest cooling. In any V engine the rear cylinders always run hotter IMHO. Not to hijack the op but what spark plugs would you check to see how the car running 7233436-63250004.jpg (49 downloads) 71 demon stock stroke 440/indy ez-1 running 10.10 @ 132.14 mph in the 1/4 and 6.36 @ 107.46 mph in the 1/8 not in the same weekend but It did it then I sold it. 67 Belvedere that worked it's way in the 10's

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: blownEFI] #1244473 06/02/12 11:26 PM 06/02/12 11:26 PM
Joined: Aug 2003 Posts: 43,172 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,172 Bend,OR USA	Usually number seven detonates first, not six or eight Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: Cab_Burge] #1244474 06/03/12 05:31 PM 06/03/12 05:31 PM
Joined: Jan 2003 Posts: 5,762 Hot Rod Ridge FastmOp master
FastmOp master Joined: Jan 2003 Posts: 5,762 Hot Rod Ridge	If you have the individual cylinder controll on the EFI. You can pull timing out.

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: FastmOp] #1244475 06/03/12 10:22 PM 06/03/12 10:22 PM
Joined: Feb 2004 Posts: 1,417 Chicago, IL blownEFI OP pro stock
blownEFI OP pro stock Joined: Feb 2004 Posts: 1,417 Chicago, IL	Quote: If you have the individual cylinder controll on the EFI. You can pull timing out. Yes, going to do just that. I'm going to trim cylinders 6 and 8 individually (both fuel and spark). But it would be nice to know why those two cylinders are more fragile than the others (on this engine anyhow). "These go to eleven", Nigel Tufnel

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: blownEFI] #1244476 06/03/12 10:29 PM 06/03/12 10:29 PM
Joined: Aug 2003 Posts: 43,172 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,172 Bend,OR USA	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 Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: Cab_Burge] #1244477 06/03/12 11:09 PM 06/03/12 11:09 PM
Joined: Feb 2004 Posts: 1,417 Chicago, IL blownEFI OP pro stock
blownEFI OP pro stock Joined: Feb 2004 Posts: 1,417 Chicago, IL	Quote: 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 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. "These go to eleven", Nigel Tufnel

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: blownEFI] #1244478 06/04/12 12:59 AM 06/04/12 12:59 AM
Joined: Aug 2003 Posts: 43,172 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,172 Bend,OR USA	Quote: Quote: 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 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. I think I would try rotating those two injectors to the other side and see if the problems follow those injectors or not Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: Cab_Burge] #1244479 06/04/12 01:17 AM 06/04/12 01:17 AM
Joined: Feb 2004 Posts: 1,417 Chicago, IL blownEFI OP pro stock
blownEFI OP pro stock Joined: Feb 2004 Posts: 1,417 Chicago, IL	Quote: Quote: Quote: 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 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. I think I would try rotating those two injectors to the other side and see if the problems follow those injectors or not Thanks. I already tried two entirely different sets of injectors, same issue. "These go to eleven", Nigel Tufnel

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: blownEFI] #1244480 06/04/12 02:13 AM 06/04/12 02:13 AM
Joined: Aug 2003 Posts: 43,172 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,172 Bend,OR USA	Let us know what you find Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: blownEFI] #1244481 06/04/12 08:36 AM 06/04/12 08:36 AM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Quote: 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. 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

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: MR_P_BODY] #1244482 06/04/12 12:17 PM 06/04/12 12:17 PM
Joined: Jan 2003 Posts: 5,762 Hot Rod Ridge FastmOp master
FastmOp master Joined: Jan 2003 Posts: 5,762 Hot Rod Ridge	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?

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: MR_P_BODY] #1244483 06/04/12 03:45 PM 06/04/12 03:45 PM
Joined: Feb 2004 Posts: 1,417 Chicago, IL blownEFI OP pro stock
blownEFI OP pro stock Joined: Feb 2004 Posts: 1,417 Chicago, IL	Quote: Quote: 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. 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 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. I also probed the other six cylinders and they looked fine, which confirms the good compression and leakdown numbers I'm seeing for those. For some reason it was just cylinders 6 and 8 that got damaged. 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. Last edited by blownEFI; 06/04/12 03:58 PM. "These go to eleven", Nigel Tufnel

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: FastmOp] #1244484 06/04/12 03:47 PM 06/04/12 03:47 PM
Joined: Feb 2004 Posts: 1,417 Chicago, IL blownEFI OP pro stock
blownEFI OP pro stock Joined: Feb 2004 Posts: 1,417 Chicago, IL	Quote: 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? "These go to eleven", Nigel Tufnel

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: blownEFI] #1244485 06/04/12 03:54 PM 06/04/12 03:54 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Quote: Quote: Quote: 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. 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 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. 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 Last edited by MR_P_BODY; 06/04/12 03:58 PM.

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: MR_P_BODY] #1244486 06/05/12 01:44 AM 06/05/12 01:44 AM
Joined: Jan 2003 Posts: 310 Castle Rock, CO W wegner426 enthusiast
wegner426 enthusiast W Joined: Jan 2003 Posts: 310 Castle Rock, CO	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?

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: blownEFI] #1244487 06/05/12 04:16 AM 06/05/12 04:16 AM
Joined: Aug 2003 Posts: 43,172 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,172 Bend,OR USA	I would definetly have those two injectors look at, maybe have all eight flowed by the same company Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: Cab_Burge] #1244488 06/05/12 10:25 AM 06/05/12 10:25 AM
Joined: Dec 2007 Posts: 12,587 Great Neck,LI,new york hemi-itis I Live Here
hemi-itis I Live Here Joined: Dec 2007 Posts: 12,587 Great Neck,LI,new york	I have felt that PAIN 7237215-SHIT!!!023.JPG (38 downloads) HEMI-ITIS has no cure. My condition is fully BLOWN!!

Re: Cylinders 8 and 6 run leaner, hotter, more prone to det [Re: wegner426] #1244489 06/05/12 06:58 PM 06/05/12 06:58 PM
Joined: Feb 2004 Posts: 1,417 Chicago, IL blownEFI OP pro stock
blownEFI OP pro stock Joined: Feb 2004 Posts: 1,417 Chicago, IL	Quote: 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? The crossover is in the front. I have a AN-10 main fuel line that runs underneath the intake manifold and Y's off into two AN-8 lines that feed the rear of the fuel rails. The regulator is mounted directly on the front end of the driver's side rail. The crossover line goes from the front of the passenger rail over to the regulator. There is a AN-8 return line from the regulator to the tank. I have a Weldon 2345-A pump. The injectors for 8 and 6 would be the first ones fed on the passenger rail. The fuel pressure rises 1 psi for every 1 psi of boost. I have an in-cockpit fuel pressure gauge (as well as a gauge on the regulator) and when we did the dyno pulls I verified that fuel pressure was rising correspondingly with boost. Fuel pressure never dropped off during the pulls. "These go to eleven", Nigel Tufnel

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