CYL. 7 lean?
01-28-2019, 09:18 AM
#1
CYL. 7 lean? Pulled the heads this weekend to change gaskets. My problem was on the passenger side head. On the dirver side however, cylinder number 7 looked much much cleaner than the others. There was literally no carbon build up at all. The piston was black and the chamber was too, but there was no build up at all like the other cylinders had. I should have taken a pic but i didnt.
Should i be concerned? Anything i can do to combat this? I want to be proactive. I know the airflow is likely higher in this cylinder. Should I have the injectors flowed and put the highest flowing one there?
Should i be concerned? Anything i can do to combat this? I want to be proactive. I know the airflow is likely higher in this cylinder. Should I have the injectors flowed and put the highest flowing one there?
01-28-2019, 09:31 AM
#2
Hi KFX,
Curious: Why is cylinder 7 flowing "more" air? I assume you mean the ratio of this cylinder is that it's running leaner.
I think you already know the answer, but you're wanting confirmation/verification.
1) Check all ignition components for cyl 7.
2) Get it flow tested/cleaned.
3) Leak down test on all cylinders - and compare leakage from others to cylinder 7.
How many miles are on this engine?
What was the passenger side issue that made you replace the head gasket?
Curious: Why is cylinder 7 flowing "more" air? I assume you mean the ratio of this cylinder is that it's running leaner.
I think you already know the answer, but you're wanting confirmation/verification.
1) Check all ignition components for cyl 7.
2) Get it flow tested/cleaned.
3) Leak down test on all cylinders - and compare leakage from others to cylinder 7.
How many miles are on this engine?
What was the passenger side issue that made you replace the head gasket?
01-28-2019, 09:32 AM
#3
Restricted User
Common problem. That's why you see so many horror stories of people breaking at cylinder 7 (and sometimes 8).
I usually just throw the highest flowing injector in it, but in reality it doesn't help much.
If your injectors are properly cleaned, you're only getting an extra 1-2% max fuel in that cylinder instead of the 5-8% you likely need.
I usually just throw the highest flowing injector in it, but in reality it doesn't help much.
If your injectors are properly cleaned, you're only getting an extra 1-2% max fuel in that cylinder instead of the 5-8% you likely need.
01-28-2019, 10:09 AM
#4
Hi KFX,
Curious: Why is cylinder 7 flowing "more" air? I assume you mean the ratio of this cylinder is that it's running leaner. I stated that it was running leaner, the rear cylinders are known for flowing more air because of the intake manifold design.
I think you already know the answer, but you're wanting confirmation/verification.
1) Check all ignition components for cyl 7.
2) Get it flow tested/cleaned.
3) Leak down test on all cylinders - and compare leakage from others to cylinder 7.
How many miles are on this engine? 100K MILES
What was the passenger side issue that made you replace the head gasket? i used graphite gaskets and it developed a external coolant leak. i did not retorque them like i was supposed to. I guess i might possibly could have been getting coolant in that cylinder, I doubt it tho. The gasket didnt appear to be leaking. doesnt mean it wasnt tho.
Curious: Why is cylinder 7 flowing "more" air? I assume you mean the ratio of this cylinder is that it's running leaner. I stated that it was running leaner, the rear cylinders are known for flowing more air because of the intake manifold design.
I think you already know the answer, but you're wanting confirmation/verification.
1) Check all ignition components for cyl 7.
2) Get it flow tested/cleaned.
3) Leak down test on all cylinders - and compare leakage from others to cylinder 7.
How many miles are on this engine? 100K MILES
What was the passenger side issue that made you replace the head gasket? i used graphite gaskets and it developed a external coolant leak. i did not retorque them like i was supposed to. I guess i might possibly could have been getting coolant in that cylinder, I doubt it tho. The gasket didnt appear to be leaking. doesnt mean it wasnt tho.
see above in bold
01-28-2019, 10:15 AM
#5
Common problem. That's why you see so many horror stories of people breaking at cylinder 7 (and sometimes 8).
I usually just throw the highest flowing injector in it, but in reality it doesn't help much.
If your injectors are properly cleaned, you're only getting an extra 1-2% max fuel in that cylinder instead of the 5-8% you likely need.
I usually just throw the highest flowing injector in it, but in reality it doesn't help much.
If your injectors are properly cleaned, you're only getting an extra 1-2% max fuel in that cylinder instead of the 5-8% you likely need.
Wish I would have thought of that when i was porting the heads and manifold. I would have purposely limited the flow on that cylinder. damnit.
what about one step colder plug on that cylinder along with a higher flowing injector?
01-28-2019, 10:29 AM
#7
Got it.
Question:
How Plausible would it be to simply run a higher rated injector in that Cylinder? for example, an injector that's rated at 2lbs more? Or w/e lb he would need to off-set the higher flow of air in that cylinder?
Question:
How Plausible would it be to simply run a higher rated injector in that Cylinder? for example, an injector that's rated at 2lbs more? Or w/e lb he would need to off-set the higher flow of air in that cylinder?
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01-30-2019, 04:59 PM
#10
On The Tree
I blew up cylinder 7 on NA motor and no knock....just too much heat. I would just command a little richer AFR. My personal theory is that cylinder gets hot and the piston rings butt up on a stock engine, which creates even more heat and cracks the piston and sometimes even cracks the cylinder liner... mine did both. Wider ring gap has shown to do wonders on even a stock motor. I don't really buy into the steam vent thing, I just haven't seen any real evidence to support it?
01-30-2019, 06:47 PM
#11
I blew up cylinder 7 on NA motor and no knock....just too much heat. I would just command a little richer AFR. My personal theory is that cylinder gets hot and the piston rings butt up on a stock engine, which creates even more heat and cracks the piston and sometimes even cracks the cylinder liner... mine did both. Wider ring gap has shown to do wonders on even a stock motor. I don't really buy into the steam vent thing, I just haven't seen any real evidence to support it?
01-30-2019, 08:06 PM
#12
TECH Senior Member
Sounds like wider ring gaps would benefit ANY engine; not just nitrous/blown.
01-31-2019, 05:15 PM
#13
9 Second Club
Any notion of the intake manifold design being a problem were dispelled years ago when Kurt tested the manifold the other way around, and 7 still ran the hottest. So ensuring no air pockets can appear in the heads, and adding a little water via the "steam ports" as they're called can only be a good thing.
It isnt an airflow or intake issue.
But a very clean cylinder more often indicates water ingress to some degree.
It isnt an airflow or intake issue.
But a very clean cylinder more often indicates water ingress to some degree.
01-31-2019, 05:22 PM
#14
Any notion of the intake manifold design being a problem were dispelled years ago when Kurt tested the manifold the other way around, and 7 still ran the hottest. So ensuring no air pockets can appear in the heads, and adding a little water via the "steam ports" as they're called can only be a good thing.
It isnt an airflow or intake issue.
But a very clean cylinder more often indicates water ingress to some degree.
It isnt an airflow or intake issue.
But a very clean cylinder more often indicates water ingress to some degree.
i picked up a steam crossover yesterday just for this. My buddy has a shop and is very well known around here for building some very fast ls powered vehicles. I stopped by last night and picked his brain. He said he always adds the four corner steam venting on higher powered stuff and boosted stuff. He keeps a handful of the truck crossover pipes on hand because they fit on the rear.