The #8, and why it failed. An inside look.
Mach 1 Member
Joined: May 11, 2012
Posts: 610
Likes: 21
From: Belle Plaine, MN
The groove between the top and second ring is known as an “accumulator groove”. The theory is that it acts like a “pressure accumulator” and dampens the impulse load imparted on the second and third rings by combustion pressure spikes. It basically helps to stabilize and keep those rings seated with more even pressure. Does it work? I don’t know. I know such features on other pistons are great at collecting carbon…
For what it’s worth I don’t think the #8 issues had anything to do with oil squirters one way or another. It could be #8 is more prone to detonation for any number of reasons. To be a gamer, let’s say it is and what Ford learned was their pistons didn’t like detonation. Among a multi-headed approach to fix the issue is the accumulator groove in the piston. A closer look at software programming and other things that make one cylinder run hotter than another leaving it more prone to detonation.
As to why Ford removed the piston squirters, it was most likely for cost Savings. Engineering most likely determined they were not necessary based on fleet data and made piston design changes, changed calibration, etc. so the engine would live fine without them. Running changes like these are not uncommon. Where I work if we suspect there could be an issue with a part or assembly and we can toss some belts and suspenders at it for a reasonable cost until we’re sure, we do it. Over time as we gain more confidence that issues will not arise, we remove the additional safety nets one at a time.
Most often oil squirters are used for cooling the piston, not for lubrication. The cylinder walls and wrist pins get ample oil windage off the crank and rods to supply them with more than a plentiful amount of lube (Sometimes way, way too much!). Fact is the oil squirters were probably causing significant parasitic power loss because of increased windage drag.
Regards,
John
For what it’s worth I don’t think the #8 issues had anything to do with oil squirters one way or another. It could be #8 is more prone to detonation for any number of reasons. To be a gamer, let’s say it is and what Ford learned was their pistons didn’t like detonation. Among a multi-headed approach to fix the issue is the accumulator groove in the piston. A closer look at software programming and other things that make one cylinder run hotter than another leaving it more prone to detonation.
As to why Ford removed the piston squirters, it was most likely for cost Savings. Engineering most likely determined they were not necessary based on fleet data and made piston design changes, changed calibration, etc. so the engine would live fine without them. Running changes like these are not uncommon. Where I work if we suspect there could be an issue with a part or assembly and we can toss some belts and suspenders at it for a reasonable cost until we’re sure, we do it. Over time as we gain more confidence that issues will not arise, we remove the additional safety nets one at a time.
Most often oil squirters are used for cooling the piston, not for lubrication. The cylinder walls and wrist pins get ample oil windage off the crank and rods to supply them with more than a plentiful amount of lube (Sometimes way, way too much!). Fact is the oil squirters were probably causing significant parasitic power loss because of increased windage drag.
Regards,
John
Thread Starter
Mach 1 Member
Joined: March 1, 2007
Posts: 669
Likes: 5
From: Kansas City
For what it’s worth I don’t think the #8 issues had anything to do with oil squirters one way or another. It could be #8 is more prone to detonation for any number of reasons. To be a gamer, let’s say it is and what Ford learned was their pistons didn't like detonation. Among a multi-headed approach to fix the issue is the accumulator groove in the piston. A closer look at software programming and other things that make one cylinder run hotter than another leaving it more prone to detonation.
As to why Ford removed the piston squirters, it was most likely for cost Savings.
As to why Ford removed the piston squirters, it was most likely for cost Savings.
-Matt
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Joined: December 14, 2007
Posts: 19,953
Likes: 4
From: State of Jefferson Mountains USA
The groove between the top and second ring is known as an “accumulator groove”. The theory is that it acts like a “pressure accumulator” and dampens the impulse load imparted on the second and third rings by combustion pressure spikes. It basically helps to stabilize and keep those rings seated with more even pressure. Does it work? I don’t know. I know such features on other pistons are great at collecting carbon…
Fact is the oil squirters were probably causing significant parasitic power loss because of increased windage drag.
Regards,
John
Fact is the oil squirters were probably causing significant parasitic power loss because of increased windage drag.
Regards,
John
B) I must not understand 'windage' drag. To me it sounds like something attached to the rotating mass, and therefore adds weight, causing a drag.
Yet the squirters are mounted to the block as noted. So how does their squirting oil cause windage drag?
Thanx for the good info.
Mach 1 Member
Joined: May 11, 2012
Posts: 610
Likes: 21
From: Belle Plaine, MN
A) Interesting...
B) I must not understand 'windage' drag. To me it sounds like something attached to the rotating mass, and therefore adds weight, causing a drag.
Yet the squirters are mounted to the block as noted. So how does their squirting oil cause windage drag?
Thanx for the good info.
B) I must not understand 'windage' drag. To me it sounds like something attached to the rotating mass, and therefore adds weight, causing a drag.
Yet the squirters are mounted to the block as noted. So how does their squirting oil cause windage drag?
Thanx for the good info.
Regards,
John
Thread Starter
Mach 1 Member
Joined: March 1, 2007
Posts: 669
Likes: 5
From: Kansas City
Member
Joined: May 2, 2014
Posts: 1
Likes: 0
Great info zeroaviation, thank you for posting.
I've been learning how to tune my car with SCT over the past few weeks. Those who know the tunes on these 2011+ cars are quite resilient to share any information, so descriptions like this are very helpful. I've figured out a lot of stuff in the tune already, but most of it has been trial and error. A good database of tuning information would benefit everyone.
I've been learning how to tune my car with SCT over the past few weeks. Those who know the tunes on these 2011+ cars are quite resilient to share any information, so descriptions like this are very helpful. I've figured out a lot of stuff in the tune already, but most of it has been trial and error. A good database of tuning information would benefit everyone.
Thread Starter
Mach 1 Member
Joined: March 1, 2007
Posts: 669
Likes: 5
From: Kansas City
Great info zeroaviation, thank you for posting.
I've been learning how to tune my car with SCT over the past few weeks. Those who know the tunes on these 2011+ cars are quite resilient to share any information, so descriptions like this are very helpful. I've figured out a lot of stuff in the tune already, but most of it has been trial and error. A good database of tuning information would benefit everyone.
I've been learning how to tune my car with SCT over the past few weeks. Those who know the tunes on these 2011+ cars are quite resilient to share any information, so descriptions like this are very helpful. I've figured out a lot of stuff in the tune already, but most of it has been trial and error. A good database of tuning information would benefit everyone.
If you have any questions be sure to ask! I will do my best to answer.
-Matt
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