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Hello everyone. Just acquired the m5 a few months ago and i have rod bearing failure. Very minor rick after she is warmed. Pull some oil and there is copper visible in it. I am going to install the acl bearings with +.001 clearance. I have built enough engines to know that this engine is likely mortally wounded.

What does that have to do with 10k rpm you ask? I have built some 140+ hp per liter NA motors. I really like high revving engines but it take a ton of time and money to do the research and development. Question is has anyone delve into the engines and really push them without stroking it? Failures are just as valuable as successes.
 

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jcolley M5 Expert (>4000)



Join Date: Apr 2006
Location: Maine
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My dream build for the S85 isn't stroked or FI :/

Destroked, bored, maintaining 5.0L. Forged tool aero profile steel crank with tungsten counterweights. Pankl titanium rods. Ultra-lightweight short skirt pistons. Reduced piston-to-wall clearance. Gapless top rings, Napier second ring, an actual useful (3 piece) oil control ring. Modified heads with 5mm threaded ports for Kistler piezo combustion pressure sensors. PVD coated titanium valves with beryllium valve guides. Modified solid cam followers with adjustable shims. Dry sump with Dailey engineering pump, VANOS pump delete. Modified VANOS actuators using external hydraulic pressure system separating engine lubrication medium from operating fluid.

Oh, and Motec M150 or Bosch MS7.4 with custom built XDI CA-10 combustion analyzer in closed loop arrangement.





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Hello everyone. Just acquired the m5 a few months ago and i have rod bearing failure. Very minor rick after she is warmed. Pull some oil and there is copper visible in it. I am going to install the acl bearings with +.001 clearance. I have built enough engines to know that this engine is likely mortally wounded.

What does that have to do with 10k rpm you ask? I have built some 140+ hp per liter NA motors. I really like high revving engines but it take a ton of time and money to do the research and development. Question is has anyone delve into the engines and really push them without stroking it? Failures are just as valuable as successes.
The only engines I've seen close are some fully built custom cammed race S65 engines that go up near 9000RPM. I've never seen any S85s go that high. For engines that are notorious for eating rod bearings with no real certain understanding as to why I think most people have written that type of thing off.
 

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The only engines I've seen close are some fully built custom cammed race S65 engines that go up near 9000RPM. I've never seen any S85s go that high. For engines that are notorious for eating rod bearings with no real certain understanding as to why I think most people have written that type of thing off.
+1
 

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Discussion Starter #5
I have a lot of experience in Japanese motors. They last forever because they are elegantly simply. Germans tend to over complicate things. I have been studying the oiling system of the s85 this week. It seems to be the weakest link. This is a great example of that German overthinking. Honestly I can't come up with a way to complicate an oiling system more. The oil pump pressure relief design is foolish at best. There are 3 times the amount of moving parts and several new points of wear and failure over a traditional oil pump. Not to mention the additional scavenging pumps scattered through out the motor. So my conclusion is a dry sump is the smart play. I can then control oil pressure properly and alleviate any oil starvation problems. The rod bearing failure is from tolerances that are too tight based on every engine builder I know as well as my experiences. :) So when the motor is being rebuilt those tolerance errors will be corrected. I need to study the oil delivery paths. The tolerances may have been held tighter due to oil delivery problems. With and external dry sump pump I can put the oil where it needs to be. Even if that means new oiling passages need to be added.

I don't mind scattering a few motors in the name of research. I would rather not but.... Has anyone seen any pictures of a full tear down? Does anyone have a junk motor they would like to get rid of? Rod hanging out the side of the block etc? I would like to pull one down that has failed and analyze it.
 

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If you have endless time and money to throw at it, you can make anything. But at the end, the whole package needs to work together. You are still left with a lot of stuff that has a high probability of failure, like throttle actuators, vanos, ionic control etc. etc. etc.

Personally, all this investment in a package that is so prone to failures will not be my preference.

But I like brave people and would love to see where you end up with this and how you get there.

Good luck! :cheers:



I have a lot of experience in Japanese motors. They last forever because they are elegantly simply. Germans tend to over complicate things. I have been studying the oiling system of the s85 this week. It seems to be the weakest link. This is a great example of that German overthinking. Honestly I can't come up with a way to complicate an oiling system more. The oil pump pressure relief design is foolish at best. There are 3 times the amount of moving parts and several new points of wear and failure over a traditional oil pump. Not to mention the additional scavenging pumps scattered through out the motor. So my conclusion is a dry sump is the smart play. I can then control oil pressure properly and alleviate any oil starvation problems. The rod bearing failure is from tolerances that are too tight based on every engine builder I know as well as my experiences. :) So when the motor is being rebuilt those tolerance errors will be corrected. I need to study the oil delivery paths. The tolerances may have been held tighter due to oil delivery problems. With and external dry sump pump I can put the oil where it needs to be. Even if that means new oiling passages need to be added.

I don't mind scattering a few motors in the name of research. I would rather not but.... Has anyone seen any pictures of a full tear down? Does anyone have a junk motor they would like to get rid of? Rod hanging out the side of the block etc? I would like to pull one down that has failed and analyze it.
 

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I have a lot of experience in Japanese motors. They last forever because they are elegantly simply. Germans tend to over complicate things. I have been studying the oiling system of the s85 this week. It seems to be the weakest link. This is a great example of that German overthinking. Honestly I can't come up with a way to complicate an oiling system more. The oil pump pressure relief design is foolish at best. There are 3 times the amount of moving parts and several new points of wear and failure over a traditional oil pump. Not to mention the additional scavenging pumps scattered through out the motor. So my conclusion is a dry sump is the smart play. I can then control oil pressure properly and alleviate any oil starvation problems. The rod bearing failure is from tolerances that are too tight based on every engine builder I know as well as my experiences. :) So when the motor is being rebuilt those tolerance errors will be corrected. I need to study the oil delivery paths. The tolerances may have been held tighter due to oil delivery problems. With and external dry sump pump I can put the oil where it needs to be. Even if that means new oiling passages need to be added.

I don't mind scattering a few motors in the name of research. I would rather not but.... Has anyone seen any pictures of a full tear down? Does anyone have a junk motor they would like to get rid of? Rod hanging out the side of the block etc? I would like to pull one down that has failed and analyze it.
Oh yeah .... going from Japanese rice rockets to German tank beasts .... tell me about it!!!
<!-- BEGIN TEMPLATE: dbtech_usertag_mention --> @LittlerocketE60 <!-- END TEMPLATE: dbtech_usertag_mention --> , what Jap makes did you mainly tinker with before ? My previous poison were Hondas of the B-series era.
 

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I have a lot of experience in Japanese motors. They last forever because they are elegantly simply. Germans tend to over complicate things. I have been studying the oiling system of the s85 this week. It seems to be the weakest link. This is a great example of that German overthinking. Honestly I can't come up with a way to complicate an oiling system more. The oil pump pressure relief design is foolish at best. There are 3 times the amount of moving parts and several new points of wear and failure over a traditional oil pump. Not to mention the additional scavenging pumps scattered through out the motor. So my conclusion is a dry sump is the smart play. I can then control oil pressure properly and alleviate any oil starvation problems. The rod bearing failure is from tolerances that are too tight based on every engine builder I know as well as my experiences. :) So when the motor is being rebuilt those tolerance errors will be corrected. I need to study the oil delivery paths. The tolerances may have been held tighter due to oil delivery problems. With and external dry sump pump I can put the oil where it needs to be. Even if that means new oiling passages need to be added.

I don't mind scattering a few motors in the name of research. I would rather not but.... Has anyone seen any pictures of a full tear down? Does anyone have a junk motor they would like to get rid of? Rod hanging out the side of the block etc? I would like to pull one down that has failed and analyze it.
As a point of clarification, the oil pressure control system in the S85 pump is not a relief, but a variable output regulation to control pressure. There is no relief path at all. Having rebuilt many of these now, I can say I've never seen a single oil pump failure that wasn't due to the drive chain. I disassemble, clean, and inspect every oil pump that comes through and have never seen one that isn't reusable. The design perspective of not using a true dry sump required the split oil pan to allow for low mounting without having the steering rack pass through the pan.

Most oiling system failures are a result of the VANOS pump failing for one of a few reasons and this in turn takes out the oil pump drive. This is classic German engineering philosophy of not designing things to fail gracefully. The non-essential oil delivery system is the driver for the essential oil delivery system. You can run the engine with the VANOS T lines disconnected and blocked off. The pump should have been switch in position IMO.

Dry sump is an option, but I'm not a fan of the current systems so working on my own. IMO, VANOS should be retained but operated on a separate hydraulic system much like the actual F1 cars were.
 

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Recent Smoking Tire podcast with Steve Dinan and Matt Farah. Steve Dinan has taken the s85 motor to its naturally aspirated limit. Fascinating how he manages to extract power beyond just bore and stroke. If I remember correctly its running a dry sump and put out 760 hp. 40k price tag!
 

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