Cylinder leakdown higher after engine rebuild?

[Chanman1029]

I want to see if I can boroscope mine soon. Just rebuilt and did a hard breakin on conventional 5-40.
Not a master at this but I have heard not to use high zinc or anything like that and hopefully you weren't spending too much time at the same/low rpms. Are you getting driveability problems?

No driveability whatsoever, feels just as it should. And no, it was varied rpm, I’m made it a point to not stay in the same rpm for long periods of time, maybe just a few times on the highway for maybe 5-6 miles, but even then I changed it up periodically.

[digger]

Do you know the ring material and coatings?

Unfortunately many modern steel rings and coatings need a specific hone to work properly as they are not as forgiving as older school stuff.

If you watch total seal videos on YT they go onto very high levels of detail about what is needed, how to measure it and how to achieve it. The deep valleys in the hone holds oil to stop rings and bores wearing and to seal air. The plateau supports the load and quickens the breakin process.

Many shops are shooting blind by using old school methods (stones, equipment and processes) on modern rings and have no idea whether what they produce is optimum so this is why many aftermarket forged builds have issues.

Im not saying this is the cause here but I like Mahle MS as they do offer a PVD moly ring and the moly is good because it’s porous and retains oil so the valley on the hone is a bit less critical for holding oil.

you should not be rebuilding an s54 without using a torque plate and using a shop that has a profilometer to ensure the hone is good. If you don’t do this it’s a lottery

[Chanman1029]

Do you know the ring material and coatings?

Unfortunately many modern steel rings and coatings need a specific hone to work properly as they are not as forgiving as older school stuff.

If you watch total seal videos on YT they go onto very high levels of detail about what is needed, how to measure it and how to achieve it. The deep valleys in the hone holds oil to stop rings and bores wearing and to seal air. The plateau supports the load and quickens the breakin process.

Many shops are shooting blind by using old school methods (stones, equipment and processes) on modern rings and have no idea whether what they produce is optimum so this is why many aftermarket forged builds have issues.

Im not saying this is the cause here but I like Mahle MS as they do offer a PVD moly ring and the moly is good because it’s porous and retains oil so the valley on the hone is a bit less critical for holding oil.

you should not be rebuilding an s54 without using a torque plate and using a shop that has a profilometer to ensure the hone is good. If you don’t do this it’s a lottery

Ring material should be chrome, coatings I am unsure. As far as procedures go, im sure lang racing probably uses a torque plate and anything else that is necessary. Its not secret they do great work, but someone went wrong, thats what I’m trying to get to the bottom of.

I reached out to the front desk at Lang and explained the new information to them that I have. I sent them the pictures but andrew had left for the day so I should be expecting a call in the morning.

[digger]

Ring material should be chrome, coatings I am unsure. As far as procedures go, im sure lang racing probably uses a torque plate and anything else that is necessary. Its not secret they do great work, but someone went wrong, thats what I’m trying to get to the bottom of.

I reached out to the front desk at Lang and explained the new information to them that I have. I sent them the pictures but andrew had left for the day so I should be expecting a call in the morning.

They will likely be farming machine work out (hopefully) as they cant be near best practice if doing internally based on the services offered being so broad.

CP often use gas nitrided steel. You would want the ducks lined up and its not to be assumed they are.

[Chanman1029]

They will likely be farming machine work out (hopefully) as they cant be near best practice if doing internally based on the services offered being so broad.

CP often use gas nitrided steel. You would want the ducks lined up and its not to be assumed they are.

Gotcha, my assumption was based on the fact that blackstone said the chrome in the oil was most likely coming from rings, and lang agreed aswell. But tbh I dont know for sure. We will see how our conversation with Lang goes tomorrow.

[Slideways]

Ring material should be chrome, coatings I am unsure. As far as procedures go, im sure lang racing probably uses a torque plate and anything else that is necessary. Its not secret they do great work, but someone went wrong, thats what I’m trying to get to the bottom of.

I reached out to the front desk at Lang and explained the new information to them that I have. I sent them the pictures but andrew had left for the day so I should be expecting a call in the morning.

They have a detailed description of their Stage 1 engine rebuild - no mention of a torque plate. I wonder how the factory blocks are machined?

https://store.langracing.com/product...long-block/

[Chanman1029]

They have a detailed description of their Stage 1 engine rebuild - no mention of a torque plate. I wonder how the factory blocks are machined?

https://store.langracing.com/product...long-block/

When does a torque plate get used? During block machine work?
I know for certain they outsource for that kind of work

[Slideways]

When does a torque plate get used? During block machine work?
I know for certain they outsource for that kind of work

Yes, it replicates having the cylinder head torqued down which, in theory, distorts the bores ever so slightly. I would think cast iron does not distort much and BMW didn't do this when machining a new S54 block. The description on the site is pretty detailed, so one would assume they would add that bit about the torque plate.

[Chanman1029]

Yes, it simulates having the cylinder head torqued down which, in theory, distorts the bores ever so slightly. I would think cast iron does not distort much and BMW didn't do this when machining a new S54 block. The description on the site is pretty detailed, so one would assume they would add that bit about the torque plate.

Makes sense, I wouldn’t know. I will try to remember to ask if those marks could be from not using a torque plate. Andrew actually just responded to my email with all 21 photos I sent, his response was, “received, thank you”

I’m really hoping for the best here, I really dont want to sink more money into the motor.

[digger]

Yes, it simulates having the cylinder head torqued down which, in theory, distorts the bores ever so slightly. I would think cast iron does not distort much and BMW didn't do this when machining a new S54 block. The description on the site is pretty detailed, so one would assume they would add that bit about the torque plate.

Didn’t you see the thread where the German fellow measured this and the bores distorted a lot. Even VAC know this and that says something

[Slideways]

Didn’t you see the thread where the German fellow measured this and the bores distorted a lot. Even VAC know this and that says something

Yeah, first time I saw a torque plate mentioned was in an old HPF video:

I wonder what the procedure is at the factory or is it just a combination of the pistons, rings and hone that get the engines to last 100k+ miles.

[sapote]

I assembled it lmao, and that’s exactly what they will say even though he assembled the short block, I only mated the block and head.
....
Cylinder 5 is by far the worst, and even has what looks like multiple spots of corrosion on the cylinder wall. This alone was pretty disturbing for me to find.

So you didn't look at the newly honed cylinder walls before bolting down the head?

[jet_dogg]

So you didn't look at the newly honed cylinder walls before bolting down the head?

That's exactly what I've been wondering this entire time.

[digger]

Gotcha, my assumption was based on the fact that blackstone said the chrome in the oil was most likely coming from rings, and lang agreed aswell. But tbh I dont know for sure. We will see how our conversation with Lang goes tomorrow.

Steel ring with CrN coating is also common

[Chanman1029]

So you didn't look at the newly honed cylinder walls before bolting down the head?

Nope, didn’t really think twice about it to be honest.

first timers mistakes

I only have a few photos that I took, but I didn’t spin the motor to inspect walls. Looking through my photos and few videos I have, its clear that many of these marks were not there.