Blown Engine: Part Deux - Teardown

[SYT_Shadow]

After having our engine sit around for two years we finally got around to disassembling it and will post the teardown here to continue building the knowledge based of the forum


Original blown engine thread:
https://www.m3post.com/forums/showthread.php?t=1520978


Some background
We bought the car with 36k miles in 2016 as a dedicated track car. 2011.5 E90 M3 slicktop DCT as the only option, no nav, cloth seats, completely stock at the time.
The first weekend after buying the car we did rod bearings. This is the car of the rod bearing DIY


We kept the engine/exhaust stock for the first ~25k miles and two track seasons, modding brakes & suspension only.
Two track seasons are around 60 track days, but the car is double-teamed so the it sees twice as many sessions per day as a regular car. In other words, the engine has 120 normal track days on it.


After 25k miles and 120 track days days we added an Epic off the shelf tune. We specified a catless tune, however, when the track day rolled around our catless xpipe hadn't arrived so instead we opted to use our ESS HFC Xpipe from our E92.
That xpipe had survived plenty of track days on our other car.
In the first day, first session with the tune and the xpipe on the E90 we did a personal best at WGI with R1 tires (2:06.7) but the engine was 'not running right'. We forfeited the weekend because something was clearly wrong. It is as if the car were running on 7 cylinders, vibrating horribly.

We took it to several mechanics and ended up $10k out of pocket troubleshooting uselessly. The mechanics kept telling us to keep driving the car even though it felt like it was about to tear itself apart. Foolishly we followed their advice.
One day we decided to remove the xpipe and saw the cats were melted, completely blocking one of the banks.

We went back to the stock xpipe and the engine started working again, but now it smoked badly.
A third mechanic identified it as bad valve stem seals, so the engine was dropped and the seals were replaced.
While we were at it, we installed our 284 cams and BE springs as well as the BW LT headers and Karbonius airbox
As there are no off the shelf tunes for 284 cams we did what I had always vowed we wouldn't do and the car went to get custom tuned. RK is in Long Island and is relatively local.
The car went to RK, got tuned on their dyno, put down 412whp and then the engine seized.

Then it sat around for 2 years until we disassembled it

The results are surprising. I'm going to leave a couple posts open to AutoTalent, kawasaki00 and greeneggs , CarBahn Autoworks , deansbimmer , jcolley


You can see some fluid in the valley of the V8










The black 284 cams


Vanos unit










Head


detonation






removing the cams


notice how different the first cylinder is than the rest on the head




Massive scratch on the cylinder wall


More detonation








this is what you see in any rod bearing job






you can see the be-arp bolts here


removing bedplate


main bearing #1 spun






bedplate removed. When you do rod bearings you can see the iron inserts on the bedplate, but removing the bedplate you see how much iron is in there! Lots of it!




Main bearing #2 doesn't look particularly happy either






Look at how much detonation there is on this piston




Another piston, lots of detonation


Broken ring besides lots of detonation




Broken ring


another shot of the broken ring






for reference, this sharp edge is what the piston should look like


this is where main bearing #1 goes. Note how it spun








Huge scratch in the cylinder wall. This is the same cylinder with the broken ring


another cylinder


another cylinder


another one


another one


more scratches

























Finally, BE rod bearings. Looking good!!






A few things to note:
-Main bearing #1 seized, just as expected. It is welded around the crank
In our opinion this was to be expected. The engine drove for 2k miles while running horribly, so this imbalance wore all the bearings out
-The block did not crack
-Multiple cylinders show signs of lots of detonation
-One cylinder has a broken ring
-BE bearings on cylinder 1 are beat up. This is to be expected from the main bearing failure
-The rest of the BE bearings look incredibly good. The damage on the engine in general is serious, yet the bearings almost look new. Excellent results from BE bearings

[SYT_Shadow]

Reserved 1

[SYT_Shadow]

Reserved 2

[SYT_Shadow]

Reserved 3

[dogbone]

Thanks for posting all those pics.

So, regarding all the detonation on the pistons---Is there a guess as to where all that comes from? Is it a tune issue? Is it a low octane issue?

And what do you think is the cause of all the scratching on the walls?

[pbonsalb]

Is the recommendation not to run a catted car on the track, not to run a catted car with a catless tune on the track, or not to run a catted car with a catless tune and cams on the track?

[SYT_Shadow]

Originally Posted by dogbone

Thanks for posting all those pics.

So, regarding all the detonation on the pistons---Is there a guess as to where all that comes from? Is it a tune issue? Is it a low octane issue?

And what do you think is the cause of all the scratching on the walls?

For me the detonation comes straight from the aftermarket tunes

The only fuel used on the engine is 93 octane, which is what it was tuned to as well. Top tier fuel always.

Some of the scratching probably comes from the engine running so rough, other parts of it are probably normal

[SYT_Shadow]

Originally Posted by pbonsalb

Is the recommendation not to run a catted car on the track, not to run a catted car with a catless tune on the track, or not to run a catted car with a catless tune and cams on the track?

Haha, good questions!

The oem tune and the oem exhaust ran many many days without issues.


A catless tune can't run with cats. It runs much hotter and melted the cats immediately. This is completely on us.


The engine never ran cats with a cam tune on the track, or even on the dyno. The dyno was done with the Bimmerworld LT headers, catless xpipe and cams.

[BayE30]

Thank you for going through the trouble to document this. I am also curious about all the detonation you are seeing here.... is the detonation primarily on the same bank as the failed catalyst?

[Obioban]

So...
-catless tune run with catted pipes caused the cats to overheat and fail
-clogged pipe interfered with exhaust flow causing detonation
-... for some reason the knock sensors didn't throw the car into a safe mode. Knock sensors turned down/off by the tune?
-detonation damaged the pistons and shook everything to failure. Main bearing 1 was the first to go, it seized, that was all she wrote
-BE bearings looking good

Sound correct?

[SYT_Shadow]

Originally Posted by SFCM3

Thank you for going through the trouble to document this. I am also curious about all the detonation you are seeing here.... is the detonation primarily on the same bank as the failed catalyst?

no, it is all over the place

[SYT_Shadow]

Originally Posted by Obioban

So...
-catless tune run with catted pipes caused the cats to overheat and fail
-clogged pipe interfered with exhaust flow causing detonation
-... for some reason the knock sensors didn't throw the car into a safe mode. Knock sensors turned down/off by the tune?
-detonation damaged the pistons and shook everything to failure. Main bearing 1 was the first to go, it seized, that was all she wrote
-BE bearings looking good

Sound correct?

I'm not sure the clogged exhaust would cause detonation. It's a bit of the chicken and egg situation

I'm also not sure whether the detonation is what took out the main bearing or not.

[Iyzmi]

Originally Posted by SYT_Shadow

For me the detonation comes straight from the aftermarket tunes

The only fuel used on the engine is 93 octane, which is what it was tuned to as well. Top tier fuel always.

Some of the scratching probably comes from the engine running so rough, other parts of it are probably normal

Thank you for posting this. Definitely not a good look for RK tunes.

[pbonsalb]

The broken ring and detonation debris could also have contributed to the scratched cylinder wall.

[SYT_Shadow]

Originally Posted by pbonsalb

The broken ring and detonation debris could also have contributed to the scratched cylinder wall.

For sure. Not sure what broke the ring but that's the cylinder with the giant scratch

[SYT_Shadow]

Originally Posted by Iyzmi

Thank you for posting this. Definitely not a good look for RK tunes.

I can't really blame RK, I'm not sure which tune and to what extent it contributed to it, only of the end result

[Scharbag]

Thanks for sharing. So is the block is salvageable for another stroker?

Given I have been fighting pre-det/VANOS noises for some time, I am a little afraid of what my pistons might look like.

Those BE bearings look pretty good. It seems that the coating is still mostly intact - is that the case?

Again, thanks for sharing.

Cheers,

[SYT_Shadow]

Originally Posted by Scharbag

Thanks for sharing. So is the block is salvageable for another stroker?

Given I have been fighting pre-det/VANOS noises for some time, I am a little afraid of what my pistons might look like.

Those BE bearings look pretty good. It seems that the coating is still mostly intact - is that the case?

Again, thanks for sharing.

Cheers,

Maybe you want to go back to the OEM tune!

It seems like the block is indeed salvageable. We'll see if it turns into a table or another stroker.

The bearings look very, very good considering what the engine has gone through. I almost want to put them back into a car hehehe.

[Scharbag]

Originally Posted by SYT_Shadow

Maybe you want to go back to the OEM tune!

The thought has crossed my mind... Sell the X-Pipe and go back to 241E...

I may pull my plugs and throw a borescope in there to see what we see.

Cheers,

[SYT_Shadow]

Originally Posted by Scharbag

The thought has crossed my mind... Sell the X-Pipe and go back to 241E...

I may pull my plugs and throw a borescope in there to see what we see.

Cheers,

Or keep the xpipe. Just get a few 'spark plug defoulers' and you should be able to avoid the CEL for a long time

[drrust]

Thanks for posting.

[bigjae1976]

Interesting