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Discussion Starter · #1 ·
I’ve been looking at pics of different engine blocks trying to get an idea of what would be the best set up for a strong reliable engine build. There are a number of options out there; Focus ST 2.0, 2016-2019 Fusion 2.0 Ecoboost or the Focus RS 2.3. All with the 2.3 internals of course.

I’m leaning more towards the 2.0’s due to the semi closed deck design, whoever, I have some questions I’m hoping our community can help answer.

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Here is a side by side comparison of the 2.0 ST (left) and 2.3 RS (right) blocks. The difference between “B 2.0” and “B 2.3” has been associated with more material and thus better reinforced, but if you follow it to the top of the deck, it is open.
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Is it an oil return passage or is it a coolant passage? This is also one of the areas the gets welded closed when using with the 2.3 RS head.
The next question for the comparison pic is, for the two areas I have circled, which oil returns, mounting points, plugs and what not get used? As well as for the front side of the engine (not pictured)? If you notice the larger circled areas on the left sides of both engines they are very different. The 2.0 ST has 2 mounting points, where as the 2.3 RS has 4. One in particular appears quite significant and approximately 3/4” in diameter. Do these points matter, are they still used just in different locations on each block?

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And finally questions for the 16-19 Fusion 2.0 block as pictured above. Notice again in the circled areas there is a difference in mounting locations and plugs. However for the left circled area, this block has 3 spots as opposed to 2, but still missing the larger 3/4” spot. Does it really matter. Also if you look at the area signified by the arrow, similar to spots “B” in the other pictures, there is no extra bracing or coolant/oil passage. Is that area really strengthening the block? Some builders are using this block, but if that area isn’t “strengthened” similar to the 2.0 ST block wouldn’t it still crack under higher horse power applications? I like the idea using this block as it appears to offer better cooling jackets around the cylinders than the 2.0 ST block (look closely) and it appears as though you don’t need to weld anything closed, but if it’s going to crack under pressure, should I just go with the 2.0 ST block?

I look forward to your thoughts and I hope this helps others as well. I need to credit DeltaT for the side by side comparison pic as found in his engine build thread here.
Building a Strong 2.3 With a 2.0 Block
 

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The B area you circled is an oil return gallery not used in the 2.3 block and the casting is filled on the 2.3 head. When you build a 2.3 with the 2.0 block I believe you use the 2.0 style head gasket so that area of the block is sealed by the gasket and the fact that the gallery on the 2.3 head is a closed casting. No need to weld the hole.
Area A you highlighted is the area where 2.3 blocks tend to crack if they do, along the casting line. Much conjecture over the how and why and a few theory's out there some of which are silly but there you go.
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Check out the TunePlus web site and talk to Adam if you can. There was a YouTube video a while back where a build shop cut a block into pieces to show the weak points and why the 2.0 blocks are the way to go.

 
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Check out the TunePlus web site and talk to Adam if you can. There was a YouTube video a while back where a build shop cut a block into pieces to show the weak points and why the 2.0 blocks are the way to go.

 

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I am building a new engine using the 2.3 block with Darton Sleeves. This is a Mountune set up and they have a car reliably pushing 680 wheel with stock gasket and studs. They indicated to me that they have not had any reported 2.3 blocks crack on this set up. That said, the 2.0 block is certainly an excellent platform to stroke and appears very reliable also.


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Taken from Adam’s Facebook post.

“Basically the 2.3 is perfectly fine unless you allow 1000psi of steam into the cylinder and then try and compress it”. It was just a gasket issue and never a block issue.
2.3L Block cracking / Headgasket update. This is worth the read.
I have posted about this before, and we have came up with a “fix” for the 2.3L block cracking along the head stud bosses on the side of the block. However this is STILL not a fix for the block cracking issue. After further investigation and testing, we have determined the cause of the factory blocks cracking on the 2.3L variants.
Deep breath, time to mash the keyboard
It has been believed that the cause of the blocks cracking have been the fact that the head stud bosses are weak and/or have casting flaws. The upward force from compression/big boost on the cylinder head has been putting stress on the side of the block and causing a stress crack as shown in PICTURE 1 below (factory engine, not built).
This is not the case, in fact in nearly every instance of a block cracking a blown headgasket has accompanied it. I say nearly because not everyone has been documented accurately. On the Focus RS side of documentation there have been mentions of the block being cracked, but never mentioned if the headgasket failed as well. Most of the time when a dealer gets a cracked block Focus RS/Mustang in their shop they simply pull and install a new OEM longblock. Obviously if you follow the Focus RS pages and many blog post you know there is a headgasket problem with the Focus RS.
 

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Taken from Adam’s Facebook post.

“Basically the 2.3 is perfectly fine unless you allow 1000psi of steam into the cylinder and then try and compress it”. It was just a gasket issue and never a block issue.
I've seen this loony theory before. So the HG fails or you get some head lift that causes the gasket to leak combustion pressure into the water jacket and into the non compressible coolant. The instant this happens the whole cooling system is now seeing additional pressure and what happens? does it lift the 21psi pressure relief tank coolant cap and dump coolant and pressure? does it blow to bits the plastic coolant tank? apparently not. All those plastic and rubber components are fine but the alloy block splits, according to this theory.

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Adam no longer builds with the 2.3 block. His website says they use the Fusion 2.0 block as the base for any customer builds.
NOTE, ALL OUR ENGINES ARE BUILT WITH 2.0 (TS) FORD FUSION BLOCKS, BUT 2.3L INTERNALS. THIS IS TO AVOID CRACKING ON THE BLOCK THAT THE FACTORY 2.3L ENGINE BLOCK HAS BEEN KNOWN TO HAVE HAPPEN. 2.0 BLOCKS DO NOT REQUIRE CYLINDER SUPPORT SYSTEMS AS THEY ARE SEMI-CLOSED DECK. "
 

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Adam and all the tuners jumped on the 2ltr wagon when it all started going wrong due to the wrong head gasket.

Months and months after they all banged the drum on the 2ltr Adam was actually brave enough to come out with his findings after his Company and others where are promoting the 2ltr.

The alloy block cracks due to hydro locking of the crank rod and pistons coming to an instant stop, not the actual pressure breaking the blocks the dead stop of all the rotating parts due to the inherent pressure release which is then released via the crack virtually instantly.

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I understand that the 2.3 headgasket is on around its ninth revision. Hydro locking may have been an issue on the early, failed headgaskets but wow - you would have to continue running a car for a hell of a long time to generate the cross over to allow the amount of coolant into the cylinders to cause hydro locking. And has been stated eloquently before, the pressure build up would be evidenced back through the coolant system with header tanks exploding or at least lines separating. I maintain that the inherent risks of LSPI associated with high compression, turbocharged direct injection vehicles is the cause of the majority of the more recent (18-24 months) RS engine failures. Insufficient oil change frequency causing the chemistry of the lubricant to become more volatile and ignite in cylinders, drivers lugging their cars and poor fuel causing high cylinder temps / reduced octane and detonation.


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Discussion Starter · #12 ·
In Nishan’s video he states that the cracks are on the exterior portion of the water jacket, I’d screen shot it but I have limited resources. If it was due to LSPI or hydro locking wouldn’t all the damage be happening to the pistons or cylinder walls? Unless there is new damage happening to our engines I’m not aware of. Also if Adam is using the 2.0 Fusion blocks, it has the same exterior cylinder bracing as the 2.3 RS blocks. Wouldn’t some engines still encounter the same cracking? Unless he’s using pre 2016 blocks which are basically 2.0 ST blocks and offer a more robust exterior cylinder bracing?
 

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In Nishan’s video he states that the cracks are on the exterior portion of the water jacket, I’d screen shot it but I have limited resources. If it was due to LSPI or hydro locking wouldn’t all the damage be happening to the pistons or cylinder walls? Unless there is new damage happening to our engines I’m not aware of. Also if Adam is using the 2.0 Fusion blocks, it has the same exterior cylinder bracing as the 2.3 RS blocks. Wouldn’t some engines still encounter the same cracking? Unless he’s using pre 2016 blocks which are basically 2.0 ST blocks and offer a more robust exterior cylinder bracing?
Yep thats correct. Plenty have had hydrolock and bent rods,broken pistons and split liners without cracking the block exterior wall. It's another "theory," a little more sensible than the leaking HG one but not by much. Truth is these people dont actually really know for sure the failure mechanism and nor do I. But I can say almost certainly what it wont be.
I think in general there is a decent argument for using the 2.0 block for high horsepower applications not the least because it has better cylinder support which most engine builders aim for with that sort of output.

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In Nishan’s video he states that the cracks are on the exterior portion of the water jacket, I’d screen shot it but I have limited resources. If it was due to LSPI or hydro locking wouldn’t all the damage be happening to the pistons or cylinder walls? Unless there is new damage happening to our engines I’m not aware of. Also if Adam is using the 2.0 Fusion blocks, it has the same exterior cylinder bracing as the 2.3 RS blocks. Wouldn’t some engines still encounter the same cracking? Unless he’s using pre 2016 blocks which are basically 2.0 ST blocks and offer a more robust exterior cylinder bracing?
Which Nishan video are you referring to? The 2.3 ecoboost mustang cylinder head tear down one?


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I lightly browsed through the TunePlus site and it looks like this is only necessary for 500+hp builds. Are there any reports of blocks cracking with light mods/tunes around 350-400 wheel hp?
 

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As far as I can tell, I actually haven’t heard of a block cracking for well over 2 years; on any forum, FB group or YT clip. Engines letting go occasionally yes, but no cracked blocks.


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As far as I can tell, I actually haven’t heard of a block cracking for well over 2 years; on any forum, FB group or YT clip. Engines letting go occasionally yes, but no cracked blocks.


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Yep, and from my memory they were all std engines and relatively low mileage which left me postulating about an assembly issue at the factory. If the block head bolt holes aren't properly cleaned or more likely have cutting/cleaning fluid in the bottom of the blind hole when you insert the head bolts and the machine runs them down and torques them up in one big action the fluid in the bottom of the holes hydraulic lock with enough pressure to micro crack a thin walled alloy casting. After that its just heat and expansion contraction cycles and you have a full blown crack.Critical to clean out all blind threaded holes in engine blocks during rebuilds esp alloy ones.
Just a theory that I've seen played out in the past.

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Agree. I noted that Nishan mentions at one point that he suspected that the composition of the blocks may have been varied since the early failures and this does seem possible - if dealers and owners of the 2016s reported blocks cracking it does resonate that the engineers on the RS team would consider stronger materials if they were unable to make geometric changes to the 2.3.


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