F2X First N55 Build
- Thread starter Dumaurier7
- Start date
Looks awesome! I see the channels milled into the top of the sleeves, did you say what type of head gasket you're going to run? Also, I can't remember, did you have that block re-sleaved as well or just closed deck?
Hi, there,
I have a question following a discussion I had with a friend.
Is it possible to use the s55 engine block on a car equipped with the N55?
What seems compatible:
-mounting points, sensors (CKP, CMP),
-Engine sensors: several sensors, such as crankshaft, AAC, etc., are in the same locations.
-Lower housing, HPFP pump location and even cylinder head are very similar, though not identical.
Do you think this is a long-term solution?
I have a question following a discussion I had with a friend.
Is it possible to use the s55 engine block on a car equipped with the N55?
What seems compatible:
-mounting points, sensors (CKP, CMP),
-Engine sensors: several sensors, such as crankshaft, AAC, etc., are in the same locations.
-Lower housing, HPFP pump location and even cylinder head are very similar, though not identical.
Do you think this is a long-term solution?
It's not a build for a novice builder, but yes, technically.
Although I'm not sure of using an N55 head on the S55 block.
The N55 and S55 are about 75% the same. I was even able to directly bolt on an xDrive oil pan with no real modifications.
I'm not 100% certain, but I think the differences in cylinder heads between n55 and s55 is limited to the material/construction of the valves (though they're the same sizes), and potentially the size of the cooling channels. Same valvetronic and vanos systems (including range of adjustmemt). For head gasket, supposedly all that's different are different cooling port channels in the s55 version. And valve covers are the same except the s55 version has the vacuum reservoir deleted.
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Also they have the same intake and exhaust cam shafts, same eccentric shafts for valvetronic, and same intake manifold.
I know they flow better too. 
I just couldn't answer directly on how the cooling ports line up with the closed deck design on s55 block vs N55 head.
And I try not to give advice on things I'm not
on.
Im almost finished uploading the S55 technical documentation from BMW, once done I'll post a link to the resource.
I just couldn't answer directly on how the cooling ports line up with the closed deck design on s55 block vs N55 head.
And I try not to give advice on things I'm not
on. Im almost finished uploading the S55 technical documentation from BMW, once done I'll post a link to the resource.
The heads should flow the same? Here's the valve lift/size details -they're identical.I know they flow better too.
I just couldn't answer directly on how the cooling ports line up with the closed deck design on s55 block vs N55 head.
And I try not to give advice on things I'm not
Im almost finished uploading the S55 technical documentation from BMW, once done I'll post a link to the resource.
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They're tricky, and/or make some cooy/paste errors from the n55 technical documentation when creating the s55 version; the n55 version (comparing it to n54) also stated valve stem diameters are 5mm and 6mm, with sodium filling in the exhaust valves
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Hi. I didn't do a re-sleeve. I did the closed deck with "O" ring groove for coper wire, for the head gaskiet I think I'll go OEM with the Custom Age 625+m studs.
Hey, copy/paste errors happen lol, their wording is confusing sometimes as well.
They do show the same specs between the two (N55-S55), but in the first section they mention the head was modified to meet racing specifications. I assume this means bowl and port shape, which can change flow rates even with having the same components.
I.E. when you port and polish a head to make it flow better, but don't necessarily change any of the valvetrain components.
From everything I've read they are the same engine, except for............the water pumps, the N55s' is electric and the S55 is mechanical so it's bolted to the block and the N55 uses a water pipe to get the water to the block. The heads can be interchanged, but the turbocharges cannot be without an adapter. The oiling system is different but the better S55 parts fit the N55, this was OEM with the M235R . I'll be using the S55 pumps, suction pipe and oil pan on my N55. All the sensors are the same and the N55 vacuum pump will work on the S55 block as well. The N55 DME should be returned if the dual HPFP's and twin turbos from the S55 are NOT utilized. The only peeve I have with the S55 is the "upgraded" aluminum sprayed cylinders, they cannot be over-bored like the steel ones used in the n55.
I have these available if you dont already have them.
My swap is in an xDrive E90, so I couldn't use them on my build.
Motor was a BMW warranty swap with only about 20K miles on it.
I'm going to be sending the head off to VAC soon, but I don't know anything about their
"VAC Motorsports Combustion Chamber Modification Service, BMW S55" anyone have any experience with this? Is there a notable performance increase?
Good point, I didn't think of that. I assumed they referred to different valve springs and valves to support the higher redline of the s55, but you're right the port and combustion chamber geometries could be different. I'm guessing combustion chambers are the same, since bore and stroke are the same, as is compression?
