Quote:
Originally Posted by jimmy9980
So if the tech is saying the m40i is a closed deck wouldn't that also mean the B58 new engine would be closed deck too? According to this BMW tech?
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BMW X4 M40i ? OK, bear with me for a moment.
The S55B30T0 engine (M3/M4) and B58 engine (M140i, M240i, 340i, 440i and 740i/Li + future) both have a 'closed deck' design and feature LDS-coated aluminium cylinder liners. LDS (
Lichtbogendrahtspritzen = twin wire arc spray process) permits a thinner/lighter cylinder wall (small when compared to the typical iron sleeve). The decreased thickness allows for greater thermal transfer and consistency, all while allowing extra cooling channels (part of the water jacket) between cylinder bores so the engine can be tuned "hotter" since the cooling properties are greater.
The M2 and X4 M40i engine both share the N55B30T0 engine. That engine does not sport LDS-coated aluminium cylinder liners, but features moulder cylinder liners made from cast iron. Pistons were adopted from the S55B30T0 engine (M3/M4). Adaptations were necessary on the first piston ring, the plain rectangular compression ring. This had to be adapted as regards the material pairing to a liner made of grey cast iron.
As pointed out in
post #1 of this thread, back in October 2015, 'closed deck' was mentioned in several M2 marketing materials, but in the course of February 2016, the 'closed deck' reference was removed from some (but apparently not all) M2 marketing materials.
So what did/do the X4 M40i marketing materials say ? Well, same story: back in October 2015 'closed deck' was mentioned, but in the course of February 2016 removal of the 'closed deck' reference from some (but apparently not all) X4 M40i marketing materials.
- X4 M40i US press release of October 1, 2015 (available here - full PDF document here): alike the M2 US press release of October 14, 2015 (available here - full PDF document here) reference is made to a 'closed deck' design:
"The newly developed M Performance TwinPower Turbo inline 6 cylinder gasoline engine for the new BMW X4 M40i combines high performance with exemplary fuel economy. Accordingly, the lightweight, thermodynamically optimized aluminium engine has been constructed with a closed-deck design. In this type of construction, the water jacket surrounding the cylinders is sealed at the top, which endows the crankcase with an exceptionally high degree of stiffness."
- X4 M40i German press release of February 17, 2016 (available here - full PDF document here): alike the updated M2 German press release of February 17, 2016 (same day) the reference to 'closed deck' design has vanished (available here - updated full PDF document here):
"Der neue BMW X4 M40i verfügt über einen neu entwickelten M Performance TwinPower Turbo Reihen-Sechszylinder-Benzinmotor. Das leichte, thermodynamisch optimierte Aluminium-Triebwerk wurde auf maximale Drehfreude bei gleichzeitig souveränem Durchzugsvermögen ausgelegt und bietet dementsprechend eine Motorcharakteristik, die begeisternde Fahrdynamik mit beeindruckender Effizienz verbindet."
- more X4 M40i press releases of February 17, 2016 (available here): except for the English version, no "closed deck" reference in the French, Spanish, Italian and Russian press releases.