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yep m5 said:
has this been done or tried before? love to Know if it can be successful. this has been done with other v8's with an offset grind crank, usually gives about 10-15% more cc's. Then the engine can take a more radical cam and would still be pretty smooth.
Any thought's
Yep, it's been done a couple times!!!!

The BMW V8 has grown from 3.5L to 4L to 4.4L to 4.6L to 4.8L to 5L thru OEM engineer stroking and poking. Not too sure about the 3.5L, but the deck height is the same on 4L thru 5L engines. Since stroking increases are limited by deck height, it's safe to say BMW has stroked and poked their 5L S62 V8 until there's no significant room left. Any further stroke increases would likely weaken the reciprocating assembly and lower safe peak RPM, so there would be no benefit. BMW did not raise deck height to allow more room for stroke because the engines can barely be crammed into the 5 series chassis' already. It'd probably cost you $10K to squeeze another 5% more cubes out of the motor thru stroking...offering approximately a 5% HP gain, assuming durability did not suffer & assuming air flow could match the new requirements.

If you have a 4.0L E34 or 4.4L E39/E53, there are plenty opportunities to increase stroke and bore to something near S62 specs. Big gains are possible here. If somebody would just contact one of those Chinese forging companies and convince them to offer a $1500 reciprocating assembly for BMW V8! The Chevy and Ford small block clans are having all the fun with their dirt cheap Chinese-sourced Eagle & similar piston/rod/crank bolt-in upgrades. I think it'd be wonderful to be able to hotrod the 4.4L M62 that's found in $10K 540i & 740i cars. Perhaps such a stroker kit would give folks a more affordable retrofit option (stroked salvage 4.4L) when BMW is asking $25K for a fresh S62 motor. Rumors are that the 5L intake system bolts on to the 4.4L block & the valve sizes are already the same.

I think the 4.6/4.8 V8 and similar found in certain X5 and new 750i indicates that added stroke and bore with mild cams with modest non-M intake systems can produce 350 HP or so. Clearly we're talking monumental labor and parts costs plus R&D retrofit efforts to see a 60 HP gain. A supercharger kit makes far more sense as it can be installed in a weekend or two for far less coin and it'll produce over 400 HP.
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