The BMW M60 V8

[M60B40 with transit tranny & new manifolds attached]

The BMW M60 V8 came into production around 1992 and was available as a 3 litre (M60B30) with 218bhp and a 4 litre (M60B40) with 286bhp (European spec). It was developed over an 8 year period and used a head design layout similar to their successful M88 and S14 engines used in the M1 and the M3.

It's an alloy block with silicon/nickel lined bores, alloy heads and magnesium valve covers. Other modern features for it's time were the nylon inlet manifold & plenum, sintered conrods with fractured big-end cap fitment and double roller-chain cam chains.

It was one of the first 32 valve V8s to come into mainstream production in a luxury saloon and was at the top of the Ward's best engine of the year list for 6 years running. It is physically quite a large engine, especially in width due to the 90 degree bank angle and multivalve DOHC cylinder heads. The 4 litre and the 3 litre have the same external block dimensions, and the bolt patterns for the sump and the gearbox are the same. Also the exhaust manifold spacing and bolt pattern is also identical. But the cylinder heads, valve covers, inlet port spacing and inlet manifold are longer on the M60B40.

The cam duration for the M60B40 is 242 exhaust and 246 inlet. Standard valve timing is 48/14 exhaust and 14/52 inlet. Cam lift is 9.7mm inlet and 9.4mm exhaust. Valves are 35mm inlet and 30.5mm exhaust.

Engine weight - after weighing all the engine components seperately (according to the old scales i was using) the bare block is around 30kg, the crank 19kg and the complete heads 27kg each. I make it a total engine weight of around 175kg complete with exhaust manifolds, alternator, starter, inlet manifold and valve covers, etc... (but minus AC & PS pumps) I've seen a quoted weight of around 200kg but can't quite see how this is arrived at even with the AC & PS pumps.

This pdf file gives a lot of useful information on the engine design :

In 1996 the engine was updated to the M62 version. And was available in 3.5 litre and 4.4 litre capacites, with 235 and 286bhp respectively, and coded M62B35 and M62B44. The 4.4L does not have any more outright peak power than the M60B40, but presumably has a stronger torque curve from lower rpm. Bore and stroke for the M62B44 is 92mm x 82.7mm. I've read on forums that the cams are softer on the M62 but don't have any data on it. I think the sump pan and the gearbox bolt patterns are the same as the M60 and i suspect that the block casting is very similar (same 98mm bore centres). The main difference is that the M62 reverted to a single-chain timing chain setup where the M60 used double cam chains. BMW enthusiast also say that the M60 inlet manifold/plenum flows better than the M62 and is often retrofitted to the later engine (sometimes with the cams as well) to improve the top-end performance of the M62.

In 1998 the M62 was updated again with BMW's VANOS system (variable valve timing) which works on the inlet cam and is known as single-vanos and these engines were coded M62TUB44. Unlike other variable cam timing systems available at this time that just switch from one fixed cam timing to a different setting at high rpm, the BMW system is completely variable throughout the rev-range. If an aftermarket ECU could control and allow adjustment of this type of continuously variable cam-timing then it would be a very powerful tuning tool.

THE M60 NIKASIL PROBLEM:   

BMW chose to use a hi-tec bore-coating process for the M60 which enabled them to do away with the iron cylinder liners that were previously used in aluminium engines like the Rover/Buick V8. The Nikasil process was an electrodeposited lipophilic nickel matrix silicon carbide coating (developed by Mahle in the late 60s) and cannot re re-applied by conventional machine shops. 

Problems arose with the coating wearing out too quickly and BMW blamed this on the high sulphur content found in low-octane fuels. When warranty problems arose BMW dealers had the engine blocks replaced with identical new blocks. 

Later M60 engines were produced using a process called Alusil, which is simpler in just being an alloy block with very high silicon content, the bores are chemically etched to expose silicon precipitate which is then honed to provide an oil-retaining bearing surface, but like Nikasil this process cannot be repeated by most machine shops outside of new car factories or Formula One. The serial number on the block should determine which engine you have :

M60B30:

• 1 725 970 - Nikasil
• 1 741 212 - Nikasil
• 1 745 871 - Alusil

M60B40:

• 1 725 963 - Nikasil
• 1 742 998 - Nikasil
• 1 745 872 - Alusil

I've had wear problems with both types so i can't really recommend either. Premature damage to the bores seems to come from overheating or injesting foreign particles, where iron blocks or liners would perhaps withstand this abuse these silicon/nickel coated alloy bores do not. And the main headache with Nikasil and Alusil is that they cannot be rebored in the way that conventional iron blocks or iron liners can. 

Alusil bores can be re-honed if enough of the exposed silicon is left, but for badly scratched or worn bores fitting ductile iron liners is the only cost-effective way of restoring an alusil/nikasil block. If the pistons are in good condition they can then be re-used with new rings if the original bore diameter is maintained.

My M60B40 block was fitted with Westwood ductile iron liners by Precision Engineering Services in Inverness and honed to the stock 89mm bore:

Some tuners have taken the bores out to 94mm (M5 S62 bore size) but with the added thickness of the liner this leaves a perilously thin amount of crankcase material remaining between the bores. This block is being machined prior to fitment of the bigger liners:

Vac Motorsports in Philadelphia are the main US specialist in reboring and providing uprated parts for the M60/62/S62 engines. In Germany Noelle Motors provides capacity increase kits to replicate the S62's 94mm bore and 89mm stroke in an M60/62 block (at a cost). 

In the UK parts availability for the M60/62 is poor, i haven't been able to find any available replacement pistons apart from VacMotorsports forged sets. The original BMW piston partnumbers are listed in Mahle's online catalogues but i haven't found any distributers that stock them. Big end & main bearing sets are available but darn expensive when compared to Ford or GM components. Full engine gasket sets are a similar story. Head gaskets and head bolt sets are fairly cheap in comparison but the head bolts are the stretch type that are only used once.

If you're buying a 2nd hand engine then i'd seriously advise finding one that still in the car so you can drive it and verify the performance, check to see it's not burning oil or water, etc... or if it's already been pulled from the car give it a compression test before you buy.