Difference between m96.21 and m96.24
 

Hi All,

does anyone know the differences between the engines and m96.21 m96.24.

M96.21 - Boxster S 1999-2002
M96.24 - Boxster S 2003-2004

Thank you, Martin.

5 chain versus 3 chain.

Do the earlier cars have the 5 chains? What are the advantages or disadvantages of the different set ups? TIA

IIRC, 5 chain motors through 2002, 3 chain motors 2003 and on. Only advantage / disadvantage that I know of is that the later 3 chain motors were more susceptible to jumping time during an IMS Bearing change. Someone smarter than I will likely have more info.

Sorry for the stupid question ... But what do you mean chain? What the chain?

I would like to raise the performance and the first thing that occurred to me is to see the differences between versions, becouse mine has 185 kilowatts and 196 kilowatts after the facelift ...

That's because eliminating the 2 individual cam to cam chains forces the 2 IMS to cam chains to be longer. This inherently causes more opportunity for slack from the chain.

Main difference is the VarioCam timing adjustment difference. 2000-2002MY changes cam timing 13 degrees in one abrupt step, this occurs between 2,200-2500rpm via a 7.2 DME.
M96.24 VarioCam has a infinitely variable cam adjustment ranging 40 degrees of crankshaft rotation. This requires the more advanced 7.8 DME. This engine has the slightly improved AOS & crankshaft pressure reduction notches at the bottom of the cylinders.

Thank you!!!

except ... they didn't put the variocam + on the boxster until 2007? ie, it got the 7.8 dme, and it got the 3 chain, but it didn't get the new heads.

When Porsche introduced the 2002 996 & the 2003 Boxsters they called the new engines VarioCam plus to highlight the improvements in Cam timing.

I guess my point is that the 3.2 engines didn't get variocam +, just the 3.4 (boxster/cayman) and 3.6 (996). the boxster didn't get the 3.4 until 2007.

I think the jump in hp from 252 to 276 between the 986 and 987 3.2L is mostly tune, exhaust and intake. makes sense if you look at the hp/displacement ratio of a 3.4L 996 engine pre-variocam + (296/3.4 = 87); applying this same factor to a 3.2L engine gets you 279 hp - they starved the 3.2 originally, and only gave it more power once they started putting bigger engines in the 911 series (imagine a 280 hp boxster s when the 3.4 996 was only making 296 hp?!?!?).