Differences between 456 and 550 V12s?

I got some feedback from the Technical Q&A section on my question, but thought maybe this is a better place to ask. The 550 carries a higher power rating than the 456, but the engines appear to be vary similar. I'm trying to track down the specific differences, e.g compression, cam timing, valve size, manifold port sizes, etc.

So far I've learned that the 550 has a bit more compression and hydraulic cam followers in place of the shims used by the 456 for valve lash. In my experience, shims typically allow for a higher rpm limit than hydraulics, so I was surprised to learn that the 550 vs 456 power difference is chiefly above 5000 rpm. This suggests that the 456 uses cam with less duration, or possibly smaller valves and ports.

Can anyone point me to a technical reference that outlines these differences? Or to separate 456 and 550 references that would enable me to work out the differences? Thanks in advance!

Jeff

 

Hello Jeff,
there was a thread, not too long ago, about the differences betw. 456, 550 and 575.
I believe it was on this same section of the forum, so if you check back, you may be able to find it.
Anyway, if I recall correctly, the differences in cam timing were of the order of 1 deg. only, betw. the 456 and the 550.
In my opinion the most significant increase in output comes from the higher compression and from the fuel system, which I am guessing, must be yet an improved version of the 456 system, not only in terms of fuel quantity, but also in terms of fuel mapping.

 

Quote from the *********** buying guide for the 550:

The 550 shares the same basic engine block as the 456, but through the use of titanium connecting rods, redesigned combustion and exhaust systems, develops 45 more bhp. Another innovation is the addition of a series of butterfly valves that open at 6000rpm, improving induction to the redline.

Maybe this will help?


Onno

 

Quite a lot of effort for 10% increase. I like the Titanium rods most of all.

What you say makes lots of sense, but the user manuals of both cars give very different figures.

6-54 / 54-10 for the 456 In / Out at 0.5 mm lash
2-44 / 42-4 for the 550 In / Out at ??? lash