This subject was there before, but I went into more detail, and here's the result. Only Engine, Gearbox and Suspension is covered. Everything not mentioned in these three areas is supposed to be (more or less) the same. Ferrari----------550-----------------------456 Engine Type----F133----------------------F116 Top Piston ring--Radiused contact surface--wedged 1.15 degrees. Piston----------4 slots on the top--------no slots Valve dia mm In--------------34------------------------32 Out------------29------------------------26 Valve guide length mm In--------------44.0----------------------40.7 Guide Material In/Out---------Iron-----------------------Bronze Valve Length In--------------98.5----------------------109.5 Out------------99.0----------------------110.0 Oil scraper on Valve stem-----Much better--------------Very small Hydr.Tappets---Yes-----------------------No Valve Lift-------9,5-----------------------9.0 Valve Spring Load Up-------------294 N---------------------331 N Down----------746 N---------------------874 N Con Rod-------386 gr (Titanium)----------496 gr (Steel) Cam Timing In-------------2/44----------------------6/54 (@ 0.5 mm) Out-----------42/4----------------------54/10 (@ 0.5 mm) LCA-----------110 degr------------------113 degr Duration-------226/226 degr-------------240/244 degr Compr. ratio---10.8:1--------------------10.6:1 Inlet Manifold Length--------410/280 mm---------------390 mm Rear exhaust Muffler--------Bypass valve at high RPM--None Exhaust Pipe Ext. Diameter--2.25 Inch----------------2.25 Inch Suspension Springs--------10% firmer as 456 Wheel Geom.---Identical as 456 Gear box plus Diff Ratios 1 st-----------12.32--------------------10.55 2 nd------------8.50---------------------6.92 3 rd ------------6.12---------------------4.99 4 th------------4.63---------------------3.89 5 th------------3.65---------------------3.17 6 th------------2.96---------------------2.68
Everything makes sense except for the 456 cam timing. The durations sound way huge for an understressed, moderate redline engine. Maybe the 550/456 specs are reversed? I'd expect the 550 to have long durations to go with its "extra" (short) intake manifold passage and muffler bypass. In any case, thanks for the research and the post! Jeff
Great info. thanks! I've driven both 456 (mine) and 550 (not mine) and I'd say the differences are ever so slightly present but not noticeable to someone getting into both cars for the first time. The 550 felt a bit more jarring and a little more rev happy (hyd. tappets?). So a 550 gearbox in a 456 would make it snappier?
I agree. I have both and they are a close match as far as feel is concerned. The 550 seems to pull harder though. The 550 also has more of a turbine like sound to it.
Jeff, I agree completely with your feeling. The timing between 456 and 550 are not reversed, they are right. I would also have expected a much longer timing for the 550. The 550 has larger valves into the same cylinder volume. Therefore the ratio cylinder volume divided by valve diameter is smaller as it is for the 456.. Normally this leads to a larger LCA, but not for the 550 !? The calculation method used by Dave Vizard gives me 114 degr for the 456, which is not too far off the used 113 degr , but for the 550 the calculation gives me 115 degr. where Ferrari uses only 110 degr ??
One correction to the list: the 550 does not have iron valve guides, but according to the workshop manual "copper alloy guides".
