Look at page EG-3 (attached, from the TCH "New Car Features Guide"), which compares the intake and exhaust valve timings and opening angles for both the "Otto" and "Atkinson" versions of the Camry's ICE. (By the way, the "Atkinson" version also has an offset crankshaft, just like the Prius's.) In the hybrid version, the intake valves stay open for fully 280 degrees, compared with the 248-degree opening angle in the non-hybrid version. (In both versions, the exhaust valves stay open for 228 degrees.) Note the stated 12.5:1 "compression ratio" for the "Atkinson" engine. That's not true, of course; because of the delayed intake-valve closing, its effective compression ratio is actually ~10:1, just like the "Otto" version. They should really say "expansion ratio" not compression ratio in my opinion. Correspondingly, the "Atkinson" engine is effectively (for power purposes) not really a 2.4-liter displacement engine, but proportionately less, because it breathes in less fuel owing to the delayed intake-valve closing. The 2.4-L rating gives a misleading indication of its power.

Stan

Attached Files

EG-02to03_Engine specs.pdf (56.2 KB, 34 views)