define engine displacement

[EG6-R]

I think engine displacement has been pretty much defined. Now talking about fuel consumption is another thing altogether.

I see people pointing to same volume for 4 & 6 cylinder engines of exact same displacement. But no one, say COMPRESSION RATIO ?. This makes a difference as well as chamber design, head design, value design, lift, timing method of timing. Pretty complex.

The comparison between HP is also not that useful. Cos the Torque part is what gets you accelerating!. Also, the "how fast" your RPM climbs. My old Accord 2.3 manual takes forever to get to 5K RPM while my new VIos 1.5 can rev from 2K to 6K very quickly delivering the much needed torque for great acceleration. Its light too so picks up pace real quick to deliver a very spirited drive.

Manufacturer's claim for fuel comsumption is typically very very optimistic. However, one can even better that by driving lightly and very accurately. Looks at Poncholo Ramirez winning the Civic Challenge. He clocked in over 45 MPG in the thing. Most people would be lucky to get 40 MPG!!!.

What?? Compression ratios, how fast rpm climbs, 45MPG in the thing??

[Leepu Awlia]

how fast rpm climbs

how fast rpm climbs under load has something to do with torque

[aranetaj]

Manufacturer's claim for fuel comsumption is typically very very optimistic.

i think the fuel consumption figures have been obtained using a standard procedure (at least in europe and NA).  the purpose of the figure is for a comparison between cars and NOT to indicate what fuel consumption one will have on the road (or at least this is what is described in the german and NA test statements).

[johnqpublic318]

i think the fuel consumption figures have been obtained using a standard procedure (at least in europe and NA).  the purpose of the figure is for a comparison between cars and NOT to indicate what fuel consumption one will have on the road (or at least this is what is described in the german and NA test statements).

Correct.  It's to compare different makes using a standardized test.  Actual U.S. condition mileage is typically 10% less than EPA figures.  Philippine mileage under heavy traffic conditons is much worse.