i-VTEC and BSFC

[BrianTheMonkey]

Hi, does anyone know how the BSFC maps of i-VTEC engines in non-hybrids generally look? (Or those of engines by other companies that have modes to enhance the efficiency at normally non-efficient load and rpm conditions (VVT-i, VANOS, etc).

There's a map of an Insight engine in the famous Autospeed article on BSFC which shows the island of highest efficiency happening between 3250-4250 rpm, and then a secondary VTEC-induced island at lower load and rpm.

I *think* my '08 Accord would have a map that is more similar to other normal cars (the island happening around 2000 rpm), with a secondary island in the "economy" mode. But I don't know. I very rarely go above 3000 rpm.

If the engine could somehow be made to stay in economy mode of iVTEC regardless of load or rpm, what would the resulting BSFC map look like? Would it still favour a moderate-to-high load around 2000 rpm? Or would the area of best fuel efficiency be say at the lower range of the load or lower rpm?

I'm just starting to learn about how this works so I'm going to do have to do some experimenting myself.

Thanks!
Brian

[gone-ot]

...the BSFC "island" is generally located at the lowest engine-speed, in the highest gear that the engine can stand without lugging...typically around 2000 rpm, give or take.

...however, the statement about "lugging" really varies with how much torque the engine produces (and it's "curve") and how much total road-load there is at that speed, ie: wind, weight, road grade, etc.