Why is the ls1 more efficient?
How come the ls1 is more efficient then the sbc, and why does it get so much better gas milage? Is it because air flows better or location of injectors?

 

its like comparing apples to oranges, better airflow, different borexstroke combo, different materials....too much to get into. bottom line is although i adore SBC i will be first to tell you GEN III motors are 10x better.....

 

A few reasons:

The cathedral port heads give great flow without losing much low end.

The 6 bolt bottom end holds the engine together at high rpms.

The intake manifold allows both low and high rpm operation.

Optimal bore/stroke ratio.

 

Sequential fire injection is arguably more efficient too, as opposed to TPI batch fire.

 

I'm just theorizing but the aluminum rather than cast seems like it would allow higher compression for the same fuel.

 

aluminum heads yes, block im not so sure about since they have a sleeve.

 

Most important item....they are 18 degree heads. (valve angle)

That makes for better flow.

 

Actually that is one half of the story...

The cathedral port shapes are the other...

They work synergistically to allow good low end flow with the top end normally associated with very large cc heads.

 

Have you noticed lately how many times they have changed the port shape?

 

Absolutely - and the changes seem to be working...

 

As mentioned by the last few posts, the cylinder head design is 95% of the differences.

 

This is how you get all the geeks out from the crowd. Nice question, i have often wanted to ask that myself, just was too shy.