So school me on something I've always wondered. Why do the car manufacturers produce engines with lower compression? What's the benefit? With these LS engines it seems you can run them up to almost 12:1 on pump gas with more power and better mpg. So why not build them that way to start with?

 

Which manufactures?
You can run a 13.5CR LS on 87 octane if you wanted to. Just run colder plug and lower timing.

 

Emissions and the variations in gasoline quality are my best guess.

 

most people're too cheap to run higher octane gas & make use of those added benefits.

even our H3 has 10:1 SCR and is advertised as made for 87... but it uses the variable exhaust cam timing to reduce DCR on top of running less ignition timing.

 

All of the above, or……they know a bunch of delinquents are gonna jam some boost into them?