What does GM mean by "Premium Gas Recommended" on the 2.4L I4?

[bgfpt]

Originally Posted by lynch mob

Just to let you know but both of the available engines for the HHR have the same compression ratio which is 10:1.The 2.2 L61 vin code "F" and the 2.4 LE5 vin code"B" both have 10:1 compression.

Right. I wasn't comparing the two engines in the HHR, only using the different compression ratios for illustrative purposes.

[doh]

Hey they can do it with E85 engines, like the 4.0L Explorer's so a little change like the 87 or 91 octane shouldn't be any problem for the PCM and engine management system to compinsate for.

[327]

Originally Posted by doh

Hey they can do it with E85 engines, like the 4.0L Explorer's so a little change like the 87 or 91 octane shouldn't be any problem for the PCM and engine management system to compinsate for.

Thats true, I think E85 is 103 or 105 octane!

[73ChevelleSS]

Originally Posted by doh

Hey they can do it with E85 engines, like the 4.0L Explorer's so a little change like the 87 or 91 octane shouldn't be any problem for the PCM and engine management system to compinsate for.

Yes the E85 vehicles use a alcohol content sensor.But as far as vehicles having a octane level sensor,i doubt it will ever happen.