What I would like to know is (long stort short)
Will a high compression 6.0l (10.8:1) lq4 with 706 heads (milled .025) get better MPG than in stock form of the lq4?
Or
Would a 5.3l get better than both? Or would a higher compression 5.3l get even better or worse?

I have a bone stock lq4 in my 05 CC on 26's (33.2" tall) and 4.10 gears and a tune everything else is stock other than catless
Im not asking whats gonna be the quickest and before anyone says "706 or 5.3l heads are gonna choke the 6.0l down" THAT IS NOT TRUE we have a 1980 ford fairmont with a CAM ONLY lq4 with .025 milled 706 heads with 3.73 gears running 7.20 1/8th mile and deep in the 6's on 150 shot...

Any info will be helpfull thanks

 

Compression equals efficiency, so in theory it should use less fuel and emissions.

 

Thats is same thing im thinking...but I want more opinions

 

My 11:1 408 got 10% better milage than my stock 5.3.

 

Keep it comin guys... Trying to decide if ima pull my 6liter out or swap heads

 

Now that is impressive because extra cubic inches should negate the benefits of the C/R efficiency.

My 404 gets much less gas mileage than my 5.3 did or a 6.0 did.

 

Didn't it have a clogged injector(s) or something?

 

No, 408 worked perfect, just had a crank bearing go out.

The 410 on the other hand, got about the same gas mileage as the 5.3, maybe a little worse.

 

I went from a LS1 5.7L 224 cam 10.4 compression 21 mpgs...in my Camaro

To a 6.0L 11.0 compression and a 232 cam 22 mpgs....all else was the same.

I also a gree that a good exhaust with goo merges from cylinder to cylinder on the header, and from bank to bank, either y or x pipe can create better mpgs.

And always make sure the tune for new mods is good!!

 

Curious as to what the dynamic compression ratio of both of those engines were, considering that the 232 cam would have more overlap than the 224 cam if they were both on the same LSA...