I used to get 1 or 2 * of KR with 10% ethanol gas, and now I couldn't tell you the last time I had more than a blip of .5 KR since using ethanol free gas

 

I'm getting 28.4 MPG Hway, and about 21.7 city. Average about 23.9. And I have a Slippy Trans and aTPS circuit problem. According to a KBB review I reed, Yes I Read, , for the 00 to 05, the 3.4 gets 28 MPG hway, the 3.8 gets 31 and the 3.8 Super Charged gets 29 MPG. Of course that was 3 new cars at GMs perfect test track under Prefect conditions. So my goal is to get to that 31 MPG. I won't stop working on her till I reach it or she Dies!
Keane, your supercharger is the reason why your "Perfectly Tuned" gas mileage is lower. And I think the intake on the 3.4 is Also the reason it's gas mileage is lower. But I don't know for sure. Maybe it's the Smaller V6 in the Big Monte?

 

Considering others are seeing 30mpg, something seems off at 25mpg and I really don't think you should have to slow down below the speed limit to achieve what others are seeing. I used to drive 75mph religiously back during my college years and that was almost all with the 03; I still achieved up to 28mpg (>75% highway) with the L36. The best tank I've run in the 06 (24.5mpg) was at 68-70mph (95% highway with the cruise control set). I don't know anyone with the LS4 that has come close to the EPA estimated 28mpg highway. Most struggle to hit 25mpg.

That's another thing to mention; I try to set the cruise control as much as possible.

 

nitehawkjcb I wasn't sure what KR was at first so I did some research and found out. Just happened to be the site I got my information from was zzperformance.com and they are a great site that makes tons of mods for our loved 3800 engine. Hopefully this link works. About Knock Retard (KR) | ZZP News

 

Wow nitehawkjcb according to this article you were losing around 4hp with the 2 degrees of KR you had. Once you switched to ethanol free gas you had a 0.5 KR which only cost you 1hp. So just switching to ethanol free gas saved you 3 extra horses! I know people on here might laugh but I'll take those extra 3 horses any day. Haha I'd rather get 3 extra horses just by changing the fuel I put in than by doing some much more expensive and labor intensive mod to the car. Now all this of course is only assuming you have any knock in your engine. No knock then no horsepower loss from KR and no horsepower gained by ethanol free gas. Now I need to find out if ethanol will gain you any power if your car has no knock to begin with. I know it is better for your fuel system as it doesn't break down and clog your injectors like ethanol does.

 

****, at one point I had like 10 degrees of KR - then ported the heads, got a plog, and added a 2750 stall torque converter. And the blip of .5 KR I get on occasion is right after I've let off the gas doing a hard 0-75 pull.

Too bad it's 2:20 AM, I'd take the Monte out for a ride right now, but it's LOUD and the neighbors would be wide awake lol. Love it, my Monte shakes the house when it's idling in the garage.

 

What is a plog? Dang that must be one loud ride. Would love to see a video!

 

A plog is a better flowing exhaust manifold (made by zzp). I've got an old video on youtube, but it doesn't do the thing justice lol

 

OK donate I an knot as k-nowkledgeable as I think. What is KB? I'VE tried to guess But I ain't got a clue!

 

I'm guessing you mean KR? KR is knock retardation, the computer pulls timing in reaction to the car knocking, too many degrees of KR and you'll chip a piston or destroy your engine. As posted above, this should answer your questions.

About Knock Retard (KR) | ZZP News