Stage 1 Kit MPGs
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Member
Joined: 12-31-2008
Posts: 30
From: North Georgia
POST GM Performance Tune upgrade in a 2008 HHR SS Automatic, 1,051 highway miles driving from NC to NJ and back with cruise control set at 71 MPH, it took 2 full tanks of 93 octane gas and I averaged 31.1 MPG per the onboard computer!!!
All I can say is im very impresses, and mostlikely attribute the higher MPG to the slightly higher boost levels (-2 to -5 psi) while the car cruises after the GM Tune. More air mixed in with the same amount of fuel gives a bigger explosion with more horsepower. Kinda like Blacksmith 101, use the bellows to put more air in the fire to create a hotter fire!
All I can say is im very impresses, and mostlikely attribute the higher MPG to the slightly higher boost levels (-2 to -5 psi) while the car cruises after the GM Tune. More air mixed in with the same amount of fuel gives a bigger explosion with more horsepower. Kinda like Blacksmith 101, use the bellows to put more air in the fire to create a hotter fire!
Senior Member
Joined: 03-28-2008
Posts: 1,115
From: Oshawa
Senior Member
Joined: 02-29-2008
Posts: 110
From: Waterville, OH
I wouldn't think so because more air with the same amount of fuel equals a lean condition.
I have been wrong before.
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Joined: 10-02-2005
Posts: 1,245
From: VA
These ECMs are pretty much locked into maintaining stoic AFRs of near 14.7 in closed loop.
Doesn't matter what the engine/ECM is, the key is to optimize MBT (Mean Best Torque) at any cruise load with spark timing with the available fuels, altititude and octane choices. Not easy to do, but can be accomplished with a good tuner and work on a load dyno.
Doesn't matter what the engine/ECM is, the key is to optimize MBT (Mean Best Torque) at any cruise load with spark timing with the available fuels, altititude and octane choices. Not easy to do, but can be accomplished with a good tuner and work on a load dyno.
Senior Member
Joined: 03-16-2008
Posts: 662
From: Cleveland, Ohio
Yes, more air equals a lean tune, which is the worst thing to have with a forced induction motor. The ECM maintains a stoichiometric AFR under closed loop, and goes richer in PE mode. The only time it permits a leaner than stoich condition is while decelerating in the overrun zone. Too lean not only causes destructive detonation, but it raises NOx levels as well. The LNF motor is a very complex beast with the direct injection and variable valve timing. A whole new host of variables are introduced that don't lend themselves to armchair analysis.
Senior Member
Joined: 03-09-2008
Posts: 123
From: Ontario, Canada
Quick question, what octane you running with the stage 1 kit? The max we can get in Canada is 94 (only available at Sunoco) most pumps carry a max of 91. Would I have any problems runing 91 octane fuel?
Member
Joined: 11-28-2008
Posts: 93
From: Phoenix, AZ
Being that the performace tune is a GM tune I would surmise they know exactly what they are doing. Hence I would call the GM tuners accomplished. Just my 2 cents.
Senior Member
Joined: 03-16-2008
Posts: 662
From: Cleveland, Ohio
From how the *dealer* explained this to me was that the stock factory tune is generally rich to begin with. They did not have to reverse engineer any of the code being that they wrote the code to begin with. Perhaps ADM could comment on this?
Being that the performace tune is a GM tune I would surmise they know exactly what they are doing. Hence I would call the GM tuners accomplished. Just my 2 cents.
Being that the performace tune is a GM tune I would surmise they know exactly what they are doing. Hence I would call the GM tuners accomplished. Just my 2 cents.
Senior Member
Joined: 07-23-2008
Posts: 1,148
From: Peoria, AZ
Senior Member
Joined: 07-23-2008
Posts: 1,148
From: Peoria, AZ
From how the *dealer* explained this to me was that the stock factory tune is generally rich to begin with. They did not have to reverse engineer any of the code being that they wrote the code to begin with. Perhaps ADM could comment on this?
Being that the performace tune is a GM tune I would surmise they know exactly what they are doing. Hence I would call the GM tuners accomplished. Just my 2 cents.
Being that the performace tune is a GM tune I would surmise they know exactly what they are doing. Hence I would call the GM tuners accomplished. Just my 2 cents.