40 mpg Trans am LS1/LS6?
THEM ALL 
07-20-2011, 11:39 AM
#24
It's a back-handed joke; meaning that an LSX engine is a powerfull beast, why clutter the site w/ setting one up for fuel mileage. Don't sweat it. He's a good guy & is very helpful here. Am not trying to speak for him. This is just my view of his post.
Remember the fuel mileage part of the tune is a different "map"/"area" within the program than the area that controls wide open throttle (peak power/torque) fueling. So, it is possible to have both within reason.
07-21-2011, 03:22 PM
#31
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I'll give my input.
Is it possible? I think so, but it would take a skilled hypermiler driver and some tuning that I'm not sure is possible with our OEM set-up, even with aftermarket software.
The truth is, you probably only need about 40-50 hp to keep a 3700lb car going a CONSTANT velocity. A car with down low torque (think very low RPMS, like 1200) and geared for effiency would be needed, along with a lean tune (as someone mentioned) and perhaps fuel shutoff on unneeded cylinders - such as GM's Displacement on Demand. I don't believe tuning software can do this on our cars, because the turning off the fuel injector to those cylinders also ties in with the lifters somehow.
As for improving fuel economy, you will be most efficient with the slowest speed possible in overdrive (or 6th gear in M6 cars) and the vehicle under very little load (which is the case with constant velocity on level roads). Typically you are looking at high 40s, to low 50s mph for this, and lets be honest, it's not exactly safe or time efficient to be driving at those speeds for long distances such as on interstates.
I bet if I hypermiled my car, I could pull near 30mpg, but 40 would be REALLY hard to imagine without running lean, less weight, and really low speeds....too low for me to enjoy anyway. I'll take what I'm getting at 75mph with the top down!
I think an M6 car would be better due to various gearing options and more opportunites to coast with the clutch disengaged.
Is it possible? I think so, but it would take a skilled hypermiler driver and some tuning that I'm not sure is possible with our OEM set-up, even with aftermarket software.
The truth is, you probably only need about 40-50 hp to keep a 3700lb car going a CONSTANT velocity. A car with down low torque (think very low RPMS, like 1200) and geared for effiency would be needed, along with a lean tune (as someone mentioned) and perhaps fuel shutoff on unneeded cylinders - such as GM's Displacement on Demand. I don't believe tuning software can do this on our cars, because the turning off the fuel injector to those cylinders also ties in with the lifters somehow.
As for improving fuel economy, you will be most efficient with the slowest speed possible in overdrive (or 6th gear in M6 cars) and the vehicle under very little load (which is the case with constant velocity on level roads). Typically you are looking at high 40s, to low 50s mph for this, and lets be honest, it's not exactly safe or time efficient to be driving at those speeds for long distances such as on interstates.
I bet if I hypermiled my car, I could pull near 30mpg, but 40 would be REALLY hard to imagine without running lean, less weight, and really low speeds....too low for me to enjoy anyway. I'll take what I'm getting at 75mph with the top down!
I think an M6 car would be better due to various gearing options and more opportunites to coast with the clutch disengaged.
07-21-2011, 03:36 PM
#32
My corvette on stock tune with Prodyno CIA, and Borla touring exhaust would get 34.7 on interstate trips with 93.
Leaned out cruise rpms and at the same 75mph. It brought down 37.6 that is getting on interstate, setting cruise from NC to FL and never touching gas or getting off highway.
Leaned out cruise rpms and at the same 75mph. It brought down 37.6 that is getting on interstate, setting cruise from NC to FL and never touching gas or getting off highway.
07-21-2011, 06:46 PM
#33
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