Modded CTS-V 27.4 MPG

[gikard]

On MPG topics...

I noticed on the CTS-V that while cruising at 75 mph, there's a huge difference in the instantaneous MPG readout between 6th (very overdrive-y) and 5th gears, about 3 mpg. I imagine this is more than just pumping losses, I wonder why.

[gikard]

Originally Posted by oringial post

... lean cruise... GM enabled on some Australian cars

Originally Posted by pgfpro

Nice set up!!!

I didn't know the Australian cars had a lean burn mode? Very cool! Anyway let us know hot the Cape Cod trip goes.

OK so how do I make the ECU think it's in Australia?

[pgfpro]

Originally Posted by gikard

OK so how do I make the ECU think it's in Australia?

LOL I don't know how he did it. Maybe hes running "HP Tuners" ???

[YukonCornelius]

Whoa, old thread, if you guys were impressed with this check out the Cape Cod results. http://ecomodder.com/forum/showthrea...0-a-24034.html

Originally Posted by gikard

OK so how do I make the ECU think it's in Australia?

It will not work on your LS2. GM made major changes to the ECU. If you had a LS6 and knew how to tune you could do it.

[YukonCornelius]

Originally Posted by Domman56

WOW Jealous You're pushing about the same power outta that as my 04 CLK55 but the best tank i've ever gotten was 25.1 MPG. Love having the V8 power when you want it and good fuel economy when you need it though

I almost switched it out for a E55 back in February, but that low compression fuel economy was too much LOL. I'm making a 100 more horsepower than a 04 CLK55. I put down 401 at the wheels which is around 460-470 at the motor. On the street the closest race I've had was with a stock 996 911 Turbo.

I have a set of ported/decked heads sitting here for it. They will net me about 40 more horsepower at the wheels, so 500+ on the motor. I'm interested to see what happens with the fuel economy. Going to 11:1 compression should help but the larger volume in the heads might hurt me.

[UltArc]

Originally Posted by Lbar

I almost switched it out for a E55 back in February, but that low compression fuel economy was too much LOL. I'm making a 100 more horsepower than a 04 CLK55. I put down 401 at the wheels which is around 460-470 at the motor. On the street the closest race I've had was with a stock 996 911 Turbo.

I have a set of ported/decked heads sitting here for it. They will net me about 40 more horsepower at the wheels, so 500+ on the motor. I'm interested to see what happens with the fuel economy. Going to 11:1 compression should help but the larger volume in the heads might hurt me.

Mike,

Do you track fuel economy on a different site or on a spreadsheet? Or does this bad boy just get limited driving, or are you close to work and family? I noticed you don't really fill up very often- or at least track it here.

I know I use fuelly and FE.gov, but those aren't updated as I go, they are updated a while after I update EM.

[YukonCornelius]

Originally Posted by UltArc

Mike,

Do you track fuel economy on a different site or on a spreadsheet? Or does this bad boy just get limited driving, or are you close to work and family? I noticed you don't really fill up very often- or at least track it here.

I know I use fuelly and FE.gov, but those aren't updated as I go, they are updated a while after I update EM.

I never tracked economy consistently until a couple months ago with my accord, which is my commuter. The Cadillac has been driven quite a bit. I wasn't on this site for a long time because of faded interest. I was only tracking these whole tanks on trips because I was willing to drive conservatively for that duration and I thought this forum would find that the most interesting. Consistently driving the CTS-V conservatively will likely never happen, that is like car abstinence to me. I do normally drive it very light and mix in wide open throttle/red line shifts for fun. This nets me averages in 24-26 range. It's kind of tough, I don't want to log a bunch of short hero runs and I don't want to log full tanks that don't reflect the driving of a true ecomodder. It leaves me with very little to work with.

[gikard]

Originally Posted by Lbar

It will not work on your LS2. GM made major changes to the ECU. If you had a LS6 and knew how to tune you could do it.

I've tuned aftermarket ECUs for many years... but never a factory one.

AFAIK HPTuners and EFILive support folk won't tell you how to enable lean cruise because of fear of reprisal from the EPA. Did you figure out how to do it on your LS6?

As for my LS2, did GM make cracking lean cruise much harder? Or the entire ECU in general?

What's the disadvantage, compared to enabling the built-in lean cruise function, of just targeting leaner AFR's (16:1 or so) at say, all loads <50% and below 3000 RPM or so?

Did they sell the LS2 version CTS-V in Australia? I wonder how hard it would be to buy and install an ECU from there.

Thanks.

[cRiPpLe_rOoStEr]

Originally Posted by gikard

The whole hp/L argument is a bit misguided, hp per external dimensions, per weight, and per BSFC @ cruise conditions are probably better metrics.

It was about time for somebody to understand why the LS engines are among the few spark-ignited engines I like

Their torque at lower speeds without too many sophisticated stuff is also an important point to take note.