Badju587

I see a ton of threads dedicated to improving the amount of kinetic energy you conserve when already moving (and the DFCO thing has been beaten to death, hopefully to the benefit of more than just myself), but I haven't seen anything yet on the most efficient way to get moving from a stop.

There are three schools of thought I've seen so far:

1. High gear, low throttle, low RPM shift: I guess the idea behind this is that the lower the throttle, the lower the IPW, which in turn gives you a low usage of gas. You shift at the minimum RPM required to save your engine from bogging on the upshift (around 2k from what I can tell). The problems I see with this are:

- Engines don't use energy efficiently at low RPM's. You're using a lot of gas just trying to keep the engine moving instead of putting it to the wheels to speed up.
- You use up a lot of ground babying the engine up to cruising speed.
- Doesn't seem to be a method that's easy on the engine.

2. High gear, high throttle, cruising RPM shift: Instead of shifting at a crazy low RPM, you accelerate briskly (meaning at a moderate pace, not like a bat out of hell) to around 2500-3000 RPM's, then do the same in the next gear. By the time you hit fifth, you are nearly flooring it getting up to cruising speed. Yes, it keeps you in boost, but I can see some advantages to it:

- It minimizes the distance you spend accelerating and maximizes cruising distance.
- Engines use energy more efficiently at higher RPM's. Less energy is spent moving the rotating mass, and more energy gets to the wheels.
- Probably easier on the engine itself since it doesn't spend all its time within a few hundred RPM's of bogging down.

3. Low gear, high throttle, high RPM shift: Not really worth looking into since accelerating too fast can hurt your mileage. Even though the car is getting energy to the wheels most efficiently at its horsepower peak, it's also using a lot of it in a short time. Winding the car out to 7k in first and shifting straight into fourth or fifth doesn't seem like a good way to conserve gas or be nice to the engine/tranny, but hey, I could be wrong.

#2 seems to work best for me, but if #1 or #3 have their merits, I'm all ears.

originaladrian

the only real rule i keep in my car is keep it under 4k for good fuel economy

B0omer19

What about for the LS 2.2L? You should add that in there for us poor people haha

Badju587

should apply to the 2.2 as well, just not the part about boost or the 7k RPM limit

Omega_5

My two cents....
I've seen my best city economy when shifting at 3000-3500rpm.
I also try to cruise in a higher gear. At 60km/h (~40mph) I roll in 4th gear.

However, the key isn't the gear, or the shift RPM though... it's how hard you mash the accelerator. I try not to let the car to any higher than 10 in-hg on the boost gauge.

Don't accelerate too hard, and shift consistently and you should see some decent economy out of the car.

nhanson

iTrader: (1)

who the **** cares about economy..red line that **** each shift!! lol

i would do around 3k rpm...

Badju587

I normally go fairly brisk on the accelerator, but nothing too fast, 1/3 throttle usually does it. I'm usually in fifth by 50.

Averaging about 34.7 MPG now on my current tank (~330 miles so far, probably good till 400 miles or so). It was as high as 35.5 at one point, then I did a lot of stop-and-go driving in town. I've got the route to and from work down fairly well though... I have the lights timed, I know when to give it a bit extra gas and when to let off for hills and such, accelerating is about the only place I think I might be able to improve my mileage. Of course, I may be running into a limitation of my S2 tune as well, no clue.

HunterKiller89

iTrader: (1)

I see it several ways. accelerating slowly allows more heat energy to dissipate throught he radiator. So quick acceleration prevents this and the hotter temperatuires in the cyl will effectively advance flame front...almost like advancing ignition...so you yield more HP for the same fuel spent. However, accelerating quickly also makes you run richer, so you want to avoid that.
Then high RPM driving will lose a lot of its HP through keeping the pistons, rods, cams, etc. spinning faster. It will take more energy to spin all of these parts at 6000rpms than it would at 2000rpms.

So i would think the quickest acceleration possible WHILE staying out of Power Enrichment is the most efficient way to accelerate, and keeping RPMs down is a bonus.

Just remember, the best way to save gas is to not use the breaks...every time you slow down, youre going to have to use more gas to accelerate again, hence why highway mileage is always better than city mileage

theneelster

The lsj has dfco so we don't really need to use brakes to slow down (other than to stop), not sure about the other cobalts and ions...I would assume the same. But the best way to get good mileage is simple...keep it the same speed and don't lay down on the hammer easier said than done.

Acey

iTrader: (3)

Every car has DFCO.

osiris

QFT.

When in "miser mode" I shift into second at 2000, third at around 2500, fourth and fifth at 3000 and 3500. My theory is that winding the engine up progressively higher according to gear compensates for the increased wind and mechanical resistance by not bogging down the engine when the next gear engages.

.... but on most days I almost redline second and third.

B0omer19

So I tried out moderate accel with 2700-3000 rpm shift points, and it has helped a tad bit.

Resetting my average mpg calculator for every trip (each trip being identical to the last [work drive]) netted me 30-31mpg instead of 28-29mpg.

Overall I'm seeing a 15-20 mile increase with my cruise range.

I've noticed that lingering in first gear accelerating slowly with an LS nets worse gas consumption. It seems the 1st gear ratios are MUCH shorter than the others, along with 4th gear.

This is most likely to augment off-the-line acceleration but also causes it to feel awkward to drive.

It's weird to see a car build revs so quickly and yet still be crawling at 15mph

freakta

iTrader: (1)

ive been doing great gas milage and i keep my boost way down between 10 and 20 easy on the accelorator and usually shift between 2k and 2250rpms. i get it into 5tgh and keep it there for a long time. i reset the milage every tank fill up and i avg about 37mpg in the 2.0

B0omer19

I noticed that when SS owners are off the boost they get better mileage than I do. Damned that increased displacement ><

>B0omer<

EatonTVS07

iTrader: (4)

i shift at 3k in every gear only cause my car will get pissed at me if i don't