Fuel Saving Engine Map

[OUScooby]

Originally Posted by vxdude

Its a 2003 wrx, i got underdrive pulleys, turbo back exhaust, perrin Y-pipe, Ported throttle body, k&n airfilter, gutted up-pipe. Stage 2 ecu from Cobb. My boost is at 16.5. The thing of it is i rarely ever go above 3000rpm.

How much difference do you think those pulleys make. Thats something I've been thinking about for awhile, but I'm skeptical about how much gain you actually get.
My peak boost is at 17.3, but my right foot gives into temptation too easily, so I've been getting 21mpg.

[OUScooby]

Originally Posted by RoadWarrior

A lot of power mods are also efficiency mods.... up until you add more fuel....

how so?

[theholycow]

Originally Posted by OUScooby

how so?

There's two types of power mods:

• Those that increase power/speed by reducing losses (these are also efficiency mods).
• Those that increase power/speed by making more power out of more fuel (these tend to reduce your fuel economy).

[vxdude]

Its hard to say how much of increase i got, i practically did all my mods in the same month. But the stock crank pulley wieghs like 12 pounds. Compared to aftermarket one that wieghs less than 5. (5-8hp) You can get all 3 pulley for under 100$ on ebay right now. Id say thats worth it.

[OUScooby]

So I have some data to provide. I've filled up my tank but only driven less than a quarter of it so I don't have the trip odometer/gallons at fill up number just yet.
I calculated an average MPG by logging my realtime fuel consumption (in mpg) with my laptop and RomRaider ECU logger. This software reads data from the ECU several times a second and can save it to a spreadsheet file. I added up all of the realtime mpg numbers and divided it by the number of reading the ECU took. The results were surprisingly high, and my highway mile were lower than my city mile so if someone can find a flaw in my methodology please point it out. Here are the results:
46.68 mpg: city driving, light traffic
40.66 mpg: city/highway mix, light traffic
37.73 mpg: highway driving, no traffic

I'll log more tomorrow on my way to and from work and see what those results are.

[spotaneagle]

funny vetts r faster and get better mpg must be the aerodynamic's

[spotaneagle]

Originally Posted by theholycow

There's two types of power mods:

• Those that increase power/speed by making more power out of more fuel (these tend to reduce your fuel economy).

boost can increase efficiency by allowing a car to now have to downshift esp if kept at 5-8psi esp on a 1.6 engine which is super efficient to begin with

[OUScooby]

Originally Posted by spotaneagle

boost can increase efficiency by allowing a car to now have to downshift esp if kept at 5-8psi esp on a 1.6 engine which is super efficient to begin with

Boost kills your gas millage. Look at a chart of fuel pressure vs. boost for your car, and see how dramatically it rises with boost.

[zero_gravity]

very true, more boost = more fuel = more power. staying out of boost range works well though

it might be a bit too in depth than what you're looking for, but take a look at megasquirt. its a total open source stand alone engine computer. its really made for people that want to play. not overly expensive since you can actually buy a kit and solder it together yourself - theres also pre-built units.

anyhow hook it up to a laptop and you can change *anything* you want to.

the downside is that its a lot of extra screwing around, can have some issues with emissions laws (if they find it i guess lol) and by the looks of things wiring can be an ***.

[theholycow]

Going off on a tangent here...

Thank you for reminding me that Megasquirt exists. Does it require a return, or does it operate returnlessly so I could use it as an easy conversion for a carbureted car? I wonder if it would go well on my 1980 Buick...