Pendulum effect - Fuel Economy, Hypermiling, EcoModding News and Forum

dhymers · 10-01-2009, 07:53 PM

2002 Subaru Impreza WRX Wagon Gas Mileage (Black) - EcoModder.com

Ok, first off, I know this car isn't exactly the best for hypermiling, but I've been impressed by the gains just by slowing down, shifting at 2000-2200 rpm and coasting a lot.
I don't plan on doing an mods currently, but maybe in the future some sort of lightweight under body aeros.
All I've done is dropped in a K+N which I think helps.
Tires are within 2psi of max sidewall, big help.

I'm just a little frustrated that my tanks seem to vary quite a bit, even if I'm driving the exact same routes and the same style. I'll get a couple of 26-30 tanks and then a 34-35 and that pattern has repeated for a while. (I know it averages out)
Can this just be put down to gas-pump inconsistencies ? I know I need to get a scanguage, but I'm a budget of well... nothing.
Are there any more accurate measurement techniques without getting a SG ?

ta.

drewwitlin@hotmail.com · 10-01-2009, 08:55 PM

the best way that I have read, and tested is to use the same pump at the same gas station, fill it the same way. I use the slowest handle setting and clean my car, check tire pressure, check out the ladies. When the pump clicks off, that's it. Same Station, Same pump, same setting, same cutoff. The stations don't change their handles very often. Pumping up your tires is NOT a bad thing, all that I have read, and my own experimenting, has me at 50psi, 9psi over the sidewall max. The more you practice the hypermileing techniques, the more consistent mileage readings you will get.

MetroMPG · 10-01-2009, 11:58 PM

I'll second the "are you sure you're filling it up the same way each time" point.

I fill to the brim at the same pump, same direction each time, so I know my calcs are as close as possible.

And also, yes, you can get accurate fuel economy instrumentation for less $ than a ScanGauge: there's the somewhat DIY route of the MPGuino; also, look up the PLX Kiwi- they have a less expensive than ScanGauge model.

Highly recommend you get some fuel economy instrumentation. It makes the game a LOT more fun, and it'll pay for itself many times over, seriously.

dhymers · 10-02-2009, 12:07 PM

Just learned about the KiwiMPG thanks

looks good.
seems on average about $50 cheaper.

Christ · 10-02-2009, 01:39 PM

How sure are you that the K&N drop in is helping, rather than hurting or doing nothing?

Regardless, you've already spent the (unrecoverable) money, so hopefully it does something for you.

Check out these links at the top of the page:

65+ Efficiency Mods

100+ Hypermiling Tips

dhymers · 10-02-2009, 02:20 PM

Call me a sucker but I actually believe K+N when they say its a high flow filter, enabling better "breathing"

(note I said I THINK it helps, no way I can be sure.)

Plus, I can clean it whenever I want, and I'm not putting paper/plastic/rubber etc.. in a land fill. I will never buy another air filter for the car again. Ever.

Christ · 10-02-2009, 03:08 PM

Quote:

Originally Posted by dhymers

Call me a sucker but I actually believe K+N when they say its a high flow filter, enabling better "breathing"

(note I said I THINK it helps, no way I can be sure.)

Plus, I can clean it whenever I want, and I'm not putting paper/plastic/rubber etc.. in a land fill. I will never buy another air filter for the car again. Ever.

What are you doing with the oil that you use to soak the cotton element? (Which also gets into your engine when you oversoak it.. potentially causing higher emissions.)

I mean, you have to wash the filter out, right? So you're letting that oil go down the drain?

Regarding the better breathing, if you're not driving over 50% throttle, it's not helping anything. They removed the improved MPG claim quite some time ago, because it was shown that they did NOT improve MPG (or airflow, in most cases) at anything near what the average person's driving would require. (IOW - they only work at WOT or close to it.) Remember, your throttle plate is the biggest single loss in your intake tract.

If you calculate how much air your stock filter will flow, then calculate how much airflow you actually NEED at a given RPM for full throttle, you'll often find that the OEM filter flows sufficient air for most situations at redline, and if you're capable of flowing more than the engine can take in, you're just wasting capacity.

Not to mention that at a couple bucks per paper filter, you'll never recover the money that you've already spent on the filter, let alone the money you'll continuously need to spend on the wash kits to keep the filter operating efficiently.