Side effect of the FWI?

My last few tanks of gas I've consistently been just a hair under 20mpg average. Halfways thru my last tank, I installed the SS 3.5" FWI made by Rob with a K&N cone filter. This replaced a gutted box with panel K&N. Filled up tonight, and registered a 21.5, or 7.5% increase from my normal mpg. I've never had a tank get hardly over 20 with my normal driving habits, and this last tank was nothing out of the norm. Is it possible or likely that the FWI alone is responsible for this, even used for only half the tank? I'm really wondering what we'll find on the next fill. I didn't anticipate this side effect, if the FWI is the reason for it. Anyone else notice this with a FWI install? I changed NOTHING else in the past few weeks.

i have been getting less since my 4" FWI 10mpg, down from 11mpg maybe my new plog will bring it back up

Possibly the new cone filter + the larger tube is letting the engine breath a bit easier. Need to test the next fuel tank to be sure. 20 mph is about my best overall as well.

Mr.Riviera wrote:

i have been getting less since my 4" FWI 10mpg, down from 11mpg maybe my new plog will bring it back up

Damn, you've got a heavy foot!

I actually check my mpg pretty much every fill, so we'll see if it holds up. Who knows, maybe the nozzle shut off just a bit early. Can't tell that by the gauge though.

AA wrote:

Possibly the new cone filter + the larger tube is letting the engine breath a bit easier. Need to test the next fuel tank to be sure. 20 mph is about my best overall as well.

It is possible you are getting better mileage, but 20% would be quite a bit out of the norm.

Unless you had a nearly 100% plugged air filter.

No Bill, it was up 7.5%, from 20 to 21.5 mpg. Both my panel K&N and the cone K&N were in similar condition, pretty clean, so I wouldn't attribute any to a cleaner filter, but maybe partially to a larger one. We'll see if the improved mpg holds true the next couple of tanks.

sorry...still working on my reading skillz !

That is still a big jump, when considering you went K&N to K&N and merely a different shape/tube.

i agree, and nothing whatsoever different in the type of miles driven either.

OK, here's the data on the followup tank. I was expecting a bit of a drop off, as I put on a lot more 35-45mph miles this last tank. However, today I registered a 22.34 mpg reading, or a 4% increase on the previous tank. This was the first full tank run with the new FWI. No other changes to the car at all. So I'm now at almost 12% higher mpg than before the FWI install, when I had only a gutted box with panel K&N.

Will post here again when I fill up in another couple weeks or so.

Hm.

I'm guessing you keep your foot out of it?

I think I take advantage of the FWI horsepower increase more than I don't, if that makes any sense. If you're a lightfoot, you might see this kind of increase.

Just a guess, though.

My right foot has been lighter for quite a while now, but has not changed during the last several tanks of gas, no. I've driven less aggressively since maybe mid winter. Not to say I don't get into it when the situation calls for it, but that's not often in the type of traffic I normally see.

Filled up this morning, paid 4.09 when the newly reopened station next door couldn't get the premium pumps to work. They opened after 2 yrs closed, with a 3.79 special, ACROSS THE BOARD. Tried last night, and this morning the premium pumps were still OOO. They told me last night the special would run for a few days, and a service truck was parked there trying to fix the problem. Not resolved as of 7am so I had to till at 4.09. Oh well, that's only about $4.

ANYWAY, this tank I only got 21mpg, but I expected a drop off. Ran the A/C a LOT with hot and humid weather, and my wife spent a day with the Riv ripping around town when I needed her van for the day. This was the first tank with any A/C time at all, really. I'll take 21 avg.

Still, that's not bad. If I could ger 21 mpg avg every day, I'd never complain.

Yeah, no complaints here, all things considered.