I have the 4.2 5-speed 3.55 get 17 in town running it hard and 18.5 going easy.just another 2 cents worth.

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------------------------- 99 SILVER XLT/REG.CAB/4.2/5SPD/3.55/K&N Airbox Mod/Rhino muffler/Westin Black nerfs and now SuperChiped

 

Mike and everybody,
Thanks for all the replies and info. Mike, i do not want you to go crazy and think that you had talked to somebody else.I was the one who told you i had gone from 29" to 31", but actually i went from stock 245/75/16 to 270/70/16, if my calcs are right that is about 30.1 to 31., so my apologies for that. also, i did account for the speedometer difference. Well, now after all the posts about the gas, it kind of makes sence why my milage is lower. Now i am hoping the s.c. finds out that there is something they can do to my chip so i can p/u some ponies and at the same time mpg. By the way i really miss the shift quality the chip gives me. I will keep you posted. thank you again guys.

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99 xlt sc,4.6 2w.d.,gibson catback,
superchip,
rsx shocks,
hellwig sway bar,
3" front lift,275/70/16 scorpions,
sst soft bed cover.

FUTURE MODS:4.10 GEARS, GORHINO BRUSH GUARD AND HELLA LIGHTS.
From: Los Angeles, CA

 

Dear Veloci,

I must be confused! I thought it was you who told me that you went from 29" to 31" tall tire & wheel combo, which is a considerable difference. (I've been talking to another F150online participant, who went from 29 to 31, about this, so perhaps I got the two of you confused! If so, please accept my apologies.) Again, it is the circumference that matters as far as changes in effective gearing. If your difference is actually only 2%, then I sure wouldn't spend the money to do a gear change to compensate either, though I notice in your signature that you are planning to get 4:10's installed! I see that you are in Los Angeles; that too, has an effect on your gas mileage, as I believe that reformulated fuels have been a requirement in that area for some time now, and reformulated gasolines have lower energy content. Hence, they give about 8%-10% worse gas mileage compared to non-oxygenated gasolines. Adding 10% to your current best of 16 mpg would put you in the mid-17's, which would be comparable to many other similar vehicles. Also, if your speedometer is off by 2%, then so is your odometer, and you are now traveling 2% further than indicated on your odometer, and that needs to be factored in to get accurate gas mileage numbers. So just reformulated gasoline and having your speedo off by 2% is enough to have your truck getting basically the same kind of mileage that others here are getting with their similar vehicles. It's funny how things can add up!

One thing that would help is if you can tell us how many rpm's are you turning at say, 60 mph? That would tell us whether or not you are below your engine's power band very quickly, and I probably should have asked this before.

One very interesting question that I hadn't thought of is, is there generally a difference between California emissions-equipped vehicles, and the rest of us, in terms of gas mileage? It used to be in the 70's and most of the 80's that all California emissions-equipped vehicles could be counted on to get worse gas mileage than the standard 49-state configurations, but this is something we haven't heard much about in the last decade or so. It used to be that some California-spec vehicles even had different camshafts, and other parts.

All California-spec Ford vehicles do have completely different computer codes, so we know there is obviously *something* that is different. A few other states that have enacted more stringent emissions standards also get California-spec vehicles, as Ford basically offers two basic emissions packages, one for California-spec vehicles, and what used to be called the 49-state emissions package. (we're not counting the high-altitude package here)

It might be very interesting or at least revealing to do an informal poll here of California-spec F-150 owners, to see what they are getting for gas mileage, compared to similar vehicles that do not have this package. We have a number of F-150 owners right here, with the 5.4 automatic combo, that are getting 19-20 mpg on the road! 20 is about the highest number we've heard from *any* F-150 owner regardless of engine size in the late-model (97 & up) F-150, by the way. The more common mileage figures for the 5.4 V-8 in a 4X4 are about 17-18 on the highway, but we get all kinds of numbers. Unfortunately, we have never tracked gas mileage in these vehicles by state, that would be some very nice data to have right about now!

We know there can be tremendous weight and aerodynamic profile differences between all the various configurations of F-150 that are available, ranging from "stripped" 4X2 "fleet" V-6's, all the way up to the 139" wheelbase 5.4 long bed super cab 4X4's. That alone is certainly enough to explain a lot of the variances that are found in basic performance levels of these vehicles, and of course weight affects mileage too.

But knowing whether it is something inherent in the California-spec package that is a detriment to optimal gas mileage is the real question here.

Anyone want to give us some mileage numbers and what state your vehicle was originally sold in? That would be helpful here to a lot of us, so please, anyone who tracks this please make a brief post if you don't mind, including what kind of gas you normally buy.

Our bests to all,

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com

[This message has been edited by Superchips_Distributor (edited 10-12-1999).]

[This message has been edited by Superchips_Distributor (edited 10-12-1999).]

 

Dear Veloci,

OK thanks for your kind reply! I'm glad I'm not losing my mind just yet, anyway.

It is amazing how these "little" things that we often overlook sometimes have such a cumulative effect on mileage. I did go ahead and start a new thread about gas milege, so we could hopefully get as many respones as possible. In that thread, I asked for respondants to give as much detailed info as they could about their vehicles and their exact configuration, what type of driving they do, and what kinds of gas they use. This should hopefully give everyone some insight as to what kinds of gas mileage other people in similar areas with the same basic type of vehicle are getting, so that comparisons *can* be made. As it is now, we get every possible kind of F-150 here, and there can be a huge weight difference between the lightest V-6' and the heaviest offroad 5.4 V-8's with a 139" wheelbase, so we have people comparing their mileage to a vehicle that might not be comparable. Because so many thing affect gas mileage, including where you live, etc. hopefully we'll see some great data there, that will do everyone some good, or at least I hope it will.

Thanks again Veloci for all your posts and responses, and best of luck!

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com