Effects Of Air Dam (Ford F350 pickup)

[IsaacCarlson]

I use paint, as it is very easy and fast.

[ECONORAM]

Originally Posted by gaorenst

what i need to know is what made the biggest difference for him. I've put a flowmaster exaust in my truck, superchipped my truck, and put cold air intact but nothing near his results.

Those mods might help, but I suspect the Superchips on 91 would be the real difference maker. I got another 1-2 mpg with that, depending upon my right foot. CAI won't really help MPG, but will help hammer down HP. A Flowmaster exhaust I am not sure. I've not hit Big Dave's numbers yet, but I have hit 25 mpg a couple times. I suggest you focus more on aerodynamics. Our trucks are about as aerodynamic as a full sheet of plywood going into the wind... I am prototyping a kit right now, and if I can get some kinks ironed out, I'll be able to market it... Work keeps getting in the way though.
I also suggest following some of the 100 tips here at Ecomodder. I do not recommend engine off coasting...very bad for the auto tranny. Our trucks do have a Decel Fuel Cutoff (DFCO), but it is meant for braking, not fuel savings. It doesn't engage until the truck shifts up to 4th, and locks the TQ, and that is going downhill...

max_frontal_area, no, I did not consider the return fuel flow. I did notice when the engine settles down it will drop to 0.4 gal/hr, but at 60 mph on the highway, I am doing very good to get below 2.5 gal/hr (that's 24 mpg). No, my 4.7 does not have MDS...5.7s only.

Now I've added a topper, pushing my drag coeff a little higher, I think. :doh:
I have a trip this weekend up I-44, where I'll be rechecking the mpg to see how the truck does with some aero tweaks.

[slowmover]

1/2 gl at idle is normal. You can find this in RV sized generators or about any automobile. It's practically a rule-of-thumb number for an IC engine. On the 325-mile commutes I was making twice-monthly last year I could watch my accumulated mpg drop by as much as this in just 1/2-hour of diesel high idle (keep oil pressure up, alternator cranking and A/C ice cold) at the 200-mile mark during a truck stop lunch break.

I have also used this figure for calculating fuel burn in the event of coastal evacuation ahead of a hurricane. The better, more reliable number is probably 3/4 to 1-gl per hour in stop-n-go traffic where one occasionally, maddeningly, slowly makes progress on the Interstate (for those who can't map read). The ironic upshot was that the 40-gl capacity Suburban was/is a FAR better choice than the tee-ninesy Prius . . it's all about fuel capacity. In other words, what is your "range" at 5-15 mph and 1-gph fuel burn?

Thanks for the info above about air dam length. I'd been wondering about the cost/benefit ratio.

.

[comptiger5000]

Slowmover - Keep in mind, a diesel will use less fuel at idle than a similarly sized gas engine. My Jeep burns at least 1 gph at idle, which is brutal in stop and go traffic. Range is still reasonable, however, with the 23 gallon tank.

[slowmover]

Originally Posted by comptiger5000

Slowmover - Keep in mind, a diesel will use less fuel at idle than a similarly sized gas engine. My Jeep burns at least 1 gph at idle, which is brutal in stop and go traffic. Range is still reasonable, however, with the 23 gallon tank.

In some scenarios.

The one contemplated would be May-November and a conservative number is needed when one is on high idle (above 1,100 rpm versus the usual 750-rpm) and A/C is constant. If I have but X-gallons, how far can I get (with a reserve) before needing to re-fuel.

You might be surprised to see how difficult it is to reach -- on ANY vehicle -- 150 miles in traffic averaging 3-5 mph. I've collected quite a few stories from others evacuating ahead of Hurricane Rita (and Ike). One can sit within the same measured mile for hours at a time.

So I use 1-gph for minimum fuel use. If, indeed, it is 3/4-gph then all to the better. But I'm not likely to try to simulate this, nor is there any way to anticipate the potential problems in full. Thus the high (conservative) number (I simply hope it is high enough). Thanks for the reminder.

[comptiger5000]

At high idle, your fuel usage could definitely climb to about 1 gph. I don't want to know what my Jeep would burn at a 1000 - 1200 rpm high idle. My guess would be 1.5 - 2 gph. Hopefully I never have to use it for something that requires letting it ide for a while...

[max_frontal_area]

Originally Posted by Big Dave

Without air dam: 26.34 MPG
With air dam: 27.00 MPG

congratulations! BUT, wouldn't eco modders commonsense (whatever that may be) dictate an air dam should do a bit better even on a heavy vehicle such as yours?

why do you think it didn't net more than that?
are you considering adding skirts to the rocker panels , at least just for a test?

[Homesplat]

Man, that is crazy high mpg for a big truck. I just joined and I have an F-150. It says I can't send you a pm yet but I was wondering if you had any simple tips or mods that would help me get over 20 mpg?

[Big Dave]

Max:
I am on my second iteration of air dam. The first one extended to within 1.5” of grade and got the 27.00 by itself. I also had side skirts where the running boards used to be. They approached 3” of the ground. Air dam & skirts that low dragged the ground a lot. No damage due to the fact they were ripstop conveyor belting but an annoyance all the same. With the air dam that low I probably lost some CdA due to increased frontal area.

Second iteration, I ditched the side skirts (more trouble than they were worth) and raised my air dam up to 6” above grade in front of the wheels and 9” above grade in the center (just covering the steering tie rod). MPG drifted back into the mid 26s. This setup obviously never drags or fouls parking curbs. It passes over most road kill.

Gonna try again, splitting the difference. Probably 3.5” in front of the wheels and 6” in the center.

Homesplat:
I’ll tell you what everyone else around here will tell you. The first order of business is to adjust the nut behind the wheel. (that would be you). Driving style matters – a lot. Read this:

Beating the EPA - The Why’s and How to Hypermile - CleanMPG Forums

Winnow through the politics and the hybrid-only stuff. He has the goods. This advice flat-out works. Few people can drive the way he does but every little thing helps.

As you get into it, everybody and his dog will be trying to sell you some snake oil or gadget for better MPG. Hold onto your wallet. Three things I’ve found to work (once you get your driving improved): Weight reduction (tough on a truck whose whole purpose is hauling cargo), gearing, and aerodynamics. Tuning is a waste of your money (Exception: Ford is notorious for reflashing you ECM for NOx reduction. Such reflashes are highly detrimental to MPG. A chip will trump the reflash.)

How gung-ho are you about mods? I know for a fact that an F-150 with a stick and a Cummins 4BT3.9 will get over 32 MPG – with extensive aero-mods. For cheap and effective (but bizarre-looking) aero-mods, check out aerohead’s trucks. He gets crazy MPG without any mechanical mods.

PM me when you can.

[Homesplat]

Thanks for all the advice. I would be willing to mod to the point where the cost of the mod wouldn't be worth the increase in mileage. I will message you once I am able.