I'll be a fun project for some

[SilveradoMike]

Oh. I forgot. I did some reading on a-b-a testing. Ill deffinatly be doing that to assure any mods are working. Whats a good test mileage for testing?

[MetroMPG]

Originally Posted by SilveradoMike

As far as vehicle mods where is the most improvment to be had?

There are precious few mods that yield "O WOW" levels of improvement (which to me means anything more than a 2-3% change). But Frank mentioned one of them:

perhaps a collapsible boat-tail as seen on semi-trailers

If you smooth out the leading edge of that cap to reduce turbulence along the top/sides, then it's worth looking into adding something at the rear of the truck that tapers the top & sides.

[wmjinman]

That does sound like a lot of starter failures! I don't know that I start my stuff 10 to 15 times a day, but it's probably at least half that (unless I'm engine-off at red lights & such, then it's probably that much), and the starter in the Gnat has been replaced ONCE since I've owned it - and that's been several years now. Can't remember EVER replacing the starter in the Jimmy, and I've owned it even longer (and driven it much more)...

Oh, mileage for A-B-A testing. Do you mean how many miles long should the test course be? I have one that's about 4.5 miles long & it works pretty well. You could probably get by with less, but I would think you'd want at least a couple miles each way. Do you have cruise control? Because like Darin (MetroMPG) sez, that's a good way to remove the variable of your right foot from the equation.

Some things to look for on a test course;
> Fairly level and flat
> Good landmarks for where you start/stop your test going each way
> Places to turn around far enough beyond your start/stop points for acceleration & settling-in to your target speed
> A speed limit & traffic volume that will not interfere with your tests (much)
> Conveniently located (you don't want to have to drive over half an hour just to get there)

As for the start/stop landmarks, I've found out the hard way that if possible, you want them to be in areas where the road is pretty straight & level. Because if it's not (like if it's climbing, as in one of my early ones, you can see the MPG dropping as you head up that hill.) When that happens, the time you read your final "current" mpg average is critical. If the number isn't changing at the moment you read it, it's gonna be a lot easier to have confidence you got a good reading.

(I'm a retired land surveyor, so I'm all about "good readings")

[SilveradoMike]

Thanks for the replys so far guys. Im currently about 1/2 way through my work day (based on milage only) and Im at 101 miles and 5.13 gallons so 19.7mpg. I think my starter "issuse" is Im starting an engine thats probably well over twice the size of the common size found here. And I know my starter isnt twice the size or larger then ones found on 2.0l and smaller engines. Twice as many or 2.5 times as many vylinders is twice as much or more resistance the starter is trying to move. Makes sence in my head I guess. lol. Ill update my fuel log here again when I get home. I already updated the 1st half my day. Only going in 1/2 day increments because Im assuming 100-130 miles is a good measurement. Most people are maybe 40 or so miles a day I would think. So my logs will be about 4 "normal" days to 1 of my days.

Thanks again for the replys. Ill be doing some stuff soon. Im thinking a front air dam and an undertray first. Ill do the undertray in aluminium for weight savings. And on the boat tail stuff... Im sorry but I really cant convince myself to drive something with those type of aero mods unless its like a 5mpg increase. lol.

[MetroMPG]

Why abandon a solution we're going to see more and more of on long haul trucks?


http://ecomodder.com/forum/showthrea...add-19523.html

It's your call of course - and your money out the tailpipe!

[SilveradoMike]

Well a couple reasons actually.
1. I think it looks absolutley riciclous (but if its for you I'm not judging)
2. I would think that a long haul trucker is in their trailer maybe once a day or once every few days. Im no and out of the back of my truck atleast 50 times a day.
3. The extended body length past rear axle centerline is bound to be beat up. (you should see all the drag marks on the rear edge of my bumper)
4. My rear cargo doors when open protrude past the outside edges of the body so a tail peice would also need to do the same. Thus lowering its effectiveness I would think.

I hope I did not or am not offend any one. If there are some lees visable aero mods Im all for it.

And the idea isn't abandoned, if i had to drive my truck across the country you better beleive I'd be building one.

[wmjinman]

Yeah, if you're constantly having to get in and out of your back, then I can see the "truck wings" being a huge pain in the ass. - unless you could rig it in such a way they don't interfere with getting into the back. But I suspect just having to walk around the extended length of the wing would would get real "old" real fast. I know from being on the survey crew that having something interfere with getting into a compartment on the truck is a major hassle.

It sounds like you do a LOT of stop & go with your deliveries. In that case, efficient acceleration/deceleration will probably be as big an issue as aerodynamics. For that, lower weight is key, but then, if the nature of your work involves hauling weight . . . ? So - hmmm... Tough question.

Try to learn the most efficient way to accelerate, I guess. I instinctively try to accelerate SLOWWWWW, but I guess that's wrong. I guess it's better to accelerate faster, keeping the engine at it's most efficient workload (BSFC - or Brake Specific Fuel Consumption) while going through the gears quickly so you're in top gear sooner.

Then the other side of that equation is learning how to decelerate efficiently. In that case, coasting is key (even closed throttle "coasting" in gear). Figure your roadspeed was hard won at the sacrafice of burning gas. Whenever you use your brakes, you're throwing away that gas. So try to "anticipate" your stops so most of the speed is lost from coasting drag rather than braking. Sometimes when going down a street in town, I'll take off from a light, accelerate, then look ahead and see the next light turning yellow, and then immediately go into coasting mode - almost from the last light & even before getting all the way up to the speed limit. If I STILL need to brake, it makes me mad at myself, because I should have looked forward sooner & stopped accelerating sooner. But anyway, constantly practicing these types of things can help a lot.

For aero, a grille block is probably the easiest & cheapest way to get the biggest effect (other than pumping up your tires as high as you dare). An air dam that hangs down as far as the other stuff hanging down is probably a good bet, too. Some sort of boattail/Kamm-back yields big gains, but is a challenge to make, and in your case, probably more trouble than it's worth. You could try slapping some rear fender skirts on. Some people see good sized gains from those, but when I tried it on my Jimmy, I didn't see any improvement at all, even in 3 different tests. That was a dissappointment.

[SilveradoMike]

Yes there is alot of stop and go on my route. My average speed per my new scangauge is 27mph. Speaking of the scangauge, Ive got mpg, avg, tps and lod displayed currently. I feel like lod isnt super helpful. It seems that mpg is most affected by tps. At 45mph in 5th gear and tps @ 33 mpg reads about 17 on flat gound and if I can get the tps down to about 10-15 mpg goes into tge 22-27mpg range.

Im going to try a grill block first. I forgot to mention that in an earlier post. And It will be a good chance to find a good a-b-a testing area. (finding flat ground will prove difficult) Im actually thinking of making two seperate grill blocks one on either side. If it proves to work Ill make some perminate ones from aluminum. Hmm... Another thought, make one big grill block riddled with loovers pointed towards the ground and then slightly angle the top rearward. Temps in my area reach the high ninetys and lower 100's in summer and Id hate to be taking the thing out all the time.

So thoughts on my loovered grill block and a different gauge on the scangauge then lod...

[MetroMPG]

I typically only monitor trip average and instant MPG. Regardless of whether you attempt to minimize TPS or maximize instant MPG, it has the same result: you only press the accelerator as hard as necessary to maintain desired speed.

wmjinman is right in talking about focusing on how you decelerate. Your goal should be to avoid the brake pedal like the plague. Every time you press it, ask yourself what you just did wrong and how to correct it for next time.

Also agree that the partial grille block is one of the easier & more effective mods.

[War_Wagon]

As for the starter issues, have you looked into a reduction starter? They are commonly used for high performance applications with high compression ratios. Being an LS series motor, you can probably get one that would fit your truck. They use a smaller starter motor running through a gear reduction setup to minimize the strain on the motor itself. MSD DynaForce Starters 5096 - SummitRacing.com this is just one example, there are less expensive ones out there.