How to get better mileage

[dahoseman]

1. I've heard claims that the larger pipe-style intake manifolds increase mpg by ~1mpg. Can anyone substantiate this? Do they seem to do anything noticeable anyway? Similar to this 03-07 Dodge Ram Cummins Intake Manifold Horn High Flow - eBay (item 230579294847 end time Feb-27-11 08:58:30 PST)

2. I'm thinking of adding a large air dam to the front of my truck instead of making an under-body aero kit for interstate speeds. With larger wheels, tires, and added leaf springs on my 4x4, there is a lot of space and air turbulence underneath. I'm thinking of using a large piece of sheet metal with a frame to bolt it to the bumper, similar to the large front bumper air dams on semis. Has anyone else done this? Any comments or experience with air dams?

If I get through with the front air dam, I will probably add side skirts under the side-rails that already on the truck.

3. I'm up in the high country of Colorado at the moment. I met a guy up here has a bone stock 97 CTD 4x4 with the 6-speed. He claims to calculate every tank and regularly gets 24mpg. Does that seem right? Is the manual tranny THAT much more efficient? I usually get 17-18mpg with my '97 club cab 4x4 auto.

[slowmover]

Originally Posted by dahoseman

1. I've heard claims that the larger pipe-style intake manifolds increase mpg by ~1mpg. Can anyone substantiate this? Do they seem to do anything noticeable anyway? Similar to this 03-07 Dodge Ram Cummins Intake Manifold Horn High Flow - eBay (item 230579294847 end time Feb-27-11 08:58:30 PST)


Unknown to me, but doubtful.


2. I'm thinking of adding a large air dam to the front of my truck instead of making an under-body aero kit for interstate speeds. With larger wheels, tires, and added leaf springs on my 4x4, there is a lot of space and air turbulence underneath. I'm thinking of using a large piece of sheet metal with a frame to bolt it to the bumper, similar to the large front bumper air dams on semis. Has anyone else done this? Any comments or experience with air dams?

My 2WD oem airdam is 10" above ground. I measured a half-dozen pickup trucks in a parking lot one day and found none below 7". The "rule" as I understand it is that the dam should -- in a straight line -- come down low enough to "shield" what is behind it, but that below 6" above ground may not yield any further benefit.


If I get through with the front air dam, I will probably add side skirts under the side-rails that already on the truck.

Super Dave has done this on his 28-9 mpg 7.3 Ferd. Also, a deep air dam. He posts under this name on ECOMODDER. Great reading!


3. I'm up in the high country of Colorado at the moment. I met a guy up here has a bone stock 97 CTD 4x4 with the 6-speed. He claims to calculate every tank and regularly gets 24mpg. Does that seem right? Is the manual tranny THAT much more efficient? I usually get 17-18mpg with my '97 club cab 4x4 auto.

HOHN makes the point that early Cummins/Dodges should see 25 mpg, and 3rd Gen 20+ hwy. Hard to say about mountains/cold, but if he really knows how to drive that stick, then, . . . . I believe I would have a distinct advantage in that terrain over an auto. Knowing how to shift isn't easy, nor is knowing when. As a truck driver I can say that each is difficult, and the combination is a real definition of skill.


.

[dahoseman]

I seem to get 17-18 whether I'm driving through mountain passes or on a flat interstate in lockup overdrive 99.5% of that tank. I also drive fast, which will not be changing while I still have breath in my body. My truck is going to be traveling at 70-75mph most of the time. I'm just trying to make it as efficient as possible at that speed, whether it's aerodynamics, fuel, or engine.

I think the steel plate semi-style air dam could reap decent benefits, especially considering a recent deer hit which removed my stock plastic valence/air dam. An aerodynamic tapered bed cap/topper is in the future also to give the upper section a bit more of a raindrop shape. I'm considering designing the bed cap to be raked out all the way out with the tailgate down. At some point, I will also add wheel well skirts and pizza pan hub caps (moon caps) to the outside of the wheels as turbulence covers.

[GAmes]

Originally Posted by dahoseman

I met a guy up here has a bone stock 97 CTD 4x4 with the 6-speed.

'97s didn't come with a 6 speed as an option, so it could not be "bone stock". I sincerely doubt he regularly gets 24 mpg, especially with a 4X4. My towing mileage improved when I swapped to the G56 because of the final ratio, but empty mileage pretty much stayed the same (18-20 at 65 mph, freeway driving).

[slowmover]

"Bondo" on ECOMODDER: Commercially produced aerodynamic bed cap. (Note all the linkbacks at page bottom to check out).



From the Aerodynamics sub-forum, here is a current thread entitled "Pickup Aerocap Design Questions"

There is a question of the rake angle/degrees to be met. Any number of very good DIY threads on this subject. The percentage FE gains are double-digit !!!

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[deezall]

ok when i bought my truck it would only get around 14-16 overall fuel eco. i have replaced the factory steel wheels with 99 model aluminum wheels( yes they fit if you machine the outer edge of the brake drum and clean the crap out of the center) and then went to 18-19. then fixed a shifting issue and now on average i am at 21 -22. i am adjusting the timing this weekend to see if there is any gain. my figures are combined fuel eco. i drive 108 miles give or take 5 days aweek round trip to and from work. now the southern burbs and country of ga arent the hills of colorado. but its not flat. my biggest help was keeping the skinny pedal away from the floor. if you look on the ecomodder website home page at the top right there are driving and modding tips to improve fuel mileage. so far most are working.

[getoutof]

That aerocap is nice I have been considering one made from tonneau fabric...I no I have seen them and they angle just like that. Wonder If they would help. Mythbusters says mesh is best.

I was posting here to probably state the obvious...I just took my A.R.E cap off...it was higher than the cab and not very aerodynamic...It seems to have improved mileage by maybe 3 mpg....when I finish this tank I will calculate ex8act numbers.

I no it may be frowned upon but 10% wvo that I filter to less than 1 micron hasn't visually touched my fuel filter nor my performance....as of yet...only 3 weeks in...

By the way anyone no where I can get a aerocap like cover made from the same material used on flat tonneau bed covers?

[slowmover]

get a aerocap like cover made from the same material used on flat tonneau bed covers?
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It's a DIY world, as of today.

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[getoutof]

Originally Posted by slowmover

get a aerocap like cover made from the same material used on flat tonneau bed covers?
__________________


It's a DIY world, as of today.

.

Another thing to add to the list I guess...

[deezall]

oh almost forgot i replaced factory air filter with k&n a week and a half ago so far it seems to have gotten me closer to the constant 22 mark wooo hoooo.

[dahoseman]

So far, my mpg-related mods are: 1) Timing advanced to 16 degrees; 2) K&N air filter; 3) Steel wheels replaced with alloy H2 rims (probably not a benefit, but it runs at lower rpm on interstate); 4) bed cap topper; 5) 4" MBRP turbo-back with straight-through 51" Donaldson muffler; 6) AMSOIL engine oil; 7) Cleaned out fuel system

I bought it 5 months ago in stock form (except for a Jasper transmission in 2004). My mpg hasn't changed, whether up or down, after any of these mods. I'm only out in Colorado for a month, after which I will be returning to Tennessee. Whether on the flat plains of Kansas in lockup OD, or driving through the freezing mountain passes of backwoods Colorado, I seem to get the same 17-18mpg. I think aero mods are where I need to focus my attention.

I'm considering getting a bumper off of an old semi and cutting/bending it to form over the front bumper. This should hang relatively low and create a decent air dam to deflect air around the undercarriage and wheel wells.

[deezall]

Originally Posted by dahoseman

I'm considering getting a bumper off of an old semi and cutting/bending it to form over the front bumper. This should hang relatively low and create a decent air dam to deflect air around the undercarriage and wheel wells.

i would recomend the 770 volvo circa 2001 easy to mod and paint