Engine/Transmission (1998.5 - 2002) How to boamb for MPG!

[brobeson]

I know, the best way to improve MPG is to slow down, but I feel there are sometimes things that can be done to increase fuel mileage if you keep you foot out of it.



I tow for a living, I just go up to the speed limit and hit the cruise.



Now at 65 mph or so would 4" exhaust help, an EZ, different injectors, Amsoil or ????



I have a KN air filter, the tornado thingy, neither seems to help. Other than that I am stock except for the Piers hx35 turbo and ATS 3 piece exhaust that are just now being installed.



Any ideas of how to get better MPG?



At 15-20K miles a month, even 1 mpg would mean a big change in my fuel bill.



TIA Bob

 

[fox]

Get rid of the mufler keep the resonator.

275 injectors.

E-Z or comp.

BHAF or AFE filter.

 

[The patriot]

Illflem did a mod on his cruise control. It made it slower to respond, but got him some good MPG's.

He has a 12 valve, so I dont know if the cruise controls would be same as yours.

Eric

 

[jrandol]

275's alone gave me 1-1. 5 mpg alone. Plus the extra power is fun too!

 

[cmckinney]

So how do the RV 275's increase the MPG?



I just installed the 275's and didn't notice to much of a power gain alone but with the EZ installed it has much more pull at 1500 RPM.



-CM

 

[jrandol]

Originally posted by cmckinney

So how do the RV 275's increase the MPG?



I just installed the 275's and didn't notice to much of a power gain alone but with the EZ installed it has much more pull at 1500 RPM.



-CM

That I could not tell you, it just is there. Now with the FMS box... ..... thats a different story. Maybe my stock injectors were really poorly balanced out? Everyones guess is as good as mine but been real pleased with the 275's. Little extra go power and mileage increase (hand calculated) is real cool.

 

[Mundgyver]

A set of stock injectors have 5 holes in the tip at a pre-measured size. (Some one will let us know, cause I don't on the exact size). The 275 injectors have 7 holes at the tip and they are smaller in size than the stock. Even though the holes are smaller, you have 2 more of them. The size of the holes being smaller contribute to atomizing the fuel into a more combustable cloud. Has to do with the size of the mist droplets. So you are burning the fuel more efficently. That is why you get a power and mileage increase running the 275's.

 

[krs]

That makes sense. Thanks Mundgyver!!

(I had wondered)

 

[fox]

Bigger injectors also deliver the required fuel quicker and this happens when the piston is still at the top of its stroke.

So, it burns more complete.

Makes me wonder what the polution control people are up too.

I think they want us to burn the stuff poorly. so we use it up.



Off of my soap box.

 

[illflem]

As patriot Eric said I modified my CC and gained 2-3 mpg, it is the same mpgs as driving by foot. Diesel engines are most efficient at a constant rpm, our stock CC responds much too fast, the throttle is constantly moving. All I did was cut the vacuum line to the cruise actuator under the battery and insert a barbed tubing coupler filled with glue and a pin hole poked though it, 10¢ mod.

Not sure which year but at some point the CC went from vacuum to electronic, you may be out of luck on this one.



I used to think that lower rpms equaled better mpgs - more power = less downshifting. They do to a point but somewhere in the equation the aerodynamics of speed comes into play and you'll get the same mpgs in 4th gear as 5th. Airtabs might do something for you.



Larger narrower tires with higher pressure will help quite a bit with mpgs.

 

[slo-ryde]

One of the easiest ways to improve fuel economy is to boost tire pressure. I'm running 65psi front and rear on my truck (unloaded) and get 18 to 22 mpg. I've been told that 65 front/80 rear when loaded would be ideal. I didn't notice what kind of tires you're running. You don't want to exceed the maximum shown on the sidewall.



Also, make sure front end is properly aligned.



Fuel additives claim to boost cetane rating, that would probably help some if the claims are true.



Aerodynamics play a huge role in fuel economy. Anything to lower the drag coefficient would have to help if you believe in the laws of physics. I have the front air dam on my truck and wonder just how much it helps.

 

[jrandol]

Originally posted by slo-ryde

One of the easiest ways to improve fuel economy is to boost tire pressure. I'm running 65psi front and rear on my truck (unloaded) and get 18 to 22 mpg. I've been told that 65 front/80 rear when loaded would be ideal. I didn't notice what kind of tires you're running. You don't want to exceed the maximum shown on the sidewall.



Also, make sure front end is properly aligned.



Fuel additives claim to boost cetane rating, that would probably help some if the claims are true.



Aerodynamics play a huge role in fuel economy. Anything to lower the drag coefficient would have to help if you believe in the laws of physics. I have the front air dam on my truck and wonder just how much it helps.

good point about fuel additives, there is a lot of hoopla and marketing gimicks out there. I run Power Service and it always seems like I might be doing a little better but everytime I put the calculator to it it makes no difference. I sure like lubricating that VP though!

 

[RO'neal]

FWIW... .



When I added the EZ I didn't notice any mileage increase no matter how I drove. I went from the EZ to the Comp, added a set of BD2's and a Stanadyne Fuel Manager and the mileage went up 2 mixed driving and 3 on the highway. It doesn't seem to matter how I drive either. I tried driving it easy and it didn't make a noticeable difference so I went back to normal.



**EDIT**

I also added the 4" exhaust at the same time.

 

[jhellmers]

I am passing along info from a very good friend of mine regarding towing mileage. Although he runs a big-block Chevy 1-ton SRW pulling a 28' Gold Rush hauler @ 10k# 375 miles each weekend, the same methods apply. First of all, wings. He towed literally for years before installing a old cab wind deflector from a big rig. He installed it midway back on his cap and adjusted it so that he would just stop seeing bugs on the top of the front of the hauler and said that once set-up, it was like he put a much stronger motor in. Power and mileage went up. Secondly, check the alignment of the TRAILER axles. He also had a problem as the axles fatigued from over a decade of running over New York State highways and cracked several times. He would repair them and set the camber and toe. After a while, he decided to replace them as they had been fixed one too many times. After installing the new axles, he said that on just the trip down, which usually took about a full tank of fuel. he now only used between 5/8-3/4 of a tank. Evidently, the old axles were toe'ed out (or in) just a little and fighting each other and the truck. It doesn't take much toe-in error to make axles pull harder. The new axles were going to pay for themselves. (They weren't more than a couple hundred bucks complete. )

Sorry this is so long, but I felt this was useful info.

 

[jponder]

I use a throttle cable that holds your throttle in one position and have gotten some really good mileage when going slow. I have thought that mods will help you to get better mileage because your engine will produce more torque at a lower RPM. Add taller tires and your ready to go. My Michellins have 70K but I plan to get the 2 in leveling kit and as tall of 19. 5s as will work. I bet I can squeeze out some more mileage if I turn up the engine some and run at a lower RPM. I have never bought that sweet spot rpm about the Cummins. You get better mileage the lower RPM you turn period UNLESS you lug the engine. I think a hoped up engine turning lower RPMs at slow speeds will yeild MAX mileage

 

[Hohn]

Originally posted by fox

Get rid of the mufler keep the resonator.

275 injectors.

E-Z or comp.

BHAF or AFE filter.

I would favor the version of the EZ that Diesel Dynamics has. It has a little less timing, and probably is better then the more (too?) aggressive EZ. I own the EZ, and have noticed no change in mileage, but I recently moved the jumper to 2 from the 3, and I think this will help with the mileage.



275s are a proven mileage enhancer.



Another thing that has worked very well for me is the Fitch Fuel Catalyst. You can look at ithere



Synthetic fluids from front to rear will reduce friction in the driveline.



As mentioned above, tall narrow (highway) tires are great too. Think about the class 8 rigs. The closer they are to that, the better they will be.



Depending on how fast you go, aerodymics could be a HUGE source of improvements. For example, if you see 10psi boost at 70mph, if you can lower the boost (to like, 5psi) it takes to go a certain speed , then you are gaining mileage.



Generally, the lower a vehicle is, the more aerodynamic. When towing, this isn't really true, since it's the truck/trailer PAIR that must be considered.



HOHN

 

[MAllred]

I pull Jayco campers for Jet and am constantly striving for mileage too. Nothing like heading west into a 25 mph headwind eh? The Jardine 4" exhaust helped by perhaps 1 mpg and the AFE conical filter makes the turbo sound cool but didn't notice mpgs going up. I put a fancy stainless bug deflector on and took it off a week later because it cost 1. 5mpg!! I may go to 275 injectors once the stock injectors begin giving me problems. The biggie bomb to come will be an Edge EZ or comp -- havn't decided which.



I tow at 62mph and bobtail home at only 65 and run 72 PSI front and 62 PSI rear for pressures (all the time). Heck, I got 134,000 miles from the original Michelins and just installed more.



Fanatically speaking, I sometimes drive at night when the winds are forcast to be really bad. They're usually half the velocity of daytime winds. AND-- I try to take little campers. My towing milage is usually 11. 5 - 13. 0 mpg and 20 to 21 mpg empty. By the way, If you've found a way to make money towing let me know! Momma needs a new pair of shoes...

Maybe this helps?

 

[jbone]

brobeson, Some talked around it, but I would think the first thing I would do would be 19. 5 rims and tires... . It would bump your 4. 10 up to about 3. 73 where I think we would all like to be!! I don't tow that Prowler as much as I would like, but I think that will be my next major mod... ... . let's hear from someone who has 19. 5's, did it help mileage????? R, J. B.

 

[Texas Diesel]

Originally posted by illflem



Not sure which year but at some point the CC went from vacuum to electronic, you may be out of luck on this one.

2001. 5 (late build) = electronic CC

Hohn

I would favor the version of the EZ that Diesel Dynamics has. It has a little less timing, and probably is better then the more (too?) aggressive EZ. I own the EZ, and have noticed no change in mileage, but I recently moved the jumper to 2 from the 3, and I think this will help with the mileage.



That is correct especially for HO's w/ larger injectors the DD IS the way to go.

 

[Huff N Puff]

Dont forget all the stuff that the engine has to turn

For example:Heavy fan,heavy wheels and tires try to lighten any thing that the engine has to spin,the rotating mass. Lighten the truck would also help but not as much. Talk to Bill Kondolay at DTT ask him about tightening the converter up. Hope this helps Merv