2000 C3500 C&C poor fuel economy: suggestions?

[jcool]

At $2 a gallon, it would take 54,945 miles to recoup a grand spent in mods. Just facts to consider.

guess your dead set against him modifying his truck.

 

[JeffsJeep04]

No not at all, but I wouldn't do it for the reasons of it paying off in fuel savings. For not a whole lot more, he could throw in a big block which I would think would serve him better.

 

[Ed HD]

Basic Mods, like an intake and exhaust will pick mileage up at least 2-3 mpg. A good tune up can gain 1 or 2 mpg. That entails plugs, wires, cap, rotor, oil, air filter, fuel filter, etc.

 

[jcool]

No not at all, but I wouldn't do it for the reasons of it paying off in fuel savings. For not a whole lot more, he could throw in a big block which I would think would serve him better.

putting in a big block would be a lot more work and money than some bolt on mods or even new heads and cam. would be a good option in the power department but you would see the same or worse mileage at best.

Basic Mods, like an intake and exhaust will pick mileage up at least 2-3 mpg. A good tune up can gain 1 or 2 mpg. That entails plugs, wires, cap, rotor, oil, air filter, fuel filter, etc.

in my 03 5.3 i saw a 2mpg increase with just the true duel exhaust. your right about the tune too, that can make a small difference as long as its economy in mind and not a high power tune. with the mileage you are getting now i doubt you need a tune-up. also does your truck run at normal temp? I ask because in my nissan the thermostat was stuck open and the engine was cool all the time and i lost 3-4mpg. now that i changed a 3 dollar part i am back up to 33mpg again.

 

[GM Guy]

I think the only mod this may see is exhaust, as this thing was a construction truck, and the exhaust has many dings and scrapes, pipe that comes from left bank got bent back a tad.

Dad is happy with it, but IMHO, it will be the first to go, if we ever want to sell any. It is the newest, cleanest lowest mileage one in the fleet.

also, the intake stays. we love the heck out of that Donaldson housing.

 

[jcool]

I think the only mod this may see is exhaust, as this thing was a construction truck, and the exhaust has many dings and scrapes, pipe that comes from left bank got bent back a tad.

Dad is happy with it, but IMHO, it will be the first to go, if we ever want to sell any. It is the newest, cleanest lowest mileage one in the fleet.

also, the intake stays. we love the heck out of that Donaldson housing.

I have never noticed any mpg or power improvements from an intake. I dont blame you, I put the stock one back on my truck without a decrease in mpg. If you are going to see an improvement at all, I am willing to bet the exhaust is the place to do it. mine was done at a local shop from the manifolds back with two cats and mufflers, true duels of course for 200 dollars total. I would also consider some headers if I were you too though. If you do the headers put a heat wrap on them though. I didnt have headers and still got 2mpg better though.

 

[Ed HD]

I have never noticed any mpg or power improvements from an intake. I dont blame you, I put the stock one back on my truck without a decrease in mpg. If you are going to see an improvement at all, I am willing to bet the exhaust is the place to do it. mine was done at a local shop from the manifolds back with two cats and mufflers, true duels of course for 200 dollars total. I would also consider some headers if I were you too though. If you do the headers put a heat wrap on them though. I didnt have headers and still got 2mpg better though.

Really? We put a K&N CAI on my mom's suburban and got almost 2 mpg, I got 1-2 mpg on my 5.7 Tahoe, and I've gotten a lot of improvement on my SSEi with a Fenderwell Intake. Any time you can get more cool, dense air into the engine is a good thing, IMHO.

 

[big block 88]

Never seen a gain from an intake on a gasser, diesel is another story though for the pre LBZ duramax's

 

[jcool]

Really? We put a K&N CAI on my mom's suburban and got almost 2 mpg, I got 1-2 mpg on my 5.7 Tahoe, and I've gotten a lot of improvement on my SSEi with a Fenderwell Intake. Any time you can get more cool, dense air into the engine is a good thing, IMHO.[/QUOTE

didnt make any difference in my 03 5.3 or my 03 duramax. mpg has stayed the same as well as power. only thing I noticed was a bit more intake noise. i even tested it when i was at the track about a year ago and got basiclly the same numbers. Unless you already have a really restrictive system then I wouldnt mess with it. I dont know enough about the mentioned trucks intake to make that call.

 

[saratoga]

If it already has the Donaldson intake with the huge canister looking filter and restriction gauge, don't mess with it IMO.

That truck is simply a lot for a 250hp vortec 5.7 to move around... any gains will be marginal at best. It does damn good for what it is from my past experience.

 

[GM Guy]

If it already has the Donaldson intake with the huge canister looking filter and restriction gauge, don't mess with it IMO.

That truck is simply a lot for a 250hp vortec 5.7 to move around... any gains will be marginal at best. It does damn good for what it is from my past experience.

I agree.

I feel that maybe an exhaust would be about it. Synthetics in everything helps as well. Got to keep it cheap!

 

[jcool]

I agree.

I feel that maybe an exhaust would be about it. Synthetics in everything helps as well. Got to keep it cheap!

looks like you answered one of your questions..... I would do the exhaust and be done with it. other than I would use amsoil throughout as well.

 

[Lancerdually]

Let me get this straight........you put Wallyworld synthetic oil in and you are worried about mpg's?

 

[GM Guy]

Let me get this straight........you put Wallyworld synthetic oil in and you are worried about mpg's?

The vehicle was bought recently, and we wanted to flush it once, as the oil in it was horrible, and we wanted to clean it up for when we put in a quality oil. It is gonna stay for just for 3K miles to flush stuff out, will never trust wally world for anything over 3K, RP, Valvoline, or Amsoil is going in.

 

[jcool]

The vehicle was bought recently, and we wanted to flush it once, as the oil in it was horrible, and we wanted to clean it up for when we put in a quality oil. It is gonna stay for just for 3K miles to flush stuff out, will never trust wally world for anything over 3K, RP, Valvoline, or Amsoil is going in.

amsoil has my vote! I have almost finished my 86 s10 blazer and im going all amsoil throughout, even though i will never drive the thing on the road till my nissan dies!

 

[GM Guy]

I agree, we have a decent local vendor, so we will probably end up with her. But for when we don't have any oil in stock, i wouldn't think twice about going to wal-mart and get some Valvoline high mileage full synthetic.

 

[jcool]

I agree, we have a decent local vendor, so we will probably end up with her. But for when we don't have any oil in stock, i wouldn't think twice about going to wal-mart and get some Valvoline high mileage full synthetic.

i cant say anything since my s10 has had the same quaker state full syn in it for the past 5 years.... given its gone maybe 5 miles... and ran for maybe 15minutes.... in the last 4 years it hasnt even been turned over.... soon that will change though!