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Best fuel milage setup???

i had my k5 350/350/203 (still full time) 3.08s/35s getting 14 highwy. 60-65mph. i was driving 55 miles each way to work. there are some steep long hills on that highway too.

i spent alot of time tuning the ignition. the biggest bang was an adjustable vacuum advance. tuned it for as much advance as i could get. set the initial at 6 degrees. then started adding more vacuum advance until it started pinging. then backed it off a little.
i also had headers/dual exh/intake/q-jet/rv cam. after i put 42s/4.88s it still gets 10. which i think is really good for a big truck.

my advice for max mpg

tune the ignition
q-jet
headers/exhaust. but not too loud. because then you will get "on it"
lower the truck as much as possible to run the tires size you want
mall terrains or hwy tires
tachometer. my truck never see's 2000rpm before i hit the highway.
dual throttle return springs.
appropriate gear/tire/trans ratio
 
This thread has me wanting to switch to a diesel instead of going with a 383. If only they weren't so bad in cold weather, as I've been told. Someone also told me they weren't very good for wheeling (I don't really crawl but moreso mudding, expi, watercross, etc...)
 
I'll post mine up again since it was lost..........

87 Suburban
TBI 350 with factory oil cooler and synthetic 5w30
700r4 with factory oil cooler and synthetic ATF
NP208 with synthetic fluid
Cold Air Intake
1" TBI Spacer
Jet Performance Stage2 Chip
160 Degree Thermostat
Stock Exhaust with Turbo Muffler

Rough Country 4" Lift
33x12.50r15 Goodyear MTRs
15x10 Steel Mags with 4" bs

I just ran a 158 mile round trip drive through mountain passes and used 10 gallons of fuel!! You do the math.......15.8 MPG
 
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Diesels are fine for wheeling...

as far as cold weather, it depends on what condition your motor is in...

they can be cold starts if you have issues... maintenance is everything on a diesel... so I have learned...

They are no speed demons, but a cummings (or newer diesel) can be crazy in a rig
 
COCHEV said:
Only issue with diesel is the added cost of diesel fuel...
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But think of the power, and all those torques... Mmm torques haha. My buddies 98 cummins weighs 8800 lbs. It gets 18.5 highway. For a truck that gigantic to get that mileage, with 230000 miles all stock, throw that in a blazer, i bet you get 25 mpg easy and have tons of power lol. And get that nice turbo wistle that blazer diesels dont have lol. love that sound
 
Deuling said:
My buddies 98 cummins weighs 8800 lbs. It gets 18.5 highway.
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8800lbs? What the heck is on this truck? A stock 3500 dually long bed/QC with a 6spd, HD241, D60/D80, and steel wheels barely weighs 7800lbs. My '06 Mega Cab weighs 75XX and it's got big tires/wheels. I own a 70 foot scale and have never seen a diesel pickup with a standard bed over 8000. Does he have a service bed or something?
 
rjfguitar said:
8800lbs? What the heck is on this truck? A stock 3500 dually long bed/QC with a 6spd, HD241, D60/D80, and steel wheels barely weighs 7800lbs. My '06 Mega Cab weighs 75XX and it's got big tires/wheels. I own a 70 foot scale and have never seen a diesel pickup with a standard bed over 8000. Does he have a service bed or something?
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Oh idk when he gets parts for it he always has to say its the 8800 pound one lol. Its a long box, ext cab, big tires. Those engines are like a ton in themselves lol

But whatever im just saying that if that big fricken truck, (which has gotta be twice as heavy as a blazer or close) can get that mileage, than a blazer would have to get some good mileage with one.
 
I'm quite sure a diesel would give the best MPG in our years of trucks.
That being said I do not even know what I am getting with my blazer with a TBI 350/700r4 3.73's and 33x10.5r15's, (cannot afford to fill the tank)
Anyone have an idea about what a good running blazer(91) with this setup averages?
 
Deuling said:
Oh idk when he gets parts for it he always has to say its the 8800 pound one lol. Its a long box, ext cab, big tires. Those engines are like a ton in themselves lol

But whatever im just saying that if that big fricken truck, (which has gotta be twice as heavy as a blazer or close) can get that mileage, than a blazer would have to get some good mileage with one.
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ah...... it's a 3/4 ton, which is rated to haul up to 8800lbs gross vehicle weight, not what it weighs empty.:waytogo:
 
Yea the reason my fuel mileage is so bad is because the fuel filter has a crack in it :haha:

So once i fix that i will get new spark plugs and see how that works.
 
I was thinkin of looking for a 5.3 vortec out of a newer silverado. I got 21 mpg with my 2001 and had plenty of power for what i do. I wonder how hard it would be to put one in if i could find somebody on CL that got rearended or something
 
trustyrusty said:
I'm quite sure a diesel would give the best MPG in our years of trucks.
That being said I do not even know what I am getting with my blazer with a TBI 350/700r4 3.73's and 33x10.5r15's, (cannot afford to fill the tank)
Anyone have an idea about what a good running blazer(91) with this setup averages?
Click to expand...

Expect 12-13 around town with a good running engine.
 
DrkZide said:
You can also make your own diesel too which should offset the cost at the pump.
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The cost to make bio diesel is a bit high at first. You need the stuff to "distill" it. Then there's the conversion costs on our trucks. You can't just pour it into the system really. Lots of folks have had troubles with home made bio. Even the stuff out of a pump has proven problematic for some.
 
Deuling said:
I was thinkin of looking for a 5.3 vortec out of a newer silverado. I got 21 mpg with my 2001 and had plenty of power for what i do. I wonder how hard it would be to put one in if i could find somebody on CL that got rearended or something
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You've got to be pretty good with electronics to do a swap like that. I think I'd just build a 350 and put on an aftermarket EFI system.
 
Can't believe no one said anything about the inline 6 motors.

I ran a 250 I6 in front of a 465/208 with 10 bolt front and 12 bolt rear and 3.73 gears on 33's and still got 18 mpg on the highways. This was a carbureted '81 also. I imagine it could have gotten better if it was TBI.

Try checking into the inline motors. 250's offer great fuel economy. If you want 35's, I'd look at running 4.10's instead.
 
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