breaking the bank

geedub6893

geedub6893

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Dec 11, 2011
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I have a 98 12 valve i bought to play around with last year. I had a company car then so i didnt care about fuel economy. Now i have changed jobs and have to drive this truck everyday. After driving it for two weeks im getting 12.5 mpgs. I know a good bit about these motors but i need help to get this thing on the right track.

1998 12 valve xcab swb 5 speed on 35's
stock injectors and delivery valves
compound turbos he351/hx55
3 piece manifold
100 plate slid forward and cranked
4k springs
stock timing (i know i need some timing)
new fuel filter
4:10 gears
 
ok i dont know anything about a twins set-up, given that i havent ever ran one, however i would suggest a bump in timing, and consider more fuel, and i know this is contrary to the idea that you are getting bad mpg's. but! i would like to think a bigger injector and larger delivery valves might help? and i might be wayyy off base in saying this, so no one make too much fun of me. im thinking from an effiency standpoint is all in realtion from air to fuel.

or even you may consider running a splitter (overdrive unit) off the back of your 5 speed, my buddy had one on a nv5600 swapping from 4:10 to 3:55
 
geedub6893 said:
I have a 98 12 valve i bought to play around with last year. I had a company car then so i didnt care about fuel economy. Now i have changed jobs and have to drive this truck everyday. After driving it for two weeks im getting 12.5 mpgs. I know a good bit about these motors but i need help to get this thing on the right track.

1998 12 valve xcab swb 5 speed on 35's
stock injectors and delivery valves
compound turbos he351/hx55
3 piece manifold
100 plate slid forward and cranked
4k springs
stock timing (i know i need some timing)
new fuel filter
4:10 gears
Click to expand...

definitely get some bigger injectors and a set of ddp 042 delivery valves. and bump the timing to around 18*
 
You're going to want to:
get some larger injectors
advance the timing
ditch the 35s for a stock wheel and something like a 265/75r16. That alone will be good for ~1 mpg even with the 4.10's

The splitter will probably not pay for itself unless you are driving a ton. The stock dv's should be fine depending on what size injector you go with.
 
Stock size tires such as 265 or 285's will help some. Switching to
3:55 gears will also help even more.

And add some timing to it. That wil help you for now.
 
1) Bigger injectors
2) Advance the timing
3) 3.55 gears
4) Smaller tires

A couple of those are big changes, but if you are really after fuel mileage, it should work. I see no reason you couldn't 17-20mpg
 
Research Smokem's AFC mod's....TUNE you AFC to work efficiently.
Advance the timing 16-18*
A conservative set of injector's 5x12 or 5x14
A smaller set of tires 285's would be ideal because your just gonna spin more RPM's on the highway with 265's.
a gear swap to 3.55's would be your most effective solution if you have the abililty to get it done cheaply.
DO NOT BUY DV'S it will be a waste of money and NOT help your mpg's
 
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