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MPG Question.

6K views 13 replies 4 participants last post by  04_6.0 
#1 ·
Contemplating a 12 Valve swap. What kind of highway MPG's (70mph) can I expect from a 12 Valve in a 2000 F250 4x4 Crew Cab 8' Bed with 3.55 gears and an NV4500? This would be my ideal application, using the stock tire size and stock engine besides maybe a straight pipe turbo back 4" exhaust and BHAF. Any input would be greatly appreciated.
 
#3 ·
Destroked thinks mid twenties with this setup. Just wanted to see what peoples real world experiences were. I drive mostly highway and like I said I'd like to keep it mostly stock besides intake and exhaust, but we all know how long that lasts :)

Anyone else?

Joe
 
#4 ·
a 4 inch exhaust will def help keeping smaller tires will too(stock size) but i still doubt that you would get mid 20s unless your truck was a single cab 2wd.not trying to be a jerk but i plan to do this with my v10 cc/sb fx-4 and it wieghts about 8k.not to mention your added more wieght with the cummins,ive read they are a good 300 pounds more than a ps 7.3. add on the bigger gas tank and the extra 2 feet of bed space that you have it will add up.there is a 4 cylinder cummins that will net you that though.same thing as the 6bt just 2 less cylinders
 
#5 ·
Thanks Im well aware of the 4bt I just really want the 6bt. Call me crazy but ive been able to find more 6bt's and at a cheaper price than 4bt's. I know the whole point of this thread was MPG's but I still want some power too. Everyone keeps saying a 4bt will be enough power but im not convinced. Yes I know they haul around delivery vans and such but have you ever driven one of those things? If I was doing a Ranger or half ton then yes I would entertain a 4bt, but for a 3/4 ton truck, I really feel the dirty dozen is the way to go. Maybe I'm wrong? Plus I think it will be easier to get parts later on if im using a dodge 12 valve, dodge clutch, dodge trans, etc. Even though I know alot of parts are interchangable. Im assuming to make the same power as a 6bt with a 4bt i'd have to increase fueling, which would decrease economy. A modded 4bt to achieve the same power as a stock 6bt would probably get around the same economy right?
 
#6 ·
i agree with the 6bt as a better option but i have seen a guy running a 4bt in his superduty for mpg and he still tows with it but towing is the only time he reallyfeels a minor lack in power.he says hes getting anywhere from 25 and up which is your goal mpg wise so thats the only reason i suggested it.i myself decided to go with th 6bt though because the power/mpg plus i plan to mod mine to about 500 hp or so
 
#7 ·
Im sure a 4bt would get the mileage I want and work just fine. I rarely tow anything. I just know i'll kick myself for not doing a 6bt if I ever want to add a bunch of power down the road like your saying. My only solution... build two trucks, one for MPG and one for power! :rock Haha I wish I had the cash for that. So you think 20 mpg would be feasable with the truck I mentioned above and a stock 6bt? I'd be happy with that.
 
#8 ·
i think its easily attainable with that setup considering you keep your foot out of it.most guys ive talked to say they average about 18-20 regularly just cruising around.it will be hard though cause the low end grunt the cummins makes.are you doing the swap yourself or having it installed at a shop?
 
#9 ·
I'll be doing it all myself with the help of fellow co-workers. Im a tech at a Mercedes-Benz dealer so I'll have all the equipment and tools I'll just be working on it after hours and on saturdays etc.
 
#10 ·
Not saying that staying stock isnt a good idea, but with the right P=pump mods, IE DVs and fuel plate coupled with the right size injectors, (say 5x12s) and a nice turbo with everything tuned correctly and timing set up right the neighborhood of seening 18- to low 20s mpg would be pretty easy.
 
#13 ·
Post up what you want to do with the truck in the 12valve dodge section and and the 12V guys can help you out. I still this mild build would net you close to a 20 MPG rig, but I am not sure what kind of numbers maybe close to 300HP
 
#14 ·
I am consistently getting 19-20 at 75mph. 4.10 with 35x12.50 tires. I have a 12v with he351 stock injectors, dv's, 3.5" exhaust and a finely tuned afc. Before I got the afc spot on I was getting around 17.
 
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