Cummins Conversion Update
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Lead Driver
Joined: Oct 2004
Posts: 7,413
Likes: 1
From: Columbia, MO
Not yet. Fuel consumption is going to be skewed for the first several thousand miles for a coupe reasons. 1) It's too much fun to drive this thing a little more...uhh, aggressive than normal. I have found comfortable cruising speed on the highway is around 80 MPH. 2) Until the engine is fully broken in, fuel mileage will continue to increase.
Also, as I start to tune and tweak things like rail pressure and timing, it can help increase MPG as well. So I'll play with it some as time goes on. I expect to see upper teens and possibly lower twenties though.
One thing I will say, with the B codes in the 7.3, about the best highway MPG I ever achieved, cruising at around 75 MPH was around 12.5. I took a highway trip earlier this week, 255 miles, covering ground at anywhere from 60-80 MPH, with lots of heavy throttle acceleration runs while already rolling at speed (to help break it in), I saw an easy 13 MPG. So without it fully broken in, running hard, and not even messed with the tuning, I'm already seeing better MPG than the 7.3 gave me.
Also, as I start to tune and tweak things like rail pressure and timing, it can help increase MPG as well. So I'll play with it some as time goes on. I expect to see upper teens and possibly lower twenties though.
One thing I will say, with the B codes in the 7.3, about the best highway MPG I ever achieved, cruising at around 75 MPH was around 12.5. I took a highway trip earlier this week, 255 miles, covering ground at anywhere from 60-80 MPH, with lots of heavy throttle acceleration runs while already rolling at speed (to help break it in), I saw an easy 13 MPG. So without it fully broken in, running hard, and not even messed with the tuning, I'm already seeing better MPG than the 7.3 gave me.
Post Fiend
Joined: Jul 2005
Posts: 14,582
Likes: 12
From: 21791
I have a super cab short bed 99 F350 without a motor, but it has the Zf6, double disk clutch ,ready to go for someone looking to destroke it! LMK if youre interested.
Post Fiend
Joined: Feb 2006
Posts: 11,892
Likes: 2
From: Middle Tennessee
Not trying to start any chit Jeremy, but 12.5 would not work for me just cruising down the interstate.
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Lead Driver
Joined: Oct 2004
Posts: 7,413
Likes: 1
From: Columbia, MO
Me either, Mike. I was pretty disappointed with the mileage, but my truck never did seem to get as good of mileage as what others did. I may also be completely wrong on that number...it's been a while since I remember figuring that. Perhaps it could have been up around 15 MPG, but still lower than what I wanted.
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Lead Driver
Joined: Oct 2004
Posts: 7,413
Likes: 1
From: Columbia, MO
Now that I think about it, I think you're right Mike. I know I had the 12.5 stuck in my head though. That had to be my city MPG. I know highway was never in the upper teens though.
Post Fiend
Joined: Feb 2006
Posts: 11,892
Likes: 2
From: Middle Tennessee
OK. But I seem to be getting in the 15-17 MPG rating right now and that is with little highway driving. When the winter grade stuff hits it falls to the 14s due to warmup and idling. Yeah, still smoking at first startup. I have to find the source of that. I hope it is not overfueling at startup.
Posting Guru
Joined: Jul 2006
Posts: 1,515
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From: Jonestown PA
Its good to hear you are liking your new set up. Almost makes me want a Dodge , power, fuel milage, sound, but I don't like the bodys to much. And to do what you have done sounds like it cost a lot. Plus I wouldn't have no idea how to do it. I do agree with you on the break in your doing. Job well done!!
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Elder User
Joined: Oct 2005
Posts: 578
Likes: 0
From: Cincy OH
One or more dumping excessive fuel could contribute to poor mileage.....
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Lead Driver
Joined: Oct 2004
Posts: 7,413
Likes: 1
From: Columbia, MO
OK. But I seem to be getting in the 15-17 MPG rating right now and that is with little highway driving. When the winter grade stuff hits it falls to the 14s due to warmup and idling. Yeah, still smoking at first startup. I have to find the source of that. I hope it is not overfueling at startup.
Jason, I agree with you. However, my truck, even with stock injectors, never did seem to get the mileage I though it should. I'd still get those sticks tested.
Elder User
Joined: Aug 2004
Posts: 544
Likes: 0
From: SLC, UT
This was cool to watch progress along the way. With so many posts it is a little overwhelming to pull all your technical info of the swap. Do you have any plan to condense to just technical data for future users to research? Maybe with the help of a moderator?
Cool to see all the progress, just a little hard for someone to learn and research with so many posts (which I have now contributed to).
Cool to see all the progress, just a little hard for someone to learn and research with so many posts (which I have now contributed to).
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Lead Driver
Joined: Oct 2004
Posts: 7,413
Likes: 1
From: Columbia, MO
Derek, yes, I have plans and am working on condensing it to just technical info to help others who are considering a swap. IB_Adrian has contacted me about doing this. It's just a matter of me having the time available to get all the text pulled out of the posts, and constructing it into something more like a tech article.
Senior User
Joined: Feb 2007
Posts: 189
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From: Omaha, NE
I with Jeremy on the fuel milage. I get crappy milage with stock suspension and 33's. I put the stock tires/wheels back on and there was maybe a 10th mile/per gallon difference. I was getting better mpg's(15-16 in town) when I could use LSD. Since I started using ULSD I only get 12-13 in town. I have done EBPV tube and sensor, CPS, synthetics and curbed my right foot to try to get better MPG's with nothing substantialy improving it. I think that some of our 7.3's get better worse MPG's than others, kind of luck of the draw.
On topic now, Jeremy this is a great thread to follow! It has shown that all the hard work is worth it. If you planning on passing through Omaha with your truck, i really like to see it, pm me if that is the case. My friend has an 01' dodge with the 24 valve. That 24 valve is the only thing from it I would want in my truck. Have fun breakin' your new powerplant in!
On topic now, Jeremy this is a great thread to follow! It has shown that all the hard work is worth it. If you planning on passing through Omaha with your truck, i really like to see it, pm me if that is the case. My friend has an 01' dodge with the 24 valve. That 24 valve is the only thing from it I would want in my truck. Have fun breakin' your new powerplant in!
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Lead Driver
Joined: Oct 2004
Posts: 7,413
Likes: 1
From: Columbia, MO
Ray, I don't think it would make any difference to me if it were a newer truck. I actually would prefer to have the 4R100 over anything. If I were to the conversion on a newer truck, a 4R100 would be going in for a couple reasons. One, you as the end user, have a lot more control over the transmission with programming -- things like shift points, TCC lock, etc. Two, the 4R100 is built and Brian has several holding up to 800+ HP right now, if not more. That was current back in July when I last spoke to him.
Now, that's just me and my personal preferences. Others may prefer to have the 5R in there. I don't know if there's a stand alone controller for it, but I assume there is.
Now, that's just me and my personal preferences. Others may prefer to have the 5R in there. I don't know if there's a stand alone controller for it, but I assume there is.