Big Ol' Engine Swap
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
Believe me I would love to see an affordable kit out there to make these ol boys run 30 mpgs. That will make someone very wealthy.
John
Logistics Pro
Joined: Feb 2011
Posts: 3,522
Likes: 11
From: Townsend, MT
As far as 7.3 vs the almighty 12valve, IMO the 7.3 IDI is the superior engine. Wider rpm range, higher power stock before you even get to the turbo upgrade, smoother and quieter operation, and it still takes one wire to make it run. It starts much easier with glow plugs, of course, but that's just another pair of wires to the battery. The 12valve has a heater grid in the intake.
Which gets better mileage? Cummins
Which is known for cavitation problems? IDI
Which is known for needing a new injection system every 100,000 miles? IDI
Which one does the manufacturer say can start at 15*F with no aid of any sort? Cummins
Now say that you have an extra $1000 to throw at performance. Which one is going to be able to get to 400 HP? Cummins
You can have your "flat torque curve". I'll just stick with a torque curve that is much higher - even if it isn't flat.
Logistics Pro
Joined: Feb 2011
Posts: 3,522
Likes: 11
From: Townsend, MT
Yup. Feels good to beat a 5.9 CR.
Posting Guru
Joined: Jul 2011
Posts: 1,650
Likes: 16
From: DFW Texas
I'm really curious what my combo will feel like.
Logistics Pro
Joined: Nov 2003
Posts: 4,371
Likes: 7
From: PA
The power to weight ratio with a built 4BT will surely astonish you. Not to mention all the shaved weight then going with a 6BT will make it handle even better. I'm curious how your truck will feel in the corners with the MII setup.
Posting Guru
Joined: Jul 2011
Posts: 1,650
Likes: 16
From: DFW Texas
While I have really stiff springs in the front (700lb) I have not added a sway bar yet. I'm sure it will badly need one but that is the very last thing on my list. I want to get it running and driving first.
Logistics Pro
Joined: Feb 2011
Posts: 3,522
Likes: 11
From: Townsend, MT
I fueled up last night and used 29.5 gallons in 659 miles.
Calcs out to about 22.3 MPG mixed highway driving (80 MPH) and running around the big city of Helena.
Calcs out to about 22.3 MPG mixed highway driving (80 MPH) and running around the big city of Helena.
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Posting Guru
Joined: Jul 2011
Posts: 1,650
Likes: 16
From: DFW Texas
Please remind us of your combo. Tranny, rear gear, tire size, any mods to the engine? Know the weight of your truck?
Logistics Pro
Joined: Feb 2011
Posts: 3,522
Likes: 11
From: Townsend, MT
I think the truck weighs about 7,800 pounds - that might be my other truck though - I'll weigh it tonight when I go through town.
Logistics Pro
Joined: Feb 2011
Posts: 3,522
Likes: 11
From: Townsend, MT
7,500 pounds full of fuel.
Posting Guru
Joined: Jul 2011
Posts: 1,650
Likes: 16
From: DFW Texas
Right on! Impressive mileage from such a big rig. Bump that mph down to 70 and I bet you would be knocking on 25 mpg. My truck will only weigh 4000 lbs with a 31.5 inch tall tire and a 3.25 gear and a lower overall vehicle profile. Looks like It will easily get 30 mpg to me. Lol
Postmaster
Joined: Nov 2012
Posts: 2,806
Likes: 8
From: Langley, BC
The 6.7L is a fantastic engine and claimed to be the best Powerstroke since the 7.3L and you can make some wicked power out of it, but it's new and therefore expensive. It all depends on where you want to go with it.
If you're on more of a budget, Cummins.
If you're on more of a budget, Cummins.