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MageRoyal · 12-02-2019, **(Subject: X15 questions )**

Mr. Hag, Mommaburt, & Unilevers.

12-02-2019, **(Subject: X15 questions )**

(12-02-2019 )03maxpower Wrote: Only problem I am having is fuel mileage isn’t good but we are still working with the tuning.

so just to clarify for everyone as this is misleading, yes hes one of our customers. there is a reason for the fuel mileage.

This truck in question is tuned very high power ~340mg/stroke. This truck is in the 600hp to the ground (700+ crank HP) range. Obviously I/we dont want it this high but its not our truck, and the owners knows and wants it there.

It is also not driven 55MPH for any kind of mileage, and it shows. Its driven on cruise at 70-75mph which is fine again not our decision. Each to their own.

All the facts must be said if your going to post reviews on fuel mileage.

03maxpower · 12-03-2019, **(Subject: X15 questions )**

(12-02-2019 )Unilevers Wrote:
(12-02-2019 )03maxpower Wrote: Only problem I am having is fuel mileage isn’t good but we are still working with the tuning.

so just to clarify for everyone as this is misleading, yes hes one of our customers. there is a reason for the fuel mileage.

This truck in question is tuned very high power ~340mg/stroke. This truck is in the 600hp to the ground (700+ crank HP) range. Obviously I/we dont want it this high but its not our truck, and the owners knows and wants it there.

It is also not driven 55MPH for any kind of mileage, and it shows. Its driven on cruise at 70-75mph which is fine again not our decision. Each to their own.

All the facts must be said if your going to post reviews on fuel mileage.

Yes true and the gears are 3:36’s also 80,000 most of the time in the northeast.
Very happy with what I’m seeing wasn’t trying to be negative if that’s the way it came across.

Magard · 12-03-2019, **(Subject: X15 questions )**

So what is meant by fuel mileage isn’t good. If 80k on cruise at 70 plus 5 to 5.5 would be expected fueling like that maybe even 4’s if no regard for wind.

03maxpower · 12-03-2019, **(Subject: X15 questions )**

Yes I’m at 4.5 most of the time. Honestly I was hoping 5 - 5.5 but it just might not be obtainable with my setup and what I do. Definitely wasn’t blaming tuning, I was just saying we are still working on it. I was definitely vague on the first post just not thinking about it. Yes there are a lot of negatives to what I’m doing and trying to obtain.

rolling18 · 11-21-2020, **(Subject: X15 questions )**

(11-30-2019 )tree98 Wrote:
(11-29-2019 )JMBT Wrote: I have a 2250 now, and proper driving methods solve the low RPM torque issues. I am just curious if there are any other inherent problems with the X15 and if anyone is running one demandated.

I don't think the X15 is that much of a design change from the isx 2350, so there probably isnt going to be a bunch of unforseen problems.

what number would the 2021 X-15 Productivity @565 / 1850 TQ be??
since most ppl here reference their motors by a certain C_____ number?

Ben50291 · 11-21-2020, **(Subject: X15 questions )**

I have a 2021 389 x15 565hp stock. I run tanker in Midwest. 80,000 loaded half the time and 27000 empty. It's mostly flat ground but we get wind. I'm at 60,000 miles and I'm conservative on the fuel still practice hyper miling. I usually am around 6.8 with calculator. I've definitely been in the 5s and in July my month average was 7.2. You really have to be patient and try hard to the mileage but it can happen.

rsmithtrk · 12-04-2020, **(Subject: X15 questions )**

(12-02-2019 )Rawze Wrote:
(12-02-2019 )03maxpower Wrote: Only problem I am having is fuel mileage isn’t good but we are still working with the tuning.

Have whoever is going to do the programming, e-mail me a copy of the program that is in your truck. I will take a look at it to ensure everything is set the way it should be for that style engine.

Can you walk me through how to send a file for you to look at, I have insite.

AKDoug · 12-05-2020, **(Subject: X15 questions )**

I guess I'll follow this one closely and contribute if I can. I have a new T880 with a 500hp productivity X15 in it. I'm leaving it stock for now. Put the first thousand miles on it this week. Most days are 200 miles of highway with 40 miles of city driving, 5 to 7 stops at warehouses, towing a 48' dry van, average 70K gross.

1000 miles is no measure of fuel mileage, but we're at 5.1mpg hand calc'd. That's a bit better than my '06 International 9400 with 565hp CM870 and '01 379 Pete with 600hp CM570. All with 18 speed manuals.