C-15

I have an '02 475 C-15, straight ten, 3.50 rears, 22.5 rubber. Seems to do best at 1400ish.

 

I have an 07' 379, C15 550 - 1850, 3:36, 18spd, LP 24.5's, and it doesn't matter where I run it at fuel mileage still sucks. I try and run it around 1350.

 

mine cruises at 68mph around 1350 rpms and i average around 5.8 tp 6.2 mpg 550hp 18spd 24.5lp 336 ratio flat top pete long wb pulling flat cats like between 1200 to 1400 rpm for best fuel economy from what i've exsperienced.

 

What year?

 

I've been playing with this for a month or so. I Have a 06 387 with a c15 acert, twin turbo. Now # 70 mph 14.5 - 15 rpm i'm getting 4.5 to 5mpg. # 64 - 65 mph 13.5 rpm i'm getting about 5 to 5.5 mpg. and at 62 mph i'm getting 6 to 6.3 mpg. Question is are you willing to slow down and get better fuel economy and get ther later or get there fast and get somewhat crappy fuel economy. For Example, I had a load pu in Mich. and del. in Antioch, Ca. 3.5 days delivery time. I had to get r done, 700 plus miles/day and 1500 dollars later im there (2400 loaded miles) Got another load pu in Elk Grove, Ca. 5 days delivery time. Took my time with it, average appox 65mph for 2300 loaded miles. spent about 1100 dollars in fuel. Almost the same amount of miles but 400 dollars more in my pocket at the end of trip #2. So mutiply that 400 times the number of trips you would do for the year. So, slow down and keep more of your money in your pocket.

 

it's an 06

 

This is a pre ACERT motor and a person really can't compare how to efficently run this motor compared to the thread starters ACERT.

The ACERT motors need to be ran in the low RPMs. Many guys don't like this idea, but its a fact. Basically with all the extra weight in the bottom end of a ACERT you just waste fuel if you spin it over 1350-1400 RPM anytime. These motors are built to run low...plain and simple. With the specs you got you should be in the neighborhood 1250 - 1300 for optimal MPGs. Try to shift at no higher than 1400 and keep the boost under 40 PSI if at all possible. Don't be afraid to pull the motor down to 1100 RPM and maybe even lower if it wants to. Also when climbing a hill try not to get into the throttle at the bottom of the hill like we all had/have to with the other engines. Basically keep a steady foot and let the TQ carry the truck up the hill. If you are looking for even more MPG, HP, and/or TQ you need to check out many of the ACERT and CAT threads in the "Garage" here on this forum. Many of us ACERT owners are getting 6+ MPG running these motors (a few guys are in the 7's) and the motors are very simple once a person gets past the compound turbo setup.

 

Very true, mine was the last of the non bridge C-15s. I've never driven a newer Acert so I'll assume your info is correct. Thanks for the info :smt023