Help; narrowing down on upgrades.

[AH64ID]

For towing go with the 12. The 14 is slower to spool, but will do better above 2500 rpms. 

[dieselautopower]

G is for gated

the GXE and SXE are updated with many features for more airflow and longevity.

 

if your goal for peak power is 450HP then the 12CM would be of benefit,  there would be a limitation for drive pressure, so if you want more peak power like 500HP then go with the 14CM, or 62/68/12 as the 68/12 and the 65/14 turbine configuration are similar in spool and flow.

 

basically there is a 50rpm difference in spool for 12cm vs 14cm. driving egt will generally be lower with a 12cm, but peak EGT lower with a 12cm.

 

If you have 3.55 gears, 35" tires then the 12cm will be better as that = pretty tall gearing and will be hard to spool

 

If you live at 5000ft then you probably want to go up a size on the compressor as there is not as much air to compress.

[DownHomeDiesel]

I called DAP yesterday and put in an order to get the ball rolling.  Thanks for the help!

[Mopar1973Man]

On 8/26/2021 at 7:00 AM, dieselautopower said:

If you have 3.55 gears, 35" tires then the 12cm will be better as that = pretty tall gearing and will be hard to spool

 

Yup. Optimal final ratio is between 3.55 and 3.73. With 35 inch tires on 3.55 is not good. Your final ratio is 3.21 with 35 inch tires. You most likely eat transmissions and have high EGT's. 

 

Just a point to make I change from 265/75 R16 to 245/ 75 R16 (30.5 Inch tire) which now bring my final ratio to 3.69:1 on the Beast. This magic of final ratio helped me get my high point 28.04 MPG. Cruising RPM is perfect 2k at 66 MPH, for 550*F EGT's. Acceleration is fast that 3.55 final gearing and pull trailers for about 200*F less EGT's. 

 

Big tires look cool but gotta be done right to make it work for you. You would need change ring and pinion to 4.10 for 35 inch tires. This would make your final ratio 3.71 to the ground. To give you a feel of 3.73 to the ground Thor is 265/70 R17 all the way around (stock tires) with 3.73 axles it cruise at 65 at 2,100 RPM. Just ditching the 275/75 R18 tires and wheels gained me a full 4 MPG getting back to the 3.73 ratio. 

 

Improper final ratio makes huge problems period... Typically result in higher EGT's, high transmission temps, and higher coolant temps. 

Edited August 28, 2021 by Mopar1973Man