F150online Forums - Gearing question

F150online Forums (https://www.f150online.com/forums/)

- F-250 / Super Duty / Diesel (https://www.f150online.com/forums/f-250-super-duty-diesel-38/)

- - Gearing question (https://www.f150online.com/forums/f-250-super-duty-diesel/501648-gearing-question.html)

bryan8252

12-10-2014 11:21 AM

Gearing question

Currently in an F150 but looking to move up to a 250. As I did the build and price on Ford's website, I couldn't get the 4.3 gears with the Diesel engine... Only the gas engine. Can anyone explain why?

JackandJanet

12-10-2014 11:35 AM

Take a look at the torque vs RPM curves of a gas engine and a diesel engine and you'll have your answer.

- Jack

bryan8252

12-10-2014 12:54 PM

Quote:

Originally Posted by JackandJanet (Post 5122264)

Take a look at the torque vs RPM curves of a gas engine and a diesel engine and you'll have your answer.

- Jack

Ok, did that. My take on that is the diesel doesn't need the higher gears since the torque is higher to start and pretty much stays constant while the gas engine starts lower on the torque so it would need higher gearing. Yes?

glc	12-10-2014 12:59 PM

Also, the redline on the diesel is a lot lower than the gas engine.

JackandJanet

12-10-2014 02:30 PM

Correct, and to add to glc's post, the 4.3 gears would have your RPMs too high at all times. It would seriously limit your top speed with a diesel.

- Jack

KMAC0694

12-10-2014 03:19 PM

Quote:

Originally Posted by bryan8252 (Post 5122282)

Quote:

Originally Posted by glc (Post 5122286)

Also, the redline on the diesel is a lot lower than the gas engine.

X2 on both of these being the reason. If you get a 6.7, even 3.08 gears would be sufficient haha. So 3.73s, or 4.10s, or whatever they come with will be more than enough.

All times are GMT -4. The time now is 07:55 AM.