engine rpm range

[TTennyson]

im doing a engine conversion into a 4x4 ramcharger and planning to run 35" tires. i need to no peak rpm for the cummins to figure the gear ratio i need to run for streetability. im running the 727 so i dont have a overdrive.

 

[BushWakr - RIP]

Your peak/max RPM should not exceed 3000 RPM.

Many of us have run higher but it is risky when you get much beyond 3200'ish.



pastor bob... .

 

[steveinaz]

3. 07 gears w/ 35" tires will be like overdrive but will probably kill a transmission

 

[TTennyson]

well with 35" tires and 4. 11 gears it equtes to 2560 rpm at 65. guess ill go with 4. 10 so it can still cruise at freeway speed and have good power( although not really a problem with any gears).

 

[Philip]

At 2560 RPM you are almost against the governers. Have you thought of how much sound deadening material you are going to need in a Ramcharger. Every R/C I have been in made good echo chambers.



If you are going to be mainly on the road. You don't need that much rear gear. With 3:07's and 31" tires you would be turning 2k RPM at 60 MPH. With the taller tires it would drop you to around 1700 or so RPM. This is a much better gear for road usage. The 3:54's would bring you up to around 2200 RPM. give or take a little.



What is your planed usage? Running around empty or towing?