I need some help in planning/ designing my engine rebuild. I intend to use my truck for occasional, recreational use and to pull my 17' camper. I plan to convert it to run on propane. I currently have a 351m and will rebuild to be a 400. I would like to stick with my C6 tranny, 2.46/1.46/1 gears, and run 31" tire. Rear end is a 3.73. I do not know what I need to be planning for as far as torque/ power curves. I think I want good low end torque up through about 4000 RPM, but that may be too high. What shift point do I need to plan for? How do I plan for torque across the RPM range. Now, with 31" tires I could would run 2800 RPM at 70MPH. Is this good? what does it do to my mileage? What mileage should I plan for? I know I can increase milage by lowering RPM at cruising speed, but what do I give up? if I increase torque at low RMP can I re-gear to get better mileage at hight RPM?

 

Check the alternative fuel forum for propane info.

 

Try this link. I think it will provide what you are looking for.

http://www.gearvendors.com/

With this you can build the motor for maximum torque at low RPM, then use your gears to keep the RPM in your range.

It is difficult to get good low RPM torque and keep pulling through 4000 RPM. A custom Hydraulic Roller cam can help, as well as great breathing heads. The gear vendors OD unit can take the guess work out of the problem.

 

Here is a link to the 434 stroker built by Tim Meyer. It has a flat torque curve out to 5000 RPM. This is an expensive motor, but a lower budget motor could be built with a similar torque curve. You could build a 408 cu inch with CHI heads and the same cam. It would have a little less torque, but will be flat out to 5000 RPM. The total cost should be less than a 408 build with stock heads and an Overdrive unit.

http://www.tmeyerinc.com/400stroker.html