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Engine/Transmission/Gear/Tire Calculation tool

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  • Engine/Transmission/Gear/Tire Calculation tool

    some years ago I put together this page to help me dream about different engine/transmission/gear/tire/t-case combinations

    It lets you select sets of engine, and any number of transmissions/t-cases, gear ratio, tire size and compare what the resulting performance will be. I don't claim that it's perfect (I don't really know how to account for the slip and loss in efficiency of a torque converter on an automatic for example), but it gives you something to talk about, and can help you see if a engine has too narrow of a power band for the transmission (you end up with some speeds where you have little/no power)

    it defaults to comparing two setups, and updates when you hit 'calculate'

    When I can get a readable graph of the R2.8 torque curve, I'll update the entry for that motor (currently the last on the list).

    this does NOT tell you what will bolt up to what, it assumes that you will make that happen somehow yourself :-)

  • #2
    That is where I know you from. I have used your page before when working with the sd33 and sd33t.

    Welcome! I couldn’t figure out where I knew your user name from.


    • #3
      I've updated it to reflect the graph that was provided, can you check that this looks right? green is rev up to 3600, red is projecting the line out to the rev limit of 4200


      • #4
        I love your site. Thanks for the work as well. Those graphs are great, especially since I know I can't just go out and test drive these engines. If you take requests it would be really cool to see some more real world base lines for other builds like some of the production gas engines, which are almost exclusively all we can get our hands on in the US. I sort of approached my build wants as, what if I could have the economy of a small 4 cylinder (not exactly a good example since these typically don't have the torque to maintain any highway speeds efficiently on boxy or heavy vehicles), but with similar torque at highway speed/RPMs in OD to my ZJ 5.2L. Trying to find any reliable real world examples are almost useless and everyone is biased to some degree. Typically anyone asked for a response to motor swaps just points out the diesel engine in question just doesn't have enough HP vs that LS engine or something, which lets me know not to take advise from that person unless I'm looking for a race car.

        Sorry to rant, but I love looking at various combinations and occasionally some odd swaps come up for sale as well in distant lands. Also I still want to do a couple more builds, but they'll have to be long term junkyard type builds as the R2.8 is to be my DD for the next few decades.


        • #5
          I am willing to add any engine, transmission (including over/under drive units, dual speed axles, t-cases, etc) to this

          I don't really like my hacks for handling automatic transmissions, and if anyone can help me with real figures for the power lost to the driveline, I'd live to make that more accurate.

          for transmissions, I just need a name and list of gear ratios
          for engines, I need either a torque graph, or a table of rpm/torque (this can be calculated from HP data, but internally it uses torque numbers)

          I created the graphs based on exactly the type of 'what would be reasonable' types of questions you are talking about.