Or my speedo is slightly off still. I've had a few different converters in there,and I know my rpms at 60mph were different with each one.
I also run a 3.73 with a 28" tire. My Autometer tachometer also says about 2800 RPM with the Gear Vendors Overdrive switched off. 150 RPM is normal converter slip. 336/28 X 3.73 X 60 = 2685 RPM
Every converter will be slightly different with some being more and or less efficient at different RPM ranges. Obviously when you get below the rate stall the RPM will get tremendously more inefficient and slip. Jim
Not with the current state of torque converter technology. Today, you can have your cake and eat it too, but it costs more. Today, you can have a converter built that will stall where you need it to when it is fed a lot of torque, but that same converter will be plenty efficient when it sees a fraction of that torque. The 10" converter in my car will stall considerably north of 3000 RPM at large throttle openings, but with my GV Overdrive engaged, it cruises with not a lot of slip. With the GV engaged (.78), the 3.73's become 2.91. With 28" tires, the RPM at 60 MPH is predicted to be 336/28 X 3.73 X 60 = 2095 RPM. My observed RPM at 60 is a little over 2200 RPM. At that speed, if I give the gas a little toe tweak, I can feel the engine bump up against the converter, it doesn't flare up at all. If I give it a little more than that, it will flare up about 300-400 RPM, but it produced about 15-16 MPG on my trip to and from Cecil County this past September, so it is plenty efficient at well below it's rated stall.
