[cgeise]

Originally Posted by Stan Weiss

Jason,
I have talked with Mike Laws (BLP) about their Dyno and software a number of times over many years and feel this is the best way to dyno test. It is an inertia based dyno that uses a time based / variable RPM acceleration rate. See attached dyno sheet from one of their Carb Shoot-outs.

Think about it. In any trans gear there is a variable rpm acceleration rate. The max acceleration will be at Max torque and you can see that by looking at the rpm/s column.

Stan

Based on your last statement explain why a car with a torque convertor set at your max torque -- say 5800 is slower than the same car with a convertor that stalls 6900 and the engine has usable HP at that range and above -- the one set at max torque DOES NOT accelerate quicker. ask me how I know!

[Stan Weiss]

Originally Posted by cgeise

Based on your last statement explain why a car with a torque convertor set at your max torque -- say 5800 is slower than the same car with a convertor that stalls 6900 and the engine has usable HP at that range and above -- the one set at max torque DOES NOT accelerate quicker. ask me how I know!

Curt,
I always like to look a manual trans / clutch cars because the torque convertor adds an extra degree of complexity. While the max acceleration in any gear is at max torque that is only really important for a drag racer in first gear (road racing is a different story). Once you get passed max acceleration in first gear the question is how many RPM to turn first gear until shifting. The starting point (track test is the final answer) is when wheel torque / HP in that gear drops below the wheel torque / HP at the RPM you drop to in the next gear. These are fixed percentages / RPM with a manual trans / clutch. With an automatic the torque convertor /stall speed acts as a modifier to that RPM. Which is why the added complexity from a torque convertor.

Stan

[KO]

Originally Posted by cgeise

Based on your last statement explain why a car with a torque convertor set at your max torque -- say 5800 is slower than the same car with a convertor that stalls 6900 and the engine has usable HP at that range and above -- the one set at max torque DOES NOT accelerate quicker. ask me how I know!

Torque converters do not have a fixed stall. When the input shaft is fixed and the pump is spinning and when both are spinning change the actual point of "lock up". Ideally you would want a converter to stall at the max RPM on the starting line but that would be called a clutch. The converter "fall back" on gear changes is important also as a slight RPM flare actually increases acceleration.