The fixed weight dyno is by far the most accurate because there are no variables. if I try and overlay three runs from my Superflow engine dyno there will be variations from 10-15 H.P. because of the load control valve trying to maintain 300 rpm per second.with the Dyno Jet all the runs will be within 1-2 H.p. unless something changes on the engine or drive train. the power is calculated by Newtons 2nd law mass X acceleration so if you accelerate that 5000 lbs or so it will show you exactly what you have at the wheels.as I said before power glides average 25/28% with a 9.0 ford,same engine with Lenco in direct is 15% same with a super T10
what gets you down the drag strip is the net rear wheel H.P. not what the engine dyno says.
drag cars with N20 converters will show more rear wheel H.P than engines with very loose converters because there is less H.P. wasted generating heat in the converter. two cars one lenco and one powerglide that weigh the same,hook the same and are aerodynamically the same and both put out 700 H.P. at the wheels would run the same number even though they had several hundred H.P. difference on the same engine dyno.Bill