Plus, if it did and you noticed, the loss must have been at least several horsepower ..... only place this could go would be (friction) heat loss which would toast your transmission fluid & plates (if clutch type) pretty quickly I would have thought
I agree with you guys but wanted some more opinions. I am at a loss here. I did a leak down on the engine and compression test and everything is fine. I think I will try a different dyno but my dyno guy has always been very reliable in the past. I have a friend who has a dynapack dyno so that is what I will try. My only other thought is I replaced the cat and perhaps it is bad somehow but I would think I would have some MIL's or something.
An LSD does add more driveline losses, possibly up to ~5hp worth.
The LSD weighs more than the open diff, and adds rotational inertia, as well as some frictional losses.
Personally I think it can add more than it takes away. I put an LSD in my Acura RSX Type-S and love it. I would put one in the Esprit in a second if they werent $2400...
A poorly installed LSD is also a possibility. There is a critical matter of shimming the differential preload to a certain amount of torque, usually measured with a spring scale. Too little differential preload, and you have slop and possible wear problems. Too much preload and you have too much friction and accelerated wear.