Most people that I have spoken with about this (includes a few well positioned engine builders) have said that the drivetrain consumes on average about 13-15% of the horsepower that you can make on a dyno. I would imagine that more finessed vehicles racing at the top levels of motor racing are at the lower side of this number or even better.
So using the 15% number in my combination and one of the online calculators, I am much closer to the mark than I thought I was. I am still off a bit by about .012 on ET and roughly 5 on MPH. I made some new changes to the car's chassis to correct the hard move to the right on launch and if those prove out, then it's a good chance I will pick up a few numbers on the ET. We also have a transbrake in the car but I have not tested with it yet - that too may help pick things up a bit. My last footbrake car that I switched over to a transbrake picked up .020 so it will be interesting to see if this car follows that pattern.
So using the 15% number in my combination and one of the online calculators, I am much closer to the mark than I thought I was. I am still off a bit by about .012 on ET and roughly 5 on MPH. I made some new changes to the car's chassis to correct the hard move to the right on launch and if those prove out, then it's a good chance I will pick up a few numbers on the ET. We also have a transbrake in the car but I have not tested with it yet - that too may help pick things up a bit. My last footbrake car that I switched over to a transbrake picked up .020 so it will be interesting to see if this car follows that pattern.