determine flywheel hp

I read somewhere if you multiply .85 to your rwhp it is your actual flywheel hp, can anyone confirm this? there must be difference for auto or manual.

multiplying your rwhp by .85 would give you a lower number, which isn't right. Typically, take your rwhp and tack on another 15% for manual, 20% for an auto.

Example, rwhp is 320, flywheel hp in an auto car is roughly 400.

thanks for clearing that up.