The 252 will be brake horse power. In the case of this engine which is well tuned I would assume it is measured on a dyno as "flywheel output". Not sure what that would equate to as power at the wheels.
In most cases with regard to 7's on this forum you will see bhp that is either manufacturer quoted (measured on dyno during engine development) for standard engines, bhp that is inferred from rolling road tuning (for most one-offs), or bhp measured on a dyno for more race developed engines.
I'll leave it to others more knowlegable than me to argue, but I understand that power at the wheels is not that useful a measure as it differs with different measurement methods due to the ways that transmission losses work.
That all being said, I have no idea how believable the 252 bhp is, but it's an oft quoted number of a race developed engine. Thus it may be quite believable!
Graham
Edited by - gridgway on 8 Dec 2002 14:44:40