We always do this at work with alot of the race engines we build. Sometimes it's $1.00 per person per guess, sometimes $5.00 per guess. Winner gets the pot. We did this on my Hemi when we dyno'd it. So many were so close but it did make more than everyone was expecting.

1963 Belvedere 440 Max Wedge Tribute
1970 Charger R/T S.E. 440 Six Pack
1970 Challenger R/T, 528 Hemi
1970 Charger 500 S.E. 440 4 BBL
1970 Plymouth Road Runner 383
1974 Chrysler New Yorker 440
1996 2500 RAM 488 V-10 4X4
2004 3500 Dually Cummins 4x4
2012 Challenger R/T Classic.