Specs are 497 horse , 520 lb ft torque On dyno last summer in 95deg 110 % humid Room. 5o5 stroker , 1.6 rockers , 20" vacuum Dyno operator chuckled and told me 400 horse , he can tell by idle. His hand flew off the throttle when the outboards Opened. It REAlly idles like a 318 stationwagon