My mustang Has a 289 2valve V8. Stock it has 200hp but i have a 4 barrel edlebrock carb, a new cam, dual exhaust w/ Headers and flowmaster 40 series mufflers. So wut wold the horsepower be? I'd really like to know.
about 230 hp, to wake it up even more pull the distributor out, crank the engine around to 3 degrees btdc then re install the distributor to fire on # 1 ( first plug on the passenger side ), and get a k&n air filter, you will really notice the difference...
230 -245hp depending on what cam you have in it. i'd put in flat top pistons brings comp ratio up to 9.8:1 with stock 289 heads. drop a set of edelbrock aluminum or widsor jr lite heads on there and you'll gain another 40hp you'll be in the 285-295 range. with a motor that will really wind out (high rpms). great motor. i put a stoker 351 (427ci)in my 68,approx 425 hp. serious power.
Take it to a dyno test just because it will give you a accurate reading but make sure the dyno test operator is good because he could blow your engine. I have blown plenty of subaru engine's on sti's and wrx's it a difficult thing.