About 2 - 3 tenths slower from its absolute best which was in mineshaft conditions but I run on a throttle stop to run 11.50s so in my case it doesn't really affect me much, I switched mainly to get away from having to use race gas. I am now redoing my 363 / W2 motor for lower compression / pump gas but its going to stay stock stroke so hp and tq will be lower but should still be over 500 hp. I ran 340s for years but in my case the 360 I have made more power,as a matter of fact I am going tomorrow to pick up a 5.9 / 360 motor I picked up cheap. another example.. years ago I had a W2 head 340 with 12 1/2 to 1 compression and a 627 lift roller cam and it made 527 on the dyno. my 363 ( 5.9 Magnum block ) W2 head, 590 lift mech cam, 11 1/2 to 1 comp made 549 hp on the dyno... 22 more hp with less compression and cam but 20 more cubes ( 340 to a 360 ) both were bored 30 over. on the track ...340 ..high 10.70s average... 363 .. solid 10.50s.
