I posted this in 5.0L Tech but since you guys are used to flat tappet tech i thought i would ask you. Ok according to desk top dyno on my current combo if all i was to do is swao from my 274 XE flat tappet cam to a Etreme Hyd Roller 282 i would see a 20 hp jump at 4000 rpm and a 47 hp jump by 5500rpm torque would also be up with 49 more ft/lbs at 6000 rpm. Now im a little scepticle. can these really be right? the roller cam actually lifts the intake valve less then the flat tappet cam. i know there is more duration but nearly 50 hp from a cam swap? is this possible?
HP gains from Cam swap.
- Thread starter 86bluecobra
- Start date
Z06killinSBF
Member
Well, the cam is bigger and the roller cam has WAY less friction. Thats a simple answer. There is actually alot different between the 2 as for the 50hp gain. As for actually testing it, maybe someone else can chime in.
the bigest advantage to a roller cam is the faster ramp rates(valves open and close faster) and most of the 280 and above grinds the valve stays open at max liftfor a short duration instead of coming down as soon as it gets there. if you were to "map out" the curve on a graph a roller cam of simalar specs would have way more area under the curve. which means the valve is opened more for the same lift and duration.
It's not the lift that affects your idle vacuum, it's the overlap between the intake and exhaust lobes that does it. You will still have better vacuum with the roller, probably more than you've got now, even going with a roller with more lift and duration. The Z303 I've got in my 331 in the 89 Ranger has plenty of vacuum at idle for it's power brakes. (.585 lift/ 228 degrees duration @.050/ 112 degree LCA , the added lift is due to the 1.7 rockers)86bluecobra said:
