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I have been having a problem with my RPM slow to rise at WOT. I can top it out at 4800 at wideopen, but once there it slowly will raise another 2-300 RPM over the course of 20-30 seconds. Of course I would like to have this RPM if not more without the delay, and am somewhat disturbed as to why it does this.
I have a 82 eliminator daycruiser with Pre-Alpha, 21' prop. Small block 350, Alum heads w/ roller rockers, comp xtreme cam, bg carb 750, stealth intake, all MSD. Dyno's at 415.
Any ideas?
There is always the chance something isn't right, however I have never seen a boat that didn't creep up the last 200 - 300 rpm's. Especially a small block. An engine in a boat sees a lot of drag and will have to work harder than a car to get it's final few hundred rpm's.
There is always the chance something isn't right, however I have never seen a boat that didn't creep up the last 200 - 300 rpm's. Especially a small block. An engine in a boat sees a lot of drag and will have to work harder than a car to get it's final few hundred rpm's.
I agree. Mine is the same way. With the current 23p cleaver on the instant hit it WOT's at 5000 rpms and slowly rises after 10-15 secs to max at 5300 rpms depending on load.
I think it's because, as the speed builds, the hull gets aired out more thus alowing the engine to gain some RPM. A lot depends on how you trim it too. Plus the cam profile comes into play. May need to get to a certain RPM to come onto the cam so to speak. Lots of variables come into play.
thanks guys, at least I know this is normal. I really don't see any speed increase as those last few hundred RPM's rise, think this has anything to do with my prop??
Could be the prop or the combination of hull, prop, drive height, etc.