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cncer691
05-26-2002, 04:31 PM
What is the cheapest way to get a little more HP out of an Olds 455. I am only getting 3800 rpm @ 60 mph. I figure if I can get to 4400 rpm, then I will surely break the elusive 60 mph ceiling. My motor is stock except for Performer intake, Holley 850, and MSD ingnition. At 3/4 throttle it is running strong, at full throttle the motor makes more noise, but doesn't gain any RPM or speed.

Jungle Boy
05-26-2002, 05:41 PM
What size of impeller are you running to get 60 mph at 3800 rpm? Is the speed recorded on GPS or speedo? Does the boat run wet at 60 mph? A diverter or some wedge may lift it a bit to get more speed. The more info you give will help.

Jetmugg
05-26-2002, 06:09 PM
Something is wrong with those numbers. If you are really going 60 at 3800 rpm, you have the best running Olds powered jet boat I have ever heard of.
Either the tach or the speed is incorrect.
SteveM

cncer691
05-26-2002, 08:15 PM
Maybe I have a bad Tach then. I GPS'd at 59.1 @ 3800 rpm. Like I said, my RPM gauge doesn't move from 3/4 to WOT, just makes more carb noise. I am running an A impeller, and the pump was just put in today. The tach is a teleflex unit made for outboards and 4,6 and 8 cylinder motors. I have a place diverter, but my pump is a 12-JC, so I don't think it can be wedged. I'm hoping my tach is right, because that is why I stayed w/ the A. I was going to run an AA, but didn't want to be below peak HP.