4.3 GXI holeshot rpms

[89retta]

Just trying to gather some info. I have an 04 Caravelle 187 weighs about 2800 pounds with average load. With The 4.3 GXI and SX 1.79 power train. Revs up to 3000 on the hole shot with a Turning point 4 blade 21" prop. Want to know what rpms people get out of the hole with this engine. I know results will be different depending on the props people are using. Want to get an average rpm. Thanks

 

[Scott Danforth]

Your max rpm is about 4800 for your motor. Are you saying you are only getting 3000 rpm, or is that all the rpms it takes to get out of the hole?

The motor is most loaded on the hole shot.

 

[89retta]

Rpms out of the hole when I punch it. I rev at 4400 rpms full throttle once on plane. Want to see what props other people are using with the 4.3 GXI.

 

[Texasmark]

I have a Turning point Hustler aluminum and It's ported......a hole about 5/16-⅜" sort of thing under the leading edge of each blade. If your 4 blade has them it's the holes causing your revving. They are there deliberately to do what you are experiencing which, when properly matched to the boat and all will result in a faster hole shot....getting on plane.

The way you use them is idle out to wherever you want to get going, and firewall the throttle, pulling back as you get to the desired speed. The holes will cause excessive rpms (for a given speed) till you get up to speed, which is usually faster than without them, especially on heavy stern boats, and once up to 20-25 mph (for a number) speed they will seal off by available slip stream water pressure and rpms will drop back to normal, increasing back up as the boat speed increases if the throttle is still firewalled. At no time should the holes cause the engine to exceed rated rpms. For me it's a 1000-2000 rpm increase compared to no holes and 3-5 seconds off the hole shot time.

 

[89retta]

Yes my prop has them. I also have a 17" turning point. The 17 will hit 4000 when I hammer it on the holeshot while the 21 only hits 3000. Just bought a 19 will try that out this weekend

 

[Texasmark]

The 19 ought to punch you out faster with lower rpms and then higher top speed. On one of my boats, a Ranger bass boat, when the holes closed and the prop locked up, somewhere around 30 mph, the engine rpm drop reminded me of back in the old days of the overdrive automobile transmission where you were in 3rd gear running at some rpm, letting off the gas, the OD kicked in and the engine settled in at a lower rpm and the mph picked up.