soldier4402

To the OP. I kind of went through the same steps as you after having my boat. Did some of things you did, but in reality those are all good maint type things that will only help your engines live longer. I really had to go through a cost effective approach to it and what I needed. Really came to the conclusion getting a different boat was the best option. But I ended up stick with that what have, I rarely go the top speed anyways, and having those bigger engines opens me up to a whole new world of performance boating and spending money.

DracoDan

Thanks for all the replies, I agree with you guys that I can't do much within reason to increase power. With that said, I have some new info to add...

I took the boat out last Wednesday and again yesterday, the water yesterday was absolutely amazing and I figured it would be great for testing where I currently stand...

My results: at WOT I hit 46mph, but at only 4100RPM. Both engines read exactly the same RPM so I doubt it's a tach problem (the tachs are brand new too, just replaced last year). The strange thing is I hit 4100RPM a fair bit before I am at WOT, but the last few inches of throttle don't seem to be doing anything, so I doubt it's a cable problem (as I previously suspected).

I don't know the outdrive ratio but the Props are 26p. I know the outdrives were rebuilt two years ago by the previous owner so the gearing may have been changed at that point. Since this is my first and only boat I don't really know if my holeshot is as quick as I think it is, but I seem to get up on a plane extremely quickly.

Cole2534

iTrader: (1)

If you were under propped you'd hit the rev limiter, instead you're about 20% short. A pair of 24's may help.

Powerquest230

Dan, any change in wide open rpm when adjusting trim up?

keith2500hd

out of curiosity, did or can you do compression test. might hook vacuum guage and timing light to be sure they are good. want to make sure engine's sound prior to spending time when somethings not right.

DracoDan

I have not, but I doubt this is the issue since both engines are hitting the EXACT same RPM and have the same oil pressure (40PSI) and temperature (180° F) while on the water. I highly doubt they would both be having the same exact compression issues.

DracoDan

It didn't seem to, but I didn't raise it very high, I never seem to need to... unless my understanding of how I'm supposed to be handling trim... I thought the goal was to keep it as far down as possible unless I'm having trouble getting on a plane. Is there a comprehensive guide somewhere on how to handle outdrive trim?

JMS322

A lot of rpm and mph can be had in proper trim and tab settings. Assuming everything else is mechanically sound this may be your problem.

DracoDan

Update: assuming the drives didn't get changed during the rebuild, they should both be 2:1 drive ratio.

Also, a seemingly dumb question, but since I don't bring the boat out of the water I don't know... For the trim tabs, when I press up on the switches should it move the tabs up or the bow up? I need to figure out how to fully retract them.

jmbighead

You needed a compression check, sounds like the motors are not performing nearly as efficient as possible, I have twin 454s on my 31 sonic and hit high 60s low 70s, I had heads machined and valves redone and was a huge difference, get a trusted boat mechanic to take that baby for a spin. If you can't get anymore speed out off that boat, then sell it don't sink drastic measures in a lemon, chicken salad/chicken ****