45hp Chrysler Prop / Top speed mystery

[jerryjerry05]

30 mph might be a dream?

My 21 with twin 88/85 only ran 32
Changed props, got 3mph more and 15-20% worse fuel economy
I changed to a 225 and only got 55
Was expecting 60 at least

I think your expecting too much from too small a package ??

I believe in the old adage, "wanna go faster? then get a bigger motor"

 

[8ender]

I figured out the issue and I want to post it here for anyone else it might help.

When I first took out the boat to test drive the engine I noticed it was bow up and porpoising a lot. I didn't check the top speed at that time. Thinking I was trimmed out too much I set the engine to the lowest trim peg and things got better.

In between that and future outings with the boat I realized the locking bracket was broken and fixed it. Turns out the engine was getting jammed on the broken locking bracket and trimming the motor out way more than it should. When I fixed it the engine rested on the trim adjustment bar properly making my trim wayyy too low and I was plowing.

My only clue was the amount of spray hitting my passenger and the low top speed. I set the trim out two pegs and was getting 30mph no problem. I feel like I should be getting a little more but 30mph is pretty hairy in a Cadet with a little chop so I'm happy.

 

[jerryjerry05]

Some people just aren't happy
What's the rpm's now the tilt problems been figured out?
You can try another smaller prop??

 

[8ender]

RPMs are around 4950 at WOT. I'm running a 12 1/2 pitch prop and I have an 11 1/2 pitch from a Force 50 parts engine but I have a feeling I'm going to be disappointed in that one. It'll get the motor to the max RPMS on the plate but I think I'm going to lose some top speed. I'll try it out when I'm on the lake this weekend.