Nitro 640 Tune Up

[Mike Nelson]

Hi all, I have the option currently to have my 90Hp Optimax remapped to 115Pro XS settings with the Carbon Reed Valves installed as well. How much performance gain do you think i should expect. Now i know the boat isnt rated for it but does anyone think it will have a problem handling it?



Currently i run a 20p Laser 2 and can do 43mph, hitting rev limiter all the time. What pitch prop woudl suit my new setup and what speed should i expect from it?



P.S. I have no jack plate, and the engine is on the 2nd highest holes, which seems to be the best spot.



Thanks

 

[john horn]

How do you change a 90 to a 115? Isn't a 115 a 4 cyclinder and a 90 a 3?

 

[Mike Nelson]

I run an optimax, optimax 75 90 115 are the same



Anyone got any ideas?

 

[fatrap]

Can't help you much there but. I used to have a 170 Nitro DC with a 90. I ran high 40ties. If your hitting the rev limiter you might want to see if you can borrow someone's 22 pitch and try that. Bet you have a hell of a hole shot.

fatrap

 

[Dan Nevill]

I have a 640LX with 90 on it. Running a 21p, 3 blade stainless and getting an average top speed of 46 on gps loaded with two people. Hole shot is great.



Dan