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I have a 06' 250xs, what I want to know is what is my best options for mods that will get me more top end speed? I am running this motor on a ranger 620 multispecies boat so I know I won't get the gains that a bass hull will but any improvement would be awesome. Let me know what you guys have done to yours!!
The only two areas that I know of are prop and jackplate/motor height. The motor is already tuned to its optimum level of performance. I had the flywheel lightened on mine by Simon motorsports but whatever gains were minimal. I have a 621 with a jackplate. I get best performance by altering the load and 21-23p tempest plus. No reason you cant run a 23 with that rig IMHO. I think your 620 would be best with a power jackplate. Search walleye central for other prop recommendations from Eric Olsen. Although I think he runs an e-tech his prop tests have resulted in speed of claimed 70 in a stripped '06 or '07 620 with a 250. Not sure of prop.
I run a atlas jackplate, I run a 24 pitch bravo 1 tuned by the master Mr. Croxton. I was thinking about a Hyrdo Tec exhaust tuner and Simon reprogram and lightened flywheel but is there anything else??? what is your take Don
Have you done a LEAKDOWN test on this engine, confirmed it's running at peak performance, and that throttle plate is actually REACHING 100% throttle? If not... these are good starting points. http://www.bassboatcentral.com/smileys/wink.gif
I'd recommend you talk with Eric Simon directly- he's a pretty straight shooter, and would steer you right.
IMHO... flywheel will improve holeshot and mid-range responsiveness (primarily). Reprogram on the PCM would depend on WHAT calibration he utilizes (talk with him about that). Eric has several different things there... http://www.bassboatcentral.com/smileys/wink.gif
The tuner (IMHO) is not going to improve your performance on that rig by any real measureable amount (other than perhaps the decibel level). http://www.bassboatcentral.com/smileys/wink.gif
The tuner will also change the way your props vent, by not forcing more exhaust out the prop at low end. So your props may need to be reworked and have vent holes added or opened. Not a bad thing, just another thing to think about.
What exactly is a leakdown test? are these tests my local mercury dealer will know about?
In short: A Leakdown Test supplies a FIXED air pressure supply to each cylinder (usually at TDC- although it can be repeated at various points in the compression stroke).
Two gauges on the unit are utilized- one showing INPUT air pressure, another showing pressure being held by the cylinder.
The DIFFERENCE (leakdown) can then be recorded as a PERCENTAGE of LEAKDOWN (the amount of air escaping past the piston rings on this case).
Leakdown tests are the MOST accurate means of assessing the health of a bore/piston/rings (other than actually tearing the engine down for inspection). http://www.bassboatcentral.com/smileys/wink.gif
Check Dave out to. Right now he's making some kits for the 300XS and the 250 Pro XS will be the next motor that he will do.http://www.davebushracing.com/