Merc 150 XR6 Mods

I have a 2002 Ranger 185 DVS bass boat with a 2002 Merc 150 XR6, 23 Tempest plus. The most I could get out of the boat was 59.2 mph(gps) 5400 rpm's. The boat would not lift so I installed a jack plate, it finally lifted on the pad and accelerated to 63.5 (gps) 5400rpm's. I'm being told by several mechanics that I can change my tuner, rejet carbs, and shave heads and also install reeds. Before I start engine mods would I see results from doing these mods? I would really appreciate advice before I do the wrong mods.

Thanks God Bless
Dusty Romero (Xtreme Car Audio)



On the Rangers I've run, the tuner/head/jet swap is not worth too much. A mile an hour or so. The big difference in the XR6 and a 200 is the porting. If you match port it to 200 spec and then run the 41941 tuner the boat will see a 8-10 mph increase. I've done probably 20 of these in the last few years and that is what we see. You'd spin the same prop 6200 and have more punch than you ever dreamed of. Be careful with head modifications, they can be quite temperamental with today's gasolines. While hotter heads on the XR6 will add 10+ horsepower, it will probably fail on pump fuel.  Carb calibration is required for all this to work and it is not just a jet swap. Careful tuning is needed to make this run like it should. Depending on the part of the country you’re in, find a shop with experience and the reputation for this set up.




Please submit whatever questions you have to  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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