Tuning Mercury Outboards
12-04-2009 | 12:14 PM
#11
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Joined: Oct 2000
Posts: 1,436
Likes: 5
From: Fresno, CA, 93722, USA
I can do the 250EFI as long as its the later PCM. More rpm and spark.
12-04-2009 | 09:09 PM
#13
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Joined: Oct 2000
Posts: 1,436
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From: Fresno, CA, 93722, USA
02-27-2010 | 01:01 AM
#16
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Joined: Dec 2003
Posts: 5,975
Likes: 495
From: Cleveland, OH / Pewaukee, WI
Be very, very careful. If you intend to use these motors for normal, dependable boating, simply keep them properly maintained acoording to factory standards, and stay away from the "tuners". Those guys are great for people interested in top speed, but adding RPM, HP, and stress simply reduces engine life. If you and your family are miles from home with a blown up engine, it is of little comfort that you gained 2.5 mph a few weeks prior. Do as the previous poster suggested, go over your setup, propeller selection and weight distribution and leave the engines alone.
T2x
T2x
Jr.
02-28-2010 | 01:33 PM
#17
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Joined: Apr 2005
Posts: 1,442
Likes: 19
From: Washington, MO
For those hardcore outboard peeps, there is one other alternative to a performance tune that hasn't been brought up yet.
About 15 years ago I worked with a company called Hydrodynamics and installed a nitrous oxide system on two 1993 Mercury 2.5's 245 HP carb engines for my 22' Talon. Sent Hydrodynamics the intake manifolds and they installed the spray bars. Used a separate fuel cell to hold a 32:1 alcohol and 2-cycle oil (castor based) mix as the enrichment fuel which was injected when the nitrous was activated. The nitrous could only be activated at full throttle. Started rich and work my way to a perfect tune using Pyrometers and reading plugs. Had several safety measures including a low enrichment fuel pressure safety switch that would deactivate the system in the event of low fuel pressure. The system gave an additional 110HP per engine at the touch of a button. One 20lb nitrous oxide bottle lasted a long time. The additional power was amazing and for the impromptu river racing I was doing back then, it was a BLAST!
I had over 250 hours on the engines before selling the rig and had no nitrous related engine problems. When done right, nitrous oxide can be an ultimate upgrade to a high performance outboard.
http://www.hydrodynamics-usa.com/nitrox/index.html
About 15 years ago I worked with a company called Hydrodynamics and installed a nitrous oxide system on two 1993 Mercury 2.5's 245 HP carb engines for my 22' Talon. Sent Hydrodynamics the intake manifolds and they installed the spray bars. Used a separate fuel cell to hold a 32:1 alcohol and 2-cycle oil (castor based) mix as the enrichment fuel which was injected when the nitrous was activated. The nitrous could only be activated at full throttle. Started rich and work my way to a perfect tune using Pyrometers and reading plugs. Had several safety measures including a low enrichment fuel pressure safety switch that would deactivate the system in the event of low fuel pressure. The system gave an additional 110HP per engine at the touch of a button. One 20lb nitrous oxide bottle lasted a long time. The additional power was amazing and for the impromptu river racing I was doing back then, it was a BLAST!
I had over 250 hours on the engines before selling the rig and had no nitrous related engine problems. When done right, nitrous oxide can be an ultimate upgrade to a high performance outboard.
http://www.hydrodynamics-usa.com/nitrox/index.html
03-01-2010 | 11:54 AM
#18
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Joined: Oct 2003
Posts: 446
Likes: 0
From: sarasota,fl
He's on the other side of the country but he is one of the best for the 3.0 liters. 
http://simonmotorsports.com/
http://simonmotorsports.com/
Call Eric he will make the most reliable HP for you on the 3.0 litre motor.
Dan
Diamond Marine
