Using a speed calculator, 4850 RPM, 1.5 drive ratio, 10% slip, 23 inch prop (assume this is a cupped 22" Mirage PLUS so I added an inch) - get a speed of 63.4.

Its going to really cost to get there - might want to just be happy where your at - the low 60s is still fast

K&N
 

The factory flame arestor flows much better than the K&N. Save your money.

k&n
 

puta k&n filter on my 496ho lost 1mph, put the stock unit back on. save your money, will sell you mine if you want.

I never had an improvement with K & N. They sold me 3"x9" marine filters for my dominators that flowed LESS than the carbs:mad: Screw them:hothead:

I am looking at upgrades for my 496 Mag also. The cam and ECU change should get you a 2 - 3 mph increase, maybe another 2 with some prop work. I am waiting for Raylar Engine Development, Phone # (619) 994-8274 to release their new heads next month and see what increases that may bring. I believe they have had some contact with Whipple, so I am hoping for a ECU calibration instead of needing to swap to another type.

Carravelle 260
First wax your bottom, then you need to work on your prop. You should be able to pull about 5200RPM at WOT with light load and calm water. Remember fresh water is about 3-5 mph slower than salt water!Use a digital back up calibrated tach and see what you are really pulling at WOT. If your still about 300-400 rpm low you should probably take about 1/2" of pitch out of the prop after it checked first to see where its really at. The 496Mag has a different cam than the 496HO so no reprograming is going to get you the 25HP you'll probably need to go 3-5 mph faster. Save your money on any other gadgets like K&N cleaner, their not going to give you anything measurable. Sounds like your hotrod's doing pretty good at 65!
The Need for Speed !
Raylar;)

THANKS ALL FOR THE ADVICE!!! SOUNDS LIKE K&N IS OUT.

YES; A true 65mph on GPS @ Table Rock Lake in 62 deg. water on a 79 deg. day juast after break-in @ 22 hrs. SPEEDO WAS 1-2 mph OFF DEPENDING ON WIND AND WATER VARIABLES. It is a strong runner w/ a deep "V" before the re-programmed ECU. Haven't tried the leaner unit yet, I expect 1mph from the re-program. I STILL RUN 65-67 ON THE RIVER.

SOUNDS LIKE LABBING THE PROP IS BEST???? AND MAYBE A 23 / 24P LABBED???? WHAT IS A SAFE W.O.T.


Bob280Silencer --- WHAT DOES YOUR BUDDY THINK OF HIS INTERCEPTOR; QUALITY ISSUES???


Fuelish Pleasures & Raylar --- MY DEALER AND mERC TOLD ME THAT MY SERIAL #'S REFLECT THAT MY ENGINE HAS THE HO CRANK. MY MOTOR IS JUST SHY OF THE ECU & FORGED PISTONS AND CAM FROM BEING THE HO ENGINE. FACTORY SENT ME A RE-PROGRAMMED ECU LAST NOV. SINCE I WAS TOO RICH AND LEAVING SOOT RESIDUE / FILM ATOP THE WATER. HAVEN'T YET RAN THE BOAT.

What part of serial number designates HO/Mag crank??

bcolmsted ---

????? --- I am guessing that they know by the date of production. Merc told my dealer that my engine was one of the first to have the upgrade, but did not have the proper ECU, thus the silent recall and the TOO rich engines. I am guessing all later dated engines were upgraded and now have the proper ratio ECU. My motor was an early model 2003 in a late model 2002 boat ---> both are titled as 2002

do a 496 search and you will find others who have also found this out; this is how I found out about the silent recall on the ECU.

I didn't think ANY of the non-HO models had the steel crank. The HO has the same pistons as the MAG which are NOT forged.