Well I don't know if you can gain performance from just a PCM reflash, but you can sure lose it. I have an early 2001 496 mag (#OMO61519) and I wanted to install a Mercmonitor on the boat. Mercury said that I had to have the PCM modified for this to work. I was skeptical of this since a scanner showed all the engine information was available, but Mercury built it and they should know. The reflash was free and part of a recall (Fix Campaign 2001-014).

Unfortunately I did not seem to get just a reflash, but a different PCM. Equally unfortunate is that I do not have the serial number from the original PCM as that may be of interest to this thread. In any event the different PCM no longer soots the transom up like my old one did, and it does provide a small improvement in fuel consumption, but I also lost 4 mph. No other running changes were made to the boat at this time.

Since the acknolowdged experts on the 496 seem to be following this thread, I thought I might fish for comments and satisfy my curiosity. Clearly if there are performance reductions in a "newer" programing spec, there might be performance enhancements available by reverting to an older specification.

Ray and others, does this make any sense to you and would you be willing to share your general knowledge of what programing changes Mercury may have made through the years?

Thanks,

Dan

I've run them to higher rpm than stock, but the power drops rapidly past 5100 rpm so there really is no point in raising the rev limit. Peak HP with the stage 1 program was 5000 rpm. Even the Raylar 103 kits peak around 5200.

The Raylar 103 pkg is designed to run at 5350 (Raylar's recommendation) and with the reprogram the limiter is set at 5450.

I had Whipple do a Stage II Flash on my 496 Mag (non-h.o.) last summer. THe main reason I had it done, is my 2001 496 mag produced way too much soot on the transom. While Merc was willing to flash for free, I opted to have Whipple to it because I would only be down for 3 days, where Merc wouldn't give me a time frame...... Anyway back to the STage II flash. THis also included a much cooler T-Stat and now the use of premium fuels. The overall speed gains were maybe 1-2 mph, but the MAJOR gain was in torque. My Velocity 260 now pops up on plain effortlessly with the Stage II flash compared to the Stock Merc Flash. That right there made it worth the $$ for the Flash. Plus the idle is completly different. It has a much more agressive sound at idle....

My dyno testing shows the peak power at 5200 and it starts dropping after that. I guess you can run it higher but it won't make more power.

Awesome thread. This question was asked earlier but I didn't see a responce. For someone doing the mag to ho upgrade would it be better to run the stock ho cam or the 103 raylar cam? Not sure on the cost difference but wondering if it would be worth it.

No offense but there is conflicting info on this one. And I will assure anyone who raises the limit running OEM pistons that you will only break them (or one) sooner.

Ray has moved on this number a couple times possibly by pure accident; I don't know but I've noticed it.

In a constant rpm engine (marine) they should never be made to go any faster.

Since you got the new computer for free perhaps you can send to Whipple and try the stage 2 and hope for noticeable results.

If you were to even bother with thinking about the time and labor to remove cam, you may as well buy the Raylar Cam if only because the stock ones are so bad it's not worth the time to reinstall. What's $400 these days in boat parts?

Just my opinion.

Well, I've had the upgrade now for most of the summer and can happily report that it has been everything I expected and alot more! I can run a little over 5000rpms with the 28s and the low end torque is amazing! Picked up about 7mph to boot! They sound great and don't soot the transom anything like they did with the Mags. Perfect upgrade in my opinion!

Which upgrade?