does any body know of performance upgrades for the PCM555 computers on the 496 Mag HO

www.whipplesuperchargers.com

The only ones that I know of who have the rights to make modifications to the pcm555.

Reprogramming your ecm on a 496HO won't do much until you change some engine parts, like heads, cam and intake. You might wan't to check out our BCK103 kit, turns a stock 496HO into a 525HP+ 496HOR real nice.
Ray @ Raylar www.raylarengine.com

OK I finally did it!!!
I just sent my PCM555 out to Dustin Whipple and will have it back by the weekend (weathers not going to be great though).
I have run my boat with GPS a number of times and know the average is 70mph with a pretty full load.
Last weekend I removed the exshaust restriction plates (Turbulators) and seen a 2mph increase.
With the two mods I will do some GPS runs and let you all know what the real deal is.
I have been waiting for someone to do some real boat testing on the PCM re-programming and thermostat change but could not wait any longer .
I will post again when the water flies.

BHOCKETT,

Can you give us some detail specs on you boat/engines?

Mike

2 mph with removing restrictor plates... any chance it was cooler out and that helped also ?

Don

I question 1-3 mph results on anything. Boating is hardly a controlled environment. My top speed can be plus or minus 2 MPH from day to day. I am thinking about taking my plates out but I may wait till the warranty expires.

I was going to take mine out this spring before I put the boat in the water. I decided I would wait, this way I can do a before and after test with a GPS. I'll post my results which will probably be next week.

The boat is a 2001 Checkmate 240ZT with a 25 Mirage Plus that was lab finished by York Propellers and the 496HO has 116 hours.
The 2mph increase I seen was an average for several runs during the whole day and the temp was in the upper 70's.
I know there are several factors that lead to a good reading and that is why I stated that I would post again after more testing was done. I’m one of the biggest skeptics and that’s why I had to do it myself.
Beside the GPS the seat of the pants meter also told me there was some increase in power throughout the upper RPM range. After 116 hours in the drivers seat you can feel when everything is running good.
When I removed the plates they did not show any sign of water as they had the black soot from the too rich PCM programming. I think these things are restricting the output in a big way. Have you ever tried to produce over 400hp with 2 1/4" exhaust?
Before, when I ran with the electric select closed and going threw the prop there was a 2-3mph drop in speed prior to removing the plates, and that is another test I want to do to confirm my numbers. Now that difference should be greater.
My hat is off to Whipple as he turned my PCM around the next day.
Now for the PCM testing, and I may put the plates back in so I get a real test of before and after.
Maybe next weekend the weather will be better.

Keep us posted!

I'll report back next week on my results taking the exhaust restrictors out of my 496HO