Simon ecu upgrade lighten flywheel

[Sundby]

Hi, I'm sure this question has been asked several times, but I want to hear your opinion, I recently bought a new ranger 620 walleye boat with a 250 proxs and hydraulic jackplate, I was wandering your thoughts on doing the simon ecu upgrade and flywheel on a new engine, performance gains, rpm gains, top end gain, etc. do you think it's a bad ideas since I still have warranty or don't you think it matters and go for it, I think the upgrade will really help my engine, and don't really want to wait 5 years. also if a dealership or mechanic doesn't know the ecu has been upgraded, are they able to tell? Your thoughts appreciated! Thanks

[obrien]

They will be able to tell if they look at your RPM readings and see run time above what your rev limiter would normally be. Personally I would wait a while until the warranty runs out.

[Speed Jr.]

[Sundby]

What if he doesn't touch the rev limiter? I'm turning a 23 tempest 5650, so I'm a ways from it??

[obrien]

The biggest problem I could see is if there are any issues before the warranty is up, it could end up costing you if mercury figures out the ecm was modified.

[Sundby]

This might be a lite over the top but can a person buy a new ecu and reflash one and keep 1 stock? And change them out if problems occur? Or is this not how the ecu works, is only one programmed at a time?

[Wayne Cammidge]

It is possible to run and modify a spare PCM, but if you had a fault, replaced the original PCM and took it into a dealer, the dealer would be able to tell that it had been changed by the missing Run History, then you could be still in the same situation with no warranty and a lot of costs. The PCM is not cheap to start with, plus, plus...

[shep70057]

Not to hijack the thread but how does the increased rev limiter help if you are not hitting it?? I mean most of us prop to the power band. Or will it free up horsepower in doing so??

[Liberator Stealth]

Not to hijack the thread but how does the increased rev limiter help if you are not hitting it?? I mean most of us prop to the power band. Or will it free up horsepower in doing so??

I had the rev limiter raised and lighten fly wheel on my 250 XS. Running the same prop as before could turn the engine 300 more rpm and gained 2 MPH and had better hole shot.