IMHO, to use the next step up in cam (Crane) is 240/248 at .050" duration, which with a 502/509 one would really need/want more compression, which can make boating a pain unless you have easy access to, and will always, purchase higher octane at all times.

You could get better heads for $3k+ for a 30-40hp gain ???? With stock cam. Headers will have wrong bolt pattern though..so would have to drill new heads for them.

The 525EFI typically dyno's in the 560+hp range. The Intake Manifold str=arts really restricting near/at/just before 600hp.

Well I had a late night in the boat again and I found out a few things again. First of all I'm surprised that the engine is Still in One part as the ignition was waay off. It went from a few degrees on Idle Up to 24deg at maximum rpm. Sounds low but the reference number were off by 23deg so at max rpm it had 24+23deg ignition!! I can't even understand how that's possible and how we just suspected a little irregular knockings sometimes. My friend told me that at least in turbo engines it sounds like throwing gravel at a car, really loud noise. We turned down the ignition at Idle to where it should be and started mapping the ignition and fuel at different rpms and we got up to around 4000rpm when our lambda sensor gave up so we had to give up.

But we noticed that when driving at around 4000rpm for a while the coolant starts to overflow, don't know why but could that be from the early ignition that is has partly broken a headgasket so when you drive harder the pressure inside a cylinder now leaks in to the coolantchannels and causes it to overflow? I really can't come up with a better reason.

Overall the boat sounds so much calmer now and is running great on Idle and in gear on minimum throttle, before the Idle was pretty rough and a pain in the ass to drive below 6-7knots.

And I always use 98octane fuel. Think that is 98RON here in Europe. In America you measure it diffrently I think

Who retuned the ECU after the engine upgrades

The previous owner himself had a basemap that he started to tune from, didn't go too well. It's Night and Day difference now, too bad it started to thow out coolant after 4000rpm, I'm pretty sure it wants to rev more than 4700 now.

are you running the 555 PCM or ?

Haltech

And the same people programmed the detonation strategy too ?

None of the the people who have programmed it before have anything to do with it now. It sounds a lot better now with nice Idle and no problem with stalling the engine when I put it in gear, but I'm Still going to pull the engine and check the pistons, bearings, head, camshaft and the gaskets and make sure everything is as it should be. And at the same time probably switch out the old Haltech e6x for a new maxxecu system that is much faster and I can run dual lambdasensors and knocksensors. Much easier to get any engine run smoothly when you have control per 40rpm If i remember correctly and ignition per 0,1 degrees. But now we all know that these engines can take 47deg ignition for att least 20 hours 😂

never heard of it

Haltech has been around for decades. Good company.