My 525 is propped to hit the limiter in perfect conditions. That usually keeps rpms down around 5,200 with passengers. I get the rev warning horn a lot when running alone and light and cool days. I have never noticed anything harsh after the horn starts. I thought the engine started pulling timing first. Can an engine guy verify for certain what happens when you hit the limiter on a 525 which I believe happens at 5,450 rpm.The power is at 5,400 so bumping the limiter is inevitable if you want get full hp.

If its an EFI motor and cuts fuel, it does just that, cuts OFF fuel. It's not lean, its just a dead 'jug' at that point pumping air. Its not lean under our normal definition.

If it cuts spark the fuel is not washing down the cylinders. Think about it, whether the motor sparks or not, the same amount of fuel is present. The only difference is that after TDC the unburned fuel vapor gets tossed out the exhaust chute. It's not sitting there cleaning out the cylinder bore any worse than a normal ignition sequence.

So unburned fuel continuously hitting a hot exhaust valve(s) is OK - would like to hear how that over time is fine.


A step further would be take the stock HP 525 out the mix completely but we have currently way more OEM stock marine apps for the past 7 years with O2 sensors - 2 incoming (pre) and 2 post plus a catalyst system / cat sub strake installed in the exhaust risers. Do you know what happens when raw fuel hits these areas because you think bumping off the rev limiter is ok ? When too much raw fuel hits the very hot cat sub strake it will flashover and blow a hole straight thru the cat. One cat sub strake is 1200 to 1800 bucks alone. Just saying. There will be a day when all marine apps really tighten the emissions and the owners of the boats. It has already started.

BUP, will the the fly by wire systems cut back on throttle angle to stop the continual 'bumping the rev limiter' scenarios. This would be far more optimal then continually dropping spark or fuel if someone leaves the sticks all the way forward.

SB it is here already - Mercruiser has released their new engines so far, the new 4.5 L V-6 and the new 6.2 L V -8 that has Adaptive Speed Control - aka ASC - I test driven the new Mercruiser 4.5 L in Oct 2014 and you could not get that to over rev no matter what you did.

Even at any speed / throttle setting with drive trimmed up and driven very hard corning - the jist of it was like a cruise / speed control would set in not allowing the rpms to increase no matter what even when the prop completely blew out, rpms stayed exact the same. Also worked at very low speeds to maintain planning speeds.

I ran the pee out that engine on the West coast of Florida. Anyways this link just talks about a bit.

http://www.boattest.com/engine-revie...5L-250-HP_2015

So with a system like that... you could drive like a maniac, launch the hell out of the boat, leave the throttle on the dash and never worry about throttling??

^^^ I hear you - its like a RPM maintainer for the boat or like I said cruise / speed control. Well I really did not want to go into more new systems nor the indepth details but you will like this as well.

Its becoming a boat does drive all by itself and the newest for 2016 is Active Trim Control plus already out to market is Joystick & Axuis & steering angle read outs and ASC plus other new tech brought forth to the marine market for the end user.

Watch the Video in the link scroll down. Talk about being lazy while driving a boat nowadays. jeez

Mercury will be offering a race version of this active trim for high performance boats that use surface drives as well.

https://www.boats.com/reviews/mercur...oating-easier/

For me and possibly most of us, a big part of the joy of driving a high performance boat is mastering the skill of throttling, tabs, trim etc. Making constant adjustments while driving at speed and reading the water. Like banging gears in a hot rod, or driving a dirt bike or quad. The more control you have and skill you develop the more fun it is. I can't let anyone else drive my boat. It took me years to master my little Donzi. Many people don't realize the skill it takes to drive it at speed or to carve that high banking slow turn. If we wanted boats that drive themselves we'd all have cruisers and kick back at the martini bar.

^^^^ agree and that holds true for anything - bikes, fast cars and fast women haha

Here is more for your enjoyment. Watch the Vid everything is taking it out of the hands of the end user. Anyways I have lots to say about all of this stuff going into boats.

http://www.tradeonlytoday.com/2016/0...sletter-010516

See, God does listen to your prayers. Ha @