Any danger in shutting engine off at WOT?
 

I thought I remembered reading somewhere that shuting your engine down at WOT could cause reversion, hydro lock, or some other problem. Is there any truth to this? What are the odds?

I have done it in the past to see how the spark plugs looked. Did not have any problem and my daughter accidently pulled the kill switch on the passenger side once at damn near full throttle. No problem that time either.

Thoughts, opinions?

Not sure, as the seawater pump would stop turning to.

does the water pump in your car keep turning after you shut it off and go in the bar or store ?:eek:

Not following you.

I stated it stops turning, thus no incoming water.

If the motor kicks back any when it shuts down it can take a gulp

Water from your own wake can come up into the tailpipes and cylinders.

If you want to check plugs after a WOT pass don't turn off the key. Slow down to an idle, pull the shifter out of gear then pull the pulgs and read them. You will be able to see what you need to see like the heat line on the ground strap and center electrode and the color of the base ring of the plug. In cars at the end of the pass they are either clutched or basically put into neutral before the engine is shut off. It may or may not hurt anything, but the idea of turning the motor off at WOT isn't a good one.

The motor will keep turning over as the water flow over the prop is sufficient to keep the rotating assembly rotating until a lower speed, usually coming off plane. As a result all the water pumps will still be turning, the recirc pump and the raw water pump.

Now if it's a Bravo drive it can be a PITA to get it into neutral again as they don't like to shift unless running.

I would be concerned with the water coming back up the pipes caused by the force of the sudden stop. There would be no exhaust pressure in the pipes to force the water back out. I would think it would depend on the setup......how much of an uphill run does the water have to make, how far down stream does the water enter the pipes, etc.
Just because one boat doesn't have an issue, it doesn't mean another won't.
Eddie

I blew a fuel pump fuse at 95 mph (single engine vee) and motor stopped pretty damn sudden, didn't seem to hurt anything though but I wouldn't want to do it on purpose EVER, Smitty

i was did several WOT shutoffs on mine this summer to do some plug checks. kill the key, then shift it to neutral while the motor is spinning down the boat will still be on plane when you already have it in neutral so the water pumps stop.

my biggest concern at first was water coming right up and over the swim platform onto the engine hatch, turns out i got no more water on my swim paltform than any other time i come to a stop. pull all the plugs and no water to be seen and able to get a great plug check.

I'm sure not all boats will react the same as to how the water come up behind them so it may be best to do your first test without actually turning the motor off so that you know the tailpipes are not gonna take a gulp of water. also in my case i have internal flappers in the tailpipes going through the transom so i know mine wouldnt take a gulp of water no matter how hard the wake came at it.

A better way to prevent water from coming up the tailpipes is to make a turn right before you completely come off plane, basically slow down in a circle. Most of the wake will hit you from the side instead of straight up the back.

But a few seconds of idle time wont kill a plug reading either.

if the bow drop and hooks you could ruin a good pair of underware !!:eek:

+100:drink::drink::drink:

Slowing down too quick can be real dangerous. They get a little squirly and want to go sideways. :eek:

I prefer the a/f meter. The rest is just guessing.

i prefer a/f ,pyro's , and reading the plugs .... makes for no melted pistons :drink:

waayyy too fancy for us normal folk....:party-smiley-004:

You A Listers get all the cool toys :coolcowboy:


Oh, and Dave, you better bring your A game the next time we run. Ran 97.3mph on Wednesday....:kiss:

Phil,

You ran that number to impress your Mom ! Don't try that everyday.

I find killing power at WOT is to risky, at least in my little hull.

I believe only what I see, and you can count on the A game next go around Phil. If you really saw that much of an increase you need to take some jet out in season, you are way rich. Put a bung in the exhaust and you can use my a/f meter if you like.

I agree that I am a bit rich during the on season, but I am also always running around with a full boat, which scrubs a ton of speed in this boat, as opposed to running with 2 people and half a tank or less.

We made three runs on Wednesday, the first at 94mph, pulled out early because of some cross wakes, the second at 97.3 and the third at 96.8. The third run definitely had more in it, at least 1-2mph because i wasnt WOT for very long, but it was into the wind and chop, which tends to get a bit hairy. These were all GPS speeds on a handheld.

I saw low 90's during the season with 4 people on board, just with this 32p, it takes alot longer to get there than it does with the broken 30p.

Your boat is bad news for me because of how hard it accellerates. Even if I get 3-4mph on you, you are already 2 boat lengths ahead, which takes A LONG time to pick back up, much longer than most boat races between friends.

I am probably going to get bungs welded on this winter, as well as get the water injection cracks in my headers welded up:lolhit:

did Rudy tell you that ???? LMFAO :lolhit:

It happened to me once. I shut down an overheating engine before coming completely off plane. I'm sure that the excess heat being suddenly cooled caused water to be pulled into the cylinders. All of the cylinders with open exhaust valves had water in them. If I had flappers, I'm sure it wouldn't have happened.