Is their anyone here that runs a nitros set up on the marine engine? I have a carburated 502MAG and am thinking of trying a 100-150 shot for a little more top end. I am looking for input good or bad. Thanks in advance.

Brian

BAD idea, to do correctly, you need foggers in each hole with another fuel pump and line on one side of the fogger. The fuel flow would have to be metered while on the bottle. NOS is a piston melter. There are very few guys who drag race using NO2 without cooking pistons.(they are only on it for seconds at a time)
Money is better spent on heads. Merlin oval port marine heads a good exhaust and a cam will give you more than what your looking for. 550hp on a 468 BBC.

tmthunder;
A common misconception about NOS is that it will toast a motor...many believe that because they've heard all the negative outcomes of NOS being put on a "weak" engine and/or being set up incorrectly. Melted forged pistons come from 1 thing...not getting enough fuel...which leads to DETONATION.

The 502 MAG has a solid bottom end (forged) that would take a 150 HP shot easily. A plate system would be the ticket. You do need a seperate fuel pump to supply the NOS plate (holley red will do the trick) You'll also need to pull out 2-4 degrees of timing and run plugs 2 steps colder to be safe. Guys that burn down motors on NOS do so for 1 main reason...not enough fuel. Next reason is cheap cast pistons and cranks. With a 150HP shot you will pick up around 500rpm INSTANTLY...so be sure not to over-rev your motor. A good fried of mine has a 125hp kit on a small block 350mag with no problems and I run 175-250HP in a 900 HP (natural) 632 Merlin with no nitrous related problem.

I agree with Baja's point of money being better spent on heads,etc. It just depends on what you want, If all you're looking for is a cheap way to "suprise" people from time to time NOS is hard to beat. One cool thing about NOS is that if you pick up say 7 mph while on it, when you get off of it you might only lose 3 mph....so you still net 4 even though you are off the squeeze....

tmthunder, you might want to check out the latest issue of "Boating" magazine(maybe last months, i will find out which one exactly and post again, it is at work). But it has a great article about it. They put it on a 260hp 350ci. They talk about the entire instalation and how to use it. Sorry I cant remember more about it right now but it is prob worth the 5 or so bucks to help you make a thousand or so dollar decision.

One question comes to mind. Is it really worth it for a 15seconds or less, blast. Not me, but if it is for you, then go for it. Remember like jdnca1 said, it's SET-UP SET-UP SET-UP.
Hope this helps, Mark

Brian;

Even if your set-up is perfect, I would only recommend you being on the button for a short while. Personally, I would not bother with it. Eventually, it will cost you a motor. If you are not experienced with it, the motor will come sooner than later.

It should be noted that the most effective use of Nitrous is on the "pull". In a boat you might be able to hole shot a little better(if you don't blow the props out) but any significant run and you risk a lean out and BOOM. IF you are setting up for a boat remember to run way richer than the same motor in a car. The thing that kills nitrous motors is lean mixture. The power will go up as you jet leaner and leaner and that's why people do it, until the pistons melt from the high comb chamber temps

Aside from the huge amount of gas needed for a long run(one mile) it is unlikely the fuel could be maintained in a high enough amount to prevent lean out.

I just had a thought about nitrous. Not that I am thinking about it. But, if you were to add a kit, how would you select a prop? If you pitch up for the extra power when using nitrous, you are over pitched when not using nitrous. If you pitch for your regular engine power, you will be on the rev limiter when using nitrous.

My opinion,
is that N2O would be a waste on a marine application, sure a few MPH's would be good but N2O adds a ton of torque ...instantly , if your running a Bravo thats not good.

N20 does NOT melt pistons unless it is set up incorrectly. And as far as your engine set up there is no difference. That is why a N2O setup has its own fuel pump and regulator. A lean condition is what hurts a motor on the spray.

I used to run at least 2 bottles a weekend thru a STOCK 5.0 litre Mustang . I was running a 250HP shot. this was on a carb motor, fuel injection adds many more issues. I had a really cold set of plugs and ran 112 octane gas and had 7lbs of fuel pressure on the nitrous side.
12.40's no spray /10.80's spraying
I also have a friend with a 600HP kit on his small block Ford, that motor was build for Nitrious.

Nitrious is your friend but not in boats

I have riecently dissasembled three NOS motors one was biult for it from the get go .... bearings were a mess ... if I was to do it to a motor I would trear down the engine and inspect it off season.

That's quite the stock mustange at 12.4!