Removing water from exhaust flow? Should I do this?
 

I've had several engine builders tell me it would be adventageous to lessen the amount of water that goes out my exhaust. Can I simply run the water that normally goes into the risors (from the thermostat housing) out the back of the boat? Is there still enough water running thru the manifolds to keep the rubber exhaust hoses from melting?? I am running EMI Thunder Exhaust with the aluminum risors.

I'm not concerned with noise. I know it will be louder. I have friends in high places on the water!! And I'm running Drew Shotguns to take the "bark" out of it anyway.

Any thoughts would be appreciated.

water,
Good question I'm welding extentions on to the back of the EMI's And cutting down the waterflow. The extentions are for reversion and the water is for HP. I'll let you know. Greg

How do you like the Shotguns. I will have them this year as well. I was wondering if you could put a cotter pin in to hold the mostly closed if you were taking a night cruise or neded it queiter. As long as all the water can get out.

WF- I have the same EMI aluminum exhaust and have the water plumbed into the manifolds in the front fittings only. I have no water going into the risers from a separate hose. No problems for 3 years.

Foul. There was a string on this a while back. I looked for it but no dice. I know that with the newer motors there is only one hose that goes to the bottom of the manifold. They no longer have one going to the riser. SO maybe you can just get the newer style T-stat and plug up the hole in the riser. Another possibility would be to use your manifolds as preheaters for the engine water and then go out the risers. This striked me as very sensible. I think that Cord started that thread a while back. I am not sure what the difference is btwn the water preasure with and with out the dual hose going to the risers. One last way to regulate the water flow that I can think of is to change your pully diameter but I would be real carefull of doing that.

Jon

'Foul,

I switched to a set of late model Merc manifolds when I installed my big block. These only have the hose connection in the lower front of each manifold - no hoses to risers. I fabricated a set of "T" fittings for the hoses coming out of the T-stat. Works fine so far - saved the cost of a new T-stat housing.

Not sure if I gained anything by doing this, as I was upgrading from a 350 mag, so nothing to compare it to.

The whole reason for running the top hose overboard is to lessen the amount of water going out of the exhaust to lessen backpreasure. The problem with doing that is untill the thermostat opens there will be almost no water going out the exhaust and you will burn up the exhaust hoses. Some people drill holes in the thermostat but at idle the engine runs way too cold. What I did was figure out the path of the water going through the thermostat housing and drilled 2 -- 1/4 inch holes bypassing water directly from the inlet side of the housing directly to the area above the thermostat ( this flows water to the bottom hoses thus sending water to the exhaust without going through the motor)

WATERFOWL if you want to do this I will drill your housing for you.

(WARNING THIS WILL MAKE YOUR EXHAUST VERY LOUD)

tHE OTHER THING I DO IS SPRAY THE DUMPED WATER DIRECTLY ONTO THE OUTDRIVES SINCE IT IS ALMOST LAKE TEMPERATURE.

I am trying to do the same thing. I just looked at mine and figured out the flow.. My housing has 2 big outlets (raw water in and water to circulating pump) and 4 small outlets ( 2 to the risers and 2 to the manifolds.. When my stat is closed the circulating pump and risers get water. When the stat opens water gets to the manifolds.

SO could I switch the hoses so all time riser water goes to the bottom of the manifolds and take the manifold water (only when stat is open) to the dumps. Really I would switching the risers outlets with the manifold outlets.


Ok. 1 more question. On the riser outlets there is this assembly of a long rod, springs and two balls (one in each outlet).. Can I take this out and throw it away?..... or is needed for something?



Travis

Tinker,
I understand what you are talking about, assuming(which I hate to do) your thermostat housing has only 2 outlets. I am not sure what housing Waterfoul has, however, I have the 4-outlet(really 2-inlet, 2-oulet) thermostat housing which has a bypass kind of like the one you created. It is from Rex marine. This bypass feeds water to the risers at all times even when the stat is closed. The bypass hoses to both risers is 5/8"dia. My thought on decreasing waterflow for this set up is to install a tee at the riser, decreasing the inlet size to the riser(thus reducing water flow)and provide a dump line from the last oultet of the tee to the transom sized smaller than the 5/8" inlet but larger than the riser feed.

Waterfoul, am I on track for what you are trying to accomplish? What stat housing do you have?


Paul

His picture of the engine on his website shows the older style housing with two large and four small fittings. I have the same type, but with the two smaller hoses going into a "tee" and then into the manifold.

I'm also curious to see what gains could be had by limiting water flow. However, I would be hesitant to try it on mine because I am running silent choice.

Tinker are you still using your silent choice?

".....(WARNING THIS WILL MAKE YOUR EXHAUST VERY LOUD) ...."
Cool :p do it mike!

don't let waterfoul kid ya, he wants the sound just as much as the performance. good thing i wont be laying back behind him listening to that every monthly "poker run" we hold.


hey, how about this idea. poor man's silent choice. a solenoid valve to open when engine is cold, cooling the rubber pipes until the thermostat opens, then close it off for more noise, power, and speed?

i'm going to submit a patent for this idea, so don't steal it Waterfoul. you can be my test fixture;)

anyone ever dyno with/without the waterflow in the exhaust.....


oh...who cares,
it's all about:
step 1) looks fast - cheapest
step 2) sounds fast - costs $$
step 3) be fast - cost $$$$$$$$$$

Yes I still run my silent choice and THE WHOLE IDEA IS TO LESSEN THE AMOUNT OF WATER GOING TO THE EXHAUST. I havn't tried this on the newer style housing. TRAVIS you don't want to switch the hoses because that won't help and may cause condensation in your exhaust since you will be putting cold water into your exhaust instead of the engine water. With the new style housing what you could do is T the lines going to each exhaust manifold and run the line overboard. put a valve or some other device into the line to control the water flow.

Hey Tinkerboater,

Do you have the early model flappers in your Y-pipe (metal with pin and bushings) or the later type (composite rubber)? I have the later type in mine, and I'm concerned about burning them out of there if I reduce the water flow to them too much. Seems to me like it might be a good idea to route some water directly to this area to keep them from burning out. Not concerned much about water in the exhaust anyway when in thru-prop mode.

What are your thoughts?

Did you see any measureable gain when you made your changes?

Tinker.. Mine is impossiable to drill.. SO what I thought was using your idea but using a bypass hose instead of holes.

So what I thought of was drilling and tapping a hole into the top of #1 and #2. SO then I could fab a bypass hose ( 1/2" i.d. ) to carry water from #1 to #2 while the stat was still closed.. so the manifolds will have water while the stat is closed


and still just running the orignal riser hoses out to the dumps.


Hows that? or am i really confusing everyone LOL!

BUDMAN the flappers in the down pipes won't last -- most people just remove them -- I did and havn't had any problems.

Travis if you have the older thermostat housing you can drill them.

Did you see any measureable gains, or did it just make it louder? :D

Tinker... check your private messages..


:D

Cutting back on ther water will lean out the engine a little and will increase rpm. How much depends on the engine. But I have seen an increase on a stock engine with stock exhaust. Just watch the exhaust hoses because it is easy to burn them up. If the hoses are getting too hot just increase the size of the bypass holes.