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Old May 12, 2015, 07:25 AM
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Tuned pipe cooling?

Hello all....I have a question regarding a tuned pipe on a boat. I am running a 32cc water cooled engine in a tunnel hull. The engine is moderately modified with a large carb with a velocity stack, electronic ignition, matched transfer ports, lightened flywheel, tuned pipe, fiberglass reed valve, etc. The head and exhaust manifold are water cooled supplied by a pump at idle and normal scoop pickup at speed.

Here's the problem. The tuned pipe has a water jacket around the inlet. If I run water thru that jacket, it comes out so hot it just spurts steam. No, the engine does not run hot. Yes, it has plenty of water flow thru the system. That water jacket just gets REALLY hot. Yes, I know that gas burns hotter than nitro/methanol.

My questions to the boat engine people: Do I need to water cool that manifold? Is there any benefit to cooling it? No, there is no silicone rubber connector on this boat. The pipe is sealed to the header with a fiberglass wrap system. Doesn't a hot exhaust flow better than a cold exhaust anyway?
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Old May 12, 2015, 09:00 AM
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As I understand it, yes hotter gases flow better thats why steel and titanium pipes would be an upgrade to aluminum ones . They hold the heat in better for this "idea" to take fruition. If the heat is not causing any problems with the coupling then I dont see why youd HAVE to run it. There are some advanced modelers using water injection at the manifold to "lengthen" the pipe and produce more torque. This limits the top end rpm. Lohring miller has utilized this effectively coming on and off the water at the right time gaining the benefit and still retaining top end. Theyre are some in Europe that actually use a telescoping header for this like youd find on some real kneelers.


"Water injection into the stinger muffler quiets the exhaust without changing the power. Water injection into the header cools the exhaust, "lengthening" the pipe. That helps the low end power but limits the peak rpm. We ran water injection on our CMB 35 SAW engine for more acceleration into the traps. The article on the CMB 35 test program (www.modelgasboats.com/magazine...5-record-engine) has dyno data on the effect.

Lohring Miller"


TTYL

Hugh
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Old May 12, 2015, 09:07 AM
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Just dump the water from the water jacket on the engine into the manifold out the pipe.
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Old May 12, 2015, 09:13 AM
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If you read through the article u will see that just dumping water in the manifold will have an effect on the running of the boat and how the engine sees the pipe.. Just be aware.
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Old May 12, 2015, 09:52 AM
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Thanks for the info. I think I'm just going to NOT use the water jacket on the pipe and let it run hot. The exhaust manifold is water cooled so it will stop "heat creep" from reaching the engine. There's no part of the boat close enough to the pipe to worry about that.
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Old May 12, 2015, 09:59 AM
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10-4 what 32cc you running?
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Old May 12, 2015, 10:28 AM
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Quote:
Originally Posted by Xfactor940 View Post
If you read through the article u will see that just dumping water in the manifold will have an effect on the running of the boat and how the engine sees the pipe.. Just be aware.
Can't read the article. Link doesn't work. This is how I run my boat. I see no affect at all. Water goes into the pump to the water jacket and out to the exhaust header out the pipe.
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Old May 12, 2015, 10:38 AM
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Im very curious as to what 32 cc u run wolf? Theres a reason youd want to know if it is 2 or 4 stroke.

I ll send u a pm with the link from Lohring.
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Old May 12, 2015, 10:43 AM
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What cc has nothing to do with how you cool your system. FYI im running a 32 cc
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Old May 12, 2015, 10:56 AM
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Quote:
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What cc has nothing to do with how you cool your system. FYI im running a 32 cc
Is water through a header on a 4 stroke and 2 stroke exhaust system going to work the same way?

Do all cc and brand engines run their best at the same head and pipe cooling temps?

I was also curious about the brand 32cc
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Old May 12, 2015, 11:22 AM
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Here is the link Ron, if you did not recieve it.

http://www.modelgasboats.com/magazin...-record-engine

TTYL
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Old May 12, 2015, 02:02 PM
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That's a nitro burning engine. I have a gas 32 cc engine.
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Old May 12, 2015, 03:10 PM
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"That's a nitro burning engine. I have a gas 32 cc engine. "

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Im sorry but the article is on The cmb 35 and 25cc which are not a nitro burning engines. This is what the engine looks like that holds the current GAS record .

See the carb?

The article is published on a gas boat forum. In it is a very detailed methodology of how they determined the effect of water injection at the header of a 2 stroke with a tuned pipe which was verified with a dyno and at the speed traps on the water.

Running the water collar on the out side the header is one thing dumping water directly into the header is something entirely different and likely has a much more prominent effect on how the engine runs based on the resultant temps. It does change things...

Setting the proper dry pipe length would likely be best for Ron .

Id still like to know what kind of 32cc were actually talking about here???

Hugh
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Old May 12, 2015, 04:59 PM
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All I run is ZENOAH A 2 ring piston.
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Old May 12, 2015, 05:12 PM
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deleted post .
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