baxternick

My Feedback: (19)

I am running a os TZ .18 in a boat of mine but came over here to get a couple questions answered. First what is the average temp you guys run these motors at? I am getting 165 peak with the head water cooled, but I am still a little rich too. I wanted to get more out of the motor but not burn it up. I dont know crap about nitro motors except airplanes, because I fly them all the time. Also where are most of you guys running your high needle at? I am at 2.5 turns out on mine. Thanks...

SManMTB

200-250F is common.

If your engine is running rich you should lean it out until it runs clean. Restrict the watercoling if needed so you get up in temperature a bit. 165F is way cold.

Colt4g63

I run boats as well and we restrict the water flow to the head when needed. You want the engine to at least run around 200 degrees. 165 is a little on the cold side and can reduce engine life.

SAVAGEJIM

Listn to SMan & colt, get this engine to at least 200degree F to get the sleve & piston diameters at proper sizes to minimize wear.

I un my TZ and it constantly is in an operating range form 210-240degrees F in dry hot (90degree F outside) conditions. With water cooling, you may want to reduce your water flow over the head so the TZ can built and keep its temp to 200-250 degrees F.

baxternick

My Feedback: (19)

I am running the motor on 30% with the high speed needle at 2.5 turns out. Do most of you have the same setting?

SAVAGEJIM

My TZ setting is probably les since mine is totally air cooled. Since yours is liquid cooled, even turning th HSN all th way out such taht it comes out may not be enough. Water has a very high specific heat as compared to air, what I mean is water will absorb a great deal more heat than air. So, you mus reduce you water flow over you engine s part oof your engine tuning. Turn out your needes such that teh TZ operates the best, but also reduce the water flow over th had such taht the TZ can reach proper operating temps.

Spetz

But water cooled motors generally should be cooler.
Of what I heard, if you run your watercooled boat motor at car motor temps, you will quickly destroy it

baxternick

My Feedback: (19)

I currently have brass tubing wrapped around the turbo head to keep the motor cool. I have it wrapped around 8 times, but I am going to decrease it to about 6 and see if that gets the temp up some. All the boat guys that have the motor are saying they try to keep it sub 200 degress so I guess I am close, but will bring it up a little. I will say this motor is a beast in my boat, and it has been the best nitro motor I have had thus far. TROUBLE FREE!! I just want to go faster. I am getting 42mph on the gps now, but most guys are getting almost 50. I have similar setup, just figured I could squeeze more out of the motor. I was thinking in relation to airplane that leaner would be more rpms (speed) as long as the temp is within a good number, but I think now that no matter how much I lean it the motor will never get to wot because of the cooling coils being to much... Thanks guys....

SManMTB

I raced boats.


Don''t lean it out too much. In a boat you should richen it up until it goes rich and then just lean it until it runs clean and then adjust temps with water flow. The engine will be cooled my the fuel. Remember you want to burn as much fuel as possible to make power and if you can make it run clean and still burn a lot of fuel you''re on your way to going fast.
Probs and pipe lengths are another big thing to play around with. If it can''t turn the prob lengthen the pipe in steps of 1/8" and try again. If it does pull the prob you can shorten the pipe until it can't pull it through the corners and then lengthen it back out until it does.

Try bigger/smaller probs. Make the leading edge of the props sharp as knives and BALANCE them. Makes a HUGE difference.

Go up in Nitro too. Marine engines are usually set up for high nitro (50% or even above that). I ran 65% Nitro in a MAC .67. Never got enough tuning time to get it running perfect but when it came on the pipe..... holy F!

Boats are finicky and squeezing those extra 2mph takes a lot of testing.

SManMTB

One last thing. Don''t run car fuel in a boat. You wan''t to have fuel with a bit more oil than is common in cars. The reason is you''re almost always at WOT when racing boats and that little extra bit of oil works wonders.
I know some are going to come in here and post about using less oil.... sure it works in cars but it''s not going to work in boats, I know because I tried and raced for many years.

I used to use RedMax 65% blend but now you can''t get any higher than 55% unless you mix your own.
[link=http://www.fhsoils.com/prices.html]FHS Oils website with fuel.[/link]

SAVAGEJIM

Yes, I believe that is tue of an engine that is designd specifically for boats. In this case, he is useing a car/truck engine in a boat and water cooling it. (I personally would never put an engine designed for a car into a boat. I would also never watercool an engine that is designd with air cooling in mind. The same is true of the converse: I would never out a boat engine into a car and try to air cool it when it is supposed to be water cooled.)

SManMTB

I guess you are out of luck then because most marine 3.5cc engines are identical to the car engines, just a different cooling head. Look at the RB, Picco, OS, CMB, OPS marine engines. They are the same as the car version. No difference in design.
Don't know what you base your statement on and why you wouldn't water cool a car engine.

SAVAGEJIM

I am basing my assumption in that there are metallurguical differences and/or heat expansion diameter expansion differences between a boat vs car engine. Granted, I do not know the exact dimensions and design tolerace diffeneces betwen a marine engine versus a car engine, I do know that the heat capacity of water is much muich greater than air, and it does not take alot of water run over the head to remove a given amount of heat that much more air would be required to remove.

Heat and maerials expansion from heat is what I base this statement on. I was unde the impression that marin engines run cooler because of water's better cooling capabilities. For a car engine to be adapted to water cooling, that engin bette reach the very same operating temps as it reaches if it were air cooled.

When you sae boat engines are identical, you mean just that dont you? The exact same materials, the exact same dsigned metal expansions and dimenstions after heating? Therefore, the exact same operating temps? If so, the cooling system would be designed and tuned by the manufacturer to cool the engine and allow it to run at the very same temp ranges as the air cooled brother.

SManMTB

Yes, identical. Marine engines are not designed to run cooler than car engines. Not at all. I have no clue where you get that impression from or who told you that. It's simply not true.

The car and marine engine are cooled at the same place (on top of the cylinder). It doesn't matter what the cooling medium is, water or air. The internal temperatures will be the same. Granted, it's very easy to over cool a marine engine and it will cause it to seize up. Seen that happen too.

The tolerances are no different either. A new marine engine is just as tight as a car engine when new. Way back (actually in '92) I raced in the World Championships for FSR-V endurance boats. I ran the 7.5cc class and my dad ran the 3.5cc class. Before the competition the 3.5cc Nova marine engine bit the dust and we needed someting fast so we headed out to the local 1/8 scale on-road track and talked to a few drivers and stumpled on a driver running Nova engines. He had a box full of used piston/liners that he felt was used up and we got a set almost for free. It was still tight as hell.
We put it in the engine and raced.

What more proof do you need? I have seen car engines being put in boats with water cooling.

SManMTB

On top of this part numbers are very often the same too. I was going to write this in teh previous post but I knew you would call me on it without proof.... so I had to find it first:

Here we go. OS RG and OS RG-M (marine) parts list. Check the piston and liner.
[link=http://www.osengines.com/parts/xr13610.html]OS RG[/link]
[link=http://www.gpdealera.com/cgi-bin/wgaprt100p.pgm?I=OSMG1624]OS RG-M[/link]

Another one. OS RZ-R and OS RZ-M (marine)
[link=http://www.osengines.com/parts/xr13830.html]OS RZ-R[/link]
[link=http://www.osengines.com/parts/xr13850.html]OS RZ-M[/link]



Hope this is enough proof.

whtleroy4you

I do believe that the only reason boat engine are water cooled is becuase most boats have a cowling over the engine so the engine never gets enough air to cool it so they came up with water cooling. plus it looks cool! but running a air cooled motor in a boat isn't bad at all and it is cheaper.

SManMTB

It's also easy to control the amount of cooling with water cooling.