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Marine vs Car Engines / Nitro Fuel?

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Marine vs Car Engines / Nitro Fuel?

Old 07-23-2007, 03:48 PM
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Default Marine vs Car Engines / Nitro Fuel?

I have converted an OS 18 TZ to marine by machining the head to accept the OS Marine Head. I have found through a lot of experimentation that there ARE diferences. Breaking it in was a PAIN because, it appears, that I was trying to cool it too much. In talking to Car and Buggy racers - they run the engines much hotter (220-250) and when I restricted the cooling the engine came alive. The TZ is a high RPM engine so that seems to work well if you prop correctly.

Now for the question: What about nitro fuel? I believe, Car and Buggy fuel uses a lower percentage oil than boat fuels. Is this because of the higher temperatures or the lower average rpms? Cars race by accelerating from near idle to high rpm over and over while a well tuned hydroplane is near flat out for six laps. Temperature or engine speed - what sets the oil content.

While we are into it, what about nitro level, Cars run 10-20% and Boats run 20-65%; why the lower nitro level in Cars?

Are the engines actually built significantly different? Port timing? Engine materials? Bearings?

Thanks for your help in advance (where to post - under boats or under cars - I need someone with experience with both)!
Old 07-23-2007, 06:02 PM
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Default RE: Marine vs Car Engines / Nitro Fuel?

I am not an expert by any means but I am running an OS CVR .12 (car engine) in a .12 rigger with 6 of the 9 cooling fins cut off and the boat actually runs at about perfect temp. I am using 50% nitro with a synthetic castor blend of atleast 20% oil. I am stuck on reading plugs now so I am trying not to break rods or bearings, trying to run on the fat side always.


p.s. I wouldn't even consider a car engine in a boat over a .18 there are very good marine engines for that.
Old 07-23-2007, 09:50 PM
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Default RE: Marine vs Car Engines / Nitro Fuel?

You can use car motors in boat,They have more rpms and HP then boat motors.But you still need to use boat fuel.Car motors doesnt use that much castor because they dont have much load on them and there geared to take the load off the motor,But boats put alot of load on the motor,so you need that extra castor oil for added protection on the motor.We use traxxas car fuel in boats because the hobby shop doesnt have the boat fuel and we add 3oz to one quart of fuel to boost the castor oil content.
Old 07-26-2007, 09:17 AM
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Default RE: Marine vs Car Engines / Nitro Fuel?

This is the O.S. Max .18CV-RMX Marine Engine
Displacement: 0.18 cu in (3.0cc)
Bore: 0.63" (16.0mm)
Stroke: 0.59" (15mm)
Practical RPM Range: 3000-32,000
Power Output: 1.35 hp @ 28,000 RPM
Weight: 8.21 oz (232.6g)

This is the O.S. Max .18CV-R Engine
Bore: 0.63" (16.0mm)
Stroke: 0.59" (15.0mm)
Displacement: .18 cu in (3.0cc)
Practical RPM: 3000-30,000
Power Output: 1.35 PS/30,000 RPM
Weight: 8.4oz (237.5g)
Width between mounting holes same side: 0.4" (11mm)
Width between mounting holes opposite side: 1.2" (31.4mm)
Crankcase width: 1.5" (39mm)
Distance from coverplate to drive hub: 1.96" (49.9mm)
Distance from coverplate to end of crankshaft: 3.1" (79.4mm)
Distance from center of crankcase to front of case: 1.4" (34.9mm)
Height/bottom of crankcase to top of cylinder head: 4" (100.9mm)
Height/center of crankshaft to top of cyinder head: 3.2" (80.9mm)

Tell me the difference cause they use both : 10 to 30% nitro. However, they suggest starting
with 20% nitro and changing to a higher or lower nitro content
if required. Fuel should also contain 18% lubricant.

FOR MY MISS VEGAS you just need to buy the cooling head from 18CV-RMX Marine Engine AND SCREW anad that s it same thing

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