Busting the Myth?

[teamvictory]

Recently, I purchased a GO Engine .25 buggy/offroad motor with the intention of putting it in my new catamaran; the engine & specs can be found at http://www.go-engine.com/in-products/R2500-M00HSG.htm

After doing an extensive amount amount of research, I learned a great deal about car motor conversions [for boats] and port timing. I found out some interesting things, though...

With my motor, came an exploded view & parts list. I checked the part numbers for the crankcase and sleeve/piston and found these to be 25-0800 and 25-2103, respectively.

I then sent an email directly to GO Engine and requested timing specification for their 'marine-spec' .25 so I could compare. In the reply I did not receive timing specs however I did learn that "MR2500-P60HOS (marine .25) crankcase parts No: 25-0800 & Cylinder sleeve/piston parts No: 25-2103"

That being said, clearly these two different motors share the very same sleeve, piston and crankcase; so, these two motors share the same port timing. The stroke of both motors is also identical, the only difference in the bottom end being one SG crank and the other OS-style. On the top end, one motor is water-cooled too, of course, and features a rotary carb instead of a slide.

Somewhat confused by my finding - especially after all I've read on the boards - I placed a call to Rick Brake of RBMods. Rick is widely regarded as one of the best in the country when it comes to nitro motor mods. What he told me also came as a surprise. With over 25 years experience working on all makes and types of nitro motors, he has seen many car motors that are exactly the same as their marine counterpart. According to Rick, most manufacturers use one design for a given size motor in car and boat applications. Apparently the only "true" boat motors are those with rear induction ports. All others with carbs mounted on the front above the crankshaft are "car motors".

Still, re-working a motor IS definitely beneficial to performance in that the powerband and output can be optimized for a specific application but that's not to say it is a requirement. I now plan on installing my GO .25 car motor AS IS to see how it performs stock in my cat. After all, it should perform just as well as GO's marine-spec .25, right?

teamvictory

 

[Jerry Wyss]

You'd probably have to go all the way to China to see somebody to run a Marine GO 25 motor :lol:

Novarossi made the most powerful 21 engine and as I remember none of them had rear

induction that I have seen,, coulda missed one though.

A 25 is not really a popular engine due to it's lack of a racing class for one, in China, it's prolly a hoot.

Pull start's suck, big drag is possible on a little motor depending on system.

Your dilema is mostly, do I want to run a 50 hp motor in my V-Dub or a 150hp,, personally I'd

take the 150 any day. I used to kill Corvettes with 150hp back in the day,, like I told you before,

it's not really what you have, its how can you make what you have, run, that makes the difference.

JW

 

[Preston_Hall]

Maybe so for a GO engine.

If you have ever tried a car pipe on a boat or vise versa then you can instantly tell that the two pipes are made for two different engines. If a manufacturer does not time their engine to the pipe................well that tells the story there.

 

[longballlumber]

Just to add to the mix...

O.S. RZ-M (marine) and the O.S. RZ-R (on road) have the same P/S, threaded crank, and rod. It's a pitty they don't make this motor any more...

 

[teamvictory]

Jerry, first of all GO Engines are not made in China. Secondly, I don't plan on racing the boat, so no .25 class isn't an issue here. Pull starters can be a bit of a drag - pardon the pun - but there are GO .25 buggy and boat motors available without.

Preston, I didn't say that all motors are the same but there are motors out there used for both cars and boats. Pipes are different story.

longballlumber, its funny you mentioned the O.S. RZ-M and RZ-R motors as O.S. is one of the manufacturers that was named by Rick. NovaRossi was another, but again that's not to say ALL of their car and boat motors are identical.

 

[tnrcboatracer]

Jerry, first of all GO Engines are not made in China.

The contact info on the GO Tech web site has them located in Taiwan (R.O.C.): R.O.C. = Republic of China.

The torque requirements for a car engine vs. a boat engine are very different. I have measured many car engines, and typically, their timing is significantly less that the typical marine engine. That does not mean that the car engine will not work, they will, but you need to rev them like a car, and that often means less torque, which in turn means a smaller prop. It can work, and in fact I have tried it on my EB Mods Rex .21; but I still raised the timing a little above the original car timing.

 

[RaceMechaniX]

Another note about the O.S. motors: The VZ-M shares most of the same parts as the current VZ-B and VZ-R with the exception of a non-SG crank and three port liner. I have not checked the port timing of the specific m versus the r or b sleeves, but shimming the liner and adjusting the squish probably make one very close to a Novarossi. I may out on a limb here, but seems like the fastest .21's are still rear exhaust motors from CMB or MAC. Granted almost any of these motors can be modified to the hilt to achieve similar performance.

TG

 

[Preston_Hall]

Jerry, first of all GO Engines are not made in China. Secondly, I don't plan on racing the boat, so no .25 class isn't an issue here. Pull starters can be a bit of a drag - pardon the pun - but there are GO .25 buggy and boat motors available without.
Preston, I didn't say that all motors are the same but there are motors out there used for both cars and boats. Pipes are different story.

longballlumber, its funny you mentioned the O.S. RZ-M and RZ-R motors as O.S. is one of the manufacturers that was named by Rick. NovaRossi was another, but again that's not to say ALL of their car and boat motors are identical.

I do not think that I implied that.

Anyway, other than pistons and sleeves, are the sleeves placed the same in the case (top of piston to top of sleeve)? And what about crank timings? Head buttons?

 

[topfuel443]

Bottom line, good car motors do not make good boat motors without work, and good boat motors do not make good car motors without work. Its not rocket surgery, its just the way it is.

~James

 

[Jerry Dunlap]

Bottom line, good car motors do not make good boat motors without work, and good boat motors do not make good car motors without work. Its not rocket surgery, its just the way it is.

~James

They're operating in rockets now? Jeez, no wonder the cost of health insurance is "out of this world."

JD

 

[Ron Olson]

Having played with several .12 engines I can tell you that some of the car and truck engines do work well in boats and many others don't. The O.S.'s do go from truck to boat very well whereas others that are hot engines in trucks like Fantom's and LRP's don't with a great deal of disappointment and money to find that out.

You're talking about a cheap Chinese knock-off engine there. Some of then they're not even changing the cranks on as they come with SG threaded shafts which are a pain to adapt for boat use. Simply throwing a water-cooled head and a flywheel doesn't neccessarily make it a good boat engine.

 

[teamvictory]

LOL. First of all, GO Engine does in fact offer motors with OS-style fully threaded cranks for marine use. Many don't know this because the company is so new and better known for their offroad motors. Some GO sellers just buy whatever they can get their hands on (i.e. offroad motors) and simply install a water-cooled head and flywheel, then sell it as a "boat motor".

Secondly, prior to purchasing my motor I read all the reviews I could find on GO's product and literally did not find one bad write-up. These motors are gaining popularity in the buggy class in Europe and are actually winning races. That doesn't make them good boat motors but as we all know, motors can be re-worked, if need be. At least the motors seem strong and for the price, I'm willing to give GO a shot. I can buy 4 of these motors for the price of one NR! If they only last half as long, I'm still way ahead.

teamvictory

 

[topfuel443]

Good points! Try em out and let us know how they compare.

~James