New Dyno in Operation: New Zenoah Findings

For the past 4 years the Zenoah G260 has been the engine of choice for the gas model boater, and it rightfully should be, it is perhaps the finest gas production engine available. When we took this engine on, replacing the G23 (23cc Zenoah) in 2003 we saw our boat speeds increase by as much as 10 miles per hour! The G260 was and is the ticket, an easy to use, very durable, and affordable purpose built gasoline engine for model marine use.

This past January we received our new Dynometer, a State-Of-The-Art engine testing machine that replaced our old analog system dating back to the late 80's. I was very excited since this new Dyno was a “water-break” design with computer interface that would now provide us with very accurate information such as; Horsepower, Torque curve, Time relations, Temperatures, and even a computer weather station to compensate for the environmental changes from day to day or hour to hour or minute to minute.

I myself was a little concerned of this type of accuracy since the older machine required a calculator and paper and pencil calculations based on the individual readings we received from our older turbine/reciprocating machine. I was very interested in seeing the actual results and hoped they were close to what we have reported prior.

The first engine we tested was the Zenoah out of the box G230 RC, a fantastic air-cooled engine that we have been using in the Super G for over 5 years. The results were identical to that of Zenoah's claims. We pulled over one dozen tests and the computer readings were all within a few tenths apart. Zenoah claims that the G230 RC makes 2.88 horsepower at 14,000 rpm's. We steadily saw similar readings of these claims.

The next engine tested was the G260 PUM out of the box and this one really suppressed us, and me to the point to where we contacted the dyno manufacture and started to dis-assemble the machine to look for problems and even re-calibrate. The G260 PUM consistently pulled 2.8 to 2.9 horsepower at over 14,000 rpm's. This is an engine that we were told makes on average of 3.5 horsepower at 12,000 rpm's?

When I took these engines on I requested peak horsepower at the appropriate rpm levels and was furnished that information, but now the numbers didn't match.

We then went on the internet to find the conversion from Kilo Watt (the function of horsepower that Zenoah uses, metric) to SAE, our standard horsepower measurement. When we made the calculation I was surprised to see that in truth the numbers we received and have been using were not correct, yet the 2.9 that the dyno read was…
Here is the proper calculation to make convert metric (kilowatt) to SAE (horsepower):
Kilowatt to Horsepower: Multiply Kilowatt by .7465 = Horsepower
Example: 1.4 Kilowatt X .7465 = 1.045 HP

Now for the good… After checking the machine, putting it back together and spending over 3 hours on the phone with the manufacturer, I started making some phone calls to my engine buddies both in NASCAR and in the hobby industry. My good friend and well known engine builder in the hobby industry, Andy Brown was gracious to talk with me about my findings. With his help he brought up an important point that I overlooked during the confusion of the day. He said think about it…The engine is making that horsepower at over 14,000 rpm's not 12,000, and if this is the case then so be it, the faster you can spin the prop relative to the horsepower needed to do so, the faster you go. He was right, I knew that, but I myself was too caught up in the horsepower hoopla that we have all seemed to care so much about. He concluded that in his 25 years of engine building, horsepower was not the most important thing on his mind, but more-so the ability to turn the correct prop at the highest speeds, or enough power to turn the highest rpm's in transmissions on his world class nitro buggy engines. Now he said you need to educate the people on this subject, and not let them be sold based on horsepower only, especially when the peak HP readings are based at a lower rpm range.

Let me tell you, if you don't know of Andy Brown, in my opinion and backed by his world records in both model boating and success in almost any division of nitro engine modifications, he is truly the best in the business. For the record, Andy broke the 100 MPH model boating speed record over 10 year ago!

After I talked to Andy I spoke with Joe Nemechek NASCAR driver and engine builder, and Joe pretty much concluded the same. I also gave him the results of some pulls with our factory race engines which also showed less horsepower tested on the new dyno. He said you are making a little less power than though but look at the curve, our horsepower was at peak at over 16,000 rpms and a constant at over 15,000. We both concluded the same thing, even though the HP was lower than first calculated the HP at the high rpm range was outstanding and certainly enough to make our customers boats run in the competitive speeds that we were being told by all. As a matter of fact I had customers telling me that they were seeing usable rpm readings as high as 18,000 rpm's, and though I really didn't believe it, with these new findings it is more than likely true. I have always said, there is nothing wrong with surrounding yourself with the best in the business and listen to what they have to say. The day you think you are the smartest guy in your business is the day you begin to go out of business. A special thanks goes out to Andy and Joe for taking the time to help me think about this in a logical manor.

So where do we go from here? I had all weekend to ponder on this and here is my take on this newly found information… Nothing has really changed, only some numbers some lower but the most important one's are higher. Now I am really wondering if there is truly such thing as a 6 or7 horsepower 25cc 2-stroke engine, (that runs on pump gas, normally aspirated) and does it even matter? We now know it doesn't take 5 or 6 horsepower to turn a 75 mm prop over 15,000 rpm's. If it did we certainly would not be seeing the speeds we have been accustom to. Also, say we can make that kind of power, if it is done at anything less than say 14,000 the only alternative is to use a bigger prop, and what good would that do running a 82mm prop on a 45 inch hull, we would have prop torque issues that we couldn't deal with.

In the weeks and months to come we are going to use our new truth telling (lie detector) piece of equipment to make our engines even more efficient and report to you our findings. I have also decided to offer a free service for a short time enabling you to send us your Zenoah or CY engine, for 6 free Dyno pulls, and we will email you and send you hard copy of the results. You will be responsible for shipping both to and from Warehouse Hobbies. Be sure to insure your engine for its value in case it is lost in shipping.

To sum this up, this is not a bad thing. We know OUR modified engines are performing and the customers are pleased. We also now know that horsepower is not the most important thing when modified or in your case purchasing a modified engine, it is the ability to turn the correct prop for your boat at the highest rpm's. This is an age old known fact, that somehow got shadowed by “Who has the highest horsepower engines”. It has been 4 years that we thought that the G260's were making 3.5 horsepower and not a single person or customer has pointed this out. Everybody seems to be very pleased with Zenoah, and they should be, there is no doubt they have offered us a great product, and our industry has profited from it. On the other hand, if I were to let this slide and not educate you of these findings we would continue to go forward and be fooled with false readings. Ok maybe it sounds good if we said that we make a 7 HP engine, heck it's good for sales right? It has seamed to work so far… That's not the right way to progress in anything in life. In business I can be loosing money, but if I were to re-write the spread sheet over and over again, I could make it look like I'm in the black, by fooling myself with factious numbers, I hope you understand what I mean?

Now let's get smarter and in doing so we can force other manufactures to do the same. I am open to comments by customers and my competitors, and I personally challenge other peoples findings to compare against my own. I can be reached Monday thru Friday from: 9:30 am-5:30 pm Est.

Sincerely,
Tony Castronovo
President, Warehouse Hobbies Inc.
2-4-08