Re: trophy engine upgrade
I suggest you go to Yamahas web site and look at "Performance Bulletins". Select your boat, engine technology you are interested in (two stroke or four stroke). then pick the HP and you can look at the test reports which include speed, rpm and fuel consumption. You might find that what you think is going to happen is actually opposite of that. Keep in mind I'm not going to do your research for you, but if you compare a 2 and 4 stroke engine and the boat speed at any given rpm you may find that the two stroke actually is faster than an equivalent four stroke at the same rpm. How can that be? Simple. 4-strokes tend to be geared lower (higher ratio) so they rev faster to make up for the loss of hole shot most of them have. It is also possible that they have a different prop pitch. Therefore the two stroke can rev slower at the same speed of the four stroke. Because it is reving slower fuel consumption may be very little different. Look at those charts very carefully and make darned sure you understand what you are looking at. You are about to spend a bunch of money. Be reasonably certain that exchange of engines does what you expect it to do. And above all, believe half of what the sales guy tells you. After all, his job is to sell you a motor regardless how much untruth he has to spew in order to do it. One thing you will also notice -- a two stroke and a four stroke at wide open throttle come very close to each other when it comes to fuel consumption. And pay particular attention to the top speed of both motors at wide open throttle as well as hole-shot (time to plane numbers). When it comes to engine selection there is more to it than just "quiet and fuel economy". Speaking of quiet, last time I checked, Yamaha quit listing noise levels. Of the many times I looked at these bulletins, it was apparent that at wide open throttle the two technologies were not that far apart. A four stroke makes a different sound than a two stroke and much of the "quieter" debate can be attributed to type of sound rather than the actual noise level.
