With that said, though, before this thread I was "sold" on upgrading to a 90 ETEC. But, I'm starting to look at the new Honda 90...
What about the lack of torque in the Honda 50? Granted a 90 is, well a 90, but maybe not the same 90 as the etec. Anyone know how the Tohatsu 90 stacks up against the etec?If it were me DLT, I would go for the Honda either way.
other than the fact that at the time i purchased my 90 TLDI, the Etec was 20% more expensive and a "new" unproven technology (high pressure injection which runs hotter than Tohatsu), the ETEC is cleaner (3 star vs 2 for Tohatsu) and is said to be smoother.delevi wrote: Granted a 90 is, well a 90, but maybe not the same 90 as the etec. Anyone know how the Tohatsu 90 stacks up against the etec?
From my teen and 20-some racing days, we were always looking to improve horsepower by overboring our Chevy or Ford engines. When bore exceeds stroke, it's called an "oversquare" engine, and favors horsepower over torque. (actually, I think it just shifts the the two curves along that engine's RPM range).delevi wrote: Anyone know how the Tohatsu 90 stacks up against the etec?
.Wikipedia wrote:Bore/stroke ratio
Bore/stroke is the most commonly used term, which is mainly used in the USA, Great Britain, Australia and some other countries.
An engine that has wider bore vs. stroke has a bore/stroke value of over 1. For example an engine which has 100 mm (millimeter) bore and 80 mm stroke has a bore/stroke value of: 100 mm / 80 mm = 1.25 .... Such an engine is referred as oversquare or shortstroke engine.
An engine that has shorter bore vs. stroke has a bore/stroke value of under 1. For example an engine which has 90 mm bore and 120 mm stroke has a bore/stroke value of: 90 mm / 120 mm = 0.75 .... This type of engine is called an undersquare or longstroke engine.
An engine that has equal bore and stroke has a bore/stroke value of 1.
For example an engine which has both 95 mm bore and stroke has a bore/stroke value of: 95 mm / 95 mm = 1.00 ..... This type of engine is called a square engine. Usually engines that have a bore/stroke ratio of 0.95 to 1.04 are referred as square engines.
Wikipedia wrote:Undersquare
A piston engine is undersquare or longstroke if its cylinders have a smaller bore (width, diameter) than stroke (length of piston travel). This can be a negative trait, since a longer stroke usually means greater friction, a weaker crankshaft, and a smaller bore means smaller valves which restricts gaseous exchange; however, with the aid of modern technology, these are not the large problems that they used to be. An undersquare engine usually has a lower redline than an oversquare one, but it may generate more low-end torque. In addition, a longstroke or undersquare engine can have a higher compression ratio with the same octane fuel compared to a similar displacement engine with a much shorter stroke ratio. This also equals better fuel economy and somewhat better emissions. An undersquare engine does not overheat as easily as similar oversquare engine. Engines can be modified with a "stroker" crankshaft, which increases an engines stroke from stock, increasing torque.
Undersquare engines are typically shorter in length, but heavier and taller than equivalent oversquare ones, which is one of the reasons why this type of engine is not generally used.
I never noticed it before, but the earlier Honda 75 and the Merc Bigfoot were also undersquare designs. I guess the undersquare strategy has been helping the carbureted 4-strokes emulate the inately more torquey 2-strokes. (The Wiki quote describes some of the relative advantages of undersquares.)beene wrote:My 2005 Merc looks very close to the NEW Honda.
1596cc ... Bore 79mm ... Stroke 81.4mm
My thinking is that this motor will have plenty of torque to help jump the Mac up on a plane with minimal effort, loaded or not.
Wikipedia wrote:Undersquare (excerpted)
... a longer stroke usually means greater friction, a weaker crankshaft, and a smaller bore means smaller valves which restricts gaseous exchange; however, with the aid of modern technology, these are not the large problems that they used to be. An undersquare engine usually has a lower redline than an oversquare one, but it may generate more low-end torque. In addition, a longstroke or undersquare engine can have a higher compression ratio with the same octane fuel compared to a similar displacement engine with a much shorter stroke ratio ...
