Re: Four-cylinder v.s. six-cylinder?
Then a 400 HP 4 cylinder auto engine vs a 400 HP V8 auto engine should be equally confusing right??? Number of cylinders and HP are sort of related but a lot less than most folks realize. There is a term called "state of tune" that affects the horsepower of any engine regardless of the number of cylinders it has as well as the displacement (cubic inch/cubic centimeter) of those cylinders. I guess the best example of how HP can be manipulated would be to compare a NASCAR race engine and your family truckster. Your family Chevy with a 350 CI (5.7L) engine was built in a number of HP configurations ranging from a paultry 155 HP in the late 1970's to well over 350 HP. NASCAR, using the same engine modified for racing purposes has achieved 750 - 850 HP from the same basic design. Granted, the NASCAR engine would not make a very good grocery getter but it illustrates the "state of tune" principle. So now lets look at V6 engines. Buick built a 3.8L V6 that Menards ran in Indy cars some years ago. That same engine appeared in the Buick Grand National and produced in the vicinity of 300 HP. It began life barely cracking 100 HP. So any engine with any number of cylinders does not have one specific HP. It can be built in any number of configurations to meet specific requires from powering a truck (low end torque) to a race car (little low end torque but lots of high end HP), to your family truckster (falling somewhere in between to provide optimum economy). Torque on the other hand is limited somewhat by displacement of an engine. 4 cylinder engines are typically limited to about 2.5 liters for auto use because of the harshness and vibration if displacement is increased above that. That's why you didn't see the 3.0 Mercruiser 4 banger in a GM car. V6's came about because of their compact dimensions (ver short engines). 90 degree engines were the same width as their V8 counterparts because they were identical except for the missing two cylinders. 60 Degree V6's were narrower and came about because of transverse (sideways) mounting in the front drive cars. V8's are still around as are V10's and if you have a few bucks, you can buy a V12. As for outboards, it is all the same theory as for automobiles. 90 HP is 90 HP whether it is delivered by a 3 cylinder, 4 cylinder or 6 cylinder engine. It takes a given amount of fuel to make 90 HP so all of those engine would consume about the same amount of fuel at wide open throttle (give or take a tad). The 4 and 6 cylinder would get out of the hole quicker and tow a skier better than the three cylinder. The three cylinder would be lighter and probably just a tad more economical than the 4 or 6. If you look at specs for any of the major outboard manufacturers you will see at least two, sometimes three, and in some cases four different horsepower ratings for what appears to be the same basic engine. The engine is the same ONLY in displacement. Different in the "state of tune".
