Go BottomThree vs Four Cylinder Engine
 | Mike
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1999-04-24 3274
What are the advantages to a Four Cylinder vs Three Cylinder engine? Thanks,Mike
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| guest
Join Date: Aug 2017 Posts: 0
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1999-04-24 3276
If all other things are equal, such as displacement, head design etc then the only advantage 4 cylinders would have is less vibration. The 3 cylinder would actually be more efficient. The most efficient engine would be 1 cylinder of the same displacement but that would vibrate a lot. The reason for the higher efficiency has to do with the ratio of cylinder volume to cylinder wall, head and piston area. The larger the wall, head and piston area relative to the cylinder volume the more it cools the combustion process and lowers efficiency. Higher efficiency would translate into either better fuel economy or more horsepower. Less cylinders also mean less parts, so it costs less to make the engine and to rebuild it. If both engines have the same design life then durability is not a factor. Three cylinder engines can run very smooth, so I don't see vibration as much of an issue. Look at all the guys that swear by the 6 cylinder Cummins in pickups over the V8's in other brands. More cylinders are not necessarly a better design. ....
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1999-04-25 3282
There are no significant advantages or disadvantages either way. Roger L ....
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1999-04-25 3284
Most 4cyl engines use mechanical balancer units to counteract the natural imbalance of the 4cyl design. 3cyl engines don't need this feature, necessitating fewer moving parts. 3cyl engines typically sound a little coarser than 4's of the same design. The reality is there is no clear advantage either way. ....
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| Andy
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1999-04-25 3286
I've heard before about 4 cyl engines having balance shafts?, but I don't understand why a 4 is less 'balanced' than a three. Could you explain more? Thanks. ....
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| guest
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1999-05-02 3384
the v8's are gas, they people who have the cummins want more low end torque to pull heavy equipment. Four cylinder engines are better depending on who makes them. The reasons why is because the engine has to do less work. A 3 and 4 cyl. engine with the same hp, the 4 cyl. will last longer, because you are taking away compression in the other 3 cyl. and putting it into the 4th cyl. which puts less stress on the engine.Same way with cars, to match the power of a v8 the manu. has to add more compression to the 6cyl to make more horse to match the v8. They do this by either adding a supercharger, turbocharger, grinding the heads down, smaller combustion chambers. ....
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1999-05-02 3396
I was comparing the 6 cyl Cummins to the 8 cyl diesels not gas. You are wrong that a 4 cyl with less HP does less work than a 3 cyl. HP is the unit for work, if they have the same HP they are doing the same work. Each cyl in the 4 does less work, but then it is smaller and usually designed with less strength. Parts in an engine are designed for the loads placed on them while operating. Compression has nothing to do with what was being discussed. The effects of compression are independent of the number of cylinders. If we used your logic then 4 cyl engines last longer than 3 cyl engines. So 6 cyl engines last longer than 4 cyl engines and 8 cyl engines last longer than 6 cyl engines. Those 16 cyl engines made by Jaguar must last just about forever and have almost no compression. ....
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1999-05-03 3441
Both engines with yield the same horsepower, everything else held equal. Three cylinders will vibrate more as deisels are 4 cycle engines. Only one of the cycles are the power stroke and the other cycles are to pull the fuel/air in, push the exhaust out, or compress the fuel/air mixture. What happens with a 3 cylinder engine is that at one point in time the engine has no power stroke underway - that is where the vibration comes from as the engine is essentially coasting for an instant (until a power stroke kicks in for one of the cylinders). Four cylinder engines always have a powerstroke at all times (one of the cylinders are firing).The practical difference is that four cylinder engines have higher low end torque as that is delivered during the power stoke. With the engine running slower at low RPMs, more time passes before the three cylinder engine has a chance to fire (this time is extremely small - milliseconds?).At higher RPMs, the difference becomes trivial between the two engines. As far as cost, that has been posted and fits common sense (more parts = harder to manufacture, etc).Hope this helps,Lee ....
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