Car Tech forum: V 4 vs V6 - same HP?

It is called an inline 4 cylinder because the cylinders are all arranged in a straight line. In a V6 the cylinders are arranged in a V with 3 cylinders on each side. There are many 4 cylinders our there that make more horsepower than V6s. Without getting to technical a V6 will usually be the larger engine with more liters because their are more cylinders, a 3.5 liter for example as compared to 2.0. Size is the first differnce.

Inline 4 cylinders typically make most of their horsepower in the upper rpm range. They are high-revving engines that have redlines in 7000rpm range or so. V6 engines make their horsepower at a slightly lower rpm. This all has to do with the size and design of the engine. Where the engines make their horsepower is the second difference.

Of course you have to look at the torque differences. Usually more liters translates to more torque. So V6 engines usually have more torque than inline 4s. Also V6s usually have more low end torque (lower rpms).

Ok lets say you 200HP Pontiac G6 and an Acura TSX
Pontiac G6
3.5L V6 (201 HP @ 5600 rpm, 220 lb-ft @ 3200 rpm)
Acura TSX
2.4L I4 (200-hp @ 6800 rpm, 166 lbs-ft @ 4500 rpm)

The Acura makes its horsepower at 6800 rpm where the G6 is much lower at 5600 rpm. The G6 has more torque than the Acura available at a low 3200 rpm. All of the torque in the Acura is at 4500 rpm. So they both have the same horsepower but many differences. Of course there are other innovations that change these numbers such as variable-valve timing and exhaust, electronic-lift, double over head cams, number of valves, and so on.

Hope that helps.

There are no V4s mass produced in an American automobile today.

''V6's also tend to be smoother, as in they rev smoother, they provide power more smoothly, and they cause less vibration.''

I'm going to argue that statement. Typically inline engines are more smooth and refined in nature because they are simpler in design.

http://www.answers.com/topic/straight-engine
Its very interesting.

Inline 4 cylinder engines are inherently rough due to a secondary imbalance from the connecting rods going side to side (front to back on a transverse engine) as the engine rotates. This becomes worse with larger displacement and is the reason 4 cylinder engines over 2 liters usually have counterbalancing shafts added to them.

Inline 6 cylinder engines have natural primary and secondary balance. It is hard to beat an inline 6 for smoothness.

V6 engines can be very smooth if they have 60 or 120 degrees between cylinder banks. They are usually also more compact and lighter than inline engines.

I'm guessing it saves space to use a V6, and probably is easier to produce. Since almost all car and truck engines have now gone to Vs, I'm guessing it's just for ease.