I-6 vs. V-6

A&Q about 350Z

What is the difference between an inline engine and a "V" engine?

An inline has all the cylinders arranged in a straight line. (like this)
|| || || || || ||

A V engine has the cylinders arranged in a V shape, like this:
.................\\ // \\ // \\ //
..................\\ // \\ // \\ //
....................\/ \/ \/

I hope those pictures kind of make sense. There's many differences between the two, but one of the main ones is that Inlines produce more torque.

exactly. Any engine in the "I" formation will produce more torque than it's "V" counterpart. 4, 6, 8 cylinders, doesn't matter.

I engines usually weigh less then V engines cause they have less metal on them, but V engines (depending on the degree of the angle) have a lower center of gravity but flat engines have a way lower center of gravity than both. although a flat engine is usually not strong enough to be a strassed member of a chassis (not good for F-1 or cart or indy or that sort of racing).

Ya, I know how the engine is arragnged. I was wondering what it did for the engine in terms of HP and torque.. I have an F-150 I-6.

Every engine will be different, while they will have the same cylinders, its all in how you set it up. Mind you this is very generally speaking, but I-6 motors tend to have a flatter torque curve, not lower but flatter. Where as a V-6 will have a sharper peak, I-6 tend to keep the same torque over a longer rpm range. A problem with I-6 is the intake. To keep costs low on the production of the vehicle, the runners on the intake mandifold will be shorter in the center two cylinders as opposed to the outter cylinders. For your truck, I really wouldn't worry about it. Im guessing your truck is perhaps a late 80's/early 90's F-150? If so, you're set, those motors tend to have a long life span and are generally 'torqy' for their displacement.

But again, for all general purposes, setup makes all the difference. For example, the nissan skyline motor is an inline 6 and can be setup to make over 1000+ hp (
) where as the buick grand national is a V-6 which can also be made to produce 1000+hp

Hope this helps...

I agree. Generally speaking, this is because I6 engines have had relatively small cylinder bores (which makes the engine a bit shorter, to fit better under the hood) and relatively longer cylinder strokes (to maintain/increase displacement) This means the I6 design lends itself to higher torque/lower rev applications, like trucks etc. The I6 diesel engine is by far the most common layout for medium and heavy trucks, for this reason. Even most 6 cyl american light trucks made since WWII use this layout.

V6 engines are not as constrained by engine length, so cylinders can have relatively larger bores and shorter strokes without making the engine too long. This allows a V6 engine to fit in a wider variety of chassis and allows them to make more power at higher revs.

V6 engines are usually slightly more expensive to manufacture than an I6 engine (more parts and more castings) but are slightly lighter than an I6 engine

Finally all things being equal, the I6 engine has two less engine bearings and slightly less internal friction, for slightly better fuel economy.

The I6 engine has perfect primary balance of the reciprocating assembly, and evenly-spaced cylinder firing sequences, so they are slightly smoother running than a typical V6 engine. However, lots of V6 engines have balance shafts, and/or staggered crank shaft journals or have a 60 degree cylinder bank spacing) so one would not notice a difference.

No engine configuration will directly affect power or torque.

The configuration of the engine is a package/vibration issue. A V6 engine is for example much more compact, torsional vibration of the crankshaft is also a much smaller problem than with the I6. The V6 engine is therefore suitable as racing engines and compact engine installations.

The I6 engine has much better balance, but there are issues with torsional vibration of the crankshaft and camshafts. This engine is suitable when you want smooth performance.

Boxer engines are not desirable in racing since there isn't room enough for exhaust manifolds and/or diffuser tunnels. A wide angle V engine is then a much better choice.

Saab, please don't take this personal, but I feel your post reflects a personal opinion rather than an ubiased point of view. Just wanted to go over some things.

I agree that the configuration of the cylinders affects vibrations. I don't agree with the statement that V-6 engines are more suited for racing than an I-6. Both are equal in this aspect. For example- As I mentioned before Buick used a V-6 for its grand national putting out some decent hp numbers (I believe 250?) BMW uses an I-6 for its M3, also a decent motor. Saying that V-6's are better than I-6's is comparable to saying "Apples are better than bannana's."

Again, a re-iteration on your previous paragraph, but you contradict yourself. You said "smooth performance" where as in the in the previous paragraph you said that V-6's are better suited for racing applications. Now assuming that racing and performance are hand in hand, there lay the contradiction.

I completely disagree with this, as I will say again, each motor has its own application. It was mentioned before that a boxer motor has a lower center of gravity. Subaru's use these motor's on their STI's, creating an astonishing 400+hp out of a 2.0L. Thats roughly a 121 cubic inch motor or roughly 3.3hp per CI. At that rate, the 6.0L LS2 Corvette should have 1227HP! Porsche also named a car, the boxter, respectively from this motor. (Sportster+Boxer=Boxter)

I stand behind my statement, again restating that all motors can be set up differently and this is generally speaking, but I-6's tend to have a FLATTER torque curve.

If you take racing to an extreme level, then I would have to agree with Sabb. A V6 IMO offers a more dynamic design than an I6 in the racing world. I mainly believe this due to the design of the engine. A V6 is much more compact allowing easier placement. With greater allotted space, suspension becomes easier to compact and design and, you have a better balance of weight throughout the structure. Locating the weight as close to center is always beneficial to steering response and a V6 has the advantage in this respect. Having a longer engine like the I6 eats up room in the engine bay, and can call for a weighty front end if its not placed properly. Look at the I6 in the Skyline GT-R, its a great car by all means, but it is known to be nose heavy.

The best dynamic setup for racing IMO would call for a V engine in a MR setup. This will allow for heightened steering response, better distributed weight during braking, and also more weight on the rear wheels when accelerating.
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