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The VW V5/VR5 is just a boondoggle for countries who tax their cars based on displacement.
The I5, "the power of a 4 with the fuel consumption of a 6" A 5 cylinder engine is inherently not as well balanced as either an inline-4 or an inline-6; it requires a balance shaft rotating opposite of engine rotation direction to counteract an inherent end-to-end vibration. This increases the cost. For the extra parts to do the balance shaft, usually you might as well add another cylinder and skip the balance shaft .
It's been pretty well explained so far. It comes to down to three things:
1. Packaging - In an application where you want more power then a regular I4 can offer the I5 generally allows a larger displacement design in the narrower space then what could be achieved with an I6 and in applications where a V configuration won't work.
2. Power/Economy - It basically splits the difference between the I4 and I6, you get I4-esque economy with I6-esque power.
3. Smoothness - An I5 is smoother since it is always in a power stroke compared to an I4 which has no overlap between cylinders. A four-stroke engine fires its cylinders once every every 720 degrees of rotation. Each power stroke of a cylinder lasts for 180 degrees. You divide 720 by the number of cylinders to determine how often a cylinder fires. So, an I4 fires one cylinder every 180 degrees and since a power stroke lasts 180 degrees, there is no overlap. An I5 fires every 144 degrees, so there is overlap and the engine is always on a power stroke. The more overlap, the smoother the engine. An I4 has zero overlap, an I5 has 36 degrees and an I6 has 60 degrees. What this means is that the difference in smoothness between an I4 and an I5 (36 degrees) is much more noticable then the difference in smoothness between an I5 and an I6 (24 degrees). With that said, I5's are still not the worlds smoothest engines, because they are inherently unbalanced do to the odd number of cylinders, while they are much smoother then an I4 at normal driving RPM's, they still require balance shafts to keep them smooth at idle and at high RPM's.
The reason they were previously not explored beyond Ford's tinkering in the 1940's was that fueling them was almost impossible. There was no way to tune a set of carbs to keep the engine running properly as a single carb wouldn't deliver adequate fuel to the cylinders furthest away and using multiple carbs created a tuning problem. The first available I5's in cars were diesels for this reason, because all diesels use direct injection the fueling problem wasn't an issue. As multi-point fuel injection came about, it solved the fueling problem and made gas I5's practical.
Overall though, they are really nothing more than a compromise for a manufacturer trying to stuff a slightly more powerful engine into a limited space.
the same reason every automaker that made 5 cylinder engines, they wanted the power of a six cylinder engine with the economy of the four cylinder engine.
But 5-cyclinder provided the power of 4 but with the economy of a 6!!!!
The VW I5 was also designed to have torque that the 4 cylinder engine lacked...and as the owner of one, I find that to be true. They're still not particularlly powerful, 170 horsepower isn't much for a 5 cylinder when modern 6 cylinders are making 250+. Fuel economy isn't bad, I always averaged 27 mpg with the 6 speed auto in my Jetta, and you'd see the low 30's on the highway. An inline 6 would be better, but you'd likely be looking at a smaller bore, or a wider car since the Jetta engine sits transversely. You can make the VR6 engine fit, but that's about it...it's either 5 cylinder, or 4.
The VW I5 was also designed to have torque that the 4 cylinder engine lacked...and as the owner of one, I find that to be true. They're still not particularlly powerful, 170 horsepower isn't much for a 5 cylinder when modern 6 cylinders are making 250+. Fuel economy isn't bad, I always averaged 27 mpg with the 6 speed auto in my Jetta, and you'd see the low 30's on the highway. An inline 6 would be better, but you'd likely be looking at a smaller bore, or a wider car since the Jetta engine sits transversely. You can make the VR6 engine fit, but that's about it...it's either 5 cylinder, or 4.
Yeah this is true... The torque curves for these 2.5's are pretty good. With the low horsepower I find myself flooring it quite a bit (5spd) to merge with high speed traffic, however you can accelerate the car in any gear as long as you start out at least around 900rpm or so. Despite my lead foot I CANNOT do any worse than 27mpg. The 2.5 is, in my opinion, an excellent example of how 5 cylinders combine the best characteristics of 4 and 6 cylinders. It must be that Lamborghini head
Supposedly the straight 6 is the most simplest layout and most balanced engine.
I am assuming the 5 is a variation of the 6?
Nope on both counts.
The simplest layout and most balanced engine is a V-twin at 90 degrees, where the primary vibration forces at an idle are rather minimal but as the RPM rises, the secondary forces take over and these are exceptionally smooth engines under load. Smoother even than a horizontal flat twin where the primary forces are neutral, but the overall forces build as the RPM rises into working range.
You lose simplicity as you pair up multiples of the V-twin to make a V-4, 6, 8, 12, or 16 cylinder engine ... but these are common in the world of stationary, locomotive, or marine engines ... and automotive, too.
The VW V5/VR5 is just a boondoggle for countries who tax their cars based on displacement.
The I5, "the power of a 4 with the fuel consumption of a 6" A 5 cylinder engine is inherently not as well balanced as either an inline-4 or an inline-6; it requires a balance shaft rotating opposite of engine rotation direction to counteract an inherent end-to-end vibration. This increases the cost. For the extra parts to do the balance shaft, usually you might as well add another cylinder and skip the balance shaft .
ps, the more cylinders =a smother engine.
NJ goat makes the same assertion ... a balance shaft required for smooth operation.
Not so in my experience.
Sure have driven a lot of miles on very smooth MB 5-cylinder diesels that never saw a balance shaft inside their cases ....
I've heard great things about the straight 6, 4.0 that u mention. People claim that it's damn near bullet proof. What makes this engine so great? I'm thinking about getting an early 90's Cherokee with the same engine and using it as a winter beater.
Great choice. I think you'll really like it. Just go over it real well and watch for rust/holes.
I think it's just pure simplicity of the engine. You'd be hard pressed to find one that can't hit the 200,000 mile mark. Let's put it this way: I had put my YJ on it's side while out on a trail. After getting her back on her feet, I pulled the plugs and turned her over to throw all the oil out of the cylinders. Added a couple quarts, put the plugs back in and she fired right up! Smoked for a few minutes but that was it. Drove it about 3 miles out of the bush to the highway, and then about 25 miles at 60mph back home with no issues. She's still fine, as if nothing ever happened. I wouldn't hesitate to take'er cross country either.
Another story? A friend and I went to check out a 93 YJ that had been sitting in a field for about a decade. The farmer said it was his daughters Jeep and after no oil changes for 3 YEARS (!!!!), the engine finally seized up. We put a battery in and sure enough it wouldn't turn over. SO, we pulled the plugs and totally soaked the cylinders with WD-40. We let it sit for about 4 hours and went to do other stuff. Came back, put the plugs in, turn the key, "vrrrroooom!"
They do leak though. Mostly from the valve cover (no biggie to chage the gasket), and the rear main seal (again, something that can be done with minor mechanical knowledge). Water pumps and alternators go too, but this stuff just wears out, like on any other engine.
However.......if my Jeep ISN'T leaking SOMETHING........that's when I get worried.
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A 5 cylinder engine is inherently not as well balanced as either an inline-4 or an inline-6; it requires a balance shaft rotating opposite of engine rotation direction to counteract an inherent end-to-end vibration. This increases the cost. For the extra parts to do the balance shaft, usually you might as well add another cylinder and skip the balance shaft .
!!!!), the engine finally seized up. We put a battery in and sure enough it wouldn't turn over. SO, we pulled the plugs and totally soaked the cylinders with WD-40. We let it sit for about 4 hours and went to do other stuff. Came back, put the plugs in, turn the key, "vrrrroooom!"
