You'll see the definition for the word reliable that comes back is "Consistently good in quality or performance; able to be trusted." The very first word is "Consistently". I believe this is crucial to understanding the problem people face in understanding and evaluating the reliability of various options out there when it comes to vanagon engine conversions.
Head of the class
"Consistently" might be scoped to an individual instance of a type of thing. Someone that infrequently has problems might consider their setup reliable. When someone is trying to decide if an entire class (group of instances similar to each other in property or nature) of things is also reliable, they sometimes transpose the instances of reliable that they have heard onto the entire class. That is where the potential problems lies.
They are trying to judge if their own eventual instance is going to be reliable, based on the reliability of the class. The problem is that unless the class is highly consistent, there is very little relationship between the instance reliability, and the class reliability. The more similar, close to identical, or consistent the instances of the class are, the stronger that relationship is, and the less error prone that transposition would be.
This is the very same concept as all bees are insects, but not all insects are bees. Bees are an instance of the insect class. Bees are also a class themselves in that all honey bees are bees, but not all bees are honey bees.
Take another instance: "the Subaru Conversion". It is a very common term in researching engine swaps. Vendors themselves have also taken to using it. However there are a few real fundamental problems. Firstly, "the Subaru conversion" doesn't actually exist as a thing, it is a class of vanagon engine conversion. "the Bostig conversion" is an instance of vanagon engine conversion. It is a thing. It has a production model and each instance is consistent with the next. Within the class of things that are Subaru conversions, the instances can be very different. These differences are the entire basis of competition between the many vendors that sell parts to build conversions based on subaru engines.
For example, someone might hold the opinion that "abc company makes a better exhaust for the subarus than xyz's". If this opinion is true, then it is also true that the sub-class of subaru based conversions with this exhaust all have better exhausts and are different to another sub-class using some other exhaust. You have a sub-class created because you don't have consistency in that aspect.
If it were just the two sub classes, it would be pretty easy. But Subaru based conversions aren't actually consistent down to very low levels of granularity. The number of combinations and permutations amongst them, even from the same vendor, are extremely high because they contain so much variation from nuts and bolts to the wiring harness.
People in the vanagon community and in most auto aftermarkets hate wiring. It is tedious, detail oriented and time consuming work. It can be overwhelming, and takes a good investment in time and effort to complete. This is one reason why having a used Subaru wiring harness reworked isn't cheap. You're paying for expertise, time, and detailed work. The wiring harness is the nervous system of the powertrain, and is in every way as important as the engine itself. A used wiring harness also has a story.
It was born in a factory, its parts were born in other factories. Someone pulled and cut its wires. A machine crimped on terminals. It was nailboarded, and then the seals, backshells and retainers were all assembled onto it. The harness was carefully taped, loomed, wrapped and boxed. At another factory it was installed into a chassis by someone, and connected later to the engine.
It was transported by ship or truck. It was then sold to someone along with the car it came in, and lived with them for however many summers and winters. It heat cycled, it oxidized a bit, its wire jackets and loom hardened and it did its job acting as the nervous system for their powertrain. Then something happened.
It was in an accident, or sold as part of the car again. Perhaps it sat for a few more summers or winters. Then someone came along, and pulled it from the chassis it had been installed in, and had conformed to. It then made a trip elsewhere.
There it was carefully and expertly dissected and unwrapped. Some wires changed in length, some removed. Many cuts, crimps and connections were made, and then it was routed, taped, loomed; rewrapped, rebundled. Perhaps it was error checked, and verified.
Then it made its way into a new chassis, this time in the back of the vehicle. It was then reunited with the same engine it came with way back at the factory (hopefully). Then a whole new chapter in the story begins. The one most relevant to us, and how it plays out exactly isn't known yet.
The important part of this story is that the harness's "life experience" isn't guaranteed to be very consistent after the first paragraph. This means the resulting harness itself isn't very consistent either, certainly not guaranteed, and nowhere near the same level of consistency as if the story had ended four paragraphs ago, like a brand new harness's story does.
Was Consistentinople, now it's IstanbullGiven that even the nervous system of the engine swap cannot be guaranteed consistent, the consistency across the class cannot be guaranteed unless the guarantee is that they are not consistent. If that were the only example of the variation, then perhaps it's too nit picky to be of much concern although this is how gremlin eggs are laid.
The problem is the variation is wildly larger in scope than just the wiring harness's story. From flywheels, to engine mounting options, mufflers, cooling manifold designs, intakes, bracketry, adapter plates, hose choice, engine management, ECU mounting, throttle cables, drive by wire utilization, engine preparation, engine options/ECU combos, fasteners, clamps... the list of variation is enormous and covers almost every part that composes the whole.
All of those variations multiply the number of sub-classes, and each new sub-class further weakens the validity of statements across classes by lack of consistency. You don't have "subaru conversions" you have ABC company's conversion, Dave's conversion, or Bill, Bob, or Mikey's conversion and they are not consistent. Even ABC company's conversions can't be very consistent since no shops that build subaru conversions have complete control over the entire system's design and composition, or settled on one.
Make no mistake, in no way am I saying it is not possible to have a lovely reliable instance of a subaru based conversion that will give you years of trouble free ownership. What I am saying is that you can't expect the result of your instance to match anyone else's unless you're already aware of why that combination yields the result it does, and can then replicate it. The problem is, even the experts struggle to do this themselves which is precisely why the variations exists in the first place. If there was no problem present, there would be no demand for the variation.
One benefit of being the only product company in the space, is that we have controlled an entire production model since we started. This unique level of consistency has been key to our growth, and delivering what the customer pays for. We have achieved such high levels of consistency, that we can reach levels of documentation that nobody else can touch, even across huge mainstream auto aftermarket segments. We can guarantee even complete novices can perform the install successfully, and we can support more customers on the road than any other vendor in the market, while also being the smallest vendor in the market. The key to all of that is reliability, and the key to reliability is consistency.
There is a lot to know and understand about doing something like an engine/powertrain swap. Unfortunately most folks doing research in vanagonland have very little experience with it. So if you see a vendor expounding the merits and reliability of "the Subaru conversion" you'll know to ask the details about THEIR subaru conversions specifically. Hopefully you'll see why the question "how does the Bostig compare to the subaru?" is really a comparison of Apples to Fruit, deeply more complex and less valuable than an Apples to Apples comparison. Since we started development in 2004, we have remained the only Apple in the marketplace.