The primary means by which we can get more power from a water boxer is simply by increasing displacement (larger bore + longer crankshaft throw, or “stroke”). Common sense would lead one to assume that the larger the displacement, the more modifications are needed, and therefore the propensity for failure would be greater. However, if done correctly, going larger can be done without sacrificing durability or reliability. There are lots of examples of this on many well-known engine designs. For example, the “small block Chevy” design was made in displacements ranging from 4.6 liter to 6.6 liters. The Porsche 911 engine started out as a 2.0 liter in 1963, and by the time production ended in 1989 it was a 3.2 liters. But almost no other engine has demonstrated an ability to get larger as a percentage as compared to the VW beetle engine design, on which the VW water boxer is closely based.
I have been a life-long enthusiast of all things VW, in particular the VW Beetle engine. The 2.1 liter waterboxer is in fact an evolution of the original 1938, 1100cc, air-cooled beetle engine originally fitted to the infamous “peoples car” created by Ferdinand Porsche during World War II. That’s right, the same, basic design almost doubled in displacement, ultimately ending up as the liquid-cooled, 2.1 liter waterboxer. It seems incredible, but you have to remember that this all happened over period of almost 50 years! The key change in the waterboxer as compared to all it’s previous renditions was the switch from air to liquid-cooling, which made getting much, much higher output possible without overheating.
The original waterboxer (1983-85) was a 1.9 liter. VW expanded that same, basic design to a 2.1 liter, and that was used from 1986-91. Starting around 2001, GoWesty simply picked up were VW left off. Our higher displacement waterboxer engines came about by utilizing the same engineering principles VW employed over the many decades that ultimately led to the 2.1 liter waterboxer. What we have done to get to our 2.7 liter version, and all others in between, is arguably no different than what VW would have done if they continued to develop the waterboxer. The result: none of our larger-displacement water boxers exhibit any statistically higher failure rate than any other. That is not to say we have not experienced failures in the process, no doubt similar to what VW faced time and time again in the past and would have with the waterboxer had they continued to develop it. But while VW almost doubled the displacement and had to do all sorts of modifications over the years to get there, we have only increased the displacement from 2100cc to 2700cc, which is only about 28.5%. As a result, we were able to stick very closely to the same basic VW design, and the only major issues we had to overcome were piston/cylinder and crankshaft related.
Our first engine was the 2.2 liter. To get from 2100cc to 2200cc, all we had to do was increase the bore size from 94mm to 96mm. We had to put some thought into the head gasket design (custom-made, GoWesty solid copper), but that was about it, no surprises. The compression ratio went up from around 8.6:1 to 8.8:1—which is no big deal. What we ended up with was an engine that ran like the best running 2100 you ever drove—in a light-weight Vanagon, but nothing really to write home about.
Our next step was the 2.3 liter, which has the same bore but also a 3.5mm increased crankshaft stroke (79.5 mm instead of 76mm). This required moving the wrist pin in the piston up 1.75mm (.070”) closer to the crown of the piston, which was not a big deal. In addition to the 200cc larger displacement, the 2300 also has a 9:1 compression ratio. Now we started to really see a true return on investment—the 2300 really performs much better than any 2100, and then some.
The next step was the 2.4/2.45/2.5 liter development. We went through several different bore/stroke iterations during this phase. We tried strokes of 82mm, 83mm, and 84.5mm, rod lengths of 137mm and 139.7mm, and bore sizes of 96mm, 96.5mm, and 97mm. Early piston designs failed miserably, cracking right down the middle. Our first stab at an 84.5mm crank also failed miserably. But we kept chipping away at the problems, and ultimately solved them all. The 2450 came out on top at 96mm x 84.5mm with a rod length of 137mm, and a compression ratio of 9.4:1. This is a very sweet engine, and still relatively affordable to build.
But, we knew the waterboxer design had even more to offer.
The final step we took was to go for broke, build the absolute largest displacement waterboxer possible, and that could hold up as well as all the rest. The limiting factor is the engine block. There is only so much room for the crankshaft, and we had already used every millimeter of it with the 84.5mm stroke crank. The largest we could possibly go on the bore and still have room for proper sealing was 101mm, so that is what we shot for. In order to do that, we needed a larger bore cylinder. The absolute largest diameter we can reliably bore the original, German 94mm cylinders to is 96mm (we found this out the hard way!). So, we had to have custom cylinders made in the USA from scratch with a larger bore (ID), but also necessarily larger on the outside (OD). In order to fit the larger OD in the block, there was quite a bit of fixturing required to properly machine the block accurately and safely. It was quite a process—way too many details to cover here. But suffice to say, the result was an absolute jewel of an engine: almost double the power and torque of the original 2100 design, more fuel efficient, and virtually indestructible! We have beat the holy crap out of the 2700 by way of endurance racing on the track (a total of six 24-hour LeMons races, ultimately winning our class), as well as in desert racing (a total of 4 NORRA Mexican 1000 Rallies, winning our class every single time). There is even a full-blown unlimited-class desert race car running one of our 2700 engines and our EFI system. And all this with zero engine failures!
That is the short but fairly detailed story of the GoWesty engine development in a nutshell. Suffice to say, we did not just “throw some bigger jugs in there, and hope for the best!” It has been a 20+ year, long and very hard road to get to where we are today!
Aim at perfection in everything, though in most things it is unattainable. However, they who aim at it, and persevere, will come much nearer to it than those whose laziness and despondency make them give it up as unattainable. Lord Chesterfield (1694-1773), British statesman
Also read: GoWesty Performance Waterboxer Upgrades Are Not "Engine Swaps"