Engine Block Story: 1.9 vs. 2.1 Waterboxer Designs

Unlike the VW Beetle engine block, the waterboxer engine block is made of much sturdier aluminum (rather than magnesium). They were all manufactured this way, which makes them extremely durable. Additionally, a key change in the crankshaft design of the waterboxer greatly reduced the stresses on the center main bearing, which is an area where Beetle engine blocks commonly failed (see our article on crankshafts for more details). The material choice, combined with the new crankshaft design, resulted in practically-unlimited engine block life, barring corrosion or catastrophic failure due to lack of lubrication (running without oil) or cooling (running without coolant). 

The 2.1 liter waterboxer engine was produced for twice as long as the 1.9 (86-91 compared to 83-85). GoWesty has purchased hundreds of used engines, as many as we possibly could to keep our rebuilt engine program going. When an engine shows up with a great big hole in the top of the block and with part of a rod sticking out, it is usually  a 2.1 liter, not a 1.9. Why? Probably because the 2.1 liter engines were built with one-time-use stretch type rod bolts. These bolts were fine THE FIRST TIME AROUND. But many rebuilders did not believe they actually had to replace the bolts EVERY TIME. Back when we were just a regular repair shop, we also learned that lesson the hard way…

So, as time has passed, we have ended up with many nice, clean 1.9 engine blocks, and fewer and fewer cherry 2.1s. Due to that fact, we decided toward the end of 2006 to start using nice, clean 1.9 liter engine blocks for many 2200cc and 2300cc engines, regardless of the year of the vehicle in which it was being fitted. In doing so, we immediately met resistance and criticism from some customers—mostly shops that felt they “knew better” and thought they were being “short changed.” It has become necessary to put this issue to rest once and for all.

These are the differences between the 1.9 engine block and the 2.1 block:

1) Main bearing #1 design: 1.9 is one-piece. 2.1 is three-piece.
2) The 1.9 was not originally fitted with an oil cooler.
3) The 1.9 was not originally fitted with a second oil pressure switch near pulley.
4) Early 1.9s are slightly different on top where the plenum bolts on (pre-85 only).
5) The 1.9 has a slightly smaller inside dimension.

None of these differences are significant. VW and Porsche engines used the one-piece #1 main bearing design for forty years, and nobody complained about it. Adding the oil cooler is as simple as replacing the fitting, onto which the filter screws, with a longer one. Adding the second oil pressure switch is a no-brainer. The only thing that took any effort at all was manufacturing a proper pair of aluminum spacers to correctly mount a 2.1 intake plenum onto the 1.9 block. We had 500 of them made specifically for that purpose. So, what’s the big deal?

Contrary to what some folks believe, the 1.9 liter block is no weaker than the 2.1 liter design. It is made from the same material and is practically, for all intents and purposes, identical. The 1.9 liter and 2.1 liter engines are identical with respect to piston diameter, and the cylinder heads were almost identical (in fact, interchangeably so). The extra 200cc comes from the crankshaft stroke. The 1.9 has a crankshaft stroke of 69mm (same as the 1600cc beetle). The 2.1 was fitted with a 76mm stroke crank. The 2.1 liter block is a little bigger inside for that reason. As it turns out, to fit the 2.1 crankshaft in a 1.9 block requires practically no modification on the inside at all. The only place where the crankshaft and rods come too close for comfort is in the area of the head stud hole bosses, the other side being where some of the head studs fasten. We are talking less than ONE millimeter, literally. It takes less than 15 minutes to make the modifications necessary. We have been building 2200cc and 2300cc engines out of 1.9 liter engine blocks for many years now. We have experienced ZERO failures of any kind related to any of these modifications.

We are using the 1.9 blocks for the 2200 in order to save our dwindling supply of 2.1 blocks for our larger engines. We need the extra space offered by the 2.1 block to build engines that require larger crankshaft strokes that used in the 2.2 and 2.3.

So, for these reasons our core policy is that if we send out an engine built with a 2.1 liter block, we expect a 2.1 liter block back. But if we send out a 1.9 liter block, either a 1.9 liter block or a 2.1 block will suffice for full core credit (assuming the core is in rebuildable condition—click here to view our core refund sheet).

The main reason we decided to use the 1.9 block for the 2200 and 2300 is cost and availability, plain and simple. The whole idea is to build these engines as cost effectively as possible without compromising quality—in order to not have to raise the price. Using 1.9 liter engine blocks is one way we have been able to keep the price of our engines down. With continued innovative thinking, we hope to continue to strive to provide unmatched quality for a reasonable price.



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