Building a Reliable and Powerful Street Engine

What do I feel a good displacement is? At least a 2110cc, but ideally, a 2276cc, which is attained through the use of 94mm pistons and cylinders and an 82mm crankshaft. Of course, engine displacements that come near this mark are fine too, but the classic combination of the 2276cc is hard to beat for horsepower, reliability and ease of assembly. For instance, I see no problem with building a 90.5mm x 78mm (2007cc) combination, but in reality, most good forged 78mm crankshafts cost the same as a comparable 82mm crankshaft, and 90.5mm "stroker" pistons cost exactly the same price as their big brothers, the 94mm's. So why pay the same price for less engine? Some enthusiasts believe that the 94mm pistons and cylinders deserve less merit than they are really worth, however I feel that if the engine is properly set up (compression ratio, cooling, jetting, exhaust, etc.), that the 94mm pistons are completely reliable, and I have used them for years in street sedans and buses with no reliability problems whatsoever. I know of plenty of 90.5mm-bore engines that have had their share of heating and ring-sealing problems, and many of these were the result of inadvisable combinations, poor assembly techniques or too high of compression ratio. Larger motors than the 2276cc require the use of an 84mm or larger crank, and in some circumstances, these engines can be quite difficult to assemble, and more expensive as well. For that reason, the 2276cc is the perfect displacement for the serious California Look VW.

Now that the matters of budget and displacement have been tackled, the fun part starts: purchasing parts. First item to consider is the crankcase itself. The crankcase is probably the most vital player in your goal to build a reliable engine. Some professionals have the opinion that only a brand new case should be used, however, I feel that if a low-mileage pre-used case can be located that is in great shape, there is little reason not to use it. I have seen a few engines built with new cases that had low or no oil pressure, and even with quality parts (crankshaft, oil pump, etc.) used in conjunction with the new case. I have talked with the fellows at Rimco in Santa Ana about this problem, and they've heard this before. They recommended I send them any case that I was considering for high-performance use and have them ream and spot-face the oil-bypass galleys.

So, in turn, I would have either a new or used case checked and machined accordingly, to ensure adequate oil pressure. Other things to look for when considering a used case are cracks (usually found on front (flywheel end) flange, or at base of cylinders, or at oil cooler flange), pounded out main saddles (quite common, especially on abused engines), and worn thrust surface at main thrust bearing location. I would suggest using only an 8mm 1972 or later case as well, as it will have larger oil galleys, 8mm head studs and case-saver inserts. Pre 1970 cases are known as "single relief" (due to the use of one bypass galley instead of two), and have small oil galleys, I would avoid these cases. Once you have found a case that suits your needs, it will need to be machined for whatever size crank and piston/cylinder combination you have chosen. Many outfits can perform this work, I prefer and use Rimco in Santa Ana, CA. Along with boring the case for the larger cylinders, and stroke-relieving the case for the larger crank, I feel the case should also be modified for full-flow oiling and shuffle-pinned.

By modifying the case for full-flow oiling, the engine can now utilize a conventional spin-on oil filter and an auxillary oil cooler (which is recommended depending on use of car and climate). Shuffle-pinning is an operation in which sleeves are inserted in one half of the case, that correspond to reliefs in the other half of the case. The point of shuffle-pinning is to prevent the case halves from fretting and moving around (like warming your hands up by rubbing them together) during hard use. These shuffle pins shouldn't be thought of as an excuse to choose a poor quality crankshaft (the primary culprit in the damage of crankcases), but as an ally of the crankshaft's. If a well-made crank is utilized, shuffle pinning the case can only aid in lengthening the case's life.

On the topic of the crankshaft: since we are discussing at least a 2000cc engine, we will be discussing longer-stroke crankshafts. Many people in the past have had success building high output engines using a "welded" stroker crank, and I have built a few as well, however, I do not suggest using one. Most welded cranks I have had experience with were poorly made, and created all kinds of problems. I have found nearly every welded crankshaft I have seen to have inconsistent side clearance tolerances with the connecting rods (regardless of the type of connecting rod used). I have had to hand -fit rod bearings because the welded crank's radius at the rod journal was machined incorrectly. The time and money spent on making a welded crank work correctly could be better spent on a forged crankshaft that is better suited to the task at hand. A quality forged crankshaft can be bought at a marginally higher cost than the average welded crank these days. I have had great results with numerous companies' forged cranks, but probably the best value on the market currently is the Bugpack unit. These cranks are well made, and only need minor detailing and polishing work to put them into service. Connecting rods and bearings fit the first time with no modifications, except a light polish (the cranks often come with a crosshatch pattern on journals, which should be polished away by a competent machine shop).