Choosing the right Engine Combination
When I first began the engine build, I had to ask questions which you will have to ask yourself. After searching around the engine forums in both vwvortex.com and thesamba.com I quickly realized that these engines are extremely adaptable towards whatever driving application you will be using it for.
To begin, the most important piece of advice that I have heard tossed around in regards to any engine inquiries (in particular when it comes to building the any high powered applications)
The Golden Rule
You have three options when building an engine and you only get to pick two: Fast, Cheap & Reliable
Having read through numerous books, and many a story from well respected builders on various forums there is no way around this rule. The most commonly ignored element is reliability. In the Volkswagen world there are plenty of "deals" out there, and more often than not the cost of using inferior parts in the name of saving a few bucks leads to headaches, poor results and ironically a couple hundred (or thousand dollars) to rebuild an engine again.
Research, Research, Research
My engine plan took approximately 2 years of research - and it was fun I might add. Not knowing too much in the ways of any type of engine building I had to start from scratch and I was helped along the way by several books, searching through forums, and helpful people who were willing to share advice. Here are some books and sites I would recommend:
How to Keep Your Volkswagen Alive by John Muir
How to Rebuild your Air-cooled Volkswagen Engine by Tom Wilson
How to Hot Rod Volkswagen Engines by Fred William Fisher
Budgeting and Planning
The most common engine is the 1600cc engine which were introduced in 1968 in Type 2 models and 1970 for Type 1. Type 2 engines continued to increase in size as they were developed for Bus applications, but the 1600 is the most common upright engine that can be used in both Beetles and Buses. I decided on using this engine as a platform for two reasons a) they are commonly found, thus aftermarket and used parts are generally cheap to buy and b) it is extremely adaptable with the sheer amount of aftermarket part aimed at this engine model.
If these engines are so adaptable, the next question I had to answer was what can I build? I wanted to build a fun (fast) engine that was reliable, efficient and under a reasonable budget - keep in mind "reasonable" falls under the definition of what I'm getting for the money. The 1600cc engine has a 69mm crankshaft x 85.5mm piston bore. By increasing the crankshaft stroke (called "stroking the engine" and/or the piston bore, one can change the displacement of the engine.
The original plan in this project was to build a stock 1600cc engine to be built the very best it could be. However, I came to two conclusions: A stock engine was already built the best it could be - by Volkswagen. Secondly, the cost increasing the displacement of the engine is extremely favorable (and would be a lot more fun to drive!) Take for example the cost of building a stock 1600 with another relatively common high powered engine, the 1776cc (69mm crankshaft x 90.5 bore). Below is the cost comparison of all the major portions of the engine:
|1600 Engine||1776 Engine|
|Crankshaft (cast)||$ 89.95||Counter Weighted Crankshaft||$ 189.95|
|Pistons/Cylinders||$ 109.95||90.5 Pistons/Cylinders||$ 235.95|
|$ 60.00||Connecting Rods (Rimco)||$ 60.00|
|Flywheel||$ 81.95||Lightweight Flywheel||$ 109.95|
|Clutch Disc & Plate||$ 65.00||Clutch Disc & Plate||$ 65.00|
|Crank Pulley||$ 33.95||Crank Pulley||$ 33.95|
|Rhino Stock Rockers||$ 136.95||Rhino Stock Rockers||$ 136.95|
|Camshaft||$ 78.95||Camshaft||$ 78.95|
|Stock Cylinder Heads||$ 144.95||044 Magnum Cylinder Heads||$ 241.95|
|Stock Carburetor||$ 123.95||Dual 34 Solex Carbs||$ 399.95|
|Machine Work (Rimco)||$ 45.00|
This comes out to a $672.00 difference between a 50 horsepower stock motor versus a 75 horsepower (low estimate) 1776 - or a 50% increase in power! For my budget and goals this made sense. Once I worked out this budget and looking at other models I realized that once you make the leap into boring out an engine, the cost to do a bigger displacement engine is also very minimal since many of the main components prices will remain the same.
For example, a high performance crankshaft costs about (if not exactly) the same regardless of the stroke - so why not put a 82mm instead of a 69mm? The things that will change, are the costs of headwork, and carburetors to accomodate your engine's newfound capacity for fuel, balancing the engine assembly (very necessary as you increase power), and clearancing the case for the added stroke of the crankshaft. This also has to be balanced with the reliability of the parts and goals of the project.
Two good examples of how this honed me in on my engine choice: Carburetors and Cylinder Walls. The 92mm and 94mm bore pistons require cylinder walls that are thinner (with the exception of thick walled 92's), which could lead to warpage. Many will argue about this, and I don't consider myself an expert - however, I didn't want to find out the hard way so I limited myself to boring out to 90.5 which shares the same stock cylinder wall thickness - giving me reliability & power. The other goals were reasonably cheap and reasonably fuel efficient. Performance carburetors are expensive! By rebuilding used Weber or Dellorto carburetors I could limit the financial impact of bigger carburetors. Limiting their size to either a 40 Dell'orto or 44 Weber I could ensure I wouldn't have a total gas hog.
Knowing the carburetor size that worked for my budget and goals then gave me an idea of the biggest displacement engine I could build without running lean - a 2110cc engine (82mm stroke x 90.5 bore). It's reliable (if built correctly), somewhat fuel efficient (if driven so), fun to drive, and most importantly fell within my budget taking into consideration all modifications to the engine, drivetrain, transmission, and braking system that this would require.
Building a VW Engine