1800cc VW Engine Combo: How to Build a Big VW Engine on a Budget
Some folks with aircooled VWs are looking to move up to an 1800cc VW engine from their stock 1600cc VW engine, but don’t want to break the bank in the process. The advice below is intended to help you build an as-economical-as-possible 1800cc Aircooled VW Engine Combo. You’ll probably also want to reference our 1800cc parts list that is the companion components list for this article. This was the first article written for our “VW Engine Combo” series. In this article we outline a bare bones 1800cc build that assumes you do NOT have unlimited funds or a big budget.
Of course, there are always going to be guys out there who have built, or claim to have built, bigger and “badder” engines “on-the-cheap”, but not everyone has a brother-in-law or buddy-at-work with engine parts connections! If you add to or change components in this engine combo you’ll wind up with a different “category” engine, with a higher end cost. We provide details and recommendations for more expensive and complex combinations in our other Engine Combo articles. (You can see all of our engine combos broken down at this Master List of Engine Combinations!)
If you are feeling nervous about doing an engine build that is bigger than “stock”, and you have more money than time, then you should consider our “Mini Stroker” Long Block…Not exactly the same combo as this article guides you through, but the next step up (which you would want to go with if you are paying to have someone else do your build!)
written by John Connolly, Aircooled.Net VW Parts
Originally Posted/Written: January 11, 2012
Last Updated April 30, 2020
The 1800cc No Machine VW Engine Combo, a Big VW Engine Build Outlined by Aircooled.Net
The first way we recommend to keep costs reasonable is to stay away from machine work – sometimes called a “no machine” VW engine. The second way we help you keep the purse strings tight is by not delving into the many available upgrade options that might tempt you to spend more than you really need to to get your VW on the road. Please also note that for this build combo we do recommend some components that are NOT “top tier” quality. There is nothing wrong with this, as long as you understand and agree with the goal of this engine combination. The reality is that you do NOT need a $400 crankshaft in a 90hp engine! A $250 crank does the job you need it to do and saves you $150.
The 1800cc No Machine VW Engine Combo, built on a budget, starts with the assumption that you will re-use your used engine case. We are also going to assume that you don’t have a machine shop nearby, since not everyone lives in Orange County, California (VW Mecca!) A budget build can’t begin with you sending your engine case off for expensive machining and $100+ in shipping fees on top of it! In most cases, it’s perfectly fine to make do with the case that you have.
This combo will make a really nice daily driver engine, that performs at a couple substantial notches up from stock! While this economical engine combo isn’t a 240hp naturally aspirated engine, it will still give you a lot more grunt than the stock power plant. The combo will work equally well in Single Port or Dual Port versions, and you can even run the stock carburetor if needed. This engine combination is outstanding for for VW Busses, Type 3s, and even Beetles and Karmann Ghias!
If you’ve never torn into a VW engine, two books you may want to read prior to getting all dirty are Tom Wilson’s How to Rebuild Your Volkswagen Engine, Jeff Fischer’s How to Hotrod Your VW Engine. And for those that prefer video to books: Rick Higgins How to Rebuild Your VW Engine DVD. You will need on hand the “usual” stuff like oil, gasket set, main bearings, rod bearings, cam bearings, Curil-T Sealant, and Dirko RTV.
BUT FIRST! If you are not experienced on aircooled VW engines, you need to know this going in. You should consider the 69-74mm stroke engines as all in the same family, and 76-84mm as a different family. “Confusion” will always be in the 74-76mm range, because they sound close in size, but are totally different from a build standpoint. Only 85.5, 90.5, 92, and 94mm pistons are available in A or B pin height, BUT if you choose 87 or 88mm you can ONLY get those in A.
CRANK AND RODS: 74mm Crankshaft, VW Rod Journals. This is the biggest stroke you can go with, with minimal case machining or other hassles. If you are on a super tight budget, you can re-use the stock connecting rods, but doing so will require more clearancing of the case than some other rod options. (This is because stock rods tend to be “fatter” on the big end, requiring more room.) The next best connecting rod option is our 5.4″ I-beam Connecting Rods. You simply don’t NEED more than this for this engine! The slickest move you can do on rods is to use a rod we have had made just for THIS application! By increasing the crankshaft stroke from 69 to 74mm, that’s a 5mm increase. This is split with 2.5mm up top, and 2.5mm at the bottom. 2.5mm = .100″. So one trick to put the piston close to the same place at TDC is to use a 5.325″ long rod, which is .075″ shorter than the stock 5.4″ rod. So the 74mm crank and 5.325″ rod combo puts you within .025″ of the original TDC location! Another option is a more expensive “H-beam” rod. Using a 5.325″ H-beam rod will wind up with an engine that assembles very close to stock! This means no special work on push rods, cylinder tin, or exhaust system either! If you have a little more $, you can use a 76mm Crankshaft, VW Rod Journals along with 5.325″ I-beam Connecting Rods. The 76mm stroke will get you to 1848ccs. If you try to run the 76mm stroke with 5.4″ rods the cylinder base shim will get too thick, and you’ll start running into hassles you weren’t expecting due to the wider engine. Now you need new longer push rods. You will also need thicker (more expensive) cylinder base shims. And then the cooling tin and fan shroud won’t fit without “massaging”. And the exhaust doesn’t line up. Ugh…. We’ll deal with other engine combinations in other articles, keep this one focused!
We’ve had some folks write us with some confusion on parts to use, so I’ll give you a quick run down on the crank, rods, and pistons.
If you want to run a 74mm crank, do this with A pistons (Pistons designed for 69-74mm strokes), and EITHER 5.4, 5.394, or 5.325″ rods. If you use the 5.4 or 5.394″ rods, you’ll wind up needing around .090″ of cylinder shim for everything to work out. If you use 5.325″ rods, you’ll need NO cylinder shims, but you may have minor piston skirt clearancing, to make sure the skirts clear the counterweights on the crankshaft.
If you want to run a 76mm crankshaft, we recommend using 5.5″ rods and B pistons (Pistons designed for 76-84mm strokes).
It is true you can build a 76mm crank with 5.4 or 5.325″ rods and A pistons, but you are going to find out (the hard way), why we recommend 5.5″ rods and B pistons!
Back to more on this engine!
88mm Slip-in THICK WALL P&Cs. These beauties are designed to fit into the STOCK ENGINE CASE at the bottom (they are REALLY thin), but up top they are super thick, using a 92/90.5mm Head Bore at the top, with a 88mm piston! Can you say THICK CYLINDERS? The cylinder is over 5mm thick on the top (that’s more than .200″)! We put this option on the table because you are putting new heads on this engine, and when you buy them you’ll simply order them already bored to the 92mm Bore size! You’ll need 85.5mm Cylinder Base Shims, AFTER you measure your deck height, with a Deck Height Measuring Tool. You can use a dial indicator or calipers if you are careful, because this isn’t a race engine! You want a deck height of .050-.070″. The actual deck height will depend on what rods and crank you decided to use, it’s easiest with the 5.325″ rods. We recommend you mock up the engine and measure, don’t try to buy the cylinder shims/spacers beforehand. If you need them, you’ll do some quick math and figure out which set of 85.5mm Cylinder Base Shims you need to put between the case and cylinders to get there. You need around .100″ of shim. Since this is not available in the 85.5mm size, what we suggest is that you use a .040″ Cylinder Base Shim AND a .060″ Copper Head Gasket in the 90.5mm Size, to achieve your goal. Combined they get you the .100″ thickness you need! IF you want a little more than 1800cc, you can use everything in this Engine Guide the same but use as large as 94mm Pistons, resulting in a 2054cc engine!
We have seen a few people tackle the skirt clearance issue on the 88mm pistons (long skirts), and have included links to see how they did it. Clearance one (symmetrical cuts on both sides of both skirts), then make a template using a piece of paper, transfer the shape to the other skirts. After you are done, balance the pistons to under .5g.
CYLINDER HEADS: The L3 Cylinder Heads, bored to 90.5/92mm bore size, are what make the whole thing work. We are assuming you are using Stock Heater Boxes, or simple 1 3/8″ (Stock size) replacement J-pipes? You can use a 1 1/2″ exhaust if you already have it, but don’t go any bigger than that, because that’s a different “class” of engine than this article is covering. If you have a Single Port Engine, this engine will still serve you very well! The longer stroke crankshaft, and additional displacement, give the engine a healthy boost in torque, but the power curve will fall off around 4500 RPM. In either case, a good valve job is a wise move, if you can’t do it bring it to a head guy or machinist that can! If you don’t have the money for our L3 Cylinder Heads, then get Upgraded Stock Size Valve Heads, which come with HD springs and are available bored to the size you want.
OIL SYSTEM: Use either a 21mm oil pump, or a 26mm oil pump if you are going to use a full flow filter kit. We are not going to go into depth on this, this is supposed to be a “Simple” engine. Another slick idea for you guys is to use the OEM VW Filter Pump Oil Pump. But these only come compatible with 4 Bolt “Dished” cams. But we have Budget 4 Bolt Dished Cams in mild performance grinds, that are PERFECT for what you are doing without breaking the bank! However, if you are going to stick with the traditional 3 bolt (FLAT) cams, Bugpack’s Filter Pump is a nice unit.
Budget Light Flywheel, which works fine because this is a mild engine. You really need to change flywheels anyways because the new crank already has 8 dowels in it, and getting those out will usually wind up with you kicking the dog or cat in frustration, and we don’t want that! You could drill the stock flywheel out to 8 dowels, but this job is tricky and is screwed up more often than done successfully by guys at home (I know, I learned this one the hard way, so take my advice here!).
Besides, a lightened flywheel is one of our top recommended items, you’ll REALLY feel the benefit, it’s a fantastic performance for the money. By using a Budget Lightened Flywheel you get 8 dowels AND lightened for under $100, you can’t beat that! Here’s a piece of advice you won’t often hear, a VW Parts Store telling you to NOT buy something; do NOT get a HD Clutch! This engine will do just fine and you’ll won’t break as many parts if you keep it simple with a Stock Clutch Disc and a Bus Pressure Plate. The Bus Pressure Plate is around 1200lbs of pressure, which is in between a stock beetle pressure plate’s 900lbs, and a Kennedy 1700lb Pressure Plate. Put simply, the stock one is not enough, and the 1700lb is too much for THIS engine. If you insist on more GRIP, we have a new Budget 1700lb Pressure Plate that is a huge savings over a genuine Kennedy 1700lb Pressure Plate.
Secure the lightened flywheel on with a New Gland Nut.
For header/muffler, Street Guys can run a stock muffler, or a Basic Street Header, with a Hideaway Muffler, Single Quiet Pack Muffler, or Glass Pack Muffler. Another great option that is not well known for guys that want to have “Pea Shooters” is the Hotdog Muffler. If you have a Type 3, the choice is obvious! Get Tri-Mil’s Type 3 “OTT” or “Tuck-a-Way” Type 3 Header and Muffler!
The Off-Road crowd will do well with a simple Bugpack Baja Header and either a Baja Quiet Pack Muffler for those that like the quiet, a Baja Stinger for those that like it LOUD, or a Glass Pack Muffler for those that want something in between! Other nice systems are the Tri-Mill Bobtail Glass Pack, and the Tri-Mill Bobtail Quiet Pack.
CARBURETION AND CAMSHAFT:
If you run a 1bbl Carburetor (like a stock carb), select a cam with around 270-276 degrees of advertised duration, NO MORE. Good cams are the SCAT C-20, SCAT C-25, Engle W-90, Engle W-100, Web Cam 86 Grind, and we also have a couple mild reground cams.
2 Barrels of Carburetion; Single 2 barrel Weber Progressive or Dual 1bbls (Bug Spray, Holley or Weber Progressive, dual Kadrons, Dual Solex 35 PDSITs for Dual Port Engines, Dual 34 PDSITs for Single Port Engines, or Dual Weber ICTs), you will be happy with a cam from between 270-286 duration. If you have an old Progressive Carburetor but the intake is a piece of crap, get our null and a Progressive Carburetor Rebuild Kit. With these carburetion options, you can select from the Web Cam 119 Grind, Engle 110, Web Cam 163 Grind, and SCAT C-35 Grind.
4 Barrels of Carburetion; Dual 2bbl carburetor (Dual Weber IDFs or Dellorto DRLAs), you can effectively use a cam duration from 276-290 degrees of duration with great results. If you go over this much duration, you’ll need Dual Valve Springs, and the engine will turn more RPM’s than the small heads and exhaust will be able to move. So if you want more than this engine can deliver, you are looking at changing a bunch of stuff (heads, carbs, cam, exhaust), which is another engine entirely. Let’s stay focused! SCAT C-35 Grind, Engle 110, Web 118, Web 163 is about your cam limit, since I’m trying to keep you using a cam compatible with HD HD SINGLE Springs. If you have some ratio rockers lying around, you could use them with the Engle FK-7 Grind and Dual Valve Springs. But I do NOT recommend you buy ratio rockers for this engine, just use them if you already have them. This is because the heads only flow well to around .450″ lift, and that cam goes to .500″. Just a waste, like trying to breathe through a straw!
Because you will have HD SINGLE Springs, you’ll need a Rocker Shaft Shim Kit or a Bolt On Rocker Shaft Kit. Either works, but one kit is a lot more basic and re-uses your rockers, but replaces the wavy washers that are so failure-prone with HD SINGLE Springs. In any case, putting a set of Courier Valve Adjusting Screws or Elephant’s Foot Adjusters in the rockers is a wise move, your valve tips will thank you! If you are really on a tight budget, use a set of Lash Caps. You will need to do one of these 3 things, because your engine is a little wider than stock, and your stock pushrods will not reach. These solutions are not ideal, but this is a “budget build”. This is a perfect example of why the Porsche Length 5.325″ H-beam Rods work so well, using them will keep your PR length stock, and you don’t have to resort to small issues like the Push Rod Length, OR our compromising solution of using the 92mm Cylinder Base Shims and the .060″ Copper Head Gasket in the 90.5mm Size.
The reason we are using the mild heads is because it allows you to retain the stock size heater boxes. If you go to a head larger than our L3s, you are forced to go with a 1 1/2 or 1 5/8″ or larger header and comparably sized heater boxes. The cost of those destroys any hope of a “tight budget” you might have had. If you re-use your exhaust, carb(s), and engine tin/ignition, you can build this engine for under $1500, which is pretty amazing!
Single Port Head Users: follow the same cam guidelines, knowing that you will be running either the stock carburetor, or dual 1bbl carburetors. It will drive like a different engine if you put a better flowing exhaust, and a set of dual 1bbl carburetors on there.
Remember, if after reading this article you want to simply buy it instead of building it, you can order one of our custom-built-to-order long blocks with our “Mini Stroker” Long Block combo.
If you have any comments or questions, feel free to give us a shout. If we have missed something or we are not clear on a topic and you mention it (e-mail is best), we will edit this article incorporating your suggestions to make it even better. We also LOVE to hear from those of you who have built and drive this engine. Let us know how your build goes, and how it works out driveability and performance-wise for you!
Thanks for reading….Aircooled.Net
“I wanted to thank you for all the advise and direction you provided in regards to my 1800cc engine build for my 1968 type 3 fastback. While it isn’t built exactly as your 1800cc article recommends the end result is a very well performing engine. To anyone considering to build this engine I say DO IT! You’ll be glad you did.
The ACN 74mm crank spec’d out perfect and is great in conjunction with the 88mm slip-ins and L3 heads. I used my factory cam and connecting rods to keep the cost down. (I had clearance issues with the factory connecting rods hitting the case which was easily fixed with a Dremel tool and file).
I also used 1.4 ratio rockers with the L3 heads. I ended up with an excellent running engine with great low to mid-range torque. The heads flow so well that my fuel injection could not keep up and was running very lean according to my Innovate air/fuel gauge which is definitely worth the money. I’ve since raised my fuel pressure to fix the problem. Thanks again.” – Aaron W.