Some Geniuses Have Figured Out That A Crapload Of Audi Engines Bolt Right Up To Porsche Boxster Transmissions Including A V8

Imagine this: It’s 11:30 p.m. and you really should be sleeping, but the itch to browse online for cheap project cars needs to be scratched. While browsing classifieds ads, you stumble upon a dirt-cheap Porsche Boxster. You click on the ad, only to find the seller claiming that the engine’s basically toast. Better luck another time, right? Well, not quite. Don’t write off that Boxster suffering from engine failure just yet, because people around the world have been resurrecting non-running examples of these sports cars using an impressive array of Audi engines, and it’s easier than you might think.

Small displacement Boxsters don’t really suffer from the bore scoring seen on 911s of the era, but they do have one achilles heel — intermediate shaft (IMS) bearing failure, which can cause the engine to fall out of timing, resulting in what is generally considered irreparable damage. It’s not usually immediate and catastrophic on cars with dual-row bearings, as they have a failure rate of less than one percent, typically shed some fine metallic debris into the oil before they actually go, and have a dipstick for visual inspection of oil condition. However, cars with single-row IMS bearings are known to suffer from sudden, catastrophic engine failure, which means there are hundreds of blown-up Boxsters out there waiting for something to happen.

As it turns out, the manual gearboxes in the first-generation Boxster share a bellhousing pattern with the Audi 01E transmission, and the five-speed manual is straight-up an Audi 012 gearbox, meaning many longitudinally oriented Audi engines bolt up to Boxster transaxles. Obviously, this has resulted in some experimentation, with results ranging from mild to absolutely wild.

Let’s start with one of the more interesting options — a V8. In the 2000s, there were essentially two naturally aspirated Audi 4.2-liter V8s: a chain-driven one with a history of largely hideous reliability, and a belt-driven one that’s actually quite reliable. A Pennsylvanian company called Project Six uses the second one, which means up to 364 horsepower and V8 noises in a small mid-engined convertible. The end result — dubbed the Storm S — features functional factory gauges, functional air conditioning, functional power steering, and weighs about 70 pounds less than an equivalent Boxster thanks to the V8 simply being a lighter engine.

While this conversion isn’t cheap, clocking in at $8,000 plus the cost of the engine, that’s with Project Six doing all the work. Considering a used belt-drive Audi 4.2-liter V8 goes for anywhere from $500 to $2,500, and a Boxster rolling chassis can be had for just a few grand, that’s not a bad all-in price for what should be a weapon of a mid-engined sports car.

Alright, so what if you’re looking for a dirt-cheap engine swap and are handy enough to DIY something like this? You might want to consider the 1.8-liter turbocharged four-cylinder engine from an Audi A4 or Volkswagen Passat. It’s roughly 160 pounds lighter than the M96 flat-six that comes standard in a Boxster and it takes a whole lot of boost, plus you can mate it to the stock Boxster transaxle using a Passat clutch and flywheel. Granted, some fabrication is required for the sake of engine mounting and plumbing, but we aren’t talking about irreversible stuff here. It’s even possible to get the stock gauges and OBDII port to work, as Rennlist forum user xoo00ooxx who’s done the swap details:

I ran the K-line from my ECM to the OBD plug so it can be scanned just like the stock engine. The ABS and cruise control were happy once I got the tach functioning properly, I had to use a MSD 8920 tach signal converter to let my ECM talk to a Dakota Digital SGI-8 tach interface to alter the output from my 4cy to make the 6cyl tach show proper engine speed. The stock Box temp gauge works fine with the 1.8t temp sensor. The alternator light also works fine with the VW alternator. It’s just a matter of looking at the wire diagrams from this engine and that of the Boxster to determine what wires go where, a time consuming job but not terribly hard, I enjoy it.

Crafty stuff, and this all proves it’s very much possible to build a quicker, more reliable Boxster for just a few grand on top of the acquisition price of a car, and things get really fun when you start upping the boost. This one made a claimed 420 horsepower on a stock, unopened 1.8T engine with a Pulsar G25-550 turbocharger and Link aftermarket engine management. Sorry in advance, headphone users.

Now, there is another, more obscure, less reliable option that a handful of people have successfully pulled off — transplanting the twin-turbocharged 2.7-liter V6 from a B5 Audi S4 or C5 Audi A6 into a Boxster. This engine isn’t exactly known for world-class reliability, but they can make some serious horsepower with mild bolt-ons — more than 325 horsepower and 350 lb.-ft. of torque. Once again, this will bolt up to a standard Boxster five-speed manual transaxle, but it will require more fabrication, more plumbing, more electrical work, and more money than the 1.8-liter turbocharged four-banger.

However, once everything’s working, the results are magnificent. Think about it — here’s a boosted mid-engined sports car that, with a flash tune, will make 300 horsepower and weigh less than 3,000 pounds, all while singing a six-cylinder tune. That sounds like a serious recipe for fun, and it should still be cheaper than building up a used replacement M96 flat-six.

Of course, there’s absolutely nothing wrong with building up a replacement flat-six. It’s the route I’ll likely eventually go on a long enough timeline, partly because it just fits right and partly because a 3.4-liter 911 Carrera engine punched out to 3.8 liters and bulletproofed with a plain IMS bearing, a deeper oil pan, and oil pan baffles sounds like an absolute riot in a Boxster. However, Porsche made 164,874 first-generation Boxsters, and not all of them are suited to the high-buck treatment, so the fact that options exist to get blown-up examples back on the road is mega.

When it comes to inherently semi-precious cars, nice examples will always exist, but having solutions for keeping non-running ones going puts a little joy back on the road. Whether a V8, a four-banger, or a V6, creative options are out there, and they can make for some incredibly fun projects.

(Photo credits: Project Six, eBay seller, Porsche)

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