The Book of Porudicay - An Audi V8 Engine Swap Story

Porudicay – pronounced “pour”, “udi” “cay”, - a 987.1 Cayman S with an Audi 4.2L V8 swapped in. Howdy y’all, this is the beginning of an engine swap/build thread by an overconfident, underskilled YouTube mechanic with way too much determination and time on his hands. Before we get too far into this, I want to make it very clear that I have never done any car work that is remotely close to this project in scope, scale or difficulty so please be patient and understanding if you catch me using the wrong terms, specs or doing things in a way that may be very…dumb. I am 100% here for help and to document this project as it so far has been pretty fun and I’m learning a ton but if y’all have ANY ideas that could even be remotely helpful, I’m all ears. With that being said, we’ll jump into the background and basic specs for the project with more updates coming down the pipe in the near future. Background Purchased my 2007 Porsche Cayman S M6 early 2022 (Nicknamed Kiki The Cayman because I’m THAT guy who names his cars) with the intent of turning into a track monster or what I like to refer to as, a poor man’s GT4. Fully anticipated doing an engine swap after researching the infamous M97 and all of it’s reliability issues when tracked. After making a slew of modifications last year to try and mitigate the issues that stem from the infamous M97 (AOS, deep sump baffled oil pan, etc.), I still managed to completely blow the engine at a track day up in Iowa at RPM with the M97 ultimately being completely seized up. After renting a Uhaul to get it home, I let it sit for a few months over the winter before tearing out the M97 to see what actually happened. The IMS Bearing itself stayed strong, but I did manage to completely strip two of the piston rod bearings with one of the pistons deciding to exit the party early as it shot through the crankcase and straight into the IMS shaft. After looking at replacement parts for an M97 rebuild, I went ahead and decided to swap in a different engine purely based on costs (anticipating $5-10K in DIY savings approximately) and the fact that I’ll get some more WHP out of the Audi V8 engine. At this point, I’d also like to note that I will be parting out the M97 over in the classifieds section over the next few days so if you’re in need of any specific part, may take a minute to see if I still have it available. After doing some research, I found a few guys who have done the same engine swap before with Audi V8’s from the D2 and D3 Audi A8’s respectively because the cool part about going with one of these engines is that it marry's up to the transmission perfectly so won't have to worry about that aspect of it. They have pretty awesome YouTube videos up and I’ve also found plenty of technical docs on the Audi forums for this engine series as well so I decided why not, let’s give an engine swap the ol’ college try. I decided to print out all of the technical docs to create, The Book of Porudicay, which is basically the equivalent of the Holy Bible for this project. Home Built by Jeff – Audi V8 into a 986 Boxster -- Jase Wilks (my exact swap I’m attempting) -- 4.2L 40V Audi V8, engine code BGK that came out of a 2006 Audi A8 Base with approximately 75K miles on it. Rated for 335BHP at 6,000 and 320 at 3500 so hoping for some decent WHP gains after the swap. Rebuild and clean the new V8 engine and put on the new parts that have been coming in. I should have all of the parts delivered within the next week. Build out a new wire harness and ECU. This is the only part that legit scares me about being too difficult or complicated for me with my lack of experience with ECU’s and electrical systems in general and I WILL NEED LOTS OF HELP ON THIS ONE IN THE NEAR FUTURE SO IF THERE ARE ANY ECU EXPERTS WILLING TO HELP IN ANY WAY, I’LL LOVE YOU FOREVER! Custom fab engine mounts and transmission mounts as the Audi engine will sit about 2” lower than the previous M97. Thankfully, it turns out that my neighbor is a welder and actually built engine mounts and supports for industrial equipment which is SUPER AWESOME because he said he can help with the mounts no problem. Custom fab an exhaust which I also know a friend of a friend who builds custom dragsters (think 4,000whp custom built insanity) and said he can build me a custom exhaust no problem which is again, super awesome and super lucky on my part if it comes to fruition. Lastly, get the engine to turn over and pray to whatever God I believe in that day that Kiki turns over and can drive under her own power. As of today, I’m currently in the process of cleaning out the intake manifold and then will be adding on the remaining parts that I have this weekend like the AC Compressor, Power Steering Pump, Alternator, Starter, Fuel Injectors, Spark Plugs and the likes. Once I have everything done here, I’ll start working on the ECU and wire harness while I have the custom mounts fabbed and welded together for the engine and transmission. All in all, I would like to try and have the car running by September which I know is going to be very difficult as I’m sure things won’t go as smoothly as my overconfident brain thinks they will. But it’s a goal, and I’m sticking to it. Included some pictures below and will be updating the thread as I move forward. Wish me luck!

I look forward to reading this as it continues but i have a question, is it still intended to be a track monster? if so, why AC? Are you in Iowa? will you be able to register Kiki with the Audi engine or will you be trailering it to tracks? Cheers, Julian KCMO

Very cool. Have you had thoughts about an S8 valvetrain swap while the engine is out and apart?

Yes, the end goal is still to turn it into a full blown caged track car and I've been going back and forth about the AC delete because the cage would be a 2024 project and I'd guess that I'll run another year of Time Trials with NASA/SCCA while I get all of the safety features taken care of so I'd say I have another 1-1.5 years until she's no-longer street legal. During that time, I'd like to be able to enjoy my spirited drives and sitting in the paddock on a July day in Kansas with the AC blowing. So I'd venture to say I will do the AC delete, but not something I want to have to figure out right now as the main goal is to just get the car running. But that's just my thoughts. Nope, I'm actually in KC myself just across the border on the Kansas side so my "home" track is Heartland and I run with the Central Regions for NASA/SCCA. As for registration, hadn't necessarily thought about that but I have a truck and will be purchasing a trailer as I'm not doing the Uhaul bull again if something else happens. Learned that lesson the hardway...

That is a great point as no, I haven't given it much thought to doing a full S8 valvetrain swap but you've peaked my curiosity and I'll have to look into more this weekend. What're you thinking? That's it's just easier while it's out? Or is there performance/reliability to be gained?

Watching intently

First update for the Audi V8 engine swap and of course things are off to a slower start than I would’ve hoped for but we are moving forward. As parts started coming in for the initial engine rebuild, I got to work in changing out the basics such as broken sensors, o-rings and the sorts. While changing out the fuel injectors and spark plugs , I was able to peak down into the cylinders with a flashlight and to my horror, I saw my own eye peaking back at me and nearly shat myself. Thankfully, it was just a reflection in all of the oil that was chilling in the cylinder. Super awesome. This meant that I now had to get down into the cylinders to get them cleaned out. But, upon reflection, I probably should’ve planned on doing this from the get go as a basic health check. Especially considering that the entire outside of the engine is caked in carbon build up and what looks like burnt oil. Mainly bummed in myself for not thinking of doing this first as I easily could’ve started this process weeks ago. Compost happens though. After breaking down the engine and stripping more bolts than I care to count, I was able to pull off the cylinder/valve heads to which I was greeted by a waterfall of oil. Thankfully, oil had only found its way into the passenger side bank of cylinders and I am assuming this is because the engine was shipped leaning at an angle on its side with the passenger side bank on the low-side. I was initially really bummed that this happened as I was given a video of the engine running by the parts company I bought it from but at this point, I knew I’d have to get in there to clean it out. And after digging into it, I’m glad I did. With everything being caked in crap and after doing a bit of research online, got a rotary cleaning tool and some heavy duty engine degreaser and got to work. Honestly, it was actually a breeze getting everything off of the cylinder heads and the block with the rotary tool and degreaser as I was done in maybe an hour or two. Next up was to give the air intake manifold a good cleaning as it also looked like oil found its way into the manifold as well. Easy to take it off and is actually pretty cool because it’s a dual-intake system with a set of flaps that open a second intake path that’s slightly longer/wider on the upper manifold section depending on what your RPM’s are. Basically, it’s a shorter intake run up to about 3500 RPM but as soon as you cross that threshold, a set of flaps open up a secondary intake path that’s longer and slightly wider to increase the air flow for RPM’s above 3500 so the engine can provide more linear powerband without any loss at the higher RPM’s. Personally, I’d never heard of something like this before and thought it was pretty cool and fun to see. The air intake manifold was by far the hardest to clean and I probably spent a solid 6-7 hours with a rotary tool just grinding away at all of the carbon build up on the sealant runs. An absolute PITA. Next up were the camshafts and valve springs which didn’t exactly go smoothly as I ended up stripping about 6 bolts trying to get the camshaft bearings off which is just a pain that I hate dealing with. But, we eventually got everything pulled off and didn’t see any signs of wear/tear that I need to be concerned with right now. So ran the rotary cleaner to get the carbon build-up off everything I could before deciding to continue moving forward. Now that she’s looking a bit better, I think it's ready to be fully put back together. I have one last (doubtful) shipment of parts coming in this week as I need a few more o-rings, gaskets and accessory parts like that but the goal is to have everything put on and the cams/crank back into time this weekend. After that, I’ll begin figuring out the ECU system while the welder who’s helping me starts on the engine/trans mounts and the custom engine cradle that’ll be needed. Still aiming to try a “first turn” by the end of August and fingers crossed we get it done.

Sorry to see what you're seeing but it's more of the norm than the exception. (If you haven't already made note of this and planned ahead) This era of VW/ Audi has terrible PCV systems and so the accumulation that you're seeing under the valve cover is pretty standard. Most owners don't adequately maintain the system nor always use the greatest oil and follow an aggressive maintenance schedule, so we get what we have here... While the covers and heads are off, take a close look at the pads on the cam tensioner (left hand side of the head photo, under the chain). Chances are that they're grooved and now is your best time for replacement. Just the pads can be bought, don't go for the full tensioner replacement. There is a small metal screen under the tensioner as well, pay attention to it when removing and installing. Make sure that its clean as well. The tensioner relies on oil pressure for full operation. And best of luck getting it cranking by the end of the month!

I like following this build! Thank you for the time and effort to share it. Most enjoyable.

So the terrible PCV systems and oil leaks on this generation of engine was something I found out about a little too late, after I had already found the oil in the cylinders unfortunately....I'd thought I'd done enough research on the problems this engine has but there were a few YouTube videos that would've been helpful a month or two ago....lesson learned. But, I had researched the cam tensioner like you brought up before I started and there are grooves in my current tensioners but they're good enough I think I can move forward to "prove out the concept" but they will need to be replaced sooner than later for sure. I did look to purchase just the pads but wasn't able to find any sites that only sold the pads (part of the reason I decided to move forward with putting everything back together) so if you remember who that was, I'd appreciate the help. But this wire mesh you speak of, that's a new one so may have to get back in there to check as I've put her back together but it'd still be easier now with no oil in it and still out.

Tensioner Pads: Cam Chain Tensioner Pads - Upper Timing Guides Screen on the underside: Urgent question on the broken filter screen on cam chain...

Nice project! I used a similar engine at a track car years ago, it’s nice light and smooth engine! Good luck!

Update number 3 I think overconfident may have been a slight understatement on my part as now that I'm looking to mount and get everything put together, starting to run into some snags. The main one I'm trying to work through right now is the starter motor that isn't lining up with my flywheel. As you can see in the picture above, the starter Pinion isn't going to meet the flywheel when it's turned on as it's currently sitting about half an inch out from the flywheel. Wanted to stage it since I got a new clutch kit and flywheel and I'm glad I did because this is now a new issue to tackle. Has anyone run into this issue on other projects? Is this as simple of a fix as upsizing the starter Pinion? After some light Googling, I'm not seeing any "oversized" Pinions on the market as they all look to be about the same size. I'll look again later but if anyone has any advice on past experiences, I'd greatly appreciate it. Other than that, I've been moving the engine in and out of the bay and trying to get everything lined up and ready for mounts which are taking longer than anticipated to be delivered but should've known this would be the case. It also doesn't help that I travel a lot for work so that's also been causing some delays along with just good ol' life stuff. One of the "hacks" I have found though this process for anyone that's tried to engine swap a cayman at home before without a lift, knows that it is a major PITA to get the engine in and out of the engine bay with the car only on jack stands. Well, I've found that it's actually easiest to get the engine in and out while the car is on jack stands through the rear passenger wheel well. After removing the suspension and entire unit, I now only have to lift the car up 2-3 inches using the rear tow hook before I can fit the entire engine through the wheel well and into the engine bay. Is it still a little sketchy raising the rear while the fronts are on jacks? Yes, no doubt about that. But, with the cherry picker and taking the engine through the wheel well, I'm only raising it a few inches and I now feel significantly less sketched out about doing this than some of the other methods I've seen online. Never saw anyone use the tow hook like I do so if someone sees a reason why I should stop other than the fact that this could lead to a catastrophic failure if the car shifts and falls off the jacks, I'm all ears. The last picture is a bit old as I've reinstalled the air intake but wanted to include it as it shows that there is plenty of room in the engine bay for this engine - granted the intake filter box has been removed on the left side of the picture - but still hopeful I'll be able to pull this off.

I think a pinion gear big enough to fill that gap would greatly reduce the torque output (looks like you'd have probably twice the number of teeth, therefor half the torque (I think)). Is there any way to slot one the starter mounting holes to rotate it into the correct position? Cheers, Julian

Agree with Julian. Maybe some custom machining in your future. Also thought of increasing flywheel gear diameter. Either way machining is in order.

There's no way to rotate the starter into the correct position with the standard pilot holes but I'll take a look at the real estate on the side of the engine block tonight because sounds like maybe drilling out another hole to see if I could position it correctly will be the route forward. I've looked at getting a larger flywheel but the problem is the 8 bolt config pattern where the flywheel marry's to the crank, wasn't able to find many reasonably priced options...but if I can't get a new set of holes drilled, may have to go a different route on the entire clutch kit and get a larger flywheel....yipee!

Or...always park on hill...

The starter tooth ring on lots of flywheels is pressed on. If it is in your case, you can press off that ring, and have one made that's a big larger. Would make the motor spin over slower on the starter, but not sure it'd impact it enough to make it not start.

If you consider how much work and money it will cost modifying your gearbox, I think it’s a better idea using an gearbox from Audi , the front wheel drive Audi and Boxster use same gearbox with the difference of starter motor localisation. You can find a good Audi unit for peanuts at your local scrapyard!

@GLTHFJ60 -- wait, what? That's a thing? Had no idea that the starter tooth ring is pressed onto some flywheels and I'll definitely have to take a look at that this weekend. Thanks for pointing that one out, I'll have to look into it more, appreciate it! @El Vikingo Tropical -- I have thought about checking out the local junkyards for spare parts a couple times and I know there are a number of junkyards near me with plenty of audi's to take a look at so if I can't think of a better option this weekend, I'll start heading to the junkyards next week.

@El Vikingo Tropical -- I have thought about checking out the local junkyards for spare parts a couple times and I know there are a number of junkyards near me with plenty of audi's to take a look at so if I can't think of a better option this weekend, I'll start heading to the junkyards next week. [/QUOTE] I used a Audi A4 3.2L box at my FunCup V8 build, the thing is midengine Porsche and front wheel driven Audi share gearboxes,

Yup, definitely a thing. Not sure if that specific flywheel has a pressed on starter ring, but many do. Worth checking. Should be able to see it just by looking at the backside of the flywheel.