Audi 4.2 Liter V8 in a Cayman S

Well, I evidently over-revved my M97 3.4 liter engine by downshifting too early entering a curve at GingerMan in late July. I don't remember the over-rev happening, but it's in the ECU . But going down the front straight, the engine stopped, and I coasted into the grass outside Turn 1. Flames shot out my exhaust when I restarted it, and my oil pan is scattered with chunks of what looks like bearing material. I went through the options of new engine (costs more than the car), a used M97 (still expensive and no guarantees on its future), a GM LS engine (won't fit without moving the seats forward, and I can't give up the legroom), or an Audi 4.2 V8. After a lot of research, the Audi seems to be the best choice for me because it will bolt up to the Cayman 's 6-speed manual, is the same length as the M97, and weighs about the same. It also has a similar generation Bosch ECU . What really tipped the scale was that I know someone who's interested in doing the same thing, and we're going to team up on it. I'm familiar with engineering power train mounting systems and accessory drives, and he is a long-time Porsche mechanic who knows electronics (of which I know very little!). I wouldn't have started this without some help - two heads are better than one. We've looked at the Audi V8 as mounted in his A6, made measurements, etc., and haven't found any show-stoppers. So we've decided to go ahead, and expect a couple of snags along the way. From studying other people's engine swaps (some on Planet-9, including Fingers' LS3), I think we've got a pretty good plan. So here goes! I'll start posting thoughts, figures, and progress in the next day or two.

Between you and the member installing the GM LS engine these will be some seriously fast and cool Caymans . As with the LS can't wait to read about the progress. What you finish with will likely eat Ferraris.

Sounds cool, that's a great choice. I loved that engine when I drove an S4. Gobs of torque everywhere and really smooth. I'm sure you've done the research on it ... but if you're getting an engine from a salvaged car or a high mileage B6/B7 S4, see if the timing chain was already serviced.

Yeah, I'm watching the LS3 swap pretty closely. One thing I forgot to say in my first post was that the choice of the Audi was mainly to avoid taking out a mortgage if I break another engine. The fact that I'll have about 50 more HP and 50 ft-lb of torque is just a bonus! But the other thing about the Audi is that I think we can make it so that the car looks and acts like it is a production Cayman S , except for the sound and power.

I'm planning on getting the earlier V8 with the belt-driven cams. I looked at the later chain-driven ones, and I couldn't find a good place for the engine mount brackets. The whole left side of the engine is covered in accessories! But I'm going to replace everything I can on the front face of the engine before installation. Might not be so easy later! So my plan is to find a complete 1st generation V8 with accessories and wiring, and hook all that up to the Porsche body. I'll post my plans on the engine mounting system soon. That's the first hurdle, but it looks like it might work out pretty clean.

I attached a cartoon of the engine mounting system we'll start with - I'm sure it will be tweaked. I used a photo I found on Rennsport: The German Car thread - Page 2 - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum that shows a Cayman with an Audi 4.2. I covered over the crossmember in their photo and put together my idea for a cradle. It has two diagonal square tubes going from the control arm inner attachment, to right behind the seats. The front part is a short crossmember that goes cross-car and bolts to the four holes that the Cayman front engine mount bolted to. The diagonal on the right slides in between the oil pan and the alternator (I'd like to keep things symmetric, but we'll see). The actual engine mounts (shown in blue) sit on the crossmember that goes across under the slot in the oil pan. We might sandwich the rear ends of the diagonals between the existing aluminum diagonal brackets and the control arm attachments. The idea is to weld the entire cradle together, bolt it in, and install the engine with the production Audi mount brackets and mounts (although I will track the car hard, I still want the noise to be bearable on the road). The existing mounts on each side of the transmission are pretty close to the location in the Audi V8 installation, so we'll leave them as they are. Once installed, the diagonal tubes will reinforce the chassis by connecting the suspension attachment forward to the structure behind the seats. Along with each existing aluminum diagonal, they each complete a triangle between the inner control arm pivot and two points on the body. The other attached photo is of an arm reaching off the front of the engine, to the right. Audi uses this to contact a "snubber" mount that limits travel. I'm planning to connect this, with a vertical strut of some type, down to the right (passenger) end of the front crossmember. This would be used to "fine tune" the mounting system to add stiffness or damping (with rubber bushings like in a stab-bar link, or a shock absorber). After all, it probably won't be perfect on the first try. Not sure the photos both attached, so it might need to be fixed.

If you search YouTube there is a video of a guy who did this conversion to a Boxster . Now would be the time to go to electric power steering to lose one accessory drive. Good Luck and keep us posted.

Love the Audi 4.2 V8. For my money its the best sounding V8 on the planet. Great choice.

Good luck with your project! I'm excited to see how it turns out. If there is anything I can help with let me know. Our projects are so different I'm not sure much of my experience will be much help but...

good luck OP. along with morbo on the timing chain and guides, make sure the coilpacks are good... miss my S4 avant...still the best sound - missing it.

Fingers, thanks, I am certainly learning from your project! And rjpeaks, does the coil pack question apply to the earlier belt-drive cam engines?

not sure if that coincides with the earlier belt-drive engines.. there was an issue with the mfr of the coilpacks back at that time. i had a few fail on me. I would order some new ones - if you cannot find them, i can order them for you and send them out to you. you know it takes 13+ qts of oil right?

This may help with the ECU system for the Audi V8. I have yet to talk to anyone who has used this system. Good Luck!

Rob VN, rjpeaks, and Bodhii, all good info. Thanks for putting it here to refer to!

I didn't get a lot more torn down this weekend (Michigan Football takes more of my time now that it's worth going to), but I did get a 1000-pound hydraulic table lift so I could move the powertrain straight up and down when I pull the mounts. I'm in the process of disconnecting and labeling hoses and wires, trying to be patient and not have to kick myself later (it's killing me!). That's the only thing left before removing the M97 powertrain. I'm to the point where I need to hunt down a donor Audi , but I need to pin down models and years to search for. I want a 40-valve version with belt-driven cams, but I know that includes quite a range of models. In the meantime, I found a really good reference for anyone who would want to perform a transplant like this. Audi calls it the Self-Study Programme 217: http://www.kpematop.com/S6/V8-5VEngine.pdf It tells you, in general terms, what all the different hoses sprouting from the engine do, how the oiling system is laid out, what the ECU is, etc. Already I've found out that the engine has an AIR pump that I'll have to mount somewhere, and that it comes with hydraulic engine mounts with damping that can be increased/decreased by switching power on to them. All the more reason to use a donor car, so I can see where it's all tucked away. Does anyone know of any versions I should prefer, or shy away from? I want to take the time to get the right one. A little more looking at photos showed me that connecting a link straight down from that snubber bracket isn't straightforward, because it would go right through the alternator! But at least there are places to bolt to on the front of the engine, and I can probably find another way to do it.

i would get on Audizine my man. there were so many iterations of that same 4.2L. R8, RS4, S4, A8, Quattro etc from 340HP to 420HP

The different versions are broken down here: https://en.m.wikipedia.org/wiki/List_of_Volkswagen_Group_petrol_engines#4.2_V8_40v v ... '04 Audi S4 sounds like a good start, hopefully pre-immobilizer, it looks like the 400hp versions are from turbocharged cars, see the section below the link.

This sounds like a very cool idea. Here's the video of Trey Walker Boxter. This is a sweet sound! https://m.youtube.com/watch?v=An6HT8TBd2M

I give you an A+ for thinking out of the box.

If you go with the older 32V version checkout motorgeek. There is a lot of ABH and ABZ information over there! Good luck with the build! motorgeek.com

The broken 3.4 liter is out! :dance: I took my time and double and triple-checked all the connections between the engine and car, and then hung a string from the top center of the engine to the floor to see if it could be worked all the way around the engine. This still found two more wired connections that would have snapped! I sat the powertrain on a hydraulic table lift so it could drop straight down. I had adjusted the release so it would move very slow when pulled all the way. The only things I left attached were the shifter cables, because they were much easier to disconnect with the transmission away from the body. The table lift did a great job for me, since the car isn't that high off the ground. The one mistake I almost made was dropping the engine too far before disconnecting the battery cable (which runs along the console with the shifter cables). It seemed like every time I ran into a snag, I found a post on this site that helped me through, like how to pop the shifter cables loose. I've got a lot of parts to clean up, tag, and store this week, so progress will be a little slow. But a couple of friends are also starting to help track down the right Audi V8, with the right supporting equipment. This is getting really interesting...

I had posted on our local Audi group; some have mentioned their for-sale engine: https://www.facebook.com/groups/1404249466533760/1527866437505395/?notif_t=group_comment

I've separated the engine from the transmission, and I'm ready to trial fit a broken Audi V8 engine to it. Once I know I can fit an engine mounting system around it the way I want, we'll get the actual engine to install. It looks like the best choice is the BBD version that came in the 2002-2003 S6. Higher horsepower and stronger rods. In the meantime, I got a Wavetrac diff to replace the open diff (that didn't belong there in the first place!). Might as well get a new front anti-roll bar and GT3 LCA 's while the underbody panels are off. I had way too much outer front tire wear last year, and slow turn-in. One thing I thought was interesting was that the air deflectors for the inner axle joint boots are symmetric to the vehicle, while the axle boots are not (one axle being longer). So they're not equally cooled. It looks like the right boot gets better flow than the left because of this. Maybe it's not coincidence that my left boot is the one that sprayed grease all over after a couple of track events. This will be one of the things that gets redone once the new cradle gets designed, and I know where vents will fit.

So what is new with your install? A lot of interest in this project.

Hey Dicket, got slowed down by spending a week going to a very rainy F1 race in Austin. Horrible weather, great race! Conflicting schedules have also kept me from getting the broken Audi engine from one of my cohorts, to trial fit in the car. It looks like it will happen the weekend after this one. We have also been researching what a donor car will cost, and looking for the right one. Don't know how long that will take yet, but I need to pull the trigger pretty soon. I've been reading up on how to make NACA ducts efficient, so that when I trial fit the engine I'll know how to build them into the cradle close-out panels. I'm also looking for advice on learning engine controls, like what rides on the communications lines, how engine and body computers talk to each other, and what type of equipment is necessary to program it. I will have help on the electronics, but don't want to be helpless in the matter. Should have another update in a couple of weeks...

LOL, it's funny how life gets in the way huh? I would have been done months ago if could have done it all in one shot. Going on 6 month now and at least a month or two out still.

Some inspiration for you.:cheers:

If it fits in a bug, how can it not fit in a Cayman ?

Come on, that's not a fair comparison to this project. It's a 911. :hilarious:

OP, the latest versions of the "FSI" coils are still (last letter) E (red, R8) and F (black). Depending on how difficult to get to in your configuration: either pop new ones in (ca. $25 shipped) or use what you have; I typically have fresh ones on hand (and as you know, only 5 min trip away). As for plugs: on our high pressure turbo Audi, we only run copper plugs (NGK BKR7E) with 0.030 gap. Stock Audi plugs may be ok for your naturally aspirated 4.2.