Boxster V8 project log
 

Till now most of my info and questions have been scattered across a number of posts, maybe it is time to create a project log to wrap it all together.

The start: A cheap-ish 1997 986 base model.
The goal: A good quality 986 V8

So I started with a 1997 Boxster because it is the only year where I can swap in a different engine and get it inspected cheaply and with minor requirements. Basically it should be technically sound, but not strict requirements on noise / emissions etc. 1998 and later require more paper work, inspection etc and I wanted to avoid that. This Boxster actually looks quite alright. It aint no beauty (but neither am I), but no big dents, tears or such. I now know that it has had a few incidents in it's life, hoping it is still straight and true but should find out in the coming months.

On to the goal. I've always wanted to have a mid engined car again (started my car career with a Pontiac Fiero) and a V8 is one of those engine you need to have had one of. So far I've only had a share of inline fours and various six cylinders (flat, V and inline). So there we have the Boxster which can combine both. And from what I have read is actually a pretty well handling car. On top of that I really engine working on cars and having a hobby car makes sense. I can work on it when it suits (many other things to do) as there is no need for the car. No stress, just enjoyment. For me working on the car and puzzling the right solution is as much fun as driving it. So I am fully aware that it makes no financial sense to do this project. It is just a hobby.

So on the list is an Audi V8, most likely coming from a VW actually, the Phaeton. Likely I'll use an Audi 0A2 gearbox as well, but the Porsche G87.21 is an option as well. Basically they are the same gearboxes, but the Audi has way taller gearing.

So a brief overview of the current status, to be detailed with some pictures during the coming weeks / months. I decided to split the project in two major parts;
1. Make the car driveable and solid. Swap the gearbox
2. Do the engine swap

Part 1 is starting to near completion. Work done so far (in no particular order)
- Fixed AOS of the engine
- Replaced clutch
- Fitted G87.21 gearbox
- Coupled some 987 Cayman S driveshafts to it
- Used 987 wheel carriers to fit these driveshafts.
- New brake discs and pads to suit
- Refreshed rear suspension (M030 springs, Bilstein B6 struts, strut mount, control and track arms)
- Removed AC (compressor, all lines, condensors. evaporator is still in)
- Replaced PCM by simple radio, CD changer removed
- Radio and Clima moved up. Bottom is now clear, trying to find console delete kit to cover it up nicely.
- Aftermarket alarm removed (what a pain)
- Old phone carkit removed
- 997 Shifter mounted
- M030 springs and B8 struts at the front
- Fixing damage on drivers side front (mainly air channel damage, lost fasteners etc.)
- Replacing radiator vent lines (dripping)
- Replaced cooling fan (wasn't functional anymore)
- Fixing front water drains, both were blocked of which one with glass. New grommets to go in.

Left to do for part 1:
- Build the front-end of the car back together (waiting for correct new fasteners and water drain stuff)
- Finish last damaged wires for radio (antenna cable is one of them)
- Put the final interior parts back together.
- Fit the exhaust. Used aftermarket one going in which just clears the longer gearbox, need to adapt the U-bends and fab a mount to the gearbox.
- Finalize rear and last engine compartment parts (fan is dangling etc.)
- Get it aligned and inspected.
- New front tyres.

Plan for Part 2:

I am expecting to pick up a moveable shell of a 2003 S. This will become very useful:
- It allows to build the whole V8 conversion into this tub, before swapping it over to my car :cheers:
- Larger coolant pipes and hoses for the center radiator (if that turns out to be needed)
- ABS 5.7 to replace my ABS 5.3. This interfaces to the 987 rear sensors.
- Wiring loom providing the connectors and wires for these sensors, also the fronts
- It has the correct front ABS sensors.
- Likely the wiring loom has some convenient connections for the new ECU, missing in the 97.
- S brakes in case I want to upgrade.

Engine wise the BGH Phaeton engine is a candidate. Available in low mileage still. Also considering the slightly older versions (S6, S8) which have higher power. The BGH seems to have convenient locations of the pulleys and water channels. It runs a DME 7.1.1 which should interface ok with the 1997 car and ABS 5.7

Gearbox is already sorted, but might couple it to the taller 0A2 instead. Need to make some calculations on this.

Plan to run the 981 PSE exhaust. I have one side with damaged pipe and this seems to fit the 986 like a glove. Cut the pipe and weld a flange on. Then the main concern would be the pipe between engine and exhaust, fitting a cat somewhere in between.

I've started on a V8 swap a few times, but never finished. The last time I stopped on it was when I realized that my engine cradle held the engine too high for the gear shift cables to reach. Be sure to consider all the details like that as you go forward. I'm looking forward to seeing your progress!

Here's a link to one that was swapped a few years ago with an AYS engine from an S8 that has a lot of good documentation. It may be helpful if you haven't already found it.
https://sites.google.com/view/boxsterv8swap/home

Thanks for the reminder ;-) Indeed shift cables was one of my questions and somehow it feels better to route them on the lower side next to the engine. Will keep an eye on it. Things like these are the reason I'll be picking up that rolling chassis. It should allow me to make this whole puzzle without having to take my car apart. My time is limited so otherwise it could easily become a long journey without a car to enjoy.

Just had another look at your link. The site and photos I have seen before, but I notice that it is still being updated. I'll have a closer look as I do see a G87 box on the pictures, but not in the car..

Pardon me for jumping in w/ an issue and not a lot of details to go along w/ it, but isn't there a problem w/ 97 986s wearing tires > 17" ? IIRC, the issue was the strength of the metal surrounding the suspension was "weak" and would potentially crack if you used bigger tires than what came from the factory. In 98 and newer models Porsche strengthened that area and it was no longer an issue.

I bring it up for consideration since a V8 will probably add weight to the equation and could stress a weak pt of the 97. Sorry I can't add more detail as I never intended to buy a 97 so I never paid those old threads debating it much mind - I have an old processor (brain) and it'll only hold so much data. But I mention it so others can chime in. It might just be internet lore and has been debunked but wouldn't want you to go hip deep into this project and then find out there's a major problem because of a structural weakness on the 97.

When I first joined the forum oh those many yrs ago, we had a member who was a MD State Patrol officer w/ a 97 and he had 18" wheels on it. In his signature, he said he was 'cheating death' w/ those wheels.

Good luck w/ your adventure.

Thanks for bringing that up. I read about that issue only after buying the car and have since not find any detail about it.

Indeed there seems to have been a change for year 98 and up and only those years are allowed to run 18" wheels. This seems a bit odd as these would not give significantly more load on the suspension. There are many 97 models with 18"out there and I have yet to read about any actual issue / failure.

For the moment I am not worried due to lack of massive failure reported. Also no recall of whatever sort for the 97 models. It seems a bit of a theoretical issue rather than a practical one. The Audi V8 weighs in about the same as the M96. With AC and PS removed I don't expect any weight increase at all. Surely it will need to put some more power down.

That said, it would be really interesting to know what the potential weak point is and how it is resolved. I'll take the car apart anyway and it could provide an opportunity to strengthen any known weak point. So if some factual info is out there, it would be great!

The main bulkhead and engine compartement side panels where replaced with substantially thicker stampings starting on the 1998 model year to address the structural failures that were observed when running larger diameter wheels on the 1997 model. This was particularly a problem when running larger diameter wheels with sticky compound track tires, but failures also occured on street driven only vehicles. I have no idea of how many failures occured, but I know we have seen atleast two cars with this problem when doing PPI inspections for potenital buyers.

My notes from almost 20 years ago taken from Porsche documentation. The '97 to '98 change was:

18” wheel option with rear chassis reinforced to accept new wheels. Rear body structural change included redesigned wheel wells and coil spring mounts, lower engine compartment bulkhead, rear wall cross member and rear axle mount reinforcements.

Thanks, that's really helpful!

I'll be sure to take a close look at the 2003 tub that will be coming and keep an eye at changes. The axle mounts can be swapped over.

Picked up some parts from the dealer today. New radiator breather hoses with new clips are now in. The clips are really nice, they now come preloaded. So you just slide them on and snap them into place. That allowed me to bolt the last things in place behind the radiator and start putting the wheel well liners back in place (with new fasteners).

Also got the new rubber pieces for the front water drains and hope to get them in this weekend. Then I should be able to bolt the whole front of the car (bumper cover, wheel liners and frunk parts) back together.

Just a wild stab — I'm guessing Marc_986 is not a Porsche purist. :)

Why would you think that? :eek: If I were a purist, this isn't the Porsche I'd have bought.

It was quite a fight getting the water drains fixed. Well, the drivers side one was fairly easy as you can reach it from the bottom and put it roughly in place. The passenger side was a sincere struggle. Ended up folding up the grommet part with a screw driver through the middle (to keep the plastic hose / pipe aligned). With the grommet in place I used a set of pliers to pull the hose / pipe up, groove by groove. All in now.

Wheel liners are in and the bumper cover is on. Much better than before.

I did spot an issue with the side markers though. When I push them in they sit too low and have a hard time to click in place. It looks like there is a ridge in the plastic part attached to the car which prevents the correct location. As the car orignally would have had amber side markers and clear ones are now in, could this be a difference between those markers?

Also got a first chance to roughly check the front camber adjustment range. Bit hard to judge as the phone level changes a bit depending on the position you hold it in (as in upside down, front to back etc.). Worst numbers on both side (least negative camber) give -0.3deg to -0.9deg. Quite equal on both sides. I set it to full negative for now.

Front now mostly back together and suspension tightened up. The new clips for the undertray are metal and snap into place very nicely, great stuff.

Yesterday I took of the rear bumper cover. One thing to fix while I am in there is the rear spoiler lip which shakes and rattles. See my thread here: https://986forum.com/forums/666361-post1.html

I think removing the rear bumper as well should give me good access to the exhaust from the rear. So I started bolting the rear back together (support plate, diagonal braces etc.). Two holes are a few mm out of alignment so I guess I have to push on one side of the car to get them to align and bolt them up. Otherwise progressing well on that side.

Just use a ratchet strap to pull them in. Very easy.

Thanks! Got the holes to align today. It was fairly easy with two people, one pulling a little bit while to other drops the bolt in. Seems to fit without issue, so giving some confidence in this car.

Measure the ride height as well today,
The front seems a bit low at 12.7mm but the tires look a bit low on pressure. So I guess it will pop back up to the correct height for M030 ROW.
The rear sits a bit on the high side, more or less at spec for normal ride height. So either it will need to sag a bit or the car doesn't have the weight yet. No big issue anyway.

Next step to do a coarse rear alignment.

Hi Marc,
I'm working on a V8 swap 914 with 6 speed Boxster gearbox. Hope we can share notes. Currently trying to decide between Audi ABZ v8 and Chev LS4.
Right now designing engine adapter plate/flywheel. I need to know the distance between the engine (M96) and gearbox mounting surfaces.
Is there any chance you could help me out with that?
Thanks

That wasn't real clear. The measurement I need is between the flywheel friction surface to the M96 engine/gearbox mounting surface. This will tell me where exactly the disc is positioned on the input shaft. Then I can design my flywheel

Hi cooler,

I don't have that measure, I looked carefully at the gearbox side (G86.00 / G87.21 and Audi 0A2), not the engine side.

Are you looking at the 6 speed 986 box or the 987 unit? To my knowledge the bellhousing of the 986 version (G86.20) does not fit the audi V8 (without adapter), where the G87.20/21 and the 986 5-speed do. Also driveshaft lengths differ.

The 986 6-speed is a bit of an odd one.

Hi Marc,
Thanks for the response. I'm using the early 986 S 6 speed G86.20. The dowel pins and a few bolt hole line up with the ABZ Audi V8, I can not confirm other Audi V8. The important thing is that the dowel pins line up and that at least some of the bolt holes also line up.
The problem conceived with the early 986 S 6 speed is the 12 o'clock starter pocket location. This conflicts with the Audi V8 starter position at 5 o'clock (viewed from the rear) as the G86.20 does not have a starter pocket at 5 o'clock unless you hacked a hole for the Audi starter nose cone. I don't like the idea of hacking a stress riser in the side of the bellhousing but, if one were to use a starter with out a nose cone, like the M96 starter, all that is needed is a notch in the bellhousing to clear the starter gear. See photo (if that works)

http://986forum.com/forums/uploads02...1742491352.jpg
http://986forum.com/forums/uploads02...1742491378.jpg

You may notice a sharpie mark at the center of the starter socket and imagine the notch required for the starter gear as it protrudes to engage the ring gear. As the ring gear is located nearly flush with engine the notch needs only to be about 10mm deep into the bellhousing and does not actually breech the outer bellhousing wall.

Marc, do you posses a M96 engine with flywheel attached?

I do have a M96 engine with flywheel attached, but the issue is that it is currently in the car, fitted with a clutch and bolted to the G87.21 gearbox. I don't plan to take that apart for the coming year as I will be building up my V8 swap in a spare tub.

There seem to be quite a few people on the forum working on their engines at the moment, so I would suggest to look around the recent post and see if someone is willing to take measurements. Otherwise I can do that in a few weeks time when I pick up the tub. That company always has a few engines around.

Thanks so much Mark
Please do measure for me when you get the opportunity. I have tried to urge others to do so without success. My adapter development depends on that measurement.
My adapter will result in a adapter that is about 30mm thinner which should interest those performing swaps that are longitudinally challenged for space.

The measurement should come any time soon, hopefully this week. I was there today to pick up the carcas, but the only engines with flywheel where high up. So he will pick one down and measure.

So, on to the carcas. As said, I was able to pick it up today. It was a 03 S, so has the right wiring loom and ABS unit for me to use. Also all cooling pipes (thicker than base) and radiators are on. Brake system is complete (I have the calipers as separate parts with me).

Some parts will go back in a few weeks and will be replaced with my own. Having them on the car now was easier for transportation and ensures no hoses are cut etc.

Rough plan is to transplant ABS and all associated parts coming winter. I might put the S brakes on as well. In parallel I intend to source my V8 and start the mechanical fitting part. Also I could move to electro hydraulic power steering.

For now I am finishing the car as it is. Final wires for the radio etc. will be soldered tomorrow so I can put the interior back together.

Picture to show what I picked up:
Attachment 23756

Hi Marc,
It's great to see you moving forward on your project. Are you still planning to use an Audi V8?

Yes, plan is still to source an Audi V8 for this project. With this scrap car I likely have all the parts needed from the Porsche side (just checked that it also has the DBW 'sensor' for example).

Just was able to confirm the ABS unit it has is the correct one for my needs, so all green lights so far.

Little set back on the radio though, the little harness I soldered works fine, but the Porsche microphone doesn't work on the radio. So I need to mount the new microphone in place of the old Porsche one.

So there are many variants of the Audi v8. I posses an ABZ I can provide information if you would like. I have also decided not to use it in favor of an Chev LS4.

Funny, I had a dream last night of a guy that was trying to sell me an air cooled 911 engine. One which he developed a fix for cracks in the heads (even though this is not an issue with those engines).

This reminded me of an air cooled 2.7 that I rebuilt 15 years ago. I spent 10K then, on parts alone for an engine that make only 200hp weighed 500lb and continued to cost thousand on fuel injection part to keep running. I spent more time working on it than driving it.

That said, this is why we swap out Porsche engines. I do not know from experience but it seams the M96 also is plagued with issues.

The Audi V8 appeared to be a natural for rear mid-engine swaps. They are very compact longitudinally, bolt directly to many Porsche and Audi gearboxes and are relatively light weight (340lb bare).

I hope I'm wrong but unfortunately it appears that many parts are no longer available and on line talk of working on them has fallen silent 15-20 years ago. I am not a machinist and can't make my own parts so I have moved on to the LS engine which will be a more difficult swap but it will always have parts availability and serviceability at least in North America.

You can have mine if you pay shipping.

Yes, fortunately here in Western Europe there is a good supply of Audi V8 engines, so it is the logical choice for me. I am strongly leaning towards the engine from the VW Phaeton. It seems mechanically the best fit, has good power and is a bit more modern than the ABZ (which is a great engine, but difficult to find with reasonable mileage). Also this era of Audi V8 runs on DME7.1.1 which is close to the ECUs used in the Boxster. It shouldn't be hard to get it to run in a Boxster.

Do you have a build log of the LS4 swap? Always interested to see what others are up to. What I have seen so far on Chevy swaps is that they do require more modifications to the car....

Still hoping someone is working on an Audi V10 swap, should be possible to get it to fit with the right gearbox. Too big of a step for me now.

Hi Mark,
Compatibility of electronics definitely deserves careful consideration. My project car is a 914 so no electronics interface to speak of.

I do not have a build log but will, when I've developed a solid plan for the engine conversion. There are several kits available but all of them add about 50mm longitudinally to the assembly. My plan is much simpler and adds only 6mm longitudinally. Popular longitudinally challenged LS swaps like the 996, 986 and A4 should require little if any body modifications.

I have seen others online working on V10 and W12 conversions using the G86.20 and the newer Audi transaxle that has the axle through the bellhousing, I think on the GT40 Forum.

Big step forward today for getting the car back on the road. One of the things to resolve was getting the speedometer to work. The reason it didn't work is that the driveshafts are not compatible with this ABS unit (ABS 5.3).

So my plan was to repin the ABS connector and swap the rear wheel sensor providing the speed signal with a front wheel sensor.

There was a trick which took me a little time to find out. The terminals in the connector are held in place by a little strip as well as by the regular tabs. Two strips in total, one pink, the other white. These come out from the sides:
Attachment 23762

Attachment 23763

Once these are removed, the terminal come out easily using a removal tool;
Attachment 23764

Swapped the pins I wanted to swap and put the connector back together. I did a quick test and I now see an indicated speed when I turn the front left wheel by hand. Hooray :cheers:

Great step today for getting the car back on the road (with flat six still). The right catalytic converter showed up yesterday. Today I was able to transfer the o2 sensor, some plug bolt and block off the second O2 port. Then the pipe was mounted and after a bit of wiggling all fits now :cheers:

Also hang the rear bumper cover to check clearance, positioning, angle.. The muffler clears my gearbox (which was the whole intention behind getting this sausage type muffler as the stock muffler doesn't clear the G87 gearbox) and also enough space to the bumper cover. At the moment it sits a bit off-center, but I hope I can wiggle it some more to get it right.

Next step is to make a bracket to hold the muffler to the gearbox. Part one of carboard template is done, part two to follow any time soon. Then I'll make a metal version. That should allow me to mount everything back up. :cool:

Why stop at V10? Give me the XJS V12 swap. European V12 mid engine roadster!


I almost bought an XJS about 20 years ago, but my brother talked me out of it. Absolute train wreck of a project, but damn do i still pine for one.

Well, I think the Audi V10 would fit as it is a compact engine. Probably similar in length as an LS. I don't know any V12 that would fit without a good stretch ;-)

Anyway, back to business. Tomorrow is crunch time for my 986. I took it off the road for a year, but that is due to expire next Tuesday. So I better get an inspection now instead of renewing the off-road status.

So after the catalytic converter arriving last week it is now mounted and a bracket was made this weekend to secure it to the gearbox. All solid now. Then I bolted the rear braces back. This morning I was able to start the car :cheers:It sat for a year and a half and so much was done that it was actually an exiting moment. Just a few turns and it sprung to life. Little lifter noise, but that was about it. Then I was even able to move it forward and backward a bit on its own power (which was another great deal as I mounted this unknown condition G87 box and had some difficulties in bleeding the clutch slave.).

This afternoon I did a coarse alignment of the rear suspension, such that I can at least drive it safely to the test center. Rear bumper mounted back up, engine cover closed and quite a number of small things that needed to be done still. Then this evening I took it for a drive (sorry mr. policeman). All gears functional :). So far, all systems green. It did smell rather strong after the drive, likely due to burning of grease and sticker stuff from the exhaust. I guess that should become better in a few drives. Alignment is off a bit, but it isn't scary to drive.

So tomorrow it will be tested. Fingers crossed it passes and I can solve minor things at my own convenience and actually start to enjoy the car for the first time :eek:

Some observations after the short drive:

- The car drives soo much better with the M030 suspension on. The original suspension was still in good shape, but this just feels a lot better in reaction. Really happy with it already.
- It is quite a bit too loud for my liking. Not a real issue when hammering it down some country roads, but I already feel it can wear me (and the cars around me) out. I'll see whether I get used to it, or whether moving to the final exhaust is in order (have my eye on either 981 or 982 OEM PSE exhausts).
- The speedo works with the ABS unit connector terminals swapped. Already checked it by hand before, but happy to see it as it surely is a requirement for the test
- Visibility is really poor. Basically I am looking straight at the window frame. Can see the road fine, but looking in the distance or even up to traffic lights is near impossible. I'll need to lower my ass at least 2" to have good visibilty.
- The new clutch (just SACHS OEM 2.5L clutch) is making the drive much more enjoyable. Previous one was worn to the rivets and made clutch actuation like driving a truck.
- Shifting is soo much improved. The old 5sp was very notchy, the lever throw was long and there was enough play in the mechanism to need to guess the gear. The G87 box is much (!) smoother and the 987 mechanism more precise. Still not as good as I would want it to be, but miles better than before.

So in many aspects the car is starting to come my way

The seating:

So my issue is that my head is far too high in the car. Not really surprising, but something to fix.

I am not that tall at all, about 6' to 6'1. But I have an odd aspect ratio having relatively short legs and a relatively tall body. Many cars have a similar issue in that the seat bottom moves up when it slides forward. So I need to slide it quite a bit forward, giving me a high position. Add my body length and you might see the issue.

Open to suggestions. Sport seats would be nice, they don't need to be racing seats (I do intend to attend some track days in the future, but primary purpose is street). The seats should be low in the forward position (don't care about the rearward position). I prefer lighter seats (no power seat stuff needed, but heated would be nice to extend the top-down driving season).

I'm guessing you've lowered the OEM seats as much as possible? I'm 6'1, and with seats lowered haven't run into an issue.

Yes, they are most downward indeed. But the main issue seems the rising of the seats when sliding forward, which I need to operate the pedals :)

The annual inspection was delayed till today. I received a phone call this morning that it failed :mad: After all the work done, it failed on the horn :eek: So I went there and indeed, no horn. Hmmm, I did remove the front bumper, pretty sure I connected the horns again, but worth a check. They were connected. Next step, the fuse. Check location B3..... no fuse. Put a fuse in and voila, it hunks. But it doesn't stop. On to the switch, removed the airbag to confirm the rubbers of the metal plate are weak. Did a short research, read that some solved it with a few washers. So that's the easiest way. I put 4 washers in and mounted the plate back. Now the horn works as expected. Remounted the airbag and voila: PASS :cheers:

Drove off with the car and at the end of the street; no gear selection :( It was still in 2nd gear so I guessed it would at least get me home. It did. Checked it this evening and expected the outer cable to have come loose from the gearbox (the plastic clips were broken, so I ty-rapped it). But no, the cable end popped off. I'll need to do some research on a fix. I don't want to buy new cables as I might need a different length when the V8 goes in.

Also noticed that one of the keys has a tendency to keep rotating in the ignition. Guessing the end of this ignition switch is coming close? Other key seems fine still. The remote on one of them also doesn't function, I hope it can be fixed with a new battery?

So some work to do, but at least I can legally test drive it now :D

Nice work!

You can buy shifter ends I believe.

For the key, it’s a pain - the fob cannot be reprogrammed. My second stopped working so trying to get it reprogrammed (and ordered a new chip). Dealer said they could do it before I bought the chip online but they are dodging my calls.

Thanks for the info :D

I'll need to address the shift cable issue first. I did a bit of a search and concluded the following;
- 987 6-speed shift cables are known to break. So OEM replacement doesn't make that much sense, I've seen quite a few reporting new cables failing in a few years.
- Options seem to be:

1. Replace the cable. OEM is expensive, Numeric is actually cheaper
2. Function first cable end inserts. Will fix my current issue, but about half the price of a Numeric cable set
3. Fab up a custom fix

Considering the prices of a fix I'll try the custom fix first. I intend to make a steel plate, slightly larger than the cable end, and slot a hole in from one side. The hole will be smaller than the ball diameter. I'll make another plate and screw them together with the cable end in the middle. This way the end can't slip off the ball anymore.

Any comments on the suggested fix are welcome.

Overall it seems the way the cables are routed are the biggest reason for the end popping off and the cable snapping. It has an odd angle as it crosses over the engine, then moves steeply down again and bend back towards the mechanism. Apparantly this has improved in the 987.2 and 981 generations of the gearbox (having a different bellhousing). I do wonder why they have chosen to route the cable over the engine creating such a big loop. It would make more sense to route it low, along the sump towards the back?