Boxster V8 project log

[Marc_986]

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.

[Marc_986]

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.

[Marc_986]

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
- 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.

[78F350]

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

[Marc_986]

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..

[husker boxster]

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.

[Marc_986]

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!

[JFP in PA]

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.

[mikefocke]

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.

[Marc_986]

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.

[Marc_986]

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.

[LoneWolfGal]

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

[Marc_986]

Why would you think that? 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.

[Marc_986]

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.

[Newsguy]

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

[Marc_986]

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.

[cooler]

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

[cooler]

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

[Marc_986]

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.

[cooler]

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)




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?