Hi All,

Hope this will turn out to be the right place for this topic (that is, the car will become a proper project). I have recently purchased a 986 Boxster, 1997 2.5L model (very basic thing). As new kit car registration is very expensive due to tax (taxed as a new car, based on CO2 emissions which are calculated in a unfavorable way for a low-weight car), it was time to move to something with existing registration. I have take a good look at the Fury of which two are for sale locally as well as a Midtec Spyder. The Furies are quite expensive and need loads of work, the Midtec is similar price, mechanically much better state, but the body needs a lot of attention (obviously).

So I settled for a Boxster. Time to dye my hair and put on some big sunglasses I guess ;-) Being a very basic car it was cheap and being a 1997 means I can pretty much drop in any other engine with minor legal paperwork involved. So the plan is to move to a Audi V8.

For now, this winter will be spend on getting the car back in a reasonable shape (it has done very few miles for the last ten years, which is great for the interior etc, but not so great for the mechanical side of things), making sure it does what it needs to do well and in the meantime make it loose some of it its fat.

First job today was removal of the 20mm wheel spacers. Yes, the car looks mean with them, but in general these are not going to make the car better, they need to go. First issue was the locking / security wheel bolts with no adapter in the car. That was resolved by the next smaller socket and a big hammer. Three came out easily, one needed to go down another socket size... New bolts (full set) are ordered. Front spacers are now removed, rear to be done this weekend. Then I'll wait for the new bolts to turn up before testing it out.

Next job will be to fix the squeek the engine has when revving (any gear, including neutral). Most likely one of the ancilleries with a shot bearing. I hope it is either the AC pump (AC will be removed completely anyway) or the PS pump (which will be replaced by an electric one).

Some pics and more info to follow for those interested.

Great plan and watching with interest, a v8 would sound epic and toyed with doing an rs4 v8 in the vx220 many years ago before using the s3 tfsi for conversion.

Certainly a lot of car for the money and plenty of off the shelf well proven upgrades means you really can just focus on engine/box change

Friend recently sold his 2.5 boxster and he put the 911 front bumper on which mated well (same headlights on era of 911 also)

Good luck!

Personally I'd just sort it out and get it running well rather than muck around with engine swaps. It will probably be an expensive and troublesome task to get anything other than the original engine to happily live in that tiny cramped engine bay.

I got your point and do agree to a large extent. However, the 2.5 really is low on power. And in honesty, it was bought as a project car, toying around with it is part of the fun.

The Audi V8 engines fit well and the porsche gearbox either mates up already, or the VW alternative drops right in. Really the benefit of taking this approach. Surely, some brackets will need to be made, an exhaust fabbed up etc.

The alternative (still open) is to drop in a 3.4L from a 996 (which shares many parts with the 986). Easy to fit and get running, much better power, but quite expensive.

Some others have dropped in the 2.7L turbo V6 from the VAG group. Easier to fit than the V8, more power easily. But I just don't want a modern turbo engine. They lack any form of character.

It will require a bit more research for sure. In any case, some more power than the 2.5 will be going in.

There's a chap in the UK that did it a few years back - but you'll have to look at Facebook to find it. Others in the US have used the LS engines...

Iirc the 5 speed box works with 1.8t vag engine but the v engines need the 6 speed boxster box

This may help Marc - if you’ve not seen it already.

He’s put a V8 in his

This guy does some great builds.

https://youtu.be/qyDBHhwCHJY

quote:

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Originally posted by MarcV
Hi All,

Hope this will turn out to be the right place for this topic (that is, the car will become a proper project). I have recently purchased a 986 Boxster, 1997 2.5L model (very basic thing). As new kit car registration is very expensive due to tax (taxed as a new car, based on CO2 emissions which are calculated in a unfavorable way for a low-weight car), it was time to move to something with existing registration. I have take a good look at the Fury of which two are for sale locally as well as a Midtec Spyder. The Furies are quite expensive and need loads of work, the Midtec is similar price, mechanically much better state, but the body needs a lot of attention (obviously).

So I settled for a Boxster. Time to dye my hair and put on some big sunglasses I guess ;-) Being a very basic car it was cheap and being a 1997 means I can pretty much drop in any other engine with minor legal paperwork involved. So the plan is to move to a Audi V8.

For now, this winter will be spend on getting the car back in a reasonable shape (it has done very few miles for the last ten years, which is great for the interior etc, but not so great for the mechanical side of things), making sure it does what it needs to do well and in the meantime make it loose some of it its fat.

First job today was removal of the 20mm wheel spacers. Yes, the car looks mean with them, but in general these are not going to make the car better, they need to go. First issue was the locking / security wheel bolts with no adapter in the car. That was resolved by the next smaller socket and a big hammer. Three came out easily, one needed to go down another socket size... New bolts (full set) are ordered. Front spacers are now removed, rear to be done this weekend. Then I'll wait for the new bolts to turn up before testing it out.

Next job will be to fix the squeek the engine has when revving (any gear, including neutral). Most likely one of the ancilleries with a shot bearing. I hope it is either the AC pump (AC will be removed completely anyway) or the PS pump (which will be replaced by an electric one).

Some pics and more info to follow for those interested.

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There is someone on Pisonheads (sorry for referencing another forum, I won't do it again!) who put an Audi V6 turbo in a boxster and went into lots of detail about how he did it. Due to a series of unfortunate issues he needed to replace it so built a second one, making it easier in the process. Worth a read, even if you are not about to dissassemble a boxster.

https://www.pistonheads.com/gassing/topic.asp?h=0&f=47&t=1695359&i=0

Have you checked out the weight of the Audi V8 engine? The intake manifold is about 18kg alone

Don't get me wrong, I have one to go into a smaller lighter car, but don't underestimate the weight!

quote:

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Originally posted by Partofthechaos
There is someone on Pisonheads (sorry for referencing another forum, I won't do it again!) who put an Audi V6 turbo in a boxster and went into lots of detail about how he did it. Due to a series of unfortunate issues he needed to replace it so built a second one, making it easier in the process. Worth a read, even if you are not about to dissassemble a boxster.

https://www.pistonheads.com/gassing/topic.asp?h=0&f=47&t=1695359&i=0

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quote:

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Originally posted by coyoteboy

quote:

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Originally posted by Partofthechaos
There is someone on Pisonheads (sorry for referencing another forum, I won't do it again!) who put an Audi V6 turbo in a boxster and went into lots of detail about how he did it. Due to a series of unfortunate issues he needed to replace it so built a second one, making it easier in the process. Worth a read, even if you are not about to dissassemble a boxster.

https://www.pistonheads.com/gassing/topic.asp?h=0&f=47&t=1695359&i=0

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V6 is a cast iron block IIRC, boat anchor.

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Thanks for the feedback!

I have seen a few swaps indeed, including the Australian guy, a facebook thread (with many pictures on google photos) and at least another one. These got me inspired and are a good source of info for sure.

I am not concerned about the weight Jeff, the Australian did weigh it in one of the videos with the fully dressed V8 coming in at 200kg, which was just some 10 or 20 kg above the flat six weight. The biggest penalty will probably come from swapping out the transaxle. The 5 speed isn't very heavy and any replacement six speed (consider the 0A2) will be significantly heavier.

That is also a major part I need to work out. There seem to be two eras of V8 with differing bolt patterns. Difficult to find where the line between both is and what bolts up to what. As far as my research goes the 0A2 will bolt up to the engine I have in mind (BBK) and is similar to Porsche G87 transaxle (out of 987 boxster). Not sure what this would mean for axles / driveshafts to use.

In the meantime I replaced the gas springs of the engine cover to keep it from falling on top of my head

I know I’m being boring but why not just go for a 3.2 ‘S’ Boxter?
The engine is the nicest engine I know of, smooth, powerful and sounds glorious

That's slightly boring indeed

To be honest, if I just wanted the best driving machine I could afford without bothering about anything I would have bought an Elise. As mentioned, the Boxster is for having a project, where a big part of the joy is in adapting, modifying etc. Actually the driving would be the reward.

A 'simple' engine swap of something that just fits in is not really the ambition. Done that and it just takes a weekend of hard work to get it done. I scaled down the ambition from a full build (realizing that the time involved doesn't fit with family situation and that my country doesn't support it) to this. Should be manageable.

The flat six hasn't stolen my heart yet, probably because it is not in the best shape it can be. So far the BMW straight sixes I have had where a lot smoother and enjoyable. However, I am keeping a larger flat six in mind.

[edit]
Just thinking that a house is a good parallel. Assuming you can afford it, the easy route is to search for and buy a house. Next thing is to search for a plot and get someone to build a catalog house (existing design) on it. Then up a level is to have your own house designed and build for you. And probably the utmost of effort is to find a plot, design your own house and build it yourself. That's what we have done the past five years (with last year easing on the amount of work). Is it the most efficient way? No. Most rewarding? for sure.

[Edited on 27-8-23 by MarcV]

If you were near me I’d offer to take you for a drive in mine. The engine is the nicest I’ve ever driven or been driven in.
A 3.4 or 3.6 from a 911 would be nice but dear.
The engine sound is restrained but a bit menacing at low revs but breaks into a howl at higher revs
If anything, the car is just too refined, I’d perhaps prefer something a bit wilder

I might add, my dream cars are lotus’s

[Edited on 28/8/23 by JonBowden]

quote:

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Originally posted by JonBowden
If you were near me I’d offer to take you for a drive in mine. The engine is the nicest I’ve ever driven or been driven in.
A 3.4 or 3.6 from a 911 would be nice but dear.
The engine sound is restrained but a bit menacing at low revs but breaks into a howl at higher revs
If anything, the car is just too refined, I’d perhaps prefer something a bit wilder

I might add, my dream cars are lotus’s

[Edited on 28/8/23 by JonBowden]

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Yeah, the howling sound I also have at high revs in this smaller engine. And I actually like it a lot. Very distinctive, characteristic.

I think the LS route is just wrong. Surely the engines are fine and it is fantastic that they are available as crate engines including OEM ECU that run standalone. But the amount of modification needed to fit it is just a bit too much of a butching job. In such case we could also fit the Audi V10.

Anyway, seems I'll need the car for the next few weeks with parents-in-law coming over. So I did a few things today.

- Seems the engine noise is ok. All ancilleries run well. Very little fore-aft play on the waterpump and the AC compressor clutch seems a little clunky. But without a belt it sounds mostly the same. Also all videos of flat 6 sounds give the same kind of noise, so seems ok. Most videos show very awfull noises on top of that... Just ordered the shorter belt so I can bypass the (not working) AC compressor.
- There was a lot of water standing next to the battery. The drain on that side was full of junk. Pulled it out for now, but seems to go to a hose. Need to check where it would lead and where the water will now go (it emptied on the street with no signs of water in the cabin yet). The other drain plug was already removed.
- This also explains the removed plug in the bottom of the frunk. Most likely the water went in there and couldn't get out anymore. I'll first fix the drains, then plug the frunk.
- Siren of the aftermarket alarm was in the way. Now removed. It was rattling anyway and was disconnected.
- The battery itself wasn't secured in the tray. Another source of rattle I guess. So I re-tapped the correct hole and tightened it.
- While in there I also removed the CD changer.
- And a few wires running from the battery terminals to nowhere.

Today I also ordered standard maintenance parts like oil, filters, spark plugs etc. Everything in the car is more than 10 years old, so seems good to refresh. Brake fluid was already ordered and high on the list to refresh.

Regular maintenance performed and happy that oil and spark plugs look good. Shorter belt fitted and it does seems a little quieter now. Also the brake fluid was refreshed. Can't really say that I'm overly impressed with the brakes yet, but when applying a good amount of force it does slow down ok.

Biggest issue on this engine / car for the moment is the strong smell of fuel combined with it running very rough when cold. Need to check this out quickly so I can enjoy and test the car a bit more before the weather turns.

Probably the best way to describe the engine behaviour is to compare with 80s race / rally cars. These carbed engines tended to be almost undriveable when cold, but once up to temp they were brilliant. This boxster is roughly the same, but it just isn't brilliant yet when it is at operating temperature (but a lot better for sure!).

Guess I need to sort myself a means of reading out the engine management, hopefully with a bit more info than just OBD codes.

Today I picked up a brand new Audi 0A2 transaxle to go in.


New Audi 0A2 gearbox

Gearing is a bit on the tall end, but I'm setting up some calculations to check in terms of 0-60 and 0-120 times. First I am mapping the available data of the car with normal engine and gearbox, then step two is to change gearing to 0A2 (first two gears will be fine) and finally checking what happens with the V8 engine data.

Pulled the old transaxle off today and it seems like the 0A2 will be an easy fit. Attachement holes look identical (some additional ones on the 0A2) even with some threaded parts to have the same stud on. Input splines also look indentical, which would be a surprise. Will test fit the old clutch later this week when I take it off the engine.


G86.00 vs 0A2

Earlier I did some measurement on the position of the output flanges relative to each other. The only difference seems to be that outputs are slightly lower on the 0A2. Doesn't seem to be enough to cause drive shaft issues. The exhaust will become rather tight, likely it won't fit, due to the length of the 0A2. Will find out once I test fit it.

With the engine bay rather empty now I will first set about removing the AC and the power steering pump. That will give even more space to look at a minor oil leak on one of the heads (dripping on the exhaust which explains part of the smell) and on the fuel system. Once that all looks ok, I will set about mounting the new gearbox.


Empty Boxster bay

[Edited on 8-10-23 by MarcV]

So. it has been a while. But some things have been done in the meantime.

The biggest issue fitting this gearbox is how to connect it up to the wheels. 986 2.5 drive shafts are the correct length, but they don't fit any flange I could find to work on the OA2 gearbox. Also it seems to be the only Boxster driveshaft with 25 splines, others have 28, so swapping CV joint is not an option.

So now I have a 987 driveshaft around which should be correct length, but doesn't fit the hub of the base 986 and it doesn't have the ABS reluctor ring. I will either fit 986 Boxster S hubs and find a way to mount a reluctor ring (gearbox or wheel side) or I will mount 987 hubs and see whether the new ABS sensors work on the old ABS. If not, then no ABS.

Second part of this journey was on the gearbox flanges. Stock Audi 0A2 has tripod flanges. It seems I can find tripods with 28 spline to fit the driveshaft, but these are plunging, while the CV joint is fixed. So it would give me two plunging sides, not sure whether that is a good idea. So I optes to swap the flanges. Didn't find any Audi units to fit (I bet they are out there, Audi 012 gearbox ones are very, very close in dimensions, 02X might be as well..), so ordered new ones from the Porsche dealer.

Installed them this week;
Old tripod ones:

Audi_0A2_tripod

New Porsche CV ones:

Audi_0A2_CV

Next step on transmission side is to work out the shift linkage. Got a 987/997 shifter around now with cables of the 987 Boxster S. These should be the correct length for this box and the improved shifter is a good bonus. Gearbox side linkage parts are crazy expensive from Porsche (About 800 quid all together), so I am going to fab up my own. Should easily be less than 100. I worked out the required ratios already and will get myself an Audi shift linkage from a scrap yard to start with. One remaining question is on the reverse lockout. The 987 has a stiff spring for selecting the reverse fork, whereas the Audi units have some push down or pull ring on shifter side. For my 986 I'll need the stiff spring approach. Does anyone know where this is located on the Porsche transmission? Should be inside for sure as it isn't on the linkage, but is it a separate part or is it a different / double detent spring? Or is the shift rod different as well.

Nice solution would be to have it in the gearbox, but if I can't find out I will add it externally. Just need to work out the appropriate spring rate.

In the meantime I also located the leak, which is coming from the air-oil separator. This makes sense with the behaviour of the engine and seeing the puddle of oil in the intake I'm not surprised it ran so badly. Quite confident that the main engine issue is resolved with the new separator I'll install over the next week. Also identified a small oil leak either on crank shaft seal or IMS seal. But I'll leave that one for now.

Also AC compressor and filter/dryer have been removed. Will remove further AC components as I progress. First I will build the engine back together, then the gearbox. New clutch is waiting. The old one was worn to the rivets, so no wonder it was sooo stiff.

[Edited on 23-12-23 by MarcV]