Porsche 996.1 cab

As it wasn't tipping it down today I got a bit of work done.

The Focal will absolutely not fit under the seat, it's now in the rear passenger footwell, with a mat over the top of it. I'll have to see if my OCD can cope with that.

I got the rear speakers in, they have different mounts from the fronts as there is much less space to put speaker in.

I labelled up everything behind the dash before taking it apart - a lack of courage maybe, but I'm now confident that I won't lock all the doors when intending on turning the traction control off.

The handbrake/gear-lever unit needs to come out tomorrow, then I can put in my newly slimmed down harness. From this:

To this (changed to line-out rather than speaker-out):

I'm also putting a bluetooth receiver in the sub-elbow storage bin that my phone can connect to. The bluetooth receiver connects to the radio and presents as "AUX", this way I don't have to have a cable visible anywhere.

Tomorrow I need to get the door cards off to install the woofers, finish the cabling in the cabin, then it's onto mounting the amp and plugging everything into it.

Day two of Fun With Wiring commences:

Luckily my car was pre-ruined from yesterday, so making it look this bad was achieved with minimal effort:

A (very small) speed hole drilled into the handbrake console, more on which later:

To get cables down from the dash the access point is at the very back-right of the cavity exposed by pulling the horseshoe and contents out, as this dreadful photograph attempts to show:

With some wiggling the cables cab be drawn through - they will try to go between the metal frame and the material of the dash, but don't allow this as the frame is sharp and will, ultimately, saw through the shielding - seen here before moving them so that they exit by the ribbed harness in the centre of the car:

Cables go in, cables come out:

Pictured here is the re-configured piggy-back harness that came with the Focal, connected to the factory harness:

This is the new Plug A:

This is the subwoofer line-out/pre-amp wire (plug C1, pin 6 fact fans!):

I read the Datsun 240 thread, and the linked to "how to make a mil-spec race-car harness" article, and found myself unable to solder this, so crimped All Of The Wires:

^Index finger is indicating the shared ground for the pre-amp signals, seen again here in new, bifurcated form:

Shared ground connected to the subwoofer ground, with Because Race-Car crimp:

I've been totally unable to get the sub-seat-sub under the seat, so it's become the sub-floormat-sub:

Jury is out on whether I can accept this long-term, but there's nowhere to put this otherwise.

Arse:

Up and out early this morning to meet the chaps at the engineering company that have been making the tappet-carrier for us. Rolled up to their unit (just outside Luton) at five to eight, then spent just over an hour perving over their impressive machines - the CMM that could measure fractions of a micron was impressive, as was the upper surface of our carrier being within 1 micron of perfectly flat.

Carriers measured and wrapped, we headed to the engine designer, arriving at just before 12. Three hours passed in what felt like half an hour, and we agreed what we are going to do in a number of key areas.

We're going to use billet cams, which means that we can actually re-space the lobes (they're slightly off centre normally, by design to make the tappets spin) in order to use the domed (and therefore pinned in one orientation) cam followers that we've decided to use. We're going to increase the valve size, because why not.

At this point in the day I'd had a single cup of decent coffee, two cups of instant, and six dreadful pain au chocolate, so headed for home, passing two car-fires on the way back from Cheltenham - people using cars for long journeys that have been parked up for ages maybe?

Rolled up to home at half five, having been on the road for 11 hours, covered 300 miles, and used a tank of fuel at 28.5 mpg.

Having slept on it, I think we're going to delete the variable valve timing (AKA, camshaft angle) as it's driven by a single chain that is the one remaining weak spot - all other chains are duplex.

We can replace the single chain with cam gears, as we can design the tappet carrier (on which the variable timing kit mounts) to accommodate said gears. 

On stock valves, at max lift, we're seeing 312 CFM at 99m/s flow through the port with 68% efficiency. 1mm on the valve will allow a much nicer seat design, and should lift flow further.

Each cylinder has an individual 50mm throttle body feeding it, from a horn that is fed from a common plenum - we need to fabricate said horns, not really sure what material to use for this.

Anyway, off to my parents to ride in the countryside over Christmas. 

Back from Christmas and New Year so plugging away again:

Tappets and cams and valves, oh my.

We had a really good meeting with the engine designer before Christmas, I believe I mentioned it but thought I'd go into a bit more detail about what we discussed and how things have shaken out since then.

The stock heads use 32mm hydraulic tappets that rotate in their carrier. The cams which actuate these tappets are chain driven from the intermediate shaft, and linked to one another with a single chain - said chain is used by the VarioCam system to adust the timing of each cam.

To make the stock tappets rotate the cam lobe is not centred with relation to said tappet - they are off centre in order that when they rotate through the tappet and push it down they also impart some spin, rotating the tappet in place so wear is even.

The stock tappet carrier is junk - poor material poorly designed and poorly made.

We have made a replacement carrier - replicating precisely the dimensions which hold the moving parts, but significantly reinforcing the original in both terms of design, material choice and execution.

If we were intending on a mild build this would be all that we would need - but we want something slightly more, so we are now designing v2.

This iteration will be designed with the cams that are designed to work with it, they'll be billet as we can't get suitable blanks.

Because they are billet, and because the carrier is also machined from billet we have some freedom in terms of placement - so we're going to centre the lobe to the tappet and move to domed tappets that remain in a single orientation.

We looked at deleting the VarioCam and replacing the single chain with cam gears, but we reversed that decision as we need to pass emissions testing, and we need the engine to work below 4,000 rpm as we're building road cars rather than racecars (something we need to continually remind ourselves of it must be said).

Cam lift and duration are yet to be finalised, we need to establish that next.

In parallel we are designing an intake manifold that uses BMW V10 ITB's drawing through a GT3-RS intake plenum. Hopefully this will be two angled sandwich plates and two sets of three horns that go to the large oval sides of the plenum, with some porting of the ITB's to suit the port shape of the head.

So whilst it may look like not a lot is happening things are continuing in the background and we hope to have an engine on the dyno by the middle of the year. 

Very cool build! Your writing is very entertaining and informative. I'm looking forward to more Porsche engine porn...

GT3 lifter, meet M96 lifter:

And the response from the engine designer when he recieved one in the post:

"Received the tappets today - thanks for that. The GT3 follower is a lovely piece of kit, extremely light considering it is a hydraulic version, the only type I have seen before have been solid versions on a Honda NSF250 Moto 3 GP engine.

Will check the heights accurately tomorrow, but it looks like it could be used in the M96, fingers crossed. This will be of great value if we can use it, as the nose radius on the cam increases for a given lift profile.

In terms of cam dynamics, this solution is only second to that of a finger follower. The domed bucket is only limited by the mass of the follower compared to a finger version. 

I'm impressed that Porsche were running this as far back as 2007 on a road car."

Fingers crossed indeed - we'd be altering this design to incorporate the domed follower, and centering the cam lobes with reference to the followers:

I though this might be useful - 3.4 litre VarioCam M96 engine cam profiles:

Below is the Std Cam Data from the Porsche 3.2L / 3.4L 996 `f6 cams.

Note Cams run on a 32.960mm Diameter Cam Follower.

Inlet:-

Cam Lift = 10.500mm / 0.413”

Cam Duration at 0.102mm / 0.004” = 272°

Cam Duration at 0.508mm / 0.020” = 238°

Cam Duration at 1.000mm / 0.039” = 224°

Cam Duration at 1.270mm / 0.050” = 218°

Cam BCD = 35.000mm

Exhaust:-

Cam Lift = 9.982mm / 0.393”

Cam Duration at 0.102mm / 0.004” = 260°

Cam Duration at 0.508mm / 0.020” = 226°

Cam Duration at 1.000mm / 0.039” = 212°

Cam Duration at 1.270mm / 0.050” = 206°

Cam BCD = 35.000mm

The above from the cam designer, who took the measurements as the first step in looking at what is feasible,

Our new, billet tappet chest does, in his view, make re-grinds the most logical "try this first" step, as it will be strong enough to survive 8,000 rpm with the stock lifters.

He has designed three options, with the wildest having 12.5mm lift on the intake and 11.5 on the exhaust.

We're scouting for some test cams at the moment to try different profiles on - would anyone know if Boxster 3.2 cams are the same profile as the 3.4?

Chasing the noise. 

I was 22-23 when the Porsche GT3 was announced, and at the time I read all of the car magazines from cover to cover - this was before the Internet changed the publishing landscape and there was a wealth of tests, driving stories and reviews. 

I read them all, and from the standpoint of an alcoholic architecture student who never opened a letter if it had a window in the front they were as relevant to my life as the space ships in the science fiction novels that I also devoured. However, the stories stuck with me over the years as my situation changed, and a series of seemingly impossible challenges fell one after another - I gave up smoking, then drinking, both things that an earlier me had considered to be literally impossible. 

I did better at work, life became more stable and then at the age of 40, reviews of that first GT3 still in my mind, I bought a 911 of my own. 

Percy was not the car I intended on buying, nor was he the car that would ever win favor with the inchoate but inescapable quorum of car enthusiasts - as despite his manual gearbox, LSD, hard-shell seats and sports exhaust he also featured the ultimate accessory of hair-dressers the world over, the convertible roof. 

I didn’t care, he was a tremendous little car and accomplished a life goal, and I concentrated on bringing his condition up to a point that was arguably better than new - challenging given that he was 20 years old and had clearly had a number of owners who were less committed than I was to attending to squeaky bushes, worn coffin arms and so forth. 

I also worked on how I fit into the car - changing the wheel, removing the lower console, having the seat modified until we gelled together in a way that I simply could not with a standard car. This was to become something of a theme - and soon Percy was riding on significantly upgraded suspension, newer, larger wheels, was resplendent in a new coat of paint and had a new mohair roof with a heated glass window replacing the original, and largely opaque plastic one. 

By this point I’d been thinking about the engine - a sea change for Porsche in that it was their first water cooled engine for the 911, and like all most initial offerings whilst it had it’s strengths it also had it’s weaknesses. I decided on a prophylactic rebuild that would remove the weaknesses (which by this point, 20 years in, were quite well understood) whilst building on its strengths. 

At the back of my mind, as ever, was the mighty GT3 and it’s Mezger engine - a unit forged in the Porsche Motorsport program, a direct relation of the Le Mans unit from the GT1 and famously carrying part numbers that demonstrated it’s heart was shared with the 964 (at least for the earliest units). 3.6 litres, 360 horsepower and 8,000 rpm in the gears, all accompanied by a spine tingling shriek that sounded like nothing else on four wheels. 

For me the sensations of Motorsport always started with the noise - the rising intonation followed by a brief pause, then a further escalating shriek of the cars running on the straight followed by what to me was always the most intoxicating sound - the driver prepares the car for a corner, engine barking in repeated short bursts whilst they change down through the gears. That whap-whap-whap almost like a super-bike engine revving on the starting grid. It was the first thing that struck you as you walked into a racing circuit, then the smell of hot motor-oil competing with that of the doughnut stands, and finally the sight of the cars themselves, primary colours of sponsors logos, flaring brake discs and flaming exhausts. But ever present, the noise- spine tingling howls punctuated by staccato barks, the defining aural signature of the sport. 

How could I miss the opportunity to bring some of that to Percy, the little silver bath-tub with his hairdressers roof? 

Enter Mike, a man who has been involved in Motorsport for his entire life, with multiple championship winning engines having emerged from his modest workshop. 

What started out as a project that wished simply to lose none of the spark and zing of the 3.4 M96 engine soon spiraled, the replacement of weak parts meant, of course, an opportunity to do better - we took the Porsche X51 version of the same engine as an inspiration as much as we did the Mezger, but what soon emerged was wholly our own. Then Martin joined the project, a fellow enthusiast who shared our passion for making the ill-favored M96 what it could have been, if the 996 Cup had been run with X51 engines rather than the race-derived Mezger. 

In creating our alternate history we soon accrued a great deal of knowledge, much of it directly in proportion to the expertise and inclusive nature of the Porsche community, and the engines themselves began to take shape. 

Mike was forever the voice of sanity, reining back some of our more “because race-car” thoughts, whilst giving full approval to our more sensible suggestions. 

We steadily designed and made parts, sometimes multiple takes on a single unit - three intake cams, two exhaust, two different tappet chests, modern iterations on once-produced X51 specific parts such as the engines iconic additional scavenge pump and “towel rail” return line. I was particularly entertained by the repurposing of a bearing that normally sees duty in a helicopters main rotating assembly, which was soon followed by parts appropriated from the E60 V10 engine. 

Through it all ran the desire for that noise, to me the epitome of racing, the sound of an engine born to rev, a weightless, effortless bark twinned with a basso growl that rapidly becomes a searing howl before dropping down to do it all again. 

We’re still a long way from the finish line, two short blocks wait on the shelf at Hartech with their new cylinders fitted whilst we finish off the critical aspects of the intake system, pistons and exhaust. But we’ve crossed the mid-point now, the design is finalized as a strategy, with only tactical decisions to be made as we make progress to the engine dyno. 

What will our pair of engines make, in the end? My 3.7 and Martins 3.9 will ultimately have to tell that story in Mikes dyno room, but whatever the final figures, they’ll both make the noise.

Brake fade.

Car projects are, by their nature, a journey to a journey (or many, if you don’t succumb to the temptation to finish the car, drive it twice, then sell it to fund the next project).

Being a journey, a succession of events, often things change - our priorities are re-ordered, the goalposts are moved. There are also many temptations - bigger is better being the one that troubles me repeatedly.

An example of this is to be found in the cars wheels and brakes. My car currently has both wheels and brakes, indeed I actually have two sets of wheels - an early manifestation of this problem, I admit.

What could I want to change? It turns out, quite a lot - and each decision has an ever ramifying set of consequences and dependencies, until the initial thought (“PCCB’s look like an interesting option, I bet they’d save a load of weight”) has turned into a spreadsheet detailing new uprights, adapter brackets, new calipers, spacers, new wheels, new tyres, rolling the arches, do I need to book it into the paint shop again afterwards, etc etc. To save a few kilo’s I now appear to have committed myself to spending over ten thousand pounds, and both scouring the worlds classifieds sites and commissioning much refurbishment of second hand parts to hold it to that ten thousand - blowing past twenty thousand is quite possible if going for new parts and paid-labour, which is, by every definition, insane.

And for what? It strikes me that the best route to what I wish to achieve would be to swap the 18’s that the car currently sits on to the 17’s that I have in my garage. In other words to go back to what the car came into my possession with, a redo-from-start that would see the car on the lightest wheels that Porsche produced for the 996, with all the dynamic benefits that that brings - less to accelerate, less to turn, less to stop. I could then really push the boat out and get some two-piece floating rotors to drop some more unsprung weight, and hopefully gain a degree of fluidity and adjustability that the move to larger rubber removed.

What I need to do is add simplicity - what I want to do is add complexity.

I think that there’s also a degree of small-boy pointing at planes here, which I hope I’m self-aware enough to deal with - I admit I’d enjoy someone saying “look at this plonker, he’s got a boggo 996 but he’s painted his calipers yellow, who does he think he is! Oh, wait a moment, actually those are ceramics. Oh.”

Which would be a momentary (and likely totally imaginary) feeling of having achieved something nebulous (and possibly shameful) but in any case 100% pointless, for a very great deal of money.

So what does this teach me? That every decision has to be scrutinized, and that I will lie to myself about my own motives with great facility, frequency and enthusiasm. That simplicity is often the best answer, but the hardest for me to accept.

I suspect that some reading this may (by this point, and possibly for some time now) be shaking their heads in disbelief whilst muttering “what about the engine then?!”, and I’d answer that what we’re doing there IS the simplest way to hit our goals - that the sauronic howl and comedic power we seek has to be supported by a degree of complexity, but even there we have tried to steer a simple path - we’ll strive to use flat tappets rather than domed ones until the point (if it ever comes) that the choice essentially makes itself. Complexity is not in of itself bad, but it must be justified, that unnecessary complexity is the enemy, and must be shown no mercy.

And I now have a use for the wheels in the garage.

Incoming!

+

Well - one, for the drivers side, and it'll be silver rather than white for the shell. I'm fitting heating elements to it, because I live in the UK.

Hope you don't have a long torso, otherwise the shoulder harness holes will be too low on those seats.  While I physically fit in them, the shoulder harness holes are close to 2" too low for me and I'm 5'11"...

Did ya ever decide which short shifter you liked more?

It's the SPG, not a Pole Position - I went and sat in one to test and the harness holes (not, I'd mention, that I currently intend on using them) are above my shoulders.

Shifter - I've got the 997 GT3 shifter in a box on the shelf with the short-shaft now, definitely prefer the Porsche SSK with the longer (fnar) shaft.

What do you think the differences between the two shifters are?  One shorter in throw than the other, more precise feeling, etc?

997.1 GT3 feels great with the stock shifter, fluid, precise, no slop- but with a longer shaft the shifts simply became too long a movement. 

I much prefer having the shifter where the longer shaft puts it, so the SSK was the only option (barring the more £$£$ stuff). 

997.1 GT3 shifter with a shorter throw would be perfect, for the FF long shaft shifter, but doesn’t (sadly) exist. 

I have the shorter FF shifter, so sounds like the GT3 one would be a good addition for me

canoe deleted

In reply to docwyte :

Happy to chuck my spare one in the post, PM me your address.

Message sent, thanks!

A somewhat exculpatory post, for reasons I'll get to at the end.

I drove to our office in Reading yesterday - this is 40 miles away as the crow flies, and took three and a half hours. Welcome to London rush hour.

Anyway, I survived, got home and noticed that, after two and a half hours of motorway and inner city London my car sounded somewhat similar to a 1980's Vanagon pulling away from a cold start. Bugger.

So, this morning:

Hopefully once Precision take a look at it we'll know that it's just a stuck lifter. If it's not, then the X51-Evolution engine schedule may get moved up rather abruptly.

Guess who left his wallet in the drivers door pocket, and then had to go and get it?

I can reveal that a C55 Estate on winter tyres does not handle like a 911 when driven hard down backroads.

Anyway - getting the car collected, then having to chase after it to get my wallet back, have prevented me from visiting the post office today - so no shifters have left for Colorado yet. Tomorrow!

Dammit said:

...getting the car collected, then having to chase after it to get my wallet back...

I'm pretty sure there's some foreshadowing here for what's about to happen to your wallet.

I concur.

On the subject of large amounts of cash vanishing unexpectedly, I ordered the BBI Autosports seat base for $395 on their online store- there's no facility to see what shipping is going to cost before you place the order, but I thought "hey, how much could it be?!".

$275 is the answer, for shipping, handling, VAT and duty, or 70% of the cost of the goods themselves.

I admit that I'd not have completed the purchase if that had been notified beforehand. I now have to hope that the base is everything I would wish it to be.

Argh.  Hope you haven't experienced something very expensive and catastrophic there. 

I usually leave my car at the shop and walk out with the car keys in my pocket.  Then have to go back to the shop to give them said keys...

And the results are in! Leaking exhaust manifold gasket, making a noise that sounds like a stuck lifter.

This is a relief, I will admit.

BBI Autosport sent me a note, "I am very sorry to hear that you are unhappy with the shipping costs and ordering experience! We understand the higher costs that are associated with international orders and do our best to keep the costs down by negotiating with our carriers for the best possible rates."

They charged $150, which is interesting as for me, a member of the public without a trade account, nor volume to offer as leverage for a discount, can send a 10kg package to BBI Autosport's address in the US for $50, via air-freight, in 3-4 days.

Is shipping things from the US three times as expensive as shipping things too the US? I'm open to it being possible - what say you GRM?

The other annoyance is that in their note they say that they'll likely ship the seat base this coming Monday, so they've taken four days to get the box off the shelf, stick a label on it and hand it to a courier. Maybe the $100 extra is actually $25/day for them to move the package from the warehouse to the courier pickup desk. 

A 100% spot-on, fantastic experience already, and I've not got the base yet. Bet it doesn't fit the seat, or they send me one for a Camaro.