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Dammit Reader
12/14/18 7:51 a.m.

And here's what the flow bench says:

Thousands of an inch lift is the x axis, CFM on the y.

Stock is the 96mm bore, oversized 100mm bore, performance is after porting.

Dammit Reader
12/16/18 12:50 p.m.

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.

Dammit Reader
12/17/18 5:53 p.m.

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.


Dammit Reader
12/22/18 5:17 a.m.

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.

Dammit Reader
12/23/18 6:59 a.m.

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


Dammit Reader
1/1/19 10:18 a.m.

Back from Christmas and New Year so plugging away again:


Dammit Reader
1/2/19 3:41 p.m.

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. 

rdcyclist Reader
1/4/19 9:04 a.m.

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

Dammit Reader
2/1/19 6:25 a.m.

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:

Dammit Reader
2/5/19 2:09 a.m.

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.



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



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?

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