Slightly O/T - 996 rebuild / Boxster transplant

[rhd racer]

I then started on the manifolds. This was always going to be a journey into the unknown - 996 manifolds use a stubby aluminium spacer that houses the injectors, whereas both 2.5 and 2.7 ones are all plastic. Another issue for the 986 conversion is that whilst the plastic part of the 996 one is less tall than the 986 part, when combined the 996 manifold height is about an inch taller overall. Most people use spacers and drop the engine and box but mine is so low (esp with slicks) I don’t want to do this if I can help it. I will need to see how it all works when it is in situ

This pic shows the height difference


The AOS pipe needs to thread through the manifold stubby (well I was guessing a bit because have not run these before but was proved right)



Next the left bank with no access issues for the back bolt this time, so I could finally fix the AOS



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[rhd racer]

The AOS can then be secured to the clips on the inside of the stubby manifolds



Next is the loom. You will see nothing is labelled! Basically I don’t tho k you can go too far wrong if you start at a given point and are methodical. In this case I used the mounting bolt I prepared earlier and bolted the loom in on that corner, and then you work forwards from there; alternator, knock sensor, throttle body, knock sensor, oil fill level etc etc



The coil packs and injectors are really easy as the lo runs rear to front so these just run in order and you cannot go wrong


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[rhd racer]

I then remembered that the crank position sensor at the back of the engine had a sheared bolt so needed swapping. Whilst trying to lever off, the sensor fell apart and left the sensor embedded in the case!



After a lot of heat I managed to knock the remaining bits out - I haven’t drilled out the bolt yet but at least this old crap is out. It was properly in there



.



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[rhd racer]

Then I did a few jobs on the throttle body. Drilling for a 2nd throttle spring (this is a requirement if scrutineering for cable operated throttles to prevent it being stuck open), swapping pipes over and blanking (with loctite) a thread which is supposed to allow a brace to be fitted to solid mount the TB. I can’t use this given I am angling the TB down to fit in the space available





And attaching the cable itself


You can see why I can’t use the bracket by how much the TB is angled down here - it gives me c2” extra clearance



Then it wax a case of some fair liquid to ease the rubbers and fit the manifolds. This should be easy, but it is all really tight and not at all easy - much worse in the car if, say, changing the starter motor or doing AOS pipes




The last job was making up a new AOS pipe from AOS to TB - it is not very elegant but you cannot use a standard pipe because the TB is not where it should be because everything is reverse - basically when I did the 2.7 conversion I got loads of old pipes from Angus ‘ scrap pile and cut/shut them to do what I needed




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[rhd racer]

So I need to replace drill out the crank position sensor bolt, fit the plugs and coil packs, fit the new injectors I have treated it to and work out what combination of fuel rails to use - the latter poses an interesting problem


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[sladey]

Sheesh! Lot of work there!

[misteralz]

Really interesting thread this. I also don't bother labelling looms nowadays - poka yoke design principles on most post '80s stuff means you're just wasting your time.

[rhd racer]

Thanks gents - that was all done yesterday at medium pace. Rest day today…


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[Gary71]

Wonderful stuff, not exactly a plug and play conversion is it!

[rhd racer]

It’s not Gary - partly fitting the engine in the reverse direction and partly that 2.5, 2.7/3.2 and 996 heads are all different so require matched inlet manifolds.

Should be worth it though. Last season the car had 189bhp per tonne versus 191 per tonne for a standard 986S. Pretty good.

However it will have 270bhp per tonne! I am in no doubt that it will require learning a totally different driving style to keeping it pinned everywhere. I think at some venues it will be instantly faster, but others (like Loton) I am not so sure. Will be a riot to drive regardless


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[rhd racer]

For reference a GT3 series 1 is 262bhp per tonne, albeit has the advantage of higher torque and rev range


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[911hillclimber]

Needs a LOT of patience that lot Wayne!
Will be a real Hot Rod when done, fabulous.

The Lola is 571 bhp / tonne....

But I would rather go fast in a Boxster.

[neilbardsley]

Looks of work. Well done

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[rhd racer]

A slightly frustrating few evenings on the car this week. Firstly, in the Dempsey book it showed the throttle body reversed to allow for a really short AOS pipe. Mine has to run underneath the TB and back in itself, so I thought it seemed like a good idea



As you can see I have already taken one half of the plastic intake manifold off in readiness for this master plan - unfortunately it didn’t quite work out as the TB is not symmetrical



Apologies for the terrible pic - my phone camera was broken and waiting a part to repair. I couldn’t turn the TB with the crossover pipe because that would cause problems with the throttle cable. When I read back about turning it round the Dempsey book stated it was the fly by wire one, so the direction did not matter. Doh

Anyhow - what is an hour wasted when things were going to get worse - much worse


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[rhd racer]

So I had resisted messing with the crank position sensor as long as I could. I was enjoying buildings stuff and making every step forward look like just that, instead of a boring and tricky job that no-one would see. But, whilst waiting for some parts to arrive I thought I had best crack on with it.

The brief was simple - drill out the m6 bolt that had sheared, pop in my 2.7 sensor and bolt up. Easy.

Wrong.

The first issue was not being able to get the drill straight in the centre punched stud remains. The engine being built means that the back of the heads are in the way, and my 90 degree drill adaptor and my drill on a wire attachment could not get me on it straight either. The stub of the remaining stud would not come out with molies after heat either. So, a slightly wonky hole it is.

By slightly wonky I mean only a couple of degrees off square, and being a bit particular I thought it a good idea to put a timesert in it because the thread would not be perfect. This proved my downfall, as having made a7.2mm hole and carefully tapping it out to accept the 6mm timesert the tap snapped in the block. No amount of hammering would get the remains out, there was no exposed end to twist it out, and it is too small to try and wind out with circlip pliers or similar.

Rats


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