Porsche 996.1 cab

Who wants to predict what the borescope and leakdown test show tomorrow?

LD= Leak Down Compression

Cylinder 1 4% LD 100PSI
Cylinder 2 2 % LD 98PSI
Cylinder 3 4% LD 105%
Cylinder 4 6% LD 100%
Cylinder 5 6% LD 90%
Cylinder 6 2% LD 90%

So, must have been a lifter taking a while to pump up, not piston slap after all. This is a small, very cold up of comfort in the bitter winter of spending that I've found myself in.

AOS (amongst a laundry list of other things) needed to be changed as the hose had collapsed, for which the engine has had to come out - so that's almost a thousand GBP to change one single part.

Those leakdown numbers are good and compression numbers are E36 M3ty. Which doesn't really make sense since leakdown is what dictates you compression results (considering that all the mechanical specs of volume at BDC vs TDC never change etc). So i'm guessing the compression gauge is off.

Either that or that second row of numbers is just the pressure they put in the cylinder during the leakdown test? But i dont know why anyone wouldn't just use 100psi every time as it makes the % conversion stupidproof.

The mechanic who did the tests had mixed his units on the compression, I've asked for clarification. He seemed very happy with them, we've taken the $14,000 rebuild off the schedule, but I'd like to get the definitive figures for my records.

Should all be PSI figures.

Ok, this is going in fits and spurts right now - I'm in Colorado and the car is in West Sussex, so a mere 4,600 miles away.

I dropped the car off for an MOT with fluids and filters being changed before I flew out here, and was expecting to get a call a few days ago saying "all done, that's £400 when you pick it up".

That hasn't happened.

Here's the list I got a few days ago:

"1. Wheel wobble at 65mph £40.00 to balance the front wheels.
2. There is a tappet type noise from cold but not there when the engine is warm. May be you do have some piston slap after all from the engine. We have another 996 with a similar noise which has been there for some years.
3.Slow speed fan on n/s not working, new resistor. £213.82
4.Only 1 horn working . £121.45
5. Non Porsche wiper blades. £34.50 Clear the screen ok.
6. Head light washer jet leaking at o/s £182.88 You may want to replace the n/s at the same time?
7. N/S/R seat back release knob missing £3.48.
8. Washer jet "T" piece broken. £53.27
9. Fault codes for bank 2 O2 sensor.£273.88
10. Rear exhaust cat bracket broken.£87.84
11. The oil air separator pipe has collapsed need to replace the unit £288.00 if we can remove the very corroded bolts that hold it in place. If not we have to remove the engine and this would cost £930.00 to replace.
12. Oil leak from bank 1 vario-cam solenoid has also contaminated the coolant pipes at the back of the engine. Vario-cam solenoid is £502.47
13. Engine coolant pipes. £274.99
14. Some surface corrosion to n/s brake pipes, we will just clean them up and put some wax oil on them.

The gear box oil looks dark not sure when this was last replaced?"

I told them to fix everything, and to address 2 I ordered the leakdown test/borescope inspection.

The results of that the avid reader will know, and it was an unusual positive to this story.

Number 11 was to prove more of a problem - and is why the engine was out of the car completely when I spoke to the garage this morning.

I asked what else we could do with the engine being out and they suggested replacing the coolant expansion vessel - I asked how much that was, and with labour it'd be ~£550. I said maybe not.

I did suggest that whilst we had the engine and the transmission out of the car it would make sense to split them and look at the clutch, which to my knowledge had been fitted by Porsche at the factory 62,000 miles ago.

They did this, they added a new clutch, clutch fork, and chain tensioner, then said that the clutch pipework would need replacing and the vario-cam solenoid "is over to one side we will now need to remove the cam cover and replace the seals ETC".

So my £400 MOT and service is going to be (I'd guess at a minimum) £4,000 by the time they stop finding new things that need replacing.

Now the question for the GRM hive-mind, and it's the absolute definition of a third-rail question, at least in the Porsche world: do I ask the garage to pull the seal on the IMS bearing? It's the original dual-row design that is meant to be much stronger than the later single row design, but I imagine that allowing some/more oil to get to it would be beneficial?

The bill was £5,300 in the end. I still like the car though.

Would anyone know where I can source camshaft blanks suitable for the 3.4 litre M96 engine? Variocam, not Variocam+.

good lord. These guys don't miss anything eh?

Well, it needs new springs in the drivers sun-visor to hold the flap up when you wish to review your dashing good-looks in the mirror, but other than that it's A1.

Which is why I'm now looking at an engine build for it, as a long term project - hence the cam question.

I bought a couple of 3.4 litre heads from a scrapper, sent them over to a chap who has very kindly offered to work on the engine project. He's been taking them apart when he has some spare time and was very impressed to find beehive springs where he expected to find conventional parallel units being used. Overall he's impressed with the quality of components which Porsche specified - interesting given that the M96/97 doesn't have a great reputation.

Another observation (yet to be borne out by the flow-bench, but soon to be) was that the port velocity for the 3.4 looks low by modern standards, which suits our purposes - they should flow at a rate much closer to modern standards with the increase in capacity to 3.7 litres.

I have an outstanding order with Porsche for the X51 intake - they've had my money for getting on for two weeks now but as yet no email saying that they can or cannot supply the parts. This is frustrating.

The longer this drags on the more tempted I am to spank a load of cash with Jenvey, and then end up staring down the barrel of getting the Porsche DME to be happy with Alpha-N rather than a MAF.

Anyway, we make gradual progress on the planning, so far the thought is that a small amount of port work and general cleanup paired with some new cams will deliver on our target of 100 bhp/litre.

I would've done the IMS bearing while the clutch was out.

Those MOT guys sure are thorough! Doubt most shops here would catch that stuff on a paid inspection.

Left the original (and perfectly healthy) IMS bearing in place, but removed it's seals so it's lubricated by oil now rather than the (likely remnants) of the factory grease. Seemed the best route to take.

When the engine is pulled and rebuilt we'll change to the final iteration of the 997 IMS bearing- purely because you can't get the dual row bearing anymore.

I'd do the LN bearing. I still would've done it with the clutch out. Not a whole lot more labor and the LN Engineering bearing isn't all that expensive.

I've considered it, ultimately I'm not happy about the forces which pulling the bearing puts on the associated parts. A chap on 911uk has 330,000 miles on the dual row IMS, it was perfect when he pulled it out- unlike the bearing shells, which is why he was rebuilding the engine.

Good lord, that is some expensive work. Have you considered doing some of that work yourself? I'm sure you could have easily tackled the suspension components and saved a bit of money there.

Eventually I want to buy a 996 911 as well, but I want the facelifted version because it has more power and I like the headlights on it more. I'm gonna do all the work myself though— I've never paid a shop to work on any of my BMW's.

I don't have the time to do the work myself, sadly. I'm promising myself that I'll make the time one day, but that day is not today.

Bosch Motronic DME/ecu- has anyone here had success getting one to run Alpha-N off TPS and IAT inputs?

I'm considering losing all sense of proportion and going for individual throttle bodies, but don't really want to go stand-alone.

Just sell it and get a turbo. Seriously. Not worth putting that kind of effort into this car, the results aren't going to be there.

I sincerely don't want a turbo - bigger, heavier, and I don't want turbo-style power delivery.

Also, this car is in absolutely no way about making sense.

I'm committed to the 3.7 litre build, the new cams, the headwork - and I guess I'll stay with the stock intake if it comes down to it, but ITB's do look and sound good.

Although given that the 996 has a letterbox for a boot opening exactly how much you'd see is questionable. But they'd still sound awesome.

docwyte wrote: Just sell it and get a turbo. Seriously. Not worth putting that kind of effort into this car, the results aren't going to be there.

Eh, given how much 996 Turbos are selling for nowadays, he'd still be ahead after doing the engine build. Plus there's nothing quite like a naturally aspirated engine that's been built properly.

Individual throttle bodies are super cool. Aside from the looks and sounds, the increased throttle response is incredible. I still remember my E39 M5's S62 with the 8 throttle bodies, that thing in sport mode was an absolute monster. It was easily the most direct-feeling drive-by-wire throttle response that I had ever felt.

If we hit my goal of 100 bhp/litre the power to weight will be better than a turbo, and I won't have that additional weight to both stop and turn. Also it is more fun to achieve this was - it'll be unique, and a product of research, planning and craft.

Dammit wrote: If we hit my goal of 100 bhp/litre the power to weight will be better than a turbo, and I won't have that additional weight to both stop and turn. Also it is more fun to achieve this was - it'll be unique, and a product of research, planning and craft.

Aaaaaand it'll be RWD, whereas the Turbo models are saddled with the AWD system that adds extra weight and makes the handling a bit different. With more power in RWD form you'll be bringing back a little bit of that original 911 fear.

Very easy to convert a 996 Turbo to rwd.

Just saying, you'll spend far more for far less performance compared to buying a 996 Turbo and converting it to rwd.

A good turbo here is £50,000.

My car would sell for between £15-18,000.

So as long as the engine work costs less than £32,000 I'm ahead.

I suspect it's going to be around £20,000 for the work, but we shall see.

It begins, machining a fixture to hold the heads to the flow bench:

Ports, as Porsche provided them:

Mike's going to test flow with a bore of 96mm and then 100mm (3.4l to 3.7l) in order to see the impact of de-shrouding the valves by moving the cylinder walls outward by 3mm.

Can anyone do me a favour and call your local Porsche garage, ask them for these parts, report back on availability?

996.110.980.42 "intake distributor" - it's the alloy X51 part, Porsche UK have "no ETA" on these, wondering if Porsche NA might be able to do better.

If someone can find five minutes I'll hammer out the flow bench test results in return.