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Porsche 996 Fast Road / Track Car - Oversize Build

Interesting- thanks for posting the details.

M97 has 3.2mm larger diameter valves than the M96, not sure which Schrick cams were fitted but they'll certainly have more lift than the M96 3.2/3.4.

Be very interesting to see what yours makes with a stock 997 intake- although you'd need to do some work to get it in there. From chatting with Wayne it it might produce a surprising amount more.
 
Yes, going by the OP's experience a stock intake may yield more. Is there much difference between the 987 and 997 intakes ? The Autofarm work had been done on the engine long before I bought it, so I have no real idea what the stock 987 set up looks like.
Interaction between the intake and exhaust sides of the engine is also interesting and untested in this scenario. I wonder if the modified intake side's capacity to flow more air is optimised by a freer flowing exhaust system (like my fully decatted system) ? ie mods on both sides producing a positive result versus the negative experience of just modding the intake side.
I realise I may be clutching at straws !!!
I have long been meaning to visit Wayne, but it's a heck of a long way from me so don't want it to be a wasted trip.
Out of curiosity I've also fitted an IPD plenum, K&N intake kit, under-drive pulley, Top Gear headers and 200 Cell back section to my early 3.4 996. I have no before or after dyno figures to offer, and the car is certainly nowhere near as quick as the Cayman, but it makes a pleasing noise and seems to go very nicely. It does not feel slower than pre modification, but that might just be my wallet deceiving my brain !!!
 
Y2K – I would also class myself as a novice, you pick things up as you go, and as with most its trial and error!

I will drop you a PM, currently still running mine in, Castle Coombe, Brands, Silverstone & Bedford are where I end up most,


Sp1Ke - I believe the 3.4/3.6/3.8 plenums are all the same size, however the design of the 3.8 is better in that it the corners are smooth bends as oppose to a 'T' shape which improves flow.



The issue with getting HP out of a 3.4 are the heads this is largely because the 996 3.4 evolved from a basic original design of a 2.5 engine.

When Porsche wanted to make a 3.6 and 3.8 they realised they needed to increase the valve sizes and inlet areas to flow enough air at peak revs. They also knew that this would reduce mid-range torque so they made a new head and valve lift and timing system to get it back.

Porsche found this variable valve timing and lift system so effective they found they could use it on a 3.4 engine and still get a good torque curve out of it and hence the Cayman S evolved.

The 3.4 Cayman has variable valve lift and double the variable inlet valve timing (as the lower lift cam is timed differently and both cam lobes have variable timing adjustment). It also has bigger valve diameters and higher gas flow characteristics so can flow more air than a 996 3.4 head at high revs when the amount of time the valves are opened is shorter.

So in essence the 996 3.4 was stretched bigger to its limits while the 3.4 Cayman was reduced down from a head that already had higher flow characteristics.
 
Hi Guys,

Have have been through the bedding in process and had 2 track days with the new engine, and just received the Dyno from the initial tune. So thought i would update you and add to the great data here.

Dyno chart attached was done when the engine was tuned straight after build so before it was properly run-in (don't know if it actually makes a difference or not?).

How it feels: will start by caveating that i didn't actually have a ton of time with the car before the engine had to be rebuilt so i won't try too compare pre- and post-rebuild.
Overall it feels quite peaky. You really need to get up in the revs to get the power, when it comes in it feels good (which is clear in the chart). I'm a novice on track and focusing on trying to have decent lines so actually staying lower in the revs than you could (higher gear out of certain corners - last track day i was not rev matching, so for example staying in third entering a corner where i could go down to second with heel and toe). To be completely honest, given my skills (or lack thereof..), it's not a bad thing - i don't think i really have the smoothness required in throttle application when close (closer) to the limit to handle the full power in the 5500RPM range up. I was considering having it tuned to lower peak power/ more power earlier, but I'll probably leave as is for now and work on my driving. I suspect when keeping it high in the revs it would feel much faster overall. It feels faster on the straights but it's so subjective - and having used it only once on track pre-rebuild - that i can't really say hows much faster. Certainly when coming out of corners and into straights it feels fast enough to put a smile on my face.
The idea with the rebuild was mainly focused on reliability (the brief was: i want to be able to drive to the track, have fun and DRIVE BACK HOME!), and so far i am satisfied.
I did 124 laps at Brands Hatch with the Porsche Club on Monday, had a spin-out, and it didn't miss a beat all way home under torrential rain.

@crash7 - I saw you were waiting to upgrade brakes to track the car: I also have third radiator, baffled sump, light weight clutch and flywheel, lsd, KWv3 and eibach anti roll bars, braided brake lines and high temp fluid but otherwise standard brakes - very surprised with how good the standard brakes are with decent pads. I've looked at upgrades but i can see I'm better off spending the money on tuition for now. I wouldn't wait for that before tracking it if i were you.

@Dammit - the cams are RPM Technik's 'CSR" Cams, i do not know who manufactures them for them.

Hope this is helpful.
 

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A brief update, performance info to follow, but steering related threads appear to be rife at the moment so..,

What with the Engine, suspension, interior & brake work, there was not much left on the car that had not been replaced or upgraded. – One thing however I did have a nagging sense of dread over was the steering rack.

Search the forums and given that these cars are circa 20 years old age-related steering failures are becoming more and more common.

Then surely enough I heard a screeching from the rear of the car and the steering began to become heavy! -I immediately pulled over suspecting the rack had sh*t itself, upon inspection under the front driver side of the car, LCA area, there was a steady drip of Pentosin.

A call to the RAC and 8 hours later, awful service, the car was on a flat bed on its way home.

While waiting for said flatbed I had a lot of time to reflect, lots of the work I have had done on the car has been to make it more reliable and remove common faults and failure modes.

In essence the steering rack will work and steer the car without fluid, however the power steering pump will not run for long without fluid, it would eventually seize, ok I could potentially live with that, however the issue I see here is that the power steering pump shares a belt with the various items including the alternator and water pump As such I would not want a steering pump failure causing issues with items such as the water pump on my new engine.

Not withstanding the fact that if the power steering pump was not engine driven, I could have probably limped the car home.

I begun to look for solutions, enter the 997 Cup car, which runs a hydraulic rack the same as a 996, but said rack is supplied via a frunk mounted electric power steering pump, as oppose to the engine belt driven one.

Porsche motorsport will sell you the kit for circa £2k – Which consists of the pump, hoses, dummy pulley, belt and electrical connections.

The pump is a TRW pump and as well as being man enough to steer a 997 Cup car on slicks, its also fitted to the Vauxhall Zafira! – And as such can be purchased without the Porsche price tag. – The same TRW electric pump is also used a lot in drift cars, hydraulic pumps are not designed to be driven on full lock for any prolonged duration.

Be sure to get the correct pump, there is an old and new version, they do look very different.

I did as much research as I could, however, apart from a few threads on random Boxster forums there was very little info available on retro-fitting this kit to a 996.

To start, I removed the old rack to see what failed, the cross lines, which are a common failure, were very badly corroded.

The rack can be removed via the driver side wheel arch without dropping the sub-frame, provided the supply and return lines into the rack have not suffered from dissimilar corrosion and welded themselves to the rack! – Which is common. - The UJ can be a little tricky but is not difficult.

You can see that the corrosion has eroded part of the aluminium rack casting away and seized solid, there was no way the pipes were coming out of the rack.

Prior to this I had already decided that I would be fitting a new rack, something had failed, everything in the rack is the same age and as such just replacing the failed item for me was not an option, in fact using any of the original circa 20 year old parts was a non-starter.

To get the rack out, I cut the supply and return lines due to the corrosion, if I were not going the 997 Cup route there was no way I would have gotten these lines out of the rack and would have been faced with a circa £1k bill from Porsche for new steering pipes.

I then set about removing the rest of the power steering lines, which run from the rack, driver side front, across the width of the car, up the passenger sill and eventually into the engine bay to the pump, some of the lines were in decent shape, some were ropey and looked prone to future leaks, removing them and the risk of future leaks felt satisfying.

Once the lines were out I removed the Power Steering pump, which was actually fine, spinning freely without issue, not difficult to remove but you need to get other stuff out of the way first, namely airbox and a/c compressor, you do not need to remove the alternator as some suggest, access to the rear a/c compressor bolt is awkward.

The pump is bolted to the top of the engine, it and its fluid, get very hot during operation, Cayman are fitted with power steering fluid coolers to try and alleviate the heat soak. – Again, I see the removal of the heat soak, to and from the engine as a bonus.

When out I also stripped the PS pump to inspect, there was no damage or wear to the internals, I then gutted it, binned the internals and the reservoir, my initial thinking was that I would need to reinstall the the gutted pump to utilised the pulley as another idle pulley in the belt circuit, the 997 Cup pulley is different as it's not designed for an M96– However as fortune would have it Tarrett had just begun to produce a 996 Power Steering delete pulley, its vastly over priced for what it is, however it is a lighter and more elegant solution, so I bought one.

The Tarrett pulley mimics the size and position of the original PS pump pulley and allows me to maintain the same belt size and routing as previous, (RSS underdrive pulley & a/c) with the pulley installed the engine was now free and disconnected from the Power Steering system.
New power steering rack, including inner tie rods and outer track arms were installed. Custom hoses would be required to install the electric pump.

The pump needs to be frunk mounted, and subsequently needs a support bracket, I investigated various options, Cup cars have a basket welded to the frunk floor, others have made custom brackets. – I figured that if TRW make the pump would TRW also make a bracket, they do, for the Zafira. TRW part number 000.0285.002.020 – I was able to modify this bracket to get it to hold the pump in a location I was happy with, I wanted to maintain as much frunk capacity as possible and keep the wiring and hydraulic hose lengths to a minimum.

One of the tricky parts is making up the hoses that connected into the rack, Porsche use a Porsche specific push fit end that is held in place with a tension shackle, the original steel power steering pipes are flared to fit and are bespoke as oppose to a standard JIC, AN fitting.

Where I have seen this retro-fit else where there have been solutions that involve cutting the Porsche PS lines, maintain the end fitting and welding on a JIC / AN / BSP thread, picture included, I was not keen on this, although it works, its all a little heath Robinson for me. – Enter Rebel Motorsports in the USA whom produce a bespoke item, it mimics the Porsche ends, utilizes the OEM Porsche seals, but allows the connection of AN fittings.

Next you need hoses, calculating the length prior to having everything installed (rack & pump) is difficult and even with them installed trying to compensate for bend radius etc still makes it a guessing game, particularly if you want it to look neat and work first time.

After much procrastinating, I landed on Earls performance hoses. Earls make a high pressure power steering hose that does not require crimping and can be made up in situ, so you can run the hose, cut to length, you then add the required AN ends, which threads in the Rebel racing fitting one end, and you need an Earls Power steering fitting that screws into the pump.(Its either M14 or M16 x 1.5, cant remember) – I don't have any pictures of the fittings, if anyone wants parts numbers etc let me know and I will dig get them off the invoice, Earls to their credit were super helpful.

The return line is low pressure again I used Earls, but their Prolite range, it's a large diameter pipe and uses lower pressure, fittings, which again are screwed in as oppose to crimped.

This should make up for my pi$$ poor explanation

https://www.youtube.com/watch?v=M2wXKfOmvF0

https://www.earls.co.uk/earls100/earls_shop/

You also need to decide on where to drill the penetrations in the bulk head to run the hoses through from the pump to the rack, lots of areas are double skinned and there are a lot brake and coolant lines running around which you need to be careful not to disturb, in addition to not wanting to put any nasty bends in the PS hoses or leaving them to long so as they catch on anything.

I wanted a single skin penetration while taking all of the above into account and ended up drilling as per the picture, I considered hydraulic bulk head fittings but access is so limited, rubber grommets were fitted to the holes to add a little more protection to the hoses, although that said it was hard work cutting the hoses with a hacksaw so I would not see them rubbing through without the grommets.

I am not 100% happy with my hose runs from an aesthetic point of view, everything works without issue, I may look to adjust the way they sit in the frunk over time, my primary concern was functionality.

Electrical wiring is straight forward when you know how. – The pump has inbuilt control, but nothing as complex as a full-blown ECU and it does not need to be run through a relay, the red block you see on the Porsche motorsport kit is a fuse, you do need to fuse it as it is a heavy load.

The thick brown cable from the pump needs to go to ground.

The thick red cable from the pump needs to go to directly to your battery, but via a suitable 80-amp fuse, there are many options available, inline etc, however I wanted mine to be accessible so used a Mega fuse and suitable enclosure which I mounted to the bulk head.

Now for the control.

The pump has three control wires of which only two are used.

The black cable requires a switched live – I ran this back to the fuse board in the drivers footwell, there are spare ways available for factory options that were not fitted. – From memory I utilised slot E8.

Blue & White cable. This tells the pump when to run, due to its heavy draw you do not want it running when you switch the ignition on, only when the car is running, finding a suitable signal was a challenge, I end up using the alternator charge indicator signal. – The easiest place to get this from was the dash cluster. - White plug, pin 23, blue 0.5mm cable, I spliced into this.

I made up an IP65 multi-pin plug for the control cables which allows me to disconnect and subsequently isolate the pump if required, I could also pull the fuse.

In turning the ignition on, the pump clicks, when you start the car the pump runs. – As with the hydraulic pump the pump runs constantly, the inbuilt FCV either recirculates the oil within the reservoir or directs to the rack as required.

Steering feel is no different from the hydraulic pump. – In fact its slightly improved, however that probably down to the new rack.

When refitting the rack, you will do well to get the UJ spline position to match up perfectly with the steering column so as everything is dead centre. – Expect to have the car tracked to centre the rack and the steering wheel to be out of centre, I simply removed the steering wheel and refitted.

In my vain of trying to be honest, weight, you may save 1 or 2 kgs over the hydraulic pump and associated pipe work, the electric pump is heavier than the hydraulic item, I have not weighted the junk I removed, but there is not much in it. – However, you are removing the hydraulic pump weight from up high at the rear and relocating the weight to low down at the front, which is a benefit.

You may gain 1-3-wheel bhp due to the removal of the parasitic lose of the hydraulic pump, don't go expecting miracles! Removing the hydraulic pump also frees up space in the engine bay so airflow will be better, and you lose the heat produced by the PS pump.

And as touched on previously, it the system does fail, you would be able to limp the car home.

Pictures, in no order below, unfortunately I am not as committed as the likes of Dammit, Mistercorn or Marky in taking pictures or documenting!

Edited to add the parts and providers I used which may be of use to some. - There are many different ways to mount the pump and run the hoses to the rack, do what works for you!


Earls 991955 ; AN-6 to 16mm x 1.5mm Power Steering Fitting – Fits into Pump

Earls 150006 ; AN-6 Power Steering Hose

Earls 130106 ; AN-6 Straight Hose End Steel – High Pressure Hose Fitting

Earls 139106 ; AN-6 90 Degree Hose End Steel – High Pressure Hose Fitting

Earls 800106 ; AN-6 Straight Swivel Hose End – Return / Low Pressure Hose Fitting Rack Side

Earls 350006 ; AN-6 Pro-Lite 350 Hose – Low Pressure / Return Hose

Earls 900107 ; AN-7 Jubilee Clip - Return / Low Pressure Hose Fitting Pump Side

Porsche 999.230.542.40 – Sealing Ring
Porsche 999.230.543.40 – Repair Seal
Porsche 996.347.769.02 – Tension Shackle

Rebel Racing Rack Fittings

https://www.rsrproducts.com/product-page/rebel-s-racing-rsr-steering-rack-fittings-for-elec-pump

TRW Rack & Pump from Western Power Steering

http://www.westernpowersteering.co.uk/

Power Steering Fluid – I upgraded to 'Motul Multi HF' , its fully synthetic and has a higher maximum operating temperature than Pentosin.
 

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Pump in situ

Tarrett PS delete pulley.

Rack Fittings, the Heath Robinson and the Rebel Racing items I used.
 

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Hydraulic pump & pipework.

Various example installs.

997 Cup install

PCGB 996 Racecar install

RSR install

You can see they all differ in method, but all work.
 

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I have no intention of following this but it's an excellent post, great reading.
many thanks.
Mike
 
maldren said:
I have no intention of following this but it's an excellent post, great reading.
many thanks.
Mike

Agreed. :thumb:
 
Jamie Summers said:
I appreciate it's not quite comparing apples with apples, but I have the original Cayman "RS" development car that Autofarm produced about 10 years ago.

It started life as a regular 987.1 S ie the M97 3.4L lump. Autofarm subjected this to one of their 3.7L Silsleeve engine conversions. In addition to many of the same bits and pieces that Hartech do as standard, Autofarm also fitted the Shrick cams, IPD plenum GT3 throttle body and a custom carbonfibre airbox. It also has stainless decat headers and Miltek back section (also decat).

The engine was dyno-mapped by the now departed Bob Watson and showed 367bhp, backed up by a dyno print from a different dyno a couple of years later showing a very similar number.

The power delivery is very linear with strong low-down torque. Getting the thing to cool properly has been the major challenge, but I think that is as much to do with the mid-engined lay out as the engine itself. I have now also gone down the line of fitting TTP Oilsafer pumps on both banks of heads together with an additional external oilcooler, deep baffled sump and larger 997 water/oil heat exchanger, low temp therm, lightweight clutch and flywheel and under drive pulley.

I think there is still more on the table with a bit more dyno time. Parr had it on their dyno relatively recently and commented that the map was fairly basic and could be improved.

Clearly comparisons with a Hartech M96 3.7 are not entirely fair, but what is interesting is that even with many of the bolt-on "performance" mods eg plenum, throttle body and airbox, which the OP found to be power-reducing, there is still a material improvement in power output over the Hartech M96, which presumably must come largely down to the cams and exhaust ???

From what I gathered from reading their information on their oversized engines, they've tried to build a torque monster rather than a peak HP engine. But don't quote me on this.
 
Dont know how I missed this thread before but now just read it in full , very very interesting and I found similar with Hartech and Wayne from Chipwizards regarding bolt on's that dont do what they say on the tin . Wayne left my IPD but removed the Fabspeed carbon twin cone induction and replaced it with my stock airbox and BMC filters as the fabspeed induction actually reduced the BHP and power curve. mine is a 997.2 so may have different characteristics to the 996.2 and I accept that Porsche had already tweaked some of the extra BHP between the 96.2 and 97.2 ,I did the same and had assumed some loss in power from new despite the Hartech rebuild so was assuming if 385bhp from factory 10 years later 370/375bhp maybe , so by the time Wayne had finished it was just over 400bhp so realistically 25/30bhp gains from Cargraphic full exhaust with 200 cell cats , IPD plenum , BMC filters and a good solid Chipwizards remap also Wayne got a really nice power curve and no flat spots.
 
sp1ke said:
For completeness I'll add the graph from the original Porsche hardback catalogue for the stock 3.6 as a comparison to the one Dammit shared for the stock 3.4.

This graph makes for interesting reading, thanks. It really stands out how much extra torque the 3.6 M96 makes and how much earlier in the rev range. It makes around 273ft/lb of torque at 4250rpm, as opposed to NedHan's 3.4 dyno run shown which makes max 239lb/ft, but more critically at 5734rpm.

Also if you look at the 3.6 graph it makes max power at 6800rpm but there is a broad plateau of power around 320bhp from 6000rpm to 7200rpm, whilst the torque drops off after 6000rpm. I have found in my limited time with my C2 so far that this reflects the real world characteristics of the car where it builds speed very fast between 4000-6000rpm and increase in power delivery tapers off slightly at the very top end. Is this the experience of other 3.6 owners - ie. upshifting at 6000-6500rpm rather than 7000rpm for best usage of the engine? I would expect the 3.4 maybe not to pull as hard but to want to rev out to the limiter a bit more.
 
dc2100k said:
sp1ke said:
For completeness I'll add the graph from the original Porsche hardback catalogue for the stock 3.6 as a comparison to the one Dammit shared for the stock 3.4.

This graph makes for interesting reading, thanks. It really stands out how much extra torque the 3.6 M96 makes and how much earlier in the rev range. It makes around 273ft/lb of torque at 4250rpm, as opposed to NedHan's 3.4 dyno run shown which makes max 239lb/ft, but more critically at 5734rpm.

Also if you look at the 3.6 graph it makes max power at 6800rpm but there is a broad plateau of power around 320bhp from 6000rpm to 7200rpm, whilst the torque drops off after 6000rpm. I have found in my limited time with my C2 so far that this reflects the real world characteristics of the car where it builds speed very fast between 4000-6000rpm and increase in power delivery tapers off slightly at the very top end. Is this the experience of other 3.6 owners - ie. upshifting at 6000-6500rpm rather than 7000rpm for best usage of the engine? I would expect the 3.4 maybe not to pull as hard but to want to rev out to the limiter a bit more.

What is the standard figures for a 3.4? I have it in my head it about 254lb torque and 296 hp. They're supposed to average 26-270hp on the dyno these days for a standard car so I was very happy with the hp figures I got. My torques obviously down but I was putting that down to the cats. Everyone says that they'll loose torque with aftermarket cats or decats which dosnt really make any sense to me. Either way, an extra 30-40lb goes a massive way to how the car will drive. Much more than a lot of people would realise.
 

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