Crown

Toby,

what I always forgot to ask (until now) is whether you would perform the same modifications if you were doing the process all over again?

Ferdie:

Toby,

what I always forgot to ask (until now) is whether you would perform the same modifications if you were doing the process all over again?

Hi Ferdie

Firstly it is worth noting that I drive this car every day including city traffic so it was essential that the drivability was like stock and importantly the clutch. I have the Sachs 890NM clutch with standard dual mass flywheel and the daily drivability is very similar to a standard car. The clutch will slip occasionally when the temp drops below 10C in higher gears between 3000 and 5000rpm so I have to be aware and drive around that to keep the clutch alive and so far so good in ~8000miles.

For the GT2 with it being RWD this engine is right on the limit or probably a bit over it depending on how "lively" one like a car to be ? The 997s traction control and PASM systems really make the car super fun to drive and for me this much torque (over 800NM from 2750rpm to virtually the rev limiter) would be undrivable in a 996GT2 for example as the electronic nannys are super nannys, flickering away all the time and quite a lot of the time when one doesn't even realize that disaster was a fraction of a second away. The nannys allow for a nice amount of wheel spin and slide, just enough for great fun driving.

I do have an issue with the tuning which manifested itself once the temperatures got below 10C and that is that the standard VTG mechanisms cannot control fast enough the onset of the boost between 2500 and 3000rpm so the volume of air overshoots the ECU targets and causes a big misfire/backfire..... I thought it was just a bit of fun like a rev limiter until I kept on the gas one time and did this

Luckily there was no engine damage and a couple of new intake manifolds (they are cheap plastic so not very strong) later I was back on the road and I just have to not play violently with the throttle around these revs, it sounds bad but in practive it is no real hardship.

Suffice to say I hope to get this issue fixed shortly but suspect it will mean lower those boost targets so it doesn't overshoot and therebye less torque (but we will see what Schmirler decides)

Apart from that the car is very fast, I recorded a 0-300 in sub 22s recently and the real piece de resistance is the throttle response, we did a test at an airfield against a 996 turbo with special fast spooling K24/20g turbos with alleged 800hp. You can see from the vid that the VTG response makes the older turbo car look ridiculous (we did this a few times in different gears and the resukt was the same, the VTG car just leaps ahead and puts 5 car lengths before the normal turboed car gets spooled up)

http://www.youtube.com/watch?v=9cQWMDhQ7W8&list=UUbyXBxuohrEFM-gfb_GJgFQ&index=1&feature=plcp

I would not give my car away again for 1 year to do this again but now I have it I am very pleased with the result and am enjoying it immensely.

3.9  GT2 2011 make over

My 2012 interior makeover, some GT2RS bits with red belts to jazz up the cabin

3.9  GT2 2011 make over

How could I miss that thread 'til now?...

Fantastic story and car! Congrats...

TB993tt:

My 2012 interior makeover, some GT2RS bits with red belts to jazz up the cabin

Not a big fan of the red interior on the RS but it is most important that you are happy. Actually forgot to thank you for your detailed response, certainly do appreciate it.

pierre:

How could I miss that thread 'til now?...

I'm thinking the same thing.

Thanks for the write-up TB993tt. Your GT2 looks fierce.

If I don't fly, I drive my .:RS 

I thought I would update this thread since I am currently daily driving my 997GT2 and REALLY enjoying it 

Back in 2014 due to oil dilution (with petrol) my engine spun a big end bearing, the fuel was getting into the oil probably because of a fault in the system which allowed fuel to squirted in but not burnt off, the car never used any oil and I thought that was great but it turned out that the oil level gauge was measuring fuel in the oil as well ! 

I had the engine reworked by RS Tuning to go from VTG turbos to conventional K24 turbos like the ones the 996 turbos use but with modified internals. They had the heads ported, gas flowed and bigger valves installed, new different and stronger pistons, exhaust manifold, air intake and all exhaust were modified to facilitate the new turbos and of course a fairly extensive rebuild was required including new oil tank due to the trashed bearing.

Emre who runs ES Motor in Turkey (and now holds quite a few Porsche drag records) was developing a special intake splitter which welded onto the 997GT3 style aluminium intake for turbo application and he kindly sold me one of his first units. you can see on the final pic how well the system equalises the air flow between the ports.

They used new type of electronic controller which converts the VTG signal into a signal which can control the conventional wastegates on the K24s in similar way as the 996t but my engine had two N75 valves one for each turbo, these are the valves which bleed boost air pushing the wastegates so that the ECU can accurately control the boost pressure and the ECU can work in the exact same way as factory M7.8 Motronic with all the safeguards and efficiencies. All other (AKAIK) non VTG turbo builds which you may read about use a fixed boost via an aftermarket boost controller which work OK but are obviously not as efficient.

When we discussed the new build Mr RS was mindful that the ported heads and big valves together with non VTG turbos would make the 3.9 litre engine lose its ultra fast spool and would not produce the power lower down in the rev range and he actually drew a predicted new curve for (in red) on the diagram below (the original curve is from a 3.9 VTG engine) and you can see how he predicted the peak power at 1.03bar and 1.08bar. He reckoned on 430PS at 3100rpm

Well many months later when it was finally signed off the power curve looked like this. As this was the first engine they had done in this configuration he didn't realise how well it would breathe at the top end and unlike the VTG motor this engine really eats up the air. One technical highlight he explained to me was how he created a vacuum in the crankcase and actually measured that whilst on the dyno, I have the numbers from a dyno data sheet here and it ran at about -0.25bar over 5000rpm apparently this allows for very efficient running and increase power

You can extrapolate the torque from this graph but it has 580NM at 2100rpm, 725NM at 3000rpm 800NM at 3000rpm then over 900NM from 35500 to 6500rpm. I'm sure I posted this before but below is the engine doing a full power dyno run.

https://www.youtube.com/watch?v=dD8ruzuVOTU

Pretty sure I posted this before but this was the performance at a vmax event which I used to frequent. 

https://www.youtube.com/watch?v=4zm8vkiugDM

The engine has actually done 40K miles that's 64K KM since the rebuild and seems to be running faultlessly the most impressive thing is actually the boost response, it comes in from 1500rpm and is so much fun, on the autobahn you can stay in 6th and smoke anything in the way !

As earlier in this thread I ran the Bilstein B16 PASM compatible shocks for many years and the car drove well, always controlled but of course quite hard with a spring rate in the high 700s in the back. Having driven other more modern cars with their advanced adaptive shocks I bit the bullet and installed the Tractive DDA shock package with works with TPCs DSC controller, this is a very clever bit of kit which uses high end shocks with ultra low stiction and the ability to react ultra fast and together with the DSC controller (which replaces the Porsche box) provides a huge range of damping, see below

One of the elements of this which I really liked was being able to run relatively soft springs, 336lb front and 616lb rear so when pootling round at low speeds the ride is really good and the DSC firms it up as the speed increases, this can actually be tuned via laptop.

Another interesting area which took some fettling was the LSD, it's fairly common knowledge that the factory LSD is made of chocolate on the 997GT3 and 2 and I think part of the reason for this is that Porsche designed the electronics to do most of the work of the LSD so it is somewhat redundant, the big benefit of the stock setup is the awesome turn in and general looseness of the car. In 2014 I installed a heavy duty Guard 40/60 unit and the car immediately lost its looseness but I thought it was the right choice to tame the big torque. The Guard unit failed in 2019 and I replaced it with a Drexler with similar locking numbers, the rear end was even tighter controlled, the car understeered like a bitch and the rear end totally dominated the car, I didn't like it. Against my better judgement I fitted an American made Wavetrac unit...... I like it, the looseness is back, I'm not sure exactly what the traction is doing, there is never very much in the lower gears, but I like the overall feel it works well with the car's nannies and I'm very happy with it.

I have played around with my gear shift over the years, trying to get the best feeling. I had a CAE shifter which is a nice bit of kit but ultimately was too much work for daily use, I then tried an SQS sequential which is a clever device which attaches to the box and selects gears with some electronic assistance and a sequential type action in the cabin which again proved not good for DDing. I recently fitted the gear pictured below, an American company Function First have designed replacement parts for the plastic internals of the shifter unit, the parts are very accurately machined aluminium and they replace the rubbery linkages at the box end...... Wow what a difference a superb rifle action but stock feeling shift, one of my favourite mods it really makes shifting a lot of fun. 

That is where I am up to to date, I had my BBS Fi wheels refurbished recently as they start to bubble after a few years, I went for a mad colour powder coat which I bout from the net and my local guy applied it, it takes a bit of getting used to but I really love it now, oh and a new number plate and if you look closely at the pic you will see that the rear air intakes stick out a bit like on the latest 991Gt2RS, these are special parts which are covered in matte CF and feed extra pressured air into the intercoolers 

--

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2021 McLaren 765LT incoming 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

Brilliant, I adore that car

1969 Mercedes-Benz 300SEL 6.3  / 2020 Mercedes-AMG C63 / 2020 Ferrari 812SF

Epic car ! Drove both 997RS last week-end and to me the pinnacle of driver involvement ! 620 HP is already a hand full into 3rd - cannot imagine running yr numbers. 

Another impec post...really enjoy the reading. 
The 997.2 GT2 and GT2 RS will be very desiralble in a near future....pure driving!

Wonderful. Amazing project and amazing car. Thanks a lot for taking the time to write that post

Very cool  thanks for posting..

2019 911 GT3 RS,1964 Type 1

Thanks for the comments guys, it's quite a self indulgent post but I like to document the journey and it is continuing 

Bjoern and pgouveia, I agree with the 997 sentiments, I specced and bought a 991.2 Turbo S new in 2017, did 750 miles and gave it back to the dealer to sell, the modern 911s do not feel like 911s any more in contrast the 997 still feels rear engined and moves around like a 911 should and of course the manual change is an awesome thing for those of us who like to shift 

911 imposter below 

--

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2021 McLaren 765LT incoming 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

I like reading these kind of posts. Inspiring and very interesting. Making a car the best for one's likes is such a reward ... and some headaches 

 964 Carrera 4 --  997.2 C2S , -20mm -- 991.2 GT3 RS 

TB993tt:

Thanks for the comments guys, it's quite a self indulgent post but I like to document the journey and it is continuing 

Bjoern and pgouveia, I agree with the 997 sentiments, I specced and bought a 991.2 Turbo S new in 2017, did 750 miles and gave it back to the dealer to sell, the modern 911s do not feel like 911s any more in contrast the 997 still feels rear engined and moves around like a 911 should and of course the manual change is an awesome thing for those of us who like to shift 

911 imposter below 

--

 

 

 

 

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2021 McLaren 765LT incoming 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

Some would argue, this is the perfect combination. An analog 911 and it's younger, fatter, turbocharged, 4 wheel drive cousin as a daily

Always enjoy your posts TB

rhino:

 

Some would argue, this is the perfect combination. An analog 911 and it's younger, fatter, turbocharged, 4 wheel drive cousin as a daily

 

Always enjoy your posts TB

Thank you 

I've always dailyed fairly extreme 911s for the last 33 years and unlike Leawood whose advancing years has led him to the dark (EV) side  continue to do so I haven't really got a need for a cushy car 

--

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2021 McLaren 765LT incoming 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

Thanks for such great posts. Nice to see your deep dive into the technical details of your engine build.

mcdelaug:

Thanks for such great posts. Nice to see your deep dive into the technical details of your engine build.

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2021 McLaren 765LT incoming 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

mcdelaug:

Thanks for such great posts. Nice to see your deep dive into the technical details of your engine build.

+1,

What a fantastic thread.  Proper enthusiast is TB993. 

throt

"I Have Done It!".

991 GT3 pick up in October 2014.

991 GT3.2 pick up April/May 2018. ( Hairy Chest Spec ).

Vauxhall Zafira 1.6 Exclusive pick up June 2013. ( Shit Box )

Rennteam Hairy Chest Advisor.

Something I hadn't really mentioned in this thread but is worthy of some discussion, intercooling.

For turbo engines we all know that intercooling is important, for the earlier Mezger motors of the 993 era when the 993 GT2s were extensively raced they were extremely sensitive to high intake temperatures which would easily cause the heads to warp and also the cylinders would oval.

The standard 993 turbo and GT2 intercooler (pic below) was a side to side design with a relatively thin core and was good for up to 540PS in the 993 turbo and GT2

Porsche developed a new unit for the first generation of the EVO GT2 race cars it again was a side to side design and a thinnish core but a lot bigger surface area (pic below)

Unfortunately this new EVO intercooler proved little better than the original unit and cars were still limited to around 540PS. This is where Porsche Motorsport brought out the big guns and had French aerospace manufacturer Secan design and produce a run of intercoolers (pic below). These units became legendary partly because they were so expensive, a friend of mine back in the mid 90s was competing in his GT2 and I remember him being exasperated at having to pay the ~20K Euros for one of these units but if you didn't have one then you would not be going north of 600PS reliably so all major racers forked out the big money. Today owners treat these intercoolers almost with reverence, like a family air loom !  

mercedes e550 amg 2015

fast forward to 2008 when some of us were modifying our 993 turbos and my tuner commissioned a run of side to side bigger volume intercoolers from Secan costing 10K Euros which enabled around the 600PS mark, a pal was talking about another aerospace manufacturer Marston having a comparable product so a few of us got together at an airfield and did back to back testing on the same car of three different intercoolers running the car (a modified 530PS unit) up to 190mph and logging the maximum intake air temperature seen,

The Secan was the best at max IAT 33 DegC then the Marston at 42DegC then stock at 54DegC doesn't sound much but critical to keep engine in shape.

Some more pics and test report from back then here:

https://rennlist.com/forums/993-turbo-forum/428101-9m-prototype-intercooler-test-report.html

Left to right, Secan, Martson, stock.

how do i get url of an image

When I started my 997GT2 engine modification journey I already understood that the limitation of the standard intercoolers was around the 620PS mark indeed the 997GT2RS got a newly developed core to be able to produce this number and under track conditions in 20DegC ambient the full 620PS will not be there. 

My tuners had commissioned Secan to produce its magic cored units for the 996 turbo platform and they used these to successfully power the Alzen 996 and 997 Race cars - remember this beast ?

The intercoolers also featured in the Mission 400 record car which broke 400kph courtesy of a 1045PS engine wearing said Secans (exact same size as factory)

photos google come

The Secan is also still used in the car used by Fritz K which has a similar 3.9l engine as mine and has some special intercooler cooling air inlets on the top on the rear wings, these can be raised or lowered to allow more or less drag/cooling air according to how fast thecircuit is.

I wanted a pair of Secans for my GT2 but I didn't want to (again, remember the 993 !) pay another 12K Euros. I started talking with a UK racer who had close contacts with Marston aerospace and eventually he produced me a set of bespoke units using their latest hand made cores. These were cheaper but not by much, still ran at £7K and that is with very little handler's margin.

So these intercoolers were validated by my tuner who was surprised that they managed to match the effectiveness of the Secan and has since used this core on a number of race car projects.

The "secret" to the tuning is to match the tuning with the ability of the intercooler to deliver a certain level of intake temperature, on the 997 engines the trigger point of 55DegC IAT was the critical number higher than that and the programming would lower the power via timing, fueling and boost to prevent onset of knock so the trick is to tune so that the engine never breaches that critical number under its user conditions, this involves mostly a lot of experience, high speed full load testing, track low speed but high load testing and finally engine dyno testing using the known limits. When they tune of the engine dyno they have various options but mostly use a water cooled intercooler so they can replicate the IATs which are experienced on the road/track and tune appropriately. 

I always find intercooler chat interesting and can see that 90% of the aftermarket stuff sold is no better than factory standard, there has been some progress in the last 20 years but not that much. The 991 GT2RS for example has to use the water sprayer to manage its 700PS, there was some discussion on here about the new 911 turbo/GT2RS going to 750PS, this is going to be very difficult as it is limited by the intercooling. The 991GT2RS 935 edition had its bigger intercoolers located in a different position at the back in the rear bumper and I noticed that the new 992 turbo has a new set up for its intercoolers no longer feeding the cooling air through the wing intakes but instead coming straight over the roof then having double channels for the hot air to exit, they say they have improved efficiency which is great and allows (along with all the other clever new stuff) the 580PS

Lastly I often see people dismissing the expensive Secan/Marston intercoolers as being ridiculously expensive and not worth it and these people think someone is doing some kind of rip off/Porsche tax.... well interestingly Marston are no longer making their special cores they shut that division down as it was not profitable ! Secan will make stuff but requires larger production runs which renders it pretty impossible so until someone with new tech comes along the day of the super intercooler has gone  

--

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2021 McLaren 765LT incoming 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

Super interesting, love to read up on your intercooler passion.

1969 Mercedes-Benz 300SEL 6.3  / 2020 Mercedes-AMG C63 / 2020 Ferrari 812SF

great insights ! 

Thanks guys..... here are some better shots of the 992 turbo set up, this is quite a development from Porsche since the old format ran from 996 in 2001 to 991.2 to 2019, I like the way the exit for the heated post intercooler fin air gets sucked out via four outlets, amazing packaging and engineering 

Exits circled in red in case you didn't spot them 

--

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2021 McLaren 765LT incoming 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

For my 996 Turbo, things were pretty simple then: I just switched the standard intercoolers with the ones from the 996 GT2. Easy peasy, perfect fit. 

RC (Germany) - Rennteam Editor Lamborghini Huracan Performante (2019), Mercedes GLC63 S AMG (2020), Mercedes C63 S AMG Cab (2019), Range Rover Evoque Si4 Black Edition (2019)

Family air loom?  Really good pun or spell check running amuck?

waiting for PDK:

Family air loom?  Really good pun or spell check running amuck?

An "air loom" is where one weaves "vapor wear" 

Mike

918 Spyder + Taycan Turbo + Tesla Roadster 1.5 & Model S P100D AP2 + BMWs (Z8 + 3.0 CSi) + Bentley Arnage T

TB993tt:

Thanks guys..... here are some better shots of the 992 turbo set up, this is quite a development from Porsche since the old format ran from 996 in 2001 to 991.2 to 2019, I like the way the exit for the heated post intercooler fin air gets sucked out via four outlets, amazing packaging and engineering 

 

Exits circled in red in case you didn't spot them 

--

 

 

 

 

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2021 McLaren 765LT incoming 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

This is a fascinating and well presented tour of turbo-passion.

I have enjoyed it immensely.

Thanks so much 

Mike

918 Spyder + Taycan Turbo + Tesla Roadster 1.5 & Model S P100D AP2 + BMWs (Z8 + 3.0 CSi) + Bentley Arnage T

waiting for PDK:

Family air loom?  Really good pun or spell check running amuck?

 I'd love to say it was a pun but nope just being dumb.... an heir loom of course 

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2021 McLaren 765LT incoming 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

W8MM:

This is a fascinating and well presented tour of turbo-passion.

I have enjoyed it immensely.

Thanks so much 

Thanks for saying so, it's appreciated 

997 GT2 2014 3.9 Mezger, 800PS @ 1.2 bar

2021 McLaren 765LT incoming 

993 Turbo, 2006 built 3.8, 577PS/797NM, 1440kg DIN sold to a worthy enthusiast.

That was very interesting!!!!

Thanks for this great story.

Blueflame