In late 2013 I swapped a 997 Carrera GTS for 981 Cayman S with PDK and have enjoyed the easier handling and greater agility of the Cayman, however the 3.4L engine it is a bit weak on power.
A few months after my purchase, rumours about the GT4 started so I placed my letter of intent in March 2014 with a friendly salesman from whom I had previously purchased cars and referred prospects to. But around September/October 2014 it was looking likely that the GT4 would be manual only and with a dodgy left knee and a recent left shoulder operation, even a left hand drive manual GT4 did not seem a good idea. I therefore started looking at other alternatives for getting more power in a PDK equipped Cayman.
It rapidly became evident that without a custom ECU tune the benefits of any engine modifications would be substantially reduced by the new generation OEM ECU which only a very few can tune. There are a number of USA firms who have installed 3.8L engines in 986 and 987 non-DFI generation Boxster/Cayman models, but first, together with a fellow PCGB member I explored using RuF. Unfortunately they wanted around €65k +VAT for just the engine swap with new exhaust system and related front/rear PUs, so that did not make much sense.
So over to the USA where BGB Motorsports in Florida are the most active and have been providing 3.8L road conversions and building and running manual and PDK 3.8L race cars. After extensive discussions with BGB primarily focussing on support and logistics (at that time they had only converted USA-based owners’ cars), their then lack of a true custom ECU tune and the prospects of shipping engines back and forth killed that alternative.
Interestingly the USA is the only territory where Porsche will give a trade-in credit for a 3.4L or 2.7L against a new or re-man 3.8L.. Therefore if I wanted to do the swap, I had to get a 3.8L engine which at £20k from Porsche UK was a tad expensive… so off to fleabay and lo and behold in December a 3.8L became available from a 3,700 mile PDK 991S involved in a front-end crash.
But in December there was still some, but not a lot of hope that the GT4 would have a PDK option. I took a deep breath and after Fearnsport had checked the 3.8L fleabay engine I bought it, thinking that if a PDK GT4 became available, I’d sell the 3.8L engine and any loss would be the option cost of having both the PDK GT4 and 3.8L upgrade choices.
In parallel, a German group led by Jens Ehresmann contacted me via planet9 and we started discussions about having them install the 3.8L engine in my Cayman. Jens had been modifying his PDK 981 Boxster S 3.4L and with intake and exhaust modifications plus custom tune had achieved around 370PS. He had also upgraded the brakes with 996 GT3 parts and fiitted 997 GT3 Cup suspension acquired from race teams that his group supports. Not content with this, Jens then acquired a 991 3.8L Powerkit engine and fitted this to his Boxster - the key to getting 370PS from a 3.4L and 434PS from the 3.8L Powerkit was his ability to custom tune the ECU, particularly for the Powerkit engine’s multi-valved plenum. Ehresmann have recently started providing custom tune ECUs to BGB, modified a 987 Cayman R to give 371PS for a Norwegian customer, and have introduced a tuning package for the GT4.
Early February, GT4 orders opened and I had to turn down the option to buy one as it was indeed manual only. With that alternative closed, I finalised arrangements with Jens’ group. I left my Cayman at Fearnsport late February to join the 3.8L engine and arranged for both to transported to Jens in Dusseldorf whilst we headed off on our Spring break. The conversion would normally take three weeks or less but as we were going to be away for some time and mine was their first Cayman swap, it seemed sensible to give them plenty of slack in the timetable.
I collected the car just in time to join April's Spring PCGB Factory Tour which took in Osnabruck, Leipzig and Stuttgart. This gave me plenty of time to get comfortable with the ‘new’ car and its reliability before leaving Germany. Back in the UK on my journey from Chunnel to Devon, I stopped off at Goodwood for a noise test (at 101db it was OK) and ran it on a dyno, which confirmed Jens' power runs.
The installation is not that "difficult” The picture below shows the 3.4L and 3.8L (or is it 3.8L and 3.4L?) engines together and they have the same overall external dimensions.
There are some differences including siting of the oil filter and some pipe runs but they all fit in the engine bay. In the 981 the gearbox is aft of the engine versus being in front of the engine in the 991 so the 3.8L engine orientation is reversed. The 981 gearbox is retained and mates directly onto the 991 engine. As Jens’ Boxster and BGB’s conversions demonstrate, there is no problem in installing a Powerkit 3.8L in either a Boxster or Cayman.
So what have I got?
3.8L 991S engine with Cargraphics 200 cell headers, IPD plenum + Y tube, and BMC air filter
Custom Tune with 412PS and 419Nm on a Maha dyno
Center radiator
991S 6 piston callipers/340mm disks
K&N anti roll bars and Powerflex Camber/Castor front bushes
Cargraphics 8.5" and 11.0” 20” wheels with Michelin Pilot Super Sport Tyres F245/35 R295/30
The power is greater than 3.8L engines in 991S and GT4 mainly due to the custom tune, better intake, and 200 cell headers/manifolds. The BMC v OEM air filter gave another 7 PS which is symptomatic of how breathless these engines are at top-end with the standard intakes.
It is not intended to be a homebrew GT4 nor a Cayman version of the lightweight 981 Boxster Spyder. I like my comforts (which is why it weighs 1428kg) and is a very much better road car with so much more usable torque. The power does not fall away at the top end and it runs to OEM rev limits with no CELs. I get 34mpg on m/way runs and it will hold 7th gear up inclines. It has very much stronger mid-range accelaration and is much less frenetic on track than in 3.4L guise. Aside from the Cargraphics wheels, the car looks completely standard.
I have not done much yet on the suspension, just stiffer anti-roll bars, extra camber adjustment and wider tyres. The car does need development in this area so I am off to Centre Gravity to have the car ‘audited’ and define and discuss options. I plan on running the car though the autumn as is and will implement over winter whatever best option emerges.
I considered fitting the TechArt aero kit because according to SportAuto, the Cayman S develops front end lift and rear downforce. However TechArt were unable to provide any data on its aero effect and as I did not take off at speed on the autobahn the €5.5k cost did not seem a good investment.
Warranty? - I would be miffed if a door handle fell off and Porsche would not fix it but I have gone well beyond different make windscreen wipers/battery/non N rated tyres.
Insurance? checked this early - it is rated as a Carrera S and all mods have been disclosed - another £75pa.
DVLA? changed V5C to show new engine serial# and capacity.
You have to be brave to do something like this but with research and cross checking to validate claims and experiences, one can manage the risks and it is a car I shall keep for a little while.
A few months after my purchase, rumours about the GT4 started so I placed my letter of intent in March 2014 with a friendly salesman from whom I had previously purchased cars and referred prospects to. But around September/October 2014 it was looking likely that the GT4 would be manual only and with a dodgy left knee and a recent left shoulder operation, even a left hand drive manual GT4 did not seem a good idea. I therefore started looking at other alternatives for getting more power in a PDK equipped Cayman.
It rapidly became evident that without a custom ECU tune the benefits of any engine modifications would be substantially reduced by the new generation OEM ECU which only a very few can tune. There are a number of USA firms who have installed 3.8L engines in 986 and 987 non-DFI generation Boxster/Cayman models, but first, together with a fellow PCGB member I explored using RuF. Unfortunately they wanted around €65k +VAT for just the engine swap with new exhaust system and related front/rear PUs, so that did not make much sense.
So over to the USA where BGB Motorsports in Florida are the most active and have been providing 3.8L road conversions and building and running manual and PDK 3.8L race cars. After extensive discussions with BGB primarily focussing on support and logistics (at that time they had only converted USA-based owners’ cars), their then lack of a true custom ECU tune and the prospects of shipping engines back and forth killed that alternative.
Interestingly the USA is the only territory where Porsche will give a trade-in credit for a 3.4L or 2.7L against a new or re-man 3.8L.. Therefore if I wanted to do the swap, I had to get a 3.8L engine which at £20k from Porsche UK was a tad expensive… so off to fleabay and lo and behold in December a 3.8L became available from a 3,700 mile PDK 991S involved in a front-end crash.
But in December there was still some, but not a lot of hope that the GT4 would have a PDK option. I took a deep breath and after Fearnsport had checked the 3.8L fleabay engine I bought it, thinking that if a PDK GT4 became available, I’d sell the 3.8L engine and any loss would be the option cost of having both the PDK GT4 and 3.8L upgrade choices.
In parallel, a German group led by Jens Ehresmann contacted me via planet9 and we started discussions about having them install the 3.8L engine in my Cayman. Jens had been modifying his PDK 981 Boxster S 3.4L and with intake and exhaust modifications plus custom tune had achieved around 370PS. He had also upgraded the brakes with 996 GT3 parts and fiitted 997 GT3 Cup suspension acquired from race teams that his group supports. Not content with this, Jens then acquired a 991 3.8L Powerkit engine and fitted this to his Boxster - the key to getting 370PS from a 3.4L and 434PS from the 3.8L Powerkit was his ability to custom tune the ECU, particularly for the Powerkit engine’s multi-valved plenum. Ehresmann have recently started providing custom tune ECUs to BGB, modified a 987 Cayman R to give 371PS for a Norwegian customer, and have introduced a tuning package for the GT4.
Early February, GT4 orders opened and I had to turn down the option to buy one as it was indeed manual only. With that alternative closed, I finalised arrangements with Jens’ group. I left my Cayman at Fearnsport late February to join the 3.8L engine and arranged for both to transported to Jens in Dusseldorf whilst we headed off on our Spring break. The conversion would normally take three weeks or less but as we were going to be away for some time and mine was their first Cayman swap, it seemed sensible to give them plenty of slack in the timetable.
I collected the car just in time to join April's Spring PCGB Factory Tour which took in Osnabruck, Leipzig and Stuttgart. This gave me plenty of time to get comfortable with the ‘new’ car and its reliability before leaving Germany. Back in the UK on my journey from Chunnel to Devon, I stopped off at Goodwood for a noise test (at 101db it was OK) and ran it on a dyno, which confirmed Jens' power runs.
The installation is not that "difficult” The picture below shows the 3.4L and 3.8L (or is it 3.8L and 3.4L?) engines together and they have the same overall external dimensions.
There are some differences including siting of the oil filter and some pipe runs but they all fit in the engine bay. In the 981 the gearbox is aft of the engine versus being in front of the engine in the 991 so the 3.8L engine orientation is reversed. The 981 gearbox is retained and mates directly onto the 991 engine. As Jens’ Boxster and BGB’s conversions demonstrate, there is no problem in installing a Powerkit 3.8L in either a Boxster or Cayman.
So what have I got?
3.8L 991S engine with Cargraphics 200 cell headers, IPD plenum + Y tube, and BMC air filter
Custom Tune with 412PS and 419Nm on a Maha dyno
Center radiator
991S 6 piston callipers/340mm disks
K&N anti roll bars and Powerflex Camber/Castor front bushes
Cargraphics 8.5" and 11.0” 20” wheels with Michelin Pilot Super Sport Tyres F245/35 R295/30
The power is greater than 3.8L engines in 991S and GT4 mainly due to the custom tune, better intake, and 200 cell headers/manifolds. The BMC v OEM air filter gave another 7 PS which is symptomatic of how breathless these engines are at top-end with the standard intakes.
It is not intended to be a homebrew GT4 nor a Cayman version of the lightweight 981 Boxster Spyder. I like my comforts (which is why it weighs 1428kg) and is a very much better road car with so much more usable torque. The power does not fall away at the top end and it runs to OEM rev limits with no CELs. I get 34mpg on m/way runs and it will hold 7th gear up inclines. It has very much stronger mid-range accelaration and is much less frenetic on track than in 3.4L guise. Aside from the Cargraphics wheels, the car looks completely standard.
I have not done much yet on the suspension, just stiffer anti-roll bars, extra camber adjustment and wider tyres. The car does need development in this area so I am off to Centre Gravity to have the car ‘audited’ and define and discuss options. I plan on running the car though the autumn as is and will implement over winter whatever best option emerges.
I considered fitting the TechArt aero kit because according to SportAuto, the Cayman S develops front end lift and rear downforce. However TechArt were unable to provide any data on its aero effect and as I did not take off at speed on the autobahn the €5.5k cost did not seem a good investment.
Warranty? - I would be miffed if a door handle fell off and Porsche would not fix it but I have gone well beyond different make windscreen wipers/battery/non N rated tyres.
Insurance? checked this early - it is rated as a Carrera S and all mods have been disclosed - another £75pa.
DVLA? changed V5C to show new engine serial# and capacity.
You have to be brave to do something like this but with research and cross checking to validate claims and experiences, one can manage the risks and it is a car I shall keep for a little while.
]
