987 GT4 Build (The 1st in the world?)

I've had my 987.1 CS for 2 years and honestly, it has been an amazing car , however... it's not like from time to time I didn't want: more power LSD to know the M97 is not going to blow up if I track it harder And so 2 weeks ago I had the engine disassembled in front of me and asked myself, is that what should go back in in this car. Long story short - I ordered a 9A2 engine from a 718 GT4 and a 981 GT4 gearbox instead . Why? I considered all options to make the car more powerful and more reliable: 1. Build this engine - it already has nikasil cylinder sleeves but the extra power (like what, 300whp?) you can get from it is not spectacular for the money, reliability will be still meh on track 2. Get a 3.8 M97 from a 997.1 S - good power but all of the same problems of my engine + bore scoring risk, I gave it a pass 3. Get a 3.8 MA1 engine from a 997.2, 991.1 or 981 GT4 - this one sounds quite good, failures are rare, bolt on in the chassis, could be run on stock ecu, will make 400+ bhp... but what if 4. GT3 engine - amazing, I thought about it, but I just can't spend 40k euro for the engine only... But then I found a good deal for a 9A2 and it actually sounded great: better power than the MA1, probably towards 420whp, that's 991.1 gt3 levels more modern, obviously good oiling (is used in the gt4 clubsport) a bit harder to fit, has to run on a standalone ECU for 2 DFI controllers... but I said screw it, let's get this done Well, I didn't find anybody to have done such a conversion, ever, so I decided to share the story and the progress. So far I've ordered almost everything I need and I'm waiting for a few parts to come. What I don't know yet: will the 718 gt4 flywheel and clutch assembly just bolt on the the 981 gearbox or will need modification will the driveshafts fit with modification or will need 981 gt4 driveshafts and modify to work with the hub will I cut my existing bumper to fit a center radiator or get some aftermarket ( if anyone has recommendations for gt3/gt4 style bumper or any other that will look cool and do the job, will appreciate the help!) probably a lot of other things when we try to mount the drivetrain but still waiting for the flywheel/clutch, the gear selector component for the gearbox and a few sensors If anybody would have some interesting insights for this project, I'm all ears! If not, I plan to entertain you with the obstacles and end result P.s. I'm parting out my whole M97 with the nickasil sleeved block, perfectly good heads and many many parts + selling parts like the 987 gearbox, exhaust manifolds and cats etc. so if you need any of that hit me up!

Wowzers, this sounds pretty incredible! I will be following your journey!

Hello, I have been recently going through the same research you've been doing and decided on a 981 GT4 engine in my 987.1 Cayman S that you can read about here: https://www.planet-9.com/threads/bl...eads/blackknight530i-987-gt4-build-981-gt4-engine-swap-to-987-1-cayman-s.258304 I had already done a DFI conversion on my car to a 3.4L out of a 987.2 Cayman S, so going from the 3.4 DFI to the 3.8 DFI is not nearly as big of a deal as what you're looking to do. The 9A2 runs on a totally different DME that would have required as much rewiring as I did on my MA1 conversion, but since the MA2 never came in the 987 chassis, it would be even more complicated to get things like the PSM and other CAN bus related things to work with it. If you go standalone, you may have to sacrifice some things working in the name of performance. You mentioned a GT4 clubsport, but that is actually the same 3.8 that is used in the 981 GT4, not the 4.0 MA2 engine. I have yet to determine if a 981 manual transmission will fit properly in a 987 chassis as I'm planning on using my 987.2 transmission and hopefully adding a LSD to it. If you find out if the 981 GT4 transmission will fit in the 987 chassis, I'd be interested to know. Regarding the front bumper for a center radiator, you can either do the normal 987 center radiator, which is much smaller than the GT3 or you can do the full GT3 radiator and get a GT3 style bumper from Getty Design ( Cayman Bumpers, Splitters 987/981 – Getty Design LLC ), which is what I was hoping to do. I don't know if the GT4 style bumper will work with the GT3 radiator or not. I think the clutch and flywheel are basically the same between the MA1 and MA2, so I think you would just get the one that matches the transmission you use. Good luck with your build. I'll be watching closely.

Nice to see someone doing another 987 GT4 and awesome insight, thanks! I didn't know the clubsport uses the MA1 and just assumed from the 420ish hp and it being 718 , it's gotta be the 4.0 9A2. As for the standalone and wiring - yep, PSM is not going to work but we're actually going to code a much better traction control with actual settings and modes on the standalone. So far I don't foresee any major sacrifices but will post updates. As for fitting the 981 transmission , I think most likely it would require some modifications. I'm still waiting for some parts of the selector mechanism, that the gearbox came without, to be shipped, but will definitely let you know how we do it! From the initial evaluation of what fits and what doesn't, you can most likely use the current gearbox, but the reason I didn't think twice about ordering the gt4 one is precisely the LSD - it was actually much cheaper to buy the GT4 gearbox and sell my G87.21 than put an LSD into it (still for sale if anybody wants it). Thanks for the suggestion for the bumpers as well - I'm mostly finding options in the US for now and I'm in Europe, so I haven't yet settled on what to do there, but I bought a 997 center radiator, just because I found one super cheap. I ordered a 718 gt4 flywheel and clutch assembly, so once they and the gearbox bit come, it'll be time to figure out the most important part of the build!

Also, the 425 hp 718 GT4 Clubsport engine is crank hp, not wheel hp like you had mentioned above. My understanding is that the 3.8 GT4 engine with a tune is around 410 crank hp, but if you add the power pack cam and heads to it, I think it gets to the 425 hp you mentioned. This is just confirming what they did to get the extra horsepower. In looking at pictures of a 981 and 987.2 transmission back to back, it certainly looks like they are basically the same, other than the transmission heat exchanger. My thought process is that it would make sense to not reinvent the transmission, but to rather modify an existing one, much like they did between the 987.1 and 987.2 versions. The transmissions were basically the same, other than the bellhousings, is my understanding. Here in the US, GT4 transmissions run about $5000-7500 used, so testing that theory is tough to justify. That and the fact that apparently the gearing is not as good as the older 987.2, so 3rd gear on GT4s tends to be a bit weak. You wouldn't have been able to use your G87.21 with the 9A1 or 9A2 engines anyways due to the bellhousing differences.

I have a 987.1 S 6 speed Manual, with a FSI 3.8 (Nickasil, IMS solution, etc, etc), Wavetrac LSD and Cayman R suspension . (Need “RS” badges?) I’d put an ultimate sump if tracking it hard. I think it’s fabulous, but now it’s sounding “pedestrian” Ambitious project!

Or, you could just buy a GT4 . 981 + $15-20k will get you to the stock 718 numbers while giving you the agility of the 981 platform, or you pay the extra for the 718 . Either way, you have a great performing car that will hold its value. Your 987 can be made to run with a GT4 , but it will cost a lot of money and you will never get it back. Ever. Sorry for the buzz kill. I believe in hot roding when it gives you something that isn't commercially available, but when Porsche actually makes what you want, at a comparitively reasonable price that will hold its value, I don't see the point. Have fun.

What price are you seeing 981 GT4s in good condition going for? My build will be nearly net zero for my engine swap once I sell my excellent condition low mileage 3.4 DFI engine, so while mine might be an exception, there are reasons this is a good investment. I don't know what the OP bought his GT4 engine for, but I'm betting he's still well under the cost of a 718 GT4 .

Isn’t the GT4 full dry sump - no oiling issues ever? I assume he is adding all of those parts to his .1.

Interesting - yeah I thought the 9A1 and 9A2 engines had a sort of Semi Dry sump system but need to study on how it works.

I happen to know someone who has stuffed a 2022 GT4 engine into a 2006 Cayman , over the last 18 months. It runs on a Motec M141, but is still a work in progress. If you are looking for an engineering and fabrication challenge and have a budget to support, I'd say go for it. If you are trying to save time or money, this isnt that kind of project. Happy to collaborate, cheers

From a curiosity standpoint, I'd love to see how the dry sump tank fits in that engine bay. What other fabrication was involved? It looks like all the stuff on top of the intake might hit the cover that goes there. Which transmission is he using and what was needed to make it work?

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Ok, did some more digging on the motor mount bracket. The GT4 RS has the same water pump housing as the 981 GT4 , which is the same as all 9A1 engines from 2014 on ( 981 that is). It has the 4 bolt holes where the 987.2 engine mount bolts up. That said, the 718 GT4 has a different water pump housing that only has 3 of the bolt holes the 987.2 motor mount needs. In theory, you could potentially use the GT4 RS/ 981 water pump housing and you'd get the 4th bolt hole again. You could also do what I'm doing and put the 987.2 water pump housing and crossover pipe on and basically just use the stock 987.2 cooling hoses and such. I think you would lose the MAP based thermostat, so not sure how that would work for you, but since you're doing a standalone ECU , it might be fine.

Thanks for all the info, lots of options for me to look at, especially the front engine mount. Interesting that the 718 GT4 has a different water pump than the GT4RS / 981 .

I don't want to answer for politecitizen, but I'm guessing he is simply enjoying the technical challenge. It will be one of a kind. It would be awesome if could get some pointers from Porsche itself. He obviously loves Porsches so much that the money he will never get back is irrelevant. Ever.

Bonjour, J'ai enfin trouvé quelqu'un avec le même projet que moi 😃. Comme tu l'as dit, je suis vraiment étonné que si peu de personnes se sont lancées sur ce type de projet. Quand tu compares le prix d'une mécanique 982 9A2 gt4 qui se trouve actuellement à des prix tout à fait raisonnables étant donné les avantages de celles-ci (autant le moteur que la boîte de vitesse) et une préparation du M97/21 ou M97/01, l'écart est encore, sans parler de la fiabilité. comme tu l'as constaté, le réel défi reste la gestion de l'injection directe et d'autant plus que les injecteurs Piezo ne sont pas supportés par la plupart des fabricants d' ECU . j'ai d'ailleurs quelques questions à ce sujet: ton ECU Motec est-il compatible avec les fonctions de base de la 987.1 (compteurs; pédales; climatisation; etc..) ? gardes tu les injecteurs Piezo ou les remplaces-tu par des solénoïde de 9A1 ? les cardans 987.1 se montent-ils sur la boîte de vitesse 982 ? pour ma part, j'hésite encore entre un 9A1 3.8 de gt4 club sport (à un prix plus que raisonnable, mais sans histoire réelle, donc vu le prix des pièces…) et un gt4 982 9A2 J'ai trouvé un groupe moteur boîte complet y comprenant les supports moteur, l'embrayage et volant et tout la visserie avec seulement 1500km pour un prix très correct. as-tu déjà étudié la possibilité de repasser le moteur en injection indirecte ? Ce faciliterait grandement la mise en marche et le calibrage de l' ECU . Avez-vous déjà trouvé une personne capable de programmer les injections stratifiées de l'injection directe ?

Pour info, je suis aussi en Europe 😉

With English Hello, I've finally found someone with the same project as me 😃. As you said, I'm really surprised that so few people have embarked on this type of project. When you compare the price of a 982 9A2 GT4 engine, which is currently available at quite reasonable prices considering its advantages (both the engine and the gearbox), with a modified M97/21 or M97/01, the difference is still significant, not to mention the reliability. As you've noticed, the real challenge remains managing the direct injection, especially since piezo injectors aren't supported by most ECU manufacturers. I actually have a few questions about this: Is your Motec ECU compatible with the basic functions of the 987.1 (instrument cluster, pedals, air conditioning, etc.)? Are you keeping the piezo injectors or replacing them with 9A1 solenoids? Do the 987.1 driveshafts fit on the 982 gearbox? Personally, I'm still hesitating between a 9A1 3.8 from a GT4 Club Sport (at a very reasonable price, but without a real history, so given the price of parts…) and a GT4 982 9A2. I found a complete engine and gearbox assembly including engine mounts, clutch, flywheel, and all the necessary hardware with only 1500 km for a very good price. Have you already looked into the possibility of converting the engine back to indirect injection? This would greatly simplify starting and calibrating the ECU . Have you ever found someone capable of programming the stratified injection of direct injection? I am in Europe

Hi, To first answer your questions: I talked to the guy who's doing the wiring, code everything and map the car and I asked some of the same questions as you, including how to control the injectors, considering indirect injection etc... He told me to stop reading crap online and get him a Link Voodoo pro and 2 DFI modules after researching the engine. I tend to believe the guy - he's certainly the best in Bulgaria and has been right multiple times in situations like that so that's what I did. the driveshafts "don't fit" but "they should fit" with some basic modification, but the gearbox I got is from a 981 gt4, not the 718 we could theoretically make the instrument cluster work, but I elected to just buy a digital dash - it's going to work easier and be more useful. We should be able to make all things work one way or another, PSM is not going to work but you can code a way better TC on the standalone ECU To sum up - it's still a much bigger challenge than the 3.8 9a1 BUT it doesn't seem that scary as initially. I was waiting on some parts but my car is probably getting assembled soon - like this or next week. I'll make sure to drop an update so you'll know if everything went as planned.

Link ECU have the CANBUS integration for 987 chassis (dash gauges). Even cruise control is available. I wasn't aware they could support DI

J'ai également discuté avec le support technique de Link, et cela semble effectivement être une bonne solution. Le protocole CAN 987.1 ne pose pas de problème. Il reste à confirmer le fonctionnement des injecteurs piézoélectriques, mais à première vue, il devrait être possible de les remplacer par des versions à solénoïde s'ils causent un problème avec le calculateur. Le calibrage de la cartographie d'injection s'avère également complexe, notamment dans les plages d'injection stratifiée à couple maximal. Cette plage est assez large en raison des variations du double arbre à cames et du collecteur d'admission variable. Le réglage à pleine charge et à puissance maximale devrait être plus simple, car le rapport air/carburant devrait se situer aux alentours de 12,8:1. Le risque est de devoir passer plusieurs jours au banc d'essai pour tout calibrer correctement. Idéalement, nous pourrions charger la cartographie d'origine de la GT4 dans le calculateur Link comme point de départ. Comment comptez-vous calibrer l' ECU Link ? Avez-vous rencontré d'autres problèmes lors du montage (tuyaux d'eau ; commande de boîte de vitesses ; câble de frein à main ; etc.) ? Concernant la pompe de direction assistée, il devrait être possible d'en installer une provenant d'une 987.2 , mais il serait finalement plus simple de passer à une pompe électrique, qui est assez facile à trouver. Avez-vous des photos ?😉

I should start taking more photos! So far not too many difficulties, but the engine still isn't in the car so let's see. Another guy is doing the electrical as mentioned, so will see what he plans to do with the Link ECU The gearbox is manual so pretty trivial, but honestly, PDK shouldn't be that much of a pain to control as well. Waterpipes we're yet to see and exhaust will probably need to be custom.

Just a heads-up, all the sensors on the 9A2 are digital/SENT sensors. The motec im using was setup to read the HPFP SENT sensors but not anything else, so I replaced the LPFP, MAP, and oil pressure SENT sensors with analog sensors. Im still trying to figure out a solution for the oil level/quantity digital sensor

@politecitizen Have you made any progress on your 3.8 swap? I've pulled my 3.4 DFI and started swapping parts over to my 3.8 and it should be going in next week most likely.

The 4.0 is in, together with the gearbox, and all of the cooling hoses etc are done. I'm having the exhaust finsihed as we speak (needed to get custom exhaust ) together with a small modification of the rear cross member. This week, we should be able to start with a basic map and try to start to car. What's left mechanically is pretty much the intake - I 3D printed window scoops to feed the air like in the gt4 rs and will need to design a custom airbox + some cutting and modifying the engine. Also it still doesn't have power steering and AC but those we left for when the car is running.

Hi, It's great to hear your project is coming along 👍🏻 You're sticking with the stock Piezo injectors from the 9A2, right? Can the Motec handle those injectors and the stock 987.1 CAN bus for the ABS, throttle, and everything else?

Yes, it's not done yet, but that's the plan. The car will have the exhaust ready tomorrow or the day after, so that's pretty much the next step. Will update when we get it running.

Have you installed a buffer tank with a second fuel pump to handle low fuel pressure? Is the exhaust pipe 60 mm? As I mentioned earlier, I also looked into this possibility of swapping, but I never really managed to get confirmation on the compatibility of ECU suppliers (Link; Sivecs; etc.) between the 987.1 and the 9A2 GT4 . So I went back to optimizing the MD97/21, but the more I look at it, the more I realize that the cost to achieve 400 hp with a decent level of reliability is really out of the question.

Just curious, how is the build going?