Try RR Racing's supercharger kit. They have a number of posts on here.

 

I would agree with the others, who suggest contacting Rick DeMan. For the 3.8 L GTS, he can make the 430 hp engine a 4.5 L, 550 hp engine. I know yours is the 3.4 L engine, but I recall reading in other threads that he can modify that engine as well. What hp that conversion would produce, I do not know, but it may be worth an email to him. All-in, including shipment of the car to and from NJ, is about $60,000.

Minor point, but if you do get a GT3 engine, you would also have to change the tachometer, as the redline in your "GT3 in a cabriolet" would be higher than the stock 3.4 L engine's redline.

 

Because you're talking about effectively inventing a swap/conversion that's never been done before. You're not only attempting to install an engine in a model it wasn't design to go in, you're trying to swap it into a body style it was never intended to be installed in. Who knows what kind of unique issues that alone will create. Anyone who's ever embarked on such a crusade understands that these kind of projects, by their very nature, always require significantly more time, effort, and money than you think they will.

There's inevitably a gigantic gap between what it should entail conceptually, and what it will actually entail when you go to execute. This isn't going to be anywhere near as simple as "drop one engine, install the other." You're going to need an engine and a transmission, since the PDK in your base car is entirely different than the PDK that mates to the engine you're trying to install. You'll also need an exhaust, a rear bumper, an instrument cluster, an ECU, a body harness, and god knows what other drivetrain components. You'll also probably have to make a boat load of coding changes to the car to get everything to play nicely. And this is all assuming you don't need to do any fabrication work to get this to work, and I think it's safe to assume there will be a healthy dose of that. This will most likely be a totally open-ended process, because you won't truly know what parts and components you'll need to replace, or what kind of fabrication you'll need to do, until you try and make all this happen.

 

It has been done (sort of).

A company commissioned by Porsche has produced a 991 4S Cabriolet (so a wide body) with a GT3 RS engine. Project was fully supported by PAG.

As far as I know it was ‘1 of 1’ car for someone in the family. A couple years ago it was for sale on German website. I believe the price was somewhere around 500k euros.

 

Because the GT3’s dme is going to see the difference in the cars modules and throw codes. Also you may have issues with the transmission. They are different as well. The reason why i say get the harness because it’s the equivalent of replacing the whole body’s nervous system along with the brain and heart all at one time. But one issues you’ll run in to is the fact you have a convertible so the wiring loom would probably need be extended and modified. This would not be cheap in any way. You’d have to really diy this to come out with any savings. I could see in the future people swapping GT engines in base cars. To people calling .1 GT3 engine junk don’t know what they are talking about i know after the 10 year warranty is up there will be a fix for this engines on the aftermarket. Just like ims was solved for the 996.

 

Doing it to save a bit of money is ironic, because for something like this you would probably need a full GT3 and Carrera just to take it apart and see what fits and what doesn't.This is not even mentioning labor, which probably would cost more than both of those cars.

Just to give an idea, I think there was someone on this forum who swapped front bumper on their GTS to GT3, with cooling from the latter, whole project came at around $20k to do properly.

Anyways, fun idea, but for someone very rich and brave.

 

Definitely one of those "If you have to ask, you don't have what it takes" projects.

BTDT...

 

Good example, I forgot about that. I know 4.Point.0 did that. The GT3 begins from the same shell as a GTS so should be easy peasy right? Apparently not so much. And that's just for a dang bumper, much less and engine and trans. This project would be super neat to see but will require many multiples of the cash outlay OP seems to expect.

OP: I don't know how much experience you have with engine swaps, but they're not easy. More modern cars like to throw codes even having a replacement engine from the same exact model sometimes. Back in the day I swapped my 1995 E36 M3 race car engine from M50 to M52 (same generation M3, very slightly changed engine) and even though that car was ancient with no driver aids and far fewer electronics, getting the engine and trans in place were the easy part. The electronics were not happy, and it took weeks of troubleshooting to work. YMMV, but this project will be a major challenge unless you're the type who can drop it off at a BGB/Deman/etc. and say have fun and let me know what I owe.

 

Some of the people who have done the bumper swap are also driving around with CEL because the sensors for the GT3 bumper didn’t play nicely with the Carrera computer. These cars are not Lego kits. Things often don’t just swap out easily without having to dig into the computer programming. I can’t even imagine how difficult it would be to get that engine and all its sensors, wiring harnesses, transmission and all its sensors/wiring, etc. to play nice. But yea, “it’s just one engine swap, Michael, how much could it cost? Ten dollars?”

 

I’m fairly adventurous, and I don’t mind spending some solid coin on my car.

I looked into dropping a GT2-RS motor into my car, and it took about 5 minutes to realise it was a bad idea.

I don’t have a cel with my GT3 bumper, but I recall my race mechanic saying he had to convert the wiring from a 9 pin to something else, or from something else to a 9 pin. Anyway, even the Air Con lines had to be replaced.
There is an Aero box to vent air to the top vent instead of under the car. Whilst the 11 pins were there to seat the box onto the chassis which is identical in GTS/GT3, the hard air con lines run straight across and block the box. So they needed to be removed, box installed, then I had to buy GT3 moulded air con lines that shape around the aero box.
There was a lot more stuff underneath as well. I wanted the full Aero effect, not just looks.

I put a full OS Giken mechanical diff in as well. That was quite a task.

Changing the motor, I believe GT3 is a true dry sump, and non GT’s are semi dry? Cooling would be an issue, oil lines. PDK TCU are matched to ECU. So you’d need at very least a TCU and thats IF the PDK’s are identical and only TCU different. So you’d need Gt3 ECU and TCU.

Then the nightmare of traction control. GT3 are split system, very different from Carrera. Then there would be ABS issues as that works with Traction control.

This is not a simple motor swap at all. This is a full rebuild.

But hey, have at it, I’ll follow with interest. 🍿

I just ordered a full Brembo GT-R BBK. To replaced the GTS BBK I melted.

 

It might be easier to just buy a GT3 and turn it into a convertible.

 

So funny. I was going to say that in my post from last week, but I decided not to for fear that he might actually go mutilate a GT3.