Unleashing the Beast
My Deman 4.5L Upgrade for the Porsche 991.1 GTS
The Starting Point
I have a 2016 Porsche 911 GTS Cabriolet. It's my first 911 and my first Porsche sports car that I've owned. For the geeks out there, it is a 991.1, the last and most powerful naturally aspirated 911 Carrera ever made with 430hp from the factory. However, I found the car underpowered, especially given that the engine sits on top of the rear wheels. My first 10k miles were enjoyable, and I love the rear engine handling dynamics, so much more engaging than a perfectly balanced mid-engine car.
This was also my first cabriolet, and it suits Austin so well. It's usable 11 months a year! As I write this, it is 90 degrees in March.
The Search for More Power
After a season, the lack of torque was really starting to bug me. When exiting a corner, I want to need some level of skill putting down the power. The new 992.2 GTS seemed like the answer, it has an electric motor to fill in the torque gap that the turbocharged motors are cursed with. Also, it can spin the turbocharger up faster. It probably is a wonderful car, but unfortunately, a bunch of people agree! The result was that Porsche of Austin wanted $30k on top of the $220k MSRP for a 911 Carrera. That's $250k for a non-special 911.
However, once I learned that a mad scientist named Rick Deman is modifying these engines to 4.5L, mainly for Boxsters and Caymans, I thought this could be the way to go.1 I tried a friend's newer turbo-powered 911 GTS, and it just isn't for me. I want to be on the edge of grip as soon as I am on the gas at corner exit, and the turbo delay, while interesting, isn't optimal.
The Modification Process
So I flew up to see Rick and his shop before I sent my 911 up to some random shop in Nyack, NY.
The process took about two months, dealing with shipping the car there and shipping it back.
When Rick's shop dropped the engine, they found that an intake manifold part was broken, and it took some time to locate another. Apparently, this is a common problem on these 2015/2016 Carrera GTS models. The intake valve is plastic and just doesn't last forever.
When I got the car back, there were some scratches on the paint, but with two different drivers and Rick holding the car, it's just part of the price of having something like this done. No way to hold anyone accountable. My guess is on the last transporter, he was throwing dirty "protectors" overtop the cars. 🤷
Looking at the mileage, Rick's shop did 137 miles of testing. From what I understand they probably did those miles and then did an oil change before sending it to me. That left the car in a great state where all that was left was for me to do 1000 miles of break-in.
The Break-In Period
Break-in was what it is - 1000 miles of not breaking 5,500 RPMs. The car felt like it had more torque down low, but I couldn't quite be sure because I couldn't really get on it and stay below 5.5k RPMs. So I had a 1,000 miles of not knowing if I’d wasted money or not.
In the break-in time, both my wife and daughter agree that if anything, the car is quieter now. My wife went so far as to say some harmonics she didn't like are now gone. I wasn't expecting that, but it is a welcome change. With all comfort options on, the car is even better in appliance mode.
What Did Rick Actually Do?
From what I understand, Rick bores the engine out and installs a stroker crankshaft. These two modifications result in the extra displacement. While I have no dyno graphs, the car should have about 150hp more now and 100-lbft more of torque, bringing it up from the original 430hp to around 580hp.
The Results - Was It Worth It?
What does it feel like after break-in, oil change and full beans? It feels awesome. Whereas the stock engine doesn't really do anything below 5k RPMs, the engine now starts pulling hard at 3k RPMs, which is really where the increased enjoyment comes from.
The biggest drawback is now the engine is powerful enough to completely overwhelm the traction control. If you floor the car with traction control on and your level of grip isn't really high, the PDK will just give up and start short-shifting after the tires spin too much. 😂 It's really quite something. You have to turn traction control off to do a 0-60 run from a stoplight now. It's wild.
After 500 miles of driving with the broken-in engine, I do love it! I'd say it is a wonderful cross between an old school AMG 6.2L and a 458's 4.5L V8. If Ferrari didn't already have a car called a 456, I'd get a 456 license plate for my 4.5L flat-six.
The Value Proposition
If you enjoy being on the edge of grip on corner exit, you should consider this setup. These 991.1 GTS cars are now trading around $90k, and you can get Rick's magic for under $50k depending on your shipping costs. At $140k all-in, I really can't think of anything that ticks all the boxes I want:
Convertible? Check.
Backseat for kids? Check.
Cheap enough to drive in a state with $30k minimum insurance? Check.
Can powerslide if you want? Check.
That's $120k cheaper than buying a new 992.2 GTS, checks almost all the boxes, and has that naturally aspirated sound!
Now when I drive my favorite roads and get on the power, I get wonderful rotation sensations. The front gets light, the rear rotates and you put in a mild counter steer, just like a 991 cup car on iRacing. It really feels the same, like I've been doing it all my life.
What's Missing?
9k RPMs. That's what. Unfortunately, you can't have it all. Porsche, please give us 9k RPMs, convertible, and backseats!
I went down the YouTube rabbit hole. Here is the playlist I compiled.