Engineering A 991 GT2 RS To 225mph & Beyond

Porsche is regarded as one of the highest heights of engineering excellence, and rightly so. But why are there so many tuning options for them?

Simply put, car people are greedy. We’re always looking for more. More performance, more power, more torque for more of the time. No one knows this better than CSF Radiators.


CSF has one of the most comprehensive ranges of cooling products for Porsche anywhere in the world. They support some of the very best aftermarket tuners on the planet and provide efficient cooling solutions to facilitate tuning goals. Just one of these happens to be a familiar name on Speedhunters: BBi Autosport.


Betim Berisha and the team have been busy over the last few years with projects like the GT3 ‘TurboCup’ (built in under 30 days), taking class records at the Pikes Peak International Hill Climb, and utilising 3D printing technology to create all manner of high-tech components for use in Porsche tuning. Their recent goal? To make a 991 GT2 RS top 225mph (362km/h). And they’ve succeeded hitting a wild 226.95mph (365.24km/h).

It’s no mean feat and requires a brave driver who’s happy to stay pinned at wide open throttle in search of every last mile per hour. It also necessitates a car up to the task.


In standard form, the 211mph (339km/h) capable GT2 RS uses a pretty 1990s-esque intercooler water spray technique to keep charge temps at bay. It’s a system that reminds us of spicy Subaru Imprezas with the ‘I/C Spray’ toggle button on the dash.

Don’t get me wrong, it’s a much more sophisticated system than that and utilises two water spray injectors in each side, mounted into carbon fibre ducts to mist the intercooler cores when they become overwhelmed. But the principal is the same.


It’s designed as a momentary fix in order to curb the increased charge temperature during sustained acceleration. Which is exactly what you’ll be doing at the track or attempting Vmax. It’s certainly not something you want to rely upon at Vmax attempts, especially when you consider that, once the water runs out, that is it. The car then runs in an ECU-controlled ‘reduced power’ mode in order to protect the components.

Climbing charge temperatures mean ever lower air density, lowered knock resistance, and ultimately higher risk of engine problems. Due to space constraints and the production viability of materials, it seems Porsche has decided that the measures of a water spray as first line defence, then an ECU power limitation ‘safety net’, was suitable for most 991 GT2 RS drivers.

The team wanted to explore what was truly possible here. Although products exist to enlarge the water tank and provide a longer period of water spray, they looked at the design of the system, and then got to work on a more effective solution to manage air intake temps of Porsche’s flagship 911. After all, people were going to want more.

Taking inspiration from the Porsche 918, for which PWR are the OEM core supplier, they began to pick up the reigns where Porsche left off.


BBi’s ‘Project VMAX’ was in the early stages and made for the perfect testbed. Cue sleepless nights in front of design boards and back and forth telephone tennis between two of the cooling world’s giants.

These GT2 RS intercoolers mark the first of many joint ventures between CSF Radiators and PWR.


PWR ordinarily provides cooling solutions to leading race teams in disciplines like F1, NASCAR, V8 Supercars, DTM and the WRC. The coupling of this motorsport technology, CSF’s tier 1 OEM supplier background and reputation for finitely accurate fitment has resulted in the first true upgrade in cooling for the 991 GT2 RS.


To understand why it works, let’s get to grips with the original system.

When the intake air temperature reaches 122°F and the driver applies more than 90% throttle above 3,000rpm, the water spray system engages. The water spray is capable of reducing the temperature of the air inside by up to 68°F. That’s a lot, but the water only lasts for as long as the tank is full, after which if no air temp reduction is seen under these circumstances the car will reduce power.


It was identified that a sustainable alternative to simply lengthening the amount of time water could be sprayed at the OE intercooler, by way of a larger tank, was to stop the air temperature reaching the temperature trigger point in the first place. It’s a more permanent solution and the only way to achieve it is with a more efficient intercooler. As you can imagine, on the greatest 911 Porsche currently makes this is easier said than done.

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Ravi’s first to highlight that the stock GT2 RS cooling system is equipped with very well specified cores. Next to the majority of OEM intercoolers they are high efficiency, as you would expect. This, however, does not mean they cannot be improved.

In the same packaging constraints, CSF and PWR have utilised an even more efficient PWR core, similar to those used in F1. The biggest difference is that CSF uses rounded tubes in the core technology, versus Porsche’s square tubes. This allows the air to hug the walls of the tubes much closer and increases the heat dissipated to the walls. Additional, manually-inserted internal turbulator fins further this effect.

This results in greater performance without taking up any more space; the CSF intercoolers fit into the OEM GT2 RS carbon fibre intercooler shrouds just like the originals. Something that is different from the originals is the billet, TIG-welded end tanks. These have a big durability improvement over the stock crimped design.


CSF’s improved intercooler design has become the hook around which BBi has been able to hang the rest of the upgrades. Simply put, without the coolers all the other tuning would be in vain; the power limitation threshold would always be met, ever-increasingly quicker as power levels advance.

In the quest for the ultimate top speed BBi has added larger BorgWarner turbochargers, their own printed titanium exhaust system, and gelled it together with a COBB Tuning ECU calibration. It’s fast and sounds pretty good too, check it out above.

If you’re thinking of creating your own 225+mph GT2 RS, here’s the shopping list you’ll need to tick off with BBi:

BBi VMAX Package

BBi Titanium Exhaust System with 3D Printed Elements
BBi Upgraded Turbochargers
CSF by PWR Intercoolers
IPD Plenum & Y-Pipe
BBi Spec Methanol System
BBi Upgraded Water Spray Tank
BBi Custom Cobb Tuning Calibration

BBi StreetCup Suspension

Manthey Racing KW Coilovers
BBi Drop Links
BBi Thrust Arms
BBi Bump Steer
BBi Corner Balance & Alignment

Wheels & Tires

Michelin Pilot Sport Cup 2 Tires with Track Connect
Forgeline GE1 Wheels, 20×9.5-inch (front) & 21×12.5-inch (rear)

BBi StreetCup Safety Package

BBi StreetCup Roll Bar
Porsche Motorsport Interior Trim
Recaro Profi XL Seats
BBi Seat Base Kits
Schroth Racing Harnesses
BBi Spec Fire Suppression System

I don’t know about you, but this is the type of high-end engineering that I can get on board with. Sure, they are products created for the few; I’m (very) unlikely to own a 991 GT2 RS any time soon and I’m less likely to be able to tune it. But the fact remains that it’s interesting to see how cars like this still leave room for improvement. BBi’s Project VMAX is certainly focussed on the task at hand.

Ryan Stewart
Instagram: 7.nth

This story was brought to you in association with CSF Radiators, an official Speedhunters Supplier



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Jeez this GT2 RS is looking to set world lap records!


The tech insight into this is really interesting. Personally I really miss reading about new product stories when they go into technical details. Dino’s HKS RB motor story a few weeks back was great to read about. Now if only I had some spare change for a GT2 RS!

Jay Soh Tsu Chung

Now this is a good read. I have always wondered how Porsche manages the radiator temps on this model, given its power output and the fact that the rear-engine layout isn't exactly generous on packaging space.


Since the advent of water-cooling in Porsche's the radiator packs have been situated at the front, also helping weight distribution since the bulk of the water mass is contained there too. It's a longer path to the radiators compared to conventional setups, but nothing about Porsche is really conventional.

Jay Soh Tsu Chung

That's interesting to know! But I still do wonder about their intercoolers, and now we know.


Imagine not just owning a GT2 RS, but then also thinking 'this needs more power'. Fantastic.

I think I'm finally coming around to them, especially in all black.


all black kind of turns the look of every Porsche GT car from track to menacing


All cars should be black IMO


I think I like it more so because it hides the contrasting carbon fibre, always thought it was a bit too try hard for a Porsche. Looks awesome when it's more subtle.


I think there are some few more colors, where the carbon fibre fits or at least doesn´t hurt, but
yeah generally the the visible CF doesn´t appeal easily.

On the other hand, i think you are the first one, who uses ´more subtle´ on a GT2RS :)


When you do temp conversion, you have to be careful because 20C=68F, but a reduction of 20C= a reduction of 36F. Sorry to nitpick, but I saw this before and it bothered me. Carry on.


Well spotted! This is the sort of imperial/metric US/UK mix up that lost NASA 125million on the Mars Orbiter project.


pardon me for saying it, but I'm pretty skeptical of the claim about the round tubes and cooling. sounds like marketing babble to me. not saying this cooler is or isn't better, but i don't find their explanation very compelling.


Air does not like to turn corners especially at high velocity, there's some more information on CSF's product page about the core technology. It's similar in principal to CSF's 'B-tube' water core tech.


The intercooler cores are WAY more detailed than this article leads on. I'm the outside sales rep for C&R (owned by PWR) and I sold several of these intercooler sets to BBI before the deal between CSF and PWR occurred. The tubes use hand-stuffed turbulators, which is one reason they are so efficient. The difference in the shape of the tube isn't as important and the quantity of tubes. We are able to achieve that by using both a shorter tube and shorter fin height. This results in much higher quantity of tubes.

When BBI did half-mile testing in Palm Springs last July, they saw IATs no higher than 125F when outside temps were around 111F ambient.


is it the ratio of surface area to volume that makes more tubes desirable?


More surface is good but you need contact as well. In a straight tube with so called laminar or smooth flow the air wants to flow towards the center and tends towards zero at the wall. So you need to induce turbulence and air flow evenly across as much surface as you can without causing any extra resistance or loss of power. So you are doing the same kind of work controlling air flow as you would with an airplane, well sort of. Look up Reynolds number its a good place to start. Also for fun what happens if you have an infinitely large intercooler?


Is this the BBi GT2 RS that ran at last year's Sun Valley Tour de Force? It was pretty cool seeing that one in person. Interesting to read more about just a few of the upgrades they did to the car.


Interesting history of CSF Racing


I dont think over 200mph, but I can start. So 60 heart beats per minute, 1heart beat per second, at 226.95mph, x 5280ft = 1,198,296ftph/60=19,971.6ftpmin/60=332.86ft per heart beat. I think its time to review the aero set up, and the brakes. So playing catch the Porsche on track days just got a bit more interesting. PS. If you like air flow or fluid dynamics remember we dont actually know where the air particles are and throw the term chaos in the waste bin. I must now return to normal space and go out to my temporary work space and finish adjusting some valve clearances. Oh how much air do we displace in 1 second no must stop procrastinating.


If your heart beats only once per second when you are going 226.95 mph you are cold as ice.


Long straights are calm out of traffic, max rpm's maybe a bit extra, smiles, well under 200 for me but its a goal. Going for max g's in turn after an all out straight, I have to remind myself breathing is not optional, and I usually have to grumble at my set up for the next corner. So yes fastest is one step back hooking all the corners perfect. But holding g's or carving a corner just so even if its off line is my jam and crackers with a spot of tea with sunny Lamborghini bees. I think I just spun out, sorry Im posting anyway


Just LS swap it, throw a couple turbos on it and run it on alcohol. It will probably go 245mph. LOL