I purchased this 944 Turbo because I loved the looks, price, and performance. It didn't hurt that I've always loved Porsches anyway. But, I also bought the 951 because it was already turbocharged, making it much easier to get substantial horsepower gains from bolt-on upgrades.

Rather than take small steps to gain power with a more efficient intake and reprogrammed software, I decided to start from a higher performance plateau and swap out the turbocharger for a larger unit. I know...I wrote in Part 1 (ec, 11/03) that the goal was 300 whp, which is not too hard to accomplish with the stock turbo. However, anyone who knows me, and those who followed along on my Project BMW M3, realizes I'm power crazy. Actually, I wanted to get past that 300 mark with a slightly larger turbo, not so much for raw power but so intake temps are kept under better control and turbo efficiency remains at a maximum. Enter Kokeln Racing Products.

Kokeln's Stage 5 turbo upgrade is comprised of several components, including an intake, dual-port wastegate, new intercooler piping, bigger injectors, a fuel-pressure regulator, Kokeln custom-programmed chips and, of course, the Stage 5 turbocharger. The new blower has a much larger compressor and exhaust side, which, according to Kokeln, and in testing has shown over 400 whp. A question to be answered is whether this setup allows more "lag" compared to the stock unit. Kokeln stated it had tested 10 stages of turbos during development, and the data shows this system is best.

"Stage 5 worked best in a high-performance, stock environment. By stock environment, I mean stock manifolds and size and location of the intercooler," said Kokeln founder Dwain Dement.

Kokeln also offers a couple of options with the Stage 5 system. For quicker spool-up, there's a ball-bearing turbo, and a Link Engine Management system overrides the ECU and completely controls fuel mapping for a truly custom setup. Required for this system to work are a different air intake boot to the turbo, new air-temp sensor and a different location for the air cleaner. For Project 951, I didn't go with the ball-bearing option, but I did end up with the Link system, and I was extremely excited about having it dialed in.

The Link system is being sold exclusively as a turn-key product for 944 Turbo owners. Currently, Kokeln sells the Link with a base map for stock as well as the big Stage 5 turbo upgrade, but the company plans to rewrite the Link instructions to make them easier to follow.

The engine management system will also allow the end user to load up the base maps and from there custom tune the car as desired, be it for more power, a race gas setup or even for better gas mileage. Even if you completely screw up the programming and accidentally save it, there's a default option that will take you back to the base 944 maps originally programmed by Kokeln. If you desire to tune your own car, the best way to do it is on the dyno.

Installation
On a 944 Turbo engine, the turbocharger sits right under the intake system, on the opposite side of the engine from the exhaust manifold. I looked at it and thought to myself, "Well that's a different place to put a turbo, but it also seems pretty easy to get to--all you probably have to do is take out the intake manifold, which will grant you access to the turbo unit for easy removal!" Boy, was I wrong, and thank goodness I had Kokeln do the installation.

Kokeln technician Joe Davis got to work on the car and cranked it out. To my surprise, the Stage 5 upgrade eliminates the factory water cooling for the turbo. In order to keep the car street legal, though, the intake system must use the same connection points for vacuum lines and breather hoses as in stock trim.

When Joe handed me the intake manifold, I couldn't believe my eyes: "What's all of this dried-up oil in there?" Joe assured me it was normal; these cars suck in lots of oil. He also said the amount of oil my car seemed to be sucking up was well below average. "You wouldn't believe some of the cars we get in here," Joe replied. "When I pull the intake off, oil just oozes out of it!"

Although having a calming effect, Joe's assurances still didn't prevent me from racing over to the nearest automotive shop and buying a few cans of parts cleaner and making sure that sucker was clean. In the future I'll be modifying the breather hoses so that no more oil makes its way into the intake plenum and, eventually, into the combustion chamber. Oil knocks off several octane points in the combustion chamber, and with our 91 pump swill as the next best thing to race gas in California, I don't need that in my life right now.

Finally, what seemed to be a simple installation is actually about a 10- to 12-hour install for a competent mechanic. Getting to the turbo involves getting a lot of stuff out of the way and loosening the entire exhaust system, including the headers. It looks as if Porsche was stating, "You shall not mess with it" by making everything an exact fit.

Testing
Prior to the install, Kokeln took the car to Vision Motorsports to get a baseline test on its Dynojet 248C. To get a valid baseline, Joe swapped in stock chips--and the car still ripped off a 198-whp run, the other graph line showing 221 lb-ft of twist. It was an impressive result for a 17-year-old engine originally rated at 217 hp at the crank. Air/fuel was relatively flat, at about 12.2:1. Keep in mind this was measured after the cats, so the actual air/fuel ratio should theoretically be richer in the combustion chamber.

When the car returned with its new turbo system, Dwain jumped on board to fine tune the Link system, and then it was time to check the gains from the new, larger turbo unit. Due to the greater energy required to spin the bigger turbine wheel, some low-end torque was sacrificed, in this case a 43.3 lb-ft loss at 3400 rpm. At both boost levels, the stock turbo spooled faster, making more torque until 3950 rpm, but I don't expect I'll ever lug the engine that low when it matters, and the top-end power will more than compensate. This sacrifice was expected. A freer-flowing exhaust should also help.

Once the turbo was working, the difference was nothing short of amazing. At the stock 10 psi level, the car went up to 236 whp, with horsepower gains seen from 4000 rpm on. Air/fuel at 10 psi was good and relatively flat, registering from the mid 12s to 13.1:1, eventually coming down to a safe 12.0:1 by 6000 rpm and 11.0:1 by 6300 rpm. We tried going richer at the 5000- to 5500-rpm levels, but the car displayed the smoothest graphs at about 13.1 to 13.3:1 air-fuel ratio--again, reading after the cats.

Dwain then tried a pull at 13 psi (0.9 bar), and the car violently spun the rollers to register 270 whp--still with the stock exhaust system! This was also after a couple of hours of tuning, during which time the car was never shut down for a cool-down period. As a result, I expect even sightly bigger gains than the ones registered. Still, Dwain wasn't concerned about getting those last few ponies to make his turbo upgrade look better to the potential buyer--he just wanted to make sure the car was dialed in properly.

At 13 psi, the air/fuel ratio was the same as it was at 10 psi--just one of the neat things about tuning with the Link system. You can tune for a certain air/fuel ratio for a measured load (i.e., boost) and essentially maintain the same air/fuel ratio for any boost level if you wish the ECU to do so. Or, you can program the car to run leaner when running low boost and richer when the boost is increased to cool things down.

Dwain decided to end the testing session at that point, because the pipes in front of the cats simply were getting too hot. It was obvious that Kokeln's Stage5 turbo upgrade can easily make over 300 whp with the stock exhaust system. Even so, I'm excited about installing a freer-flowing exhaust system to reduce backpressure and allow the turbo to really breathe. We will probably be able to get much more accurate air/fuel ratio readings this way as well. Stay tuned.

Special thanks to Travis Ishida of Kokeln for his help getting Project 951 off to a great start.

Kokeln
Kokeln Racing Products was started in 1992 from the development of a 930 Turbo intercooler. At the time, founder Dwain Dement was working at Exclusive Motorsports, where he reportedly had a flexible schedule, allowing him to research and develop certain products.

In the years following, Dwain left Exclusive and continued his entrepreneurial journey by starting Vision Motorsports, a race shop that's built some of the most successful Porsche race cars the West Coast has ever seen. Currently, Vision does all the testing for Kokeln Racing products and is also one of Kokeln's distributors.

Once he got Vision to where he wanted, Dwain got help from racing partner Tak Ishida, whose business expertise, paired with Dwain's engineering and mechanical skills, helped take Kokeln to where it is today. The business eventually expanded to its current 12,000-sq-ft facility in Laguna Hills, Calif.

Kokeln Racing Products was never about copying other product manufacturers' ideas. Said Dwain, "If we feel we can't improve on a product that is already out there, we won't make one--we're not into copying what's already out there." Similarly, if Kokeln feels a product from some other company is good enough to use, the company doesn't have any reservations about buying it and using the part on its cars. "But if Kokeln feels a product can be made better, then we'll make it," Dwain continued. "And if after testing our product does prove to be better, then we'll sell it!"

Kokeln is dedicating its R&D right now to the Boxster, including wings, body parts, A-arms, exhausts and headers. When asked if Kokeln was still developing parts for the 944, Dwain had one thing to say: "We're done with 944s!"

Look for Kokeln products on Team Vision's Porsche 996 race car at the 24 Hours of Daytona in early 2004.

At a Glance
Installers: Vision Motorsport
Estimated Time: 16 hours
Upgraded Parts: $3,500 (turbo system) $500 (Link eng mgmt)
Labor: $100/hr
Total: $5,600
SOURCE
Kokeln Racing Products
22681 Granite WY
Laguna Hills
CA  92653
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