746 WHP @ 45 PSIBig Al Friedman's flame-embellished Evo VIII was last updated in the September, 2005 issue. At that time, Al had just become the first Evo VIII to run 9 seconds on all turbo. He was running the GT35R turbo which has become the most common turbo upgrade on high-power Evos in the U.S. due to its excellent power-making potential and decent street driveability. Big Al's Evo VIII has made more power and gone faster with a GT35R than any other Evo VIII in the world-667 whp without nitrous yielded a 9.98 in the quarter mile and a record 144 mph trap speed. The previous update explained all the details of how Al pushed the GT35R in to 9's and got all the power down to the ground.
The combination has proven to be very effective at the track this year. Al has tallied four wins and two runner-up finishes out of seven races he's entered. Al says Exedy Racing Clutches deserves a lot of credit for the success during this year's racing season for its continued support and sponsorship of what has now become the Exedy Evo VIII.
New Modifications"At one point, going 11 seconds was my goal," says Al "Having gone 10s and now 9s it's like an illness. You can never have too much power. Tuners can never have enough power and always are looking to find more. Of course, I wanted more power and I was very shortly going to come into conflict with the law of diminishing returns. The first 50 whp is fairly easy and straightforward, the last 50 whp materialized into something very difficult and expensive.
"We were up against the very edge of how much power we could make from the GT35R. I made this assessment based upon examination of the datalog files, which revealed we had reached, and pushed right up against, the comfortable limit of detonation activity. Further, the data showed way too much backpressure in the turbo housing and manifold to support the kind of power we wanted. The boost was turned up all the way and it would not go any further. The GT35R was maxed out, it was time to move beyond the familiar and comfortable. Simply put, we had gone well beyond the turbo's volumetric efficiency."
GT40R"It was David Buschur of Buschur Racing who gave me the suggestion to try the GT40R, a hard-to-find turbo from Garrett. The GT40R, which we obtained had a divided turbine housing which afforded us the opportunity to run a true twin-scroll setup. On a four-cylinder engine one exhaust pulse is created every 180 degrees of crankcase rotation. Keeping each pulse properly timed as it reaches the turbine wheel helps speed spool up and makes slightly more top-end power. This technology is employed on the stock Evo VIII engine in the form of a totally divided exhaust manifold and twin wastegate flappers.
"No one has released a turbo upgrade kit using the GT40R so I asked my good friends at Pruven Performance in Milford, Conn., to fabricate an exhaust manifold which employs twin scroll technology, totally divided exhaust flow into the divided turbo housing and twin TiAL 44mm external wastegates. The manifold itself is made with special 8-gauge stainless tubing supplied by Buschur Racing, which has proven to be totally indestructible.
"Theoretically, the GT40R is capable of 70 to 80 more horsepower than the GT35R. Realizing that theoretical gain would prove to be very costly and time consuming. As soon as we fired up the car on the dyno with the new turbo we realized that we were going to run out of fuel. The 1,000cc injectors immediately hit 100 percent-plus duty cycle. So a four pack of 1,600cc injectors from Marren Motorsports were sourced. But it was soon discovered that an injector driver box was needed to work in collaboration with the AEM EMS system in order to properly control the larger, low-impedance injectors.
"Also, we were able to secure a pre-production AEM CDI ignition, which is an updated version of the original CDI, which has experienced some reliability problems. The new ignition box is stronger, more reliable and worked without a hitch.
"Testing with the new fuel supply we were super frustrated to find that the larger turbo at higher boost was not making any additional power over the previous GT35R setup. It's a real shock to put on a bigger turbo and get no return on investment. This was super frustrating and we obviously needed to go back to the drawing board to find the missing power. A turbo system is like a chain, it's the weakest link that sets the limitation and everything must work in coordination to realize optimal power."
Gremlins"Examination of the AEM EMS datalogs is a great trouble-shooting tool that can give you virtually unlimited information about how your car is running. In this case the air intake temps were identified as a significant problem. The previous intercooler was ideally suited to the GT35R and was showing its limits with the 40R. The charge temps were suddenly rising to over 180 degrees because of the restriction caused by the intercooler. A Buschur Racing 'RACE' FMIC kit, which somehow manages to directly bolt into the factory location and yet is rated at an astonishing 1,150 horsepower was positioned at the leading edge of the Evo."
Proper intercooling serves two purposes. First, it lowers the intake charge temps which results in a denser charge and more power because there is more oxygen to burn. Secondly, lower air charge temps enhance the process of combustion and improves detonation resistance allowing for a more aggressive tune while maintaining a proper safety margin against detonation.
Another aspect of intercooling is pressure drop; the loss of pressure as measured from the turbo discharge to the intake valve. The lower the loss of pressure, the less you have to crank the turbo to achieve a given boost level and, therefore, less heat will be generated in the intake charge.
Beyond the FMIC review, the AEM datalogs showed that the restriction included more than just the chiller. It showed the old 2.5-inch intercooler pipes were becoming a significant issue, the intake manifolds suddenly became a serious problem as they started to pop like balloons under the stress of 40-plus psi of boost from the GT40R turbo. And there may be issues with the stock throttle body.
The solution was a new set of Buschur Racing stainless steel 3-inch intercooler pipes, Accufab 70mm throttle body and AMS intake manifold. The AMS unit is superior to other designs currently available as it is constructed from super thick metal. Also, its superior design creates a wonderful compromise between low-end power and top-end breathing.
The newly released re-designed Accufab throttle body has a new multi-piece shaft design which is stronger than previous designs which have been noted for frequent failure in DSM applications.
Clutch"As soon as we strapped the car to the dyno with the new intercooler and throttle body setup we realized that it was going to be wicked wild," says Al. "The clutch slipped like crazy and the dyno recorded over 700 whp. Exedy has been working super hard to keep up with the clutch demands of the power-hungry USDM market. The unit we were using was a triple twin carbon clutch with the soft street-style pressure plate.
"The solution was the new upgraded race-style pressure plate with more clamping force. The new pressure plate not only totally eliminated the slipping problem, it also eliminated the need to heat up the carbon disk prior to launch which was required with the old setup. Surprisingly the pedal effort is only slightly greater than the previous street plate and the feel is actually improved."
Transmission"With over 22,000 miles on the original gearbox I figured it was time for some freshening up and I sent it off to the master of all DSM gear boxes Shepherd Racing. John Shepherd had just broke the record for the world's fastest AWD DSM with an amazing 8.13 at 176 mph in his 1991 Eagle Talon drag car so he knows how to hook up off the line. His Evo transmission program updates all the synchros and gears to improve shifting and power handling capacity. When I got it back it shifted much smoother and faster than ever before."
Nitrous"Following the lead of my fellow tuner Gadiel, from Puerto Rico, who has had great success with the use of nitrous to aid in off-the-line acceleration. I added a ZEX wet nitrous kit which is using a 35-shot fogger in the intercooler pipe. The nitrous is used at the launch to help spool the turbo and allow launching at a lower rpm than is otherwise possible with a larger turbo.
"When I saw the Big Valley STi making some passes down the track at Raceway Park in New Jersey I was very impressed with the smooth launching of that car and decided to apply the use of nitrous to improve my 60-foot times and possibly delivering less shock to the driveline."
Results"With all the proper ingredients finally in place the car started to really come alive and it hit 746 whp on the Pruven Performance dyno. This netted me an 80 whp gain over the old GT35R setup and there was more power left on the table. However, once you reach the 700 whp-plus level it is my firm belief that it is better to tune at the track. The dyno pulls are so quick at that power level that it is very difficult to get a good loading on the car and an accurate tune. At the track the first pass with the new setup yielded a 10.2 at 144 mph, which is a very promising start. Sadly, on the next outing a rocker arm broke in half during the 1-2 shift at 9800 rpm so the engine now has to come out.
"Buschur Racing recently tested a 2.3-liter stroker kit with the GT40R and they have reported excellent results. It seems the additional displacement really helps the turbo spool much earlier and harder. The Buschur Racing stroker kit consists of a 4G64 crank, which has a 100mm stroke, stock length billet rods and special Buschur-spec pistons, which utilize a custom wrist pin height. The plan is to dial in this new combo and go deep into the 9s. Stay tuned."