Project EVO X GSR- More power with Garrett, Full Race and Cosworth
By Mike Kojima
In the last edition of Project EVO X, we upgraded the fuel system in anticipation of more serious mods. Well the time for more serious mods has come and we are going to see exactly what can be done to the 4B11 with bolt ons. In this go around, we are going to install some camshafts by Cosworth, Garrett’s direct bolt in upgrade turbo and a tubular exhaust manifold by Full Race Motorsports.
|We obtained some of Cosworth’s MX1 4B11 cams with matching springs. The MX1 cams have 266 degrees of duration on both the intake and exhaust with 10.8mm of intake lift and 10.4mm exhaust lift. With the tuning freedom of having MIVEC variable cam timing on both the intake and exhaust cams, we were anticipating a best of both worlds situation where we would gain power across the board.|
|Before installing the cams, we sent them out to be WPC treated for reduced friction and longer life.|
|We also used Cosworth’s single valve springs matched to our cams. The springs are made of Japanese Kobe steel which is super trick electro purified and vacuum degassed steel. These processes eliminate inclusions and pockets within the steel which are the major cause of valve spring failure. Many high end valve springs around the world are made of Kobe steel for this reason. The Cosworth springs have double ground and tapered ends to reduce fatigue and are shotpeened for long fatigue life. The springs are good for 8000 rpm which will allow us to bump the rev limiter.|
|After installation we did some tuning with Naji Dahi of Looney Tuning. After correcting the boost curve and A/F ratio we had to retard the intake cam and advance the exhaust cam to reduce overlap because the car was sneezing out of the intake on part throttle due to our previously programmed aggressive MIVEC map. Once we were done tuning, the results were impressive. The Cosworth cams got the turbo spooling earlier, greatly reducing lag. We had huge gains across the board with peak gains of 17 whp and 28 lb/ft of torque. Unfortunately, a few days ago Cosworth USA announced that they were halting operations and that the parts programs future was uncertain. We really hope Cosworth continues to stay in the market. The market needs quality well engineered parts. Cosworth bigshots, are you listening?|
|With impressive gains from the cams, we next installed Garrett’s GT direct bolt in upgrade turbo. This turbo is based on the proven GTX3071 ball bearing center section turbo with Evo X specific housings and internal wastegate. The turbo kit is very complete with water and oil lines included.|