Table of Contents:
Overview:
It's been over a year since I dropped my car off at Auto Talent to build the 4.7L low compression, supercharged S65 stroker motor. The custom pistons had been ordered in April 2010, and the plan was to wait for the pistons to arrive and then drop off the car as soon as they arrived.
RD Sport had built the original 4.6L high compression stroker motor. A custom ESS VT2 supercharger was then added as an afterthought, and we came up with the idea to hit 200 MPH in the Texas Mile. I knew it was a long shot already because I knew I would need about 725whp in order to hit 200. We sat with 615whp -- knowing that 200mph wasn't going to happen. But we tried anyways and hit 186.1mph. We learned whenever we turned up the boost past 6.25 PSI, two things happened: 1) the fuel system couldn't supply enough fuel, and 2) the high EGT's of the 4.6L supercharged motor would burn O2 sensors. The only solution was to redesign parts of the fuel system and build a low compression motor. So I decided to order the pistons in April 2010 and patiently waited for them to arrive.
Once the piston landed in customs, I drove my car down to Auto Talent. Once the motor was out, we inspected everything and began to notice some changes we wanted to make. (Pictures shown here[/url].) After pulling the motor, we received our first piece of bad news. This was going to be an omen of many delays that were to come in the future. Basically, Mahle made the wrong pistons. Mahle made 94mm pistons for high (12.0:1) compression, not the 10:1 low compression that we ordered. It was going to take Mahle another eight weeks to manufacture and ship the replacements. So, the waiting game started.
During the eight weeks, I didn't sit idle and uninvolved. I had a big decision to make: who was going to build the motor? I considered my top choices Auto Talent, RD Sport, or possibly my former racing engine collegues at Van Dyne Engineering in Huntington Beach, CA (formerly from Drake Engineering -- from the famed "Drake Offy" racing motor). Using Van Dyne had a certain appeal because I know their standards are very high and they do things quite a bit differently than most street engine builders. The downside was Van Dyne had never built a BMW S65 motor. I untimately worked out a deal where Van Dyne would build the motor to their standards, and Zolti from Auto Talent would be directly involved as a participant and consultant during the motor building process.
In hindsight as I would later discover, chosing Van Dyne might have been the smartest decision I made. Today, the bottom end has been completed: it is now built. But the road leading to this point was filled with delays, setbacks, and challenges. Over the course of the next few days, I will write one article focussing on each of the challenges and decisions we faced. As usual, I will provide plenty of pictures of the build and the painstaking perfectionist process that we have been going through. For the most part, I will share everything we discovered -- with one exception. Certain technical details of the measurements we made and the tolerances we measured and adjusted will remain confidential because some of these measurements and adjustments will make their way into future products.
- Overview
- New Pistons
Overview:
It's been over a year since I dropped my car off at Auto Talent to build the 4.7L low compression, supercharged S65 stroker motor. The custom pistons had been ordered in April 2010, and the plan was to wait for the pistons to arrive and then drop off the car as soon as they arrived.
RD Sport had built the original 4.6L high compression stroker motor. A custom ESS VT2 supercharger was then added as an afterthought, and we came up with the idea to hit 200 MPH in the Texas Mile. I knew it was a long shot already because I knew I would need about 725whp in order to hit 200. We sat with 615whp -- knowing that 200mph wasn't going to happen. But we tried anyways and hit 186.1mph. We learned whenever we turned up the boost past 6.25 PSI, two things happened: 1) the fuel system couldn't supply enough fuel, and 2) the high EGT's of the 4.6L supercharged motor would burn O2 sensors. The only solution was to redesign parts of the fuel system and build a low compression motor. So I decided to order the pistons in April 2010 and patiently waited for them to arrive.
Once the piston landed in customs, I drove my car down to Auto Talent. Once the motor was out, we inspected everything and began to notice some changes we wanted to make. (Pictures shown here[/url].) After pulling the motor, we received our first piece of bad news. This was going to be an omen of many delays that were to come in the future. Basically, Mahle made the wrong pistons. Mahle made 94mm pistons for high (12.0:1) compression, not the 10:1 low compression that we ordered. It was going to take Mahle another eight weeks to manufacture and ship the replacements. So, the waiting game started.
During the eight weeks, I didn't sit idle and uninvolved. I had a big decision to make: who was going to build the motor? I considered my top choices Auto Talent, RD Sport, or possibly my former racing engine collegues at Van Dyne Engineering in Huntington Beach, CA (formerly from Drake Engineering -- from the famed "Drake Offy" racing motor). Using Van Dyne had a certain appeal because I know their standards are very high and they do things quite a bit differently than most street engine builders. The downside was Van Dyne had never built a BMW S65 motor. I untimately worked out a deal where Van Dyne would build the motor to their standards, and Zolti from Auto Talent would be directly involved as a participant and consultant during the motor building process.
In hindsight as I would later discover, chosing Van Dyne might have been the smartest decision I made. Today, the bottom end has been completed: it is now built. But the road leading to this point was filled with delays, setbacks, and challenges. Over the course of the next few days, I will write one article focussing on each of the challenges and decisions we faced. As usual, I will provide plenty of pictures of the build and the painstaking perfectionist process that we have been going through. For the most part, I will share everything we discovered -- with one exception. Certain technical details of the measurements we made and the tolerances we measured and adjusted will remain confidential because some of these measurements and adjustments will make their way into future products.