1990 928 S4
September 24, 2011
Before this season started Bill and I went back to the dyno to get the engine tuned for the new fuel system. After a few run it confirmed that the knock count was way up, even when we had the AFR in the desired range (11.8 - 12.5:1). The next dyno session we ran with 100 octane unleaded race gas, but we still had lots of knocks. The only option we had left was to retard the timing to control the knocks, but we lost 30-70 rwph.
When we got up to Ely , we did some more tuning. At 6,000 feet, we found we could advance the timing some and still control the knocks. We didn't get all the power back, but we got some. After the race, I told Bill I wanted to install a methanol/water injection system to get the knocks under control and hopeful get all our power back. I checked out the available systems: AEM, Snow, and Alcohol Injection Systems and decided on the Alcohol Injections Systems set up. I ordered a 2 nozzle system from them with -4AN stainless lines. They didn't have their Progressive Controller in stock, so I ordered an AEM controller from another source.
Also because of the long distances involved in ORR, 90-130 miles, I had to get a larger tank. After talking with Rodney at Alcohol Injection, I ordered a 5 gallon fuel cell made by JAZ from Summit Racing. I also had to measure the different runs of hose. Four sections in all which Alcohol Injection Systems had made up for me.
Once I got all the parts, We started the install. I mounted the fuel cell in the rear passenger seat area and the pump behind the passenger seat. I made a fitting for the main nozzle out of 3/4" round aluminum stock that fit in the MAF boot. I also tapped a 1/8" NPT hole in the air box to mount the small secondary nozzle. The controller I mounted under the roll bar between the seats. Here's a diagram of the system:
I routed the -4AN line out under the car, up the wheel well, and into the engine compartment. There I put in the Tee splitting the line to go forward to the air box and back to the MAF boot.
I added a over ride switch and a LED to show when the system was active and a line into the LMA-3 to log the pump output. For ORR I was required to add an enclosure around the fuel cell. I fabricated one out of 3031 sheet aluminum (.063" and .050"). I made the patterns out of cardboard before cutting out of the aluminum. Here is a shot of the finished enclosure.
After the install we went back to the dyno to tune the engine for the water/methanol system. We found the knocks were way down even with 91 octane pump gas and the timing we used at 6,000 ft. We were even able to advance the timing more and still stay safe. The next day we drove up to Ely, Nevada for the Silver State Classic. While there we did a little more Sharktuning and were able to advance the timing by more then we had last year. We haven't done a final dyno session to measure the power gains, but we hope it gets us over where we were last season.
The system cost about $700 and took several days over a 4 month period to install. I want to thank Bill Ball for all his hard work helping me install the system and sharktuning on the dyno.
Copyright 2011, George A Suennen