DYNO TUNING DAY 12-19-03

This dyno day started as a result of adding an FMU to the system. The FMU was added to give proper fuel to the system to run higher boost and hence, more power. I'm in the process of trying to see where the limits of my current system fall.

Below are the results of runs 7, 8 and 9 of 3rd gear runs. Most all the runs of 14 were in 3rd to get the tuning of the AFR proper. My first run showed overly righ at 10.5AFR. Subsequent runs were made to get the AFR in line. Well, fixing the AFR curve never quite happened, and I stoped after 9. The issue is with the Dinan TurboTronics box. As described in the DME tuning page, the DME leaves "headroom" for the injector duty cycle(IDC) to alloy the coolant temp sensor to properly richen the fuel curve with changes to coolant temp. Since I was only able to tune the DME, I couldn't competely lean the rich bubble starting at 5krpm to 5.7krpm using the DME values. Unfortunately, I was unable to re-tune the TT box to get the AFR curve correct due to technical difficulties(didn't have the proper EPROM at the time) :-(

As I found out during the day, the torque is very sensitive to overly rich AFRs. As seen in the torque curves, the curve drops very quickly as the AFR goes from 12.6AFR to 11AFR. As the AFR leans out, torque agian rises, and pushes the hp curve back up. 0.97at is 13.8psi. Although, through out the entire pulls, the boost drops a bit from the 0.97at, so the boost through the entire pull is really from 0.93at to 0.97at.

All pulls are with 91 octane, and relatively cool IC. Between runs, I was burning chips, so there was ~4 minute cool down between runs.

Next are the last two runs of the day at 1.1at(15.4psi) and 0.97at(13.8psi) in 4th gear. On my initail tuning on the street runs, I was able to consistently run 1.1at, but as I found out at the dyno, I was runing extremely rich to do this, in the range of 10.5AFR. Using the 3rd gear runs above to tune to a more proper 12.5AFR, I had to drop the pressure way back to keep the engine from detonation. I tried the below 1.1at run, but had to pull out as the pinging was bad. The AFR is still a bit low and not very flat, that will have to be tuned out at a later date.

The next 4th gear run was my last with the boost pulled back to 1.0at(14.2psi). Overall, the results were not what I expected. In the intial street runs for tuning, I had the system way to rich, giving a false sense of how much boost I could run with the system set up and CA 91 octane. It seems I just can't get the system to run more than 325lb/ft at 5krpm! This limits system power to ~313whp. If I can get the AFR nuts on, I'm guessing the hp limit is maybe another 10whp, or 325whp. I'm guessing now that the turbo is too small and the exhaust too restrictive.