This last Friday I took DRB#5 up to Kurgan Motorsports for a Dyno session and final tune. I had spent the last two weeks fixing the few things that were glaringly obvious. A vacuum leak with the intake manifold allowing the O2 sensor to read lean. I also found the change in timing/position of the distributor(phasing) which was causing everything from igniting the fuel on random cylinders on the intake stroke to backfiring up the injectors. I got the phasing fixed after the new intake manifold gaskets were in place. It required taking the injectors off twice as the fuel rail sits right on top of the distributor. In changing the plug wires to the distributor cap with a hole drilled in it I discovered the #8 plug wire had melted at the plug end. even though there was a fireproof plug insulator on the end. After all this the car ran much better. So scheduled for the run.
On arrival we immediately put the car on the Dyno for a baseline. We managed to forget to close the rear clip and the first run smoked the paint on the underside of the clip. The first run was rather disappointing. The highest hp reading was only 340. We noticed that the hp and torque values began dropping from 4-5000rpms. The wave form was rather jerky which led us to believe it was a timing issue.
We also notice the mph reading on the dyno was very high for the rpms that we were seeing. Bob asked me if the output of the trans was 1:1. I wasn't sure so we Googled it and for all models of 930 trans the value is .062 Essentially an overdrive. that explained the 182mph reading. With the old tires I have on the car we decided to make all other runs in 3rd gear. Still not 1:1 but closer than 4th.
After changing some timing in the software we did a second run. This yielded only 40 more hp and still a drop off at higher rpms. We took a break and Bob dug into the software to find the gremlin, which he did. There was a retard sitting on the timing at the higher rpms that was not evident in the timing page of the software. This FAST electronic box(XFI) when I purchased it was second hand. We think the previous owner put the retard in to save the engine at higher rpms?? This was corrected and the third and final run was made and it was a fantastic run making over 100hp over the first run.
I am still new to this video rendering but here is the final run.
https://www.youtube.com/watch?v=_U1JOgl1Lqk
Bill
On arrival we immediately put the car on the Dyno for a baseline. We managed to forget to close the rear clip and the first run smoked the paint on the underside of the clip. The first run was rather disappointing. The highest hp reading was only 340. We noticed that the hp and torque values began dropping from 4-5000rpms. The wave form was rather jerky which led us to believe it was a timing issue.
We also notice the mph reading on the dyno was very high for the rpms that we were seeing. Bob asked me if the output of the trans was 1:1. I wasn't sure so we Googled it and for all models of 930 trans the value is .062 Essentially an overdrive. that explained the 182mph reading. With the old tires I have on the car we decided to make all other runs in 3rd gear. Still not 1:1 but closer than 4th.
After changing some timing in the software we did a second run. This yielded only 40 more hp and still a drop off at higher rpms. We took a break and Bob dug into the software to find the gremlin, which he did. There was a retard sitting on the timing at the higher rpms that was not evident in the timing page of the software. This FAST electronic box(XFI) when I purchased it was second hand. We think the previous owner put the retard in to save the engine at higher rpms?? This was corrected and the third and final run was made and it was a fantastic run making over 100hp over the first run.
I am still new to this video rendering but here is the final run.
https://www.youtube.com/watch?v=_U1JOgl1Lqk
Bill
