September 4, 2010

Changes to the car: 

We found some stuff that was holding the car back over the last month. First and foremost, we replaced the left rear torsion bar. I believe the old torsion bar was worn out and was "sagging." A bad left rear torsion bar will cause all sorts of handling issues, but especially will hamper forward bite off the corner. I also did a few other changes, but I honestly don't want my competition to know these changes to the suspension.

Next, I flowed the fuel injectors and found a major disparity across the four injectors. I removed the teflon filter screens that are installed in the injectors and reflowed them. Wow, what a difference - they flow great now. I cleaned the injectors by backflowing them with compressed air and reinstalled to races.

Hot Laps: 

The track is narrow and tacky. The car runs pretty well, but the engine is getting way too much fuel. The engine is miss firing a little due to this 'rich' fuel condition.

Changes before the Heat:

Downloaded the data from the MoTeC computer and sure enough we are far too rich (too much fuel). Obviously, removing the filter screens from the fuel injectors opened them up and now my fuel map is too rich. I lean it down by 15% -- yep, 15%!!!!!

Track is getting slick with a usable cushion.

Tightened the car:
Changed RR air pressure (6psi)
Moved top wing back and increased angle.
Started with the shock compressions at: LR and RR set to #3 position I also added rebound to both rear shocks to hold the rear end down coming off the corner.   

Heat Race: (started 6th / finished 4th) 

Engine ran much better and we actually passed cars in a heat race! Car is handling pretty good and for the first time in a month the handling is predictable and I can relax (no 'death grip' on the steering wheel).

Changes before Feature: 

Engine is not taking off the initial start very well and sure enough the data log shows a lean fuel condition when accelerating from low RPM. I add fuel in this area of the fuel map.

The track is wide and slick with a cushion that doesn't look very usable (too far out there and not consistent)

Tightened the car:
Changed right rear tire to a lesser grooved RD12 compound with a 5psi bleeder and move the wheel in on the axle.
Set RR and LR shocks to #2 compression position to start the race and put more clicks into the rebound on both rear shocks.
.   

Feature: (started 6th, finished 4th) 

Upon initial start - I knew we had a car capable of winning tonight as I immediately move from 6th to 3rd. I get under the second place car and we race side by side for a few laps. I finally make the pass and then run down the leader. I start working on the leader, but I just can't complete the pass. The leader is running the bottom and isn't making any mistakes; thus, forcing me to run a lane higher on a track that doesn't have much bite coming off either corner. I pull up side-by-side getting in to each corner, but loose ground coming off. Lap after lap. I really need some lap traffic to help me out here, but we keep getting cautions every 3 or 4 laps just before we get into traffic. Finally, get to lap traffic on lap 25, but by lap 27 my top wing mount fails and the wing crashes down in front of my face! The wing is bouncing up and down on my down tubes (the chassis tubes that run to the front of the car) and I cannot see out the front of the car entering the corners. I have to slow down and I end up loosing two spots to finish 4th.

Wrapup:

The wing mount failed and killed my chances of winning. Once again, we have thrown away a potential race win - but all-in-all, I am not too upset. The car is handling great and the engine is running well. It has been a LONG month with a poor handling car - just getting the car to go around the track like it should made this a GREAT night.