1990 928 S4
August 21-24, 2008
Open Road Rally
Battle Mountain, Nevada
I had entered my 928 in the 160 class with a 200 mph tech (unlimited in the speed traps). Rich S had agreed to
be navigator again, even after the last adventure (2007 Bonneville 100 )
We arrived in Battle Mt. on Thursday, and went through Tech then to Practice on Friday. The car
had some problems at Practice, lot's of oil blowing off on top of the engine and was a way down on
power. We were only able to hit 192 mph, only 3 mph higher then last year! Something wasn't
right. When we got back to the motel, Rich spotted a 1 1/2" split in the oil breather line going to
the oil separator. So this was the easy problem to fix. I studied the LM-1 logs, and found lots of
knocking at above 180 mph, even with the AFR mostly in the 11.5-12.4 range. So I decided I should
run Race Gas (104 unleaded), change to colder plugs, and change the EZ-K chip. The Race Gas
was pretty easy:
Getting colder plugs were a problem. The coldest plugs we could find in Battle Mt. turned out to be 1 heat range hotter then what I was already running, so no go with this solution. After changing the EZ-K chip I did a "test" run and found the AFR was a too lean, though it got richer as the RPM increased. I bumped up the fuel pressure 5 psi and did another run. It got a closer to what I wanted, but since it was getting dark and I couldn't test over 150 mph, I had to call it a day.
Sunday was race day, we were grid last so we got to hang out while the temperature went from 75 degrees at 8 AM to 100 degrees by noon. I bumped up the fuel pressure a little more and hoped it would be enough.
Here are a few shots from the Starting Grid:
As you can see we had washed the night before.
They started the Supersport cars at 11:30 AM, we were the 4th SS car, so we left at 11:39. Well the car still had some problems, when shifting into 4th the AFR was in the 14-13 range and the car had trouble accelerating. As the speed increased, the AFR dropped. By 5000 RPM (~174 mph) we were in the 12.5 range, and the car felt a lot better. We cruised at 175-178 mph until we got to the first speed trap. There's a left hand sweeper before the straight, we went through at 170 and started the speed run at around 175 mph. As we passed the speed trap, the sign displayed 198 mph.
Right after the trap the GPS went to 199 mph and we were still accelerating. We didn't miss it by that much. Without the 5-10 mph head wind we would have been at 204-209 mph...
There's another turn before the 2nd speed trap, a Right Hand Sweeper. The course notes said 155 mph, but I knew if we went that slow I couldn't accelerate out of it very well. So we discussed our options. I could keep it above 170 and try for 200 again, or slow down and just see what we get. Since we didn't get the 200 in the first trap (and we need both over 200 to get into the 200 mph club) we decided it wasn't worth pushing it, and I slowed to 155. The car struggle to get back up to speed, but we still got to 186 mph.
Then while in the Gap, a slow twisty section of the course, I lost throttle response coming out of a right hand turn. We had to coast into the next turn and park at the open space on the side of the road, which turned out to be Checkpoint 6 at House Curve. There was a AFR (Advanced Fire Rescue) truck stationed there. The fire crew rushed to the car saying there's oil all over the car (driver's side) and then smoke started coming out of the hood vents. We opened the hood, no fire, just hot oil on the manifold...
Our race was over. The sweep vehicle came by and took Rich to the South stagging area and I stayed with the car to take photos of the other cars. After the race Rich Kimble offered to pick up the car and take it into Battle Mt. Moday I borrowed a truck and trailer from Les S, here in the Bay Area, and drove up on Tuesday with Bill B, to retrieve the car.
Bill and I checked the engine on the following Saturday. We pulled the oil filter, and the oil looked good:
We then pulled some plugs, they looked good, next we turned the engine by hand, checked the compression on a couple of cylinders. That was fine, so we tried to start the car. The engine cranked, fuel pressure built up, turned over twice then died. Tried a couple times and no go. Bill suggested it's the LH, so we swapped in my spare 87 LH. Engine started, but ran real rough, so we figured that's the problem. Opened up the 87 LH, installed the latest Sharktuned chip from Tim and tried again. Crank, but no start again. Ah, it's the EEPROM Tom burned... Try an earlier EPROM chip, again no go. Talk to Dave A and Brian who suggests to check the electrical wiring around the engine. While I was removing the intercooler, Bill noticed the MAF moved too easily. Sure enough the MAF was loose. After a closer inspection, we found this:
So it was the MAF boot again... 2008 Bonneville 100
I pull out my spare MAF boot and go to install it, but I found another problem:
The Y that goes into the boot had melted. I know I've got a spare of that also, but after an hour of searching the garage, Bill and I gave up. I guess I'll have to order one of those now.
As a side note, I've been doing a lot of logging with the LM-1 and LMA-3. I had a chance to log the run in the Speed Trap. For those that are interested, here is a screen shot of the LogWorks view of the run:
Still a lot to work out in the tuning department, but it'll have to wait until we get the engine running again.
Even though it wasn't quite what I wanted, it's still a decent showing. I want to thank Dave L at Motorsport for the work on the engine, Tim M (Murf) and Tom C (PowerBroker) for help tuning the motor, Mike S, Theo J. and Dave A for help with the logging, and most of all to Bill B for all his tireless helping with this project. Also thanks to all on the Rennlist that donated to the cause. I plan to be back next year.
In-car video from my car
First Speed Trap
Copyright 2008, George A Suennen