Pistonhead Open 4-2015 8-9 August
The weekend prior this one we were at the magazine Bilsports event at Mantorp.
We managed to sort out some trigger issues but we only made one full throttle low boost run.
That was pretty far from fantastic, but it was with a brend new engine and everything worked.
Now we were heading for our home track Kjula Dragway.
The track is 1,5-2 hour drive away but even if we start at noon it still gets dark
until were at the track, the pit is set up and the car is scrutineered.
This weekend as often we got to borrow Råttans teambus to live in at trackside.
Brekfast in the bus is a luxury one can get used to.
After warming up the engine and drivetrain it was time to drag the car up to the starting area.
We had a good tune going on from last weekend that we wanted to continue so there were verry little adjustments done.
The weather was just as the mood splendid.
The expectations were rather high. We all fealt that a high 8 sec run were to count on.
I got a little hot on the trigger and fired up the engine just a bit too early.
It is a tight balance when to fire up this kind of engines. If fired up too late the engine runs too cold,
causing missfires and poor performance. So poor it will hardly perform a proper burnout so thats ruled out.
If I fire up too early the oil gets too warm leading to poor oil pressure. We ran Wolf Head 20/50 and when the oil is 70-80 degrees C
the oil pump doesnt manage to make enough oil pressure for a safe run.
We had to abort that run. I have programmed a security function in the ECU that refuses revs past 3000rpm
if the oil pressure does not exceed 30psi. This is no problem in normal cases and if our trouble
is a result of poor oil quality or from a too small pump section I do not know.
We solved it by blending our 20/50 with straight 50 oil from Fredde Fagerström with the ProMod pickup
who was at the track for some testing. A warmup in the pit showed us good results.
There were pretty few teams in place so it was soon our turn again.
This time it wasnt as critical when to fire the engine up so that part was ok.
In the images the burnouts looks kind of weak, and thats not just how it looks.
In our erge to get a smooth rpm limiter we added lots of fuel and retarded the ignition.
Maby a bit too early prior the actual rpm limiter so when the engine gets close it gets weak.
During the actual run the rpm limiters caracteristics does not matter since I shift well before them.
Here we ran a smooth 9,16-245kmh. No drama.
What obviously steals lots of time is the starts and poor 60fts.
After the run we noticed some metallic sparkling in the oil,
so Filip ripped the bottom end and checked the bearings.
All was ok. We noticed some small issues with the thrust bearings so we put it back together.
We missed one run but its better to check it one time too much.
The plan was to repeat the previous run again to make shure we know where we are tuningwise.
it may seem boring to repeat the run but for us it is about presition. Not chanses.
We did have the repeatability for shure.
We only added some slight power to the second half of the run wich resulted in this fine slip.
The run was no drama but it shure was annoying I ran 8,990 with the Cherry...
This was the last run we got on saturdays qualifying runs.
Next was Saturdays eliminations so back in the pit we lifted the engine to get access to serve the clutch.
We did some software updates too. We tightened the fuel enrichment and ignition retard towards the rpm limit.
That gave us a slightly better 60ft time but one run doesnt do it for us. Could just as well be the weather.
Obvious though, without repeat is that the car went really wide. I had a hard time keeping the car under controle.
It was so bad I aborted the run. We figured out it had to be a result of a worn out torsen differential.
While we packed up our pit Fredde Fagerström and Jöran Persåker ran a matchrace with their pickups.
On our way home we stopped for some food.