Well it's almost been a year since posting about the slo998 and that means it's almost hay again! I had to get the car re Dyno tuned to get things right after a few changes to the car.
I wasn't happy with the diff ratio as it was very hard to get off the line with the dog box with out having to launch it or slip the clutch lots just to get the speed up or the revs didn't drop right down and die.. So I changed from a 3.6:1 to a 4.2:1 and will see how it goes. Ultimately I think I will buy a 3.9:1 but will wait and see.

The dog box still looks brand new, extremely happy with it!

When the motor was out we pulled it down to see how things were going. First of all we noticed the head studs and rocker posts had started sinking into the head.


Next the 3 layer head-gasket had broken one of the layers, wasn't really blown yet but on it's way. I think this was mainly down to running anti-lag as it was between 2-3 right where the valve relief pockets are and the head studs losing tension after they had sunk in wouldn't have helped much!
Next we noticed that the chambers around the spark plugs had started to melt a little, again anti-lag prob didn't do anything many favors but it is cool seeing full boost at 3000rpm before the car has started moving while popping flames out the back


So the chambers got relived around the spark plugs, decked to increase the comp to around 13:1 and I thought we would try some bigger valves as we had hit the wall power wise last time and it wasn't where id had hoped for.. The head was flowed before and after and compared to my old 5 port head that I had done at home years ago. Head now has 37mm inlet up from 33mm and 31mm Ex from 29mm, CNC muilt cut seats and CNC blended back to the ports.




I have been really keen to try different cams in the turbo motor and am extremely happy with the change!
After all that it was put back in with the new disk brakes front and rear and the new force racing wheels. It was locking the rears so I fitted an adjustable bias valve before the handbrake to limit the rear bias.


The brakes only just fit under 12's!!



So we started tuning on low boost and got things rolling with around 80kw at 8psi boost about the same as last time but it kept holding the power to the rev limiter at 7900. This was increased to 8500. Then we started winding it up the boost, 14psi saw 103kw 16psi saw 115kw, 18psi saw 123kw and we tried for 20psi but the wastegate couldn't hold it without opening so only made 125.9 and was very dippy as you can see in the sheet! On lower boosts it was much smother starting to come on around 3000 and seeing full boost by 4500-5000.

We backed it down to 17.5psi and took a few degs of timing out to make it safer and left us with 120kw.
I haven't really driven it much and it will hopefully be at a track day on the 30th and then going to hay. To say it's fast is silly.. Makes my 250kwatw Evo and near 300kwatw F6 ute feel like toys!
Can't wait to get it to the track!
Thanks for reading Nathan.