27th December 2007

BACK ON THE DYNO!

Sorry again for the lack of updates to the website! I've been having real problems with my broadband service at home.

Since the last update I have been getting the car ready for a new dyno session at Dyno Demon. I got the engine running fine on the new 65lb injectors after a few issues. I decided to up the boost by fitting the new 3.85 inch pulley to the supercharger. I could also now fit the original belt that came with the ProCharger. It's 64.5 inch long.

Below is a pic of the 4.25 inch pulley which has been on the supercharger all year. The two on the right are the new ones. 3.85 inch and the 3.4 inch on the far right.

Below is a pic of the new 3.85 inch pulley fitted to the supercharger. As you can see the size is stamped into the inside face of the pulley. This pulley should be good for 1bar of boost.

Once I had it setup I took it round to my mates dyno just down the road from me. My mates dyno can only measure 300bhp at the wheels which is fine for getting the basics sorted out. After about three hours it was all sorted.

Part way though the session we were getting some spectacular flames coming from the exhaust on overrun. You can see the video here.

www.youtube.com/watch?v=nq5vSgES9Pk

I met up with my mate Aid from my local dyno at Dyno Demon to finish off the mapping. After a short time running on the rollers we noticed that the tyres were suffering badly from the steady state load we were applying to them. They were melting and chunks of rubber were coming off them.

In the pic below you can see tyre and the damaged caused. Some of the missing chunks were 6mm deep. I'll be fitting new tyres for the MOT in April next year.

We had to keep letting things cool down before trying again. We managed to get up to 6,200rpm before things were getting too bad. It was a combination of the tyres getting too hot, that casued vibration and the dyno was also getting too hot. By this time the fuel map was all but done. All that was remaining was the ignition map. We decided to just to do power runs and add a little more timing for each run. We had more problems. Under full power the rear tyre on the drivers side was touching the bodywork. We had to stop and re-strap the car. But on the next power run the clutch started to slip. It slipped at 4,600rpm. At that point we were making 579bhp. The torque figured peaked during that run at 690lbs/ft at 4,000rpm. I was very happy with these results. If I extended the graph the engine would have made over 620bhp. I don't think the clutch slipping would be an issue on the road as you could never apply that much load.