Supercharged and Over Fuelled
Posted by Ant Pearson on
Working at AET Motorsport means we get to see all sorts of vehicles, not just motorsport based items. But when we do they tend to be weird, wonderful and mad.
Take this Mini grass tracker, for example, it’s an engineering masterpiece all built in-house by Martin and his team at Newsholme Engineering. Looking over this mini you know that everything that has been installed has had a great deal of thought and time gone into it.
Powering this Mini grass tracker is a Honda 1.8 Vtec engine with a Rotrex supercharger bolted to the side of it. The engine has been treated to a number of uprated parts including being forged and finished off with a ported head from the states. Martin initially dropped the Mini off for some power runs. With the head returning from the states and the engine buttoned together including a map being provided for the engine. He was interested in seeing what sort of power the car was making. It certainly wasn’t going to be shy. (This thing sounds mental!)
Jack set the car up on the Dyna pack hub dyno and started to do some initial test to make sure it was ready to rev just all the way to just over 7k, without leaving us with a mess to clean up and an expensive bill for the customer. These initial runs up just a few 1000 rpms showed that the engine was over fuelling heavily. This meant that Jack had to change tactics and set about live mapping the fuelling to make sure it didn’t over fuel and cause some serious damage. This resulted in a few hours of running the mini and adjusting the fuel while increasing the rpms 500 – 1000 increments at a time to make sure the fuelling was correct throughout the rev range. Before having full confidence in a max power run.
As the rev climbed it was apparent that the fuel pump and lines were unable to provide the fuel required to run past 6k. With this diagnosed Jack advised the customer that some new lines and fuel pump from Racing lines were necessary to get the maximum from the engine. With the new lines and fuel pump installed it was back to the Dyna pack hub dyno for Jack to finish of mapping the car up to the limiter.
With it all mapped and fuelling correctly Martin informed us that the engine builder mentioned it should be making a bit more power than what we had initially quoted. So back to the dyno to do some more runs resulted in Jack noticing that the supercharger belt was slipping causing a loss of about 40bhp. With this adjusted and a final run saw the Mini producing 370whp and pulling like a Mini on steroids.
One final request was that Jack installs a flat shift function that can be enabled and setup using the Motec M84 ECU. With the sensors being provided by KA sensors this is Jacks next task before Martin take it and competes.
Dyno Video of the Mini running on the Dyna pack hub dyno.