I have just written a piece for AutoItalia Magazine about a track test I carried out at Spa-Francorchamps in a Ferrari P3/4. I also write a fortnightly column for a magazine on another continent and am amazed that I never run out of material. One of my racing clients recently asked me to try a £20,000 race car simulator to see if it would help his driver development. This will be the subject of a column and a future blog. My race instructor and race driving work is thankfully quiet in the UK winter. This has given me time to play with a Lister Chevrolet, or Lister Corvette, as it is known in the USA and on its FIA papers.
The Lister’s 5.7litre V8 engine is back from its repair. A core plug popped out during qualifying for the Sussex Trophy at the 2013 Goodwood Revival. When it comes to noise measurement, remember that the DB decibel scale is logarithmic. This denotes that every increase of 3DBs represents twice the noise. When the car was last noise tested (with silencers!) it was over 118db at 3500rpm, which means that it could only be used on the public highway, or on those rare unrestricted, noisy race days. ie, no good for ‘quiet’ races, most test days or trackdays. I decided to tackle the noise issue myself and began by buying a noise meter. I now have 4 exhaust systems:
- A system for noisy race days comprising of two conventional 4-into-1 manifolds with two unsilenced 3-inch diameter tail-pipes. Circa 130db
- A system for road use comprising of the same two conventional 4-into-1 manifolds with two straight through silencers. The silencer dimensions are 6-inch outside diameter, 3-inch inside diameter and 18 inches long (118db at 3500rpm).
- A system for quiet days comprising of system number-2 with some very special inserts that offer little restriction and a huge reduction in noise down to 101db at 4000rpm.
- Finally, and the most fun, the Zoomies at 130+db. Zoomie is the name that Americans use for open pipes or drag pipes. Each of the eight cylinders has its own 2-inch diameter exhaust pipe. Each side of the car are four very short exhaust pipes. This is most inefficient. There is no collector. The job of the collector is so that the gas exiting one cylinder helps the gas exit from another. The horse power loss is considerable, but this might be useful in the wet.