more info on dyno run
OneFastLotus and others,
There was no slippage between the dyno drum and the tires. The car was tied down enough to prevent it. I suspect that you want a tight fit to prevent slipping but not so tight that you compress the tires more than if the car were sitting on the ground. The picture I posted here obviously shows the rear wheels in motion. I checked my high resolution pictures of the car strapped but stationary and noted that the tires were not overly compressed, but appeared normal like on the ground.
The software on the unit was recently upgraded and therefor more accuracy implied. They were using version 7 for those counting. I will be posting more pictures and the scan of the dyno sheet on my site in the next several days.
The operator noted that the runs were extremely consistent. This was unusual compared to other cars. In some cases the power developed varies 5-10 horsepower. My curves were almost identical. It might have been possible for heat soak to influence the third run. We did two runs, talked a bit and looked at the results and then did the third run. No change. They were impressed.
The sniffer was one of the more elaborate I have seen. I was impressed with the connection, the fact it was actually an active sniffer with its own fans, and its consistency. But you are correct, that all this equipment requires constant and correct maintenance if it is to provide correct and consistent data.
I agree about not putting much importance in the actual numbers. Ambient temperature, humidity, maintenance of the unit, operator variance, and the phase of the moon all play a part in determining actual horsepower. I just wanted some confirmation that I did not do anything wrong while breaking in the car and to provide a reference in case I decide to add go fast goodies later.
(I doubt I will add any go fast goodies any time soon. The car has plenty of power for my use. I know some of the tricks employed to get more power and the risks associated. Right now I believe Lotus did a good job tuning this engine and that it is not likely, but not impossible, for someone to do a better job.)
I agree with Stan that holding down the front end might be better done by strapping the wheel. I do not like pulling on the suspension pieces and do not want to stress them beyond what it takes to move the car. The suspension on the Elise is not like a lot of other cars, so the experience of the dyno operator is important. Do not hesitate to ask questions or take your car back if you do not like what they are doing.
Michael