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Old 16-03-2009, 09:08 PM
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Scott.T Scott.T is offline
Admin, Meets/Events Organiser.... formerly known as SilverSurfer
 
Join Date: Sep 2008
Location: Hastings, East Sussex
Posts: 9,485
Default Re: Rolling road day 14th March 2009

Just to put things straight,
There is nothing wrong with the results achieved for both Nige's and Worzels car on the rollers and no-one is at fault (mapper or RR operator).
For the boost they achieved at the top end of the rpm range, the power is about right.
My car was actually 0.1-0.2bar higher then their's hence I was marginally ahead on power.

Don't just look at the power figure plot, look at all the others that Charlies supplied, they all tell a story.....
Neither car made the boost on the rollers that they do on the road, regardless of gear.
If the car was hitting the top limit of the WGDC (Max Waste Gate Duty cycle) it wouldn't make much difference which gear it was in).
Normally a car will achieve slightly higher boost in the higher gears, hence more power. But the ECU in these cars has 2 WGDC maps to help maintain a more even boost per gear with a degree of self-learning. However, too much WGDC and you get boost spikes/oscillation in 5th/6th which can lead to lean mixture/detonation etc.....it's a fine balance.

Both cars hold 1.4bar out on the road so will be getting v.close to the expected figures of 340-350BHP for Worzel and 360-370BHP for Nige.

Retrospectivley looking a Nige's log we took when Road dyno'd he was hitting 35% WGDC for 1.45bar, Initial WGDC was 33, top limit was 38%.
On the rollers it may of been hitting 38% due to the different load effect of the rollers. It will not go beyond 38%, hence boost levels may not hit target.

All this is my take on the situation, and I am investigating further........
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