sfai said:
If you want to see the rolling roll for a cl9 pre map and after you can go to tdi north facebook. They have project 'Barge' which is a 53 plate k24 cl9.
Stock roll was 197 and after remap was 210 and gain 10 torque.
that's a good find, useful to know that there are other people onto this
they appear to be doing many different cars, one of which as mentioned is ....
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Project "Barge" finally happening.
Been mad busy recently but finally had some time to do the ecu conversion and do a base map today.
Car is a 2004 CL9 K24 with just over 110k on it.
It made 197 on the base run and I hit 210 with the re...map and a good 10+ ftlb across the whole rev range.
We are going to mod this in.the most cost effective way possible ........etc etc
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[one of the accompanying pictures is a photo of the dyno run for the car ....errr maybe]
BUT........
if you look on the graph, both plots peak in the y-axis intervals between 200 and 210, so if the plots are a before and after, then the before is also greater than 200.
there is a BIG problem with the absolute y-axis values of engine power on nearly all rolling-road dyno plots
the issue is this.
let's go with the statement "It made 197 on the base run": why not 196 or 198?
A number like this implies an accuracy of 1 in 200, which is 0.5%
It really is totally and absolutely impossible to measure the shaft BHP using a "cheap" RR dyno (rolling road dyno), to an accuracy of 0.5%. An RR dyno will need a correction to "lift" or "correct" the power at the wheels to the power at the engine shaft, and you can make out a tiny bit of the correction plot on the graph. On other dyno photos on their facebook, you can see more of the correction plots.
But, it is impossible to know what the corrections should be. The
only way to actually measure shaft power to this level of accuracy, without removing the engine from the car, is to.
1. use a "compound" dyno that bolts onto the wheel studs (with wheels removed)
2. run up the compound dyno in motoring mode with the gearbox in a chosen gear with the clutch pedal down. This gets the power required to rotate the driveshafts, diff, and gearbox, at all speeds up to max speed in the selected gear
3. run the compound dyno in brake mode, to measure the power produced at the wheel studs using the same chosen gear, then add back the curve measured in 2.
If the above procedure is used with an RR dyno that can motor with the wheels in place, then the level of accuracy will be less because of tyre temperature changes during the runs.
If the RR dyno does not have any kind of motoring mode (as in the case of most RR dynos) then the corrections have to be manually entered. If it uses a database, it begs the question, can any database possibly contain, to the level of accuracy required, the power lost in each model of car at speed intervals for: gearboxes in different gears, driveshafts, different wheel types, different tyres, different tyre pressures? Without that level of information, these types of RR dyno, where the corrections are manually entered, are probably capable of giving engine shaft power to an accuracy of 5% at best i.e. 10 HP in 200.