A number of Westfield power plots. Four plots are from Power Engineering, torque and bhp. 'Stg3' is the car in it's original form with stage 3 heads, piper 285 cam and modified ECU. 'Carbon Fibre' is the same spec but with the RPi Carbon fibre plenum chamber and ported inlet manifold/trumpet, 'twin throttle' is identical but with the twin throttle plenum replacing the carbon fibre plenum. The 'Std v8' is not my car but another Westfield that was run up on the same rollers at Power Engineering on the same day that I was working on the plenums. This is interesting in that it extremely close to the 'Stg 3' plots except it tails right off after peaking at 185 bhp at 4725 rpm. The 4.6 plot is the final version of the car, basically the same as the stage 3 plot but with a 4.6 bottom end and a V8 Developments cam. The 5.1 is a 5.1 engine from V8 Developments with basically the same set up but with stage 4 heads and a different cam. The other plot is a 4.6 from JE. Beware of comparing these figures, the V8D plots are in the same engine dyno so can be compared, the JE plot was done on a different engine dyno and the rest are done on a rolling road with all the vagaries that introduces, albeit a reasonably accurate rolling road.

Download your own copy here dynocompare.xls

The twin throttle can be seen to be a little bit lacking, but unlike all the other plots, peak power was never reached. At 6,400 rpm and 225 bhp the power was still going up. Although the car has never been run with the twin throttle plenum on the road, the design of the intake was such that it would fit under the bonnet, this lead to some tight bends which may well explain the lack in performance. At 6000 rpm, the carbon plenum can be seen to be making 17 bhp difference.

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