I had now sold the Silvia, so I had the funds to make my ute a bit more potent. The next major round of mods were for Ultra Tune Kalgoorlie to fit a set of Pacemaker Tri-Y extractors, metal catalytic converters, 3.9:1 differential centre, OTR Air Induction, and a lumpier camshaft (224/228 in this case).

So from the start of the combustion process, first was the removal of the restrictive airbox and its accessories and in its place an OTR Air Induction complete with reusable K&N air filter. The below pics show the difference in air flow between the OTR and the standard airbox.

Stock LS1 Air Intake

OTR Intake

Next in line is the Comp Cams 224/228 Camshaft, chosen because of its popularity and because of the power range I required. Other cars around town, generally have larger cams than mine. I probably should have gone with an even smaller cam, but this one is pretty good.

As we continue along the combustion cycle we get to the exhaust. The ute was already fitted with a Manta twin 2.5″ cat back (last half of the exhaust), so I chose not to change this unless it was too loud. To hopefully maximise the low down power, tri-y extractors were chosen over 4-1 style (Im not sure this is so true anymore, as the dyno graphs I have since seen with 4-1s seem to show just as much bottom end). To further free up restrictions, high flow catalytic converters were also fitted. People commonly remove their cats altogether and replace them with straight through pipe, this however is illegal and in this environmental day and age not recommended. A tad ironic that a V8 driver mentions the environment…

So with the intake and exhaust taken care of, the next item on the list was the differential. The standard ratio is 3.46:1 which is okay, but with the 6 speed sixth gear was really too low for our max. highway speed of 110kph, and I wanted more acceleration. A ratio of 3.9:1 was chosen because it has a balance between acceleration and top end cruising. 4.11:1 gears are available and are used on many drag Commodores and could possibly be perfect for a car that doesn’t really leave the confines of the city where 100kph is generally the top freeway speed.

So to tie that all together, the computer was re-tuned in a MAFless configuration. The resulting power can be seen below. I had Ultra Tune make the tune lumpy at idle for that look-at-me wank factor. The car physically rocks at the lights now which is always good for a few chuckles. :)

Dyno Sheet

The overall feel of the car now is awesome! The only let down from the whole experience is the poor fuel consumption which is now around 21 litres per hundred kilometres. My average speed around town though is less than 40kph, with the max speed reached being 70kph, so I am thinking that could have a great effect on the usage compared to other cars on the forums I read. Highway runs get consumption figures in the high 10s and low 11s, so someone doing a bit of freeway driving would get better consumption than I do around my small town.

One Response to “More power…”
  1. AFR could be smoothed a bit, you would regain some better fuel consumption not to mention more HP. A pretty smooth curve though.

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