Well we have achieved all
our initial aims for Project VE dipping well into the 12's but
as usual we want more .
Previous models responded
well to a set of diff gears so the next logical step
was to see what affect a set of diff gears would achieve
, comparing the gear ratios in the new 6 speed auto combined
with the diff ratio of 2.92 to the older 4l60e transmission
combined with a 3.08 rear end ratio showed that there
wouldn't be as significant gains due to the lower first gear
and closer gear spacing . The decision was made to go for
the biggest jump in ratio so the gains would be
magnified but with some possible loss of fuel economy.
|
|
VE |
Effective ratio |
VY |
Effective ratio |
|
Diff ratio |
|
2.92 |
3.73 |
|
3.08 |
3.73 |
|
1st gear |
4.02 |
11.74 |
14.99 |
3.06 |
9.42 |
11.41 |
|
2nd gear |
2.36 |
6.89 |
8.80 |
1.75 |
5.39 |
6.53 |
|
3rd gear |
1.53 |
4.47 |
5.71 |
1.00 |
3.08 |
3.73 |
|
4th gear |
1.15 |
3.36 |
4.29 |
0.70 |
2.16 |
2.61 |
|
5th gear |
0.85 |
2.48 |
3.17 |
|
|
|
|
6th gear |
0.67 |
1.96 |
2.50 |
|
|
|
A brand new HSV 3.7 diff
was sourced and fitted , initial on road improvements
where immediately evident , acceleration felt improved and
economy hadn't suffered as much as feared going from a city
driving average of 12.2L/100 to 12.6L/100 kms.
Back at the track with
some street slicks we where a little disappointed that the
ET had dropped but only very slightly to
12.6@110 mph . Improvements gained
from the diff was pretty
poor so we would most probably leave the diff gears of our
list of to do at present on the VE or only go a HSV 3.23
ratio.
The next step forward was
needed so it was time to remove the engine and slip a small
camshaft into it to unleash the potential of the new L98
motor in the VE. Given the superior breathing
characteristics of the L98 with its new head compared to the current HSV LS2 which uses the same basic head
as the old LS1 , it was decide to go with a custom grind
224/228 cam developed by
John@StreetQuick Performance that showed great top end
gains but without sacrificing any bottom end torque as is
normally found with this size camshaft.
We have seen way to many
cam conversions on LSx engines where the engine has suffered
low oil pressure symptoms so it is cheap insurance to remove
the motor to do the cam change. This enables the sump to be removed
so the
oil pump pickup can be aligned properly when doing a cam
change. It also allows the cam to be dialed in properly
which is very hard to do properly when doing a cam change
without removing the engine.
While the cam was being
done a double row timing chain was fitted to ensure long
term accurate valve timing as well as a mandatory valve
spring change as the LSx engine is prone to weak valve
springs .
A few days where spent
fine-tuning the PCM calibration to ensure that the engine
runs as perfectly under every situation , with maximum
performance and efficiency in mind. The engine now starts
and idles as smoothly as a stock engine but with a slight
lope to the idle indicating the potential lurking under the
hood , open the throttle and the engine just keeps pulling
all the way to the new higher rev limit with the power
seeming to just keep on going. Midrange torque and top end
power have hugely improved with day to day driving in
traffic a pleasure , so much so that any excuse is found to
take it out for a drive and listen to the sweet exhaust note
and feel the power underfoot.
Time to take it back to
the track , first time out the car reeled of a
12.1@118mph and then
proceeded to back it up with 12.1 sec passes at will.
Bang for buck what an improvement dropping over 1/2 sec and
picking up 8 mph while
returning awesome street manners .
With the car finally
performing it was time to add some bling , after a few
aborted attempts at ordering rims and giving up waiting for
them to arrive we spotted a set of DTM Flairs on the
showroom floor that gave the aggressive stance and look we
were after.
.
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