issue we addressed the exhaust deficiencies of the GENIII
and managed to meet our target of exceeding the power of
a GTS , at the same time providing a real low down torque
increase over both the std Monaro and the GTS.
both at the drag strip and on the dyno showed that we had
a intake problem , both in terms of heat buildup and intake
the Monaro intake system is better than the STD SS it had
some flow issues and was drawing excess heat from in the
engine bay , especially when the A/C was on. Initial testing
using the dynamometer data logging of intake pressure showed
we were drawing a vacuum under full load still . Ideally
the full load intake pressure should be the same as atmospheric
pressure if the intake is working correctly.
first test was to check if the air filter was a restriction
, tests were conducted on a new std air filter element ,
a K&N element and no element at all to see what benefits
we could find. Testing showed that a std air filter was
as good as the K&N and no element at all, obviously
after 5000kms of use the std filter would be blocked more
than the K&N so we elected to keep the K&N in as
it has the added benefit of being able to clean it at will
and being reusable.
it was time to look at the MAF pipe as it appeared to have
be a restriction in cross sectional; area , a Convoluted
pipe and a smooth bore 4" custom pipe and a new plastic
4" moulded pipe was trialed. Power gains were found
with all of the intake pipes but we elected to stick with
the Moulded 4" pipe as much for appearance sake as
the added power increase .We will use this same intake pipe
for all our testing .
tune was then optimized again to suit this new pipe as our
baseline , power had at this point picked up226.9kw with
the std air box modified and the K&N air filter installed.
air boxes were now tested , with our std Monaro modified
air box used as the baseline , and a modified HSV air box
system , power at this point was unchanged but the HSV box
produced a slightly lower intake temp consistently due to
it being better sealed around the headlamp than the std
Monaro CAI which draws air from around the top near the
radiator as well resulting in hot radiator air being ingested.
We also tested a popular widemouth CAI but found large horsepower
losses above 4500rpm due to a restriction over the radiator
cowling so we abandoned any further testing.
MAF at this level has become the next restriction so it
was time to remove it. On a manual this can be done as the
GTS runs without a MAF std but on a auto the original
coding has no input for this and the auto box will not change
gears properly , locking itself in 2 gears. A intensive
disassembly of the operational code in the ecu was required
, resulting in Daniel rewriting the code to allow auto to
function properly without the MAF.
a couple of sessions on the dyno to optimize the fuel curve
as we were now running in speed density mode rather than
MAF mode the power had suddenly had a huge increase , further
optimization of the tune resulted in 241.8rwkw , some
minor intake restrictions where still present and as we
had seen minor power gains from running with no air cleaner
it was decided to test again with a large K&N pod filter
to see if the extra surface area was going to help. Power
jumped again to 248.2 rwkw after a mild session reoptimization
the tune to suit the increase airflow. This created a dilemma
as a pod is ok on the dyno where it can be positioned to
get some cold air feed to it but on the road with the bonnet
closed this would not work so a complete air box was designed
to house the pod still utilizing the seal around the headlight
to draw air from under the vehicle ( we could have cut big
holes in the body but that went against our idea of keeping
the car street legal as there are issue with cutting in
the engine bay due to it being a crumple zone)
we tried a larger throttle body , on the GENIII the manifold
is necked down to 75mm on the opening and there is no real
way to overcome this so we looked at various Throttle bodies
on the market and utilized one that was 84mm on the entry
and had a larger area as it passed through the throttle
blade before squeezing back down to 75mm at the neck , this
helped to funnel the air into the manifold and elevated
the throttle blade and shaft restriction. Minor power gains
were found with peak power coming to 251.2 rwkw
all the spark and fuel mapping modified to suit it was time
to hit the road and optimize the transmission calibration
to get the shift points were we wanted them and to optimize
the shift pattern for the street as well as the drag strip.
mode became our auto calibration for normal street use and
power mode became our drag strip mode with hard crisp shifts
and increase shift points to suit our new found power. power
mode now resulted in the car turning the tyres hard on the
street in every gear change so it will be reserved for the
track as it would be lethal in the wet as it is.
to head to the track and see how it had all panned out,
first pass out resulted in wheel spinning
passes later and out sixty foot times were going backwards
due to the wheel spin so it was back to the workshop to
try and find a solution.
slicks at this stage would solve the problem but our aim
is to see how far we can push the std car so it was decided
to try and tame the low down power output at the track ,
a careful look at the data logging using efilive showed
that traction was being achieve once the car go to the 330
foot mark , so if we could limit the power output below
3000rpm the we should be able to get the car off the line.
A careful detuning session resulted and we headed down to
the track again.
did it , the car was now running 12.98@109
mph , making it the fastest std LS1 in the country , with
no slicks , no converter , stock suspension , stock motor
and a careful approach to bolt ons and tuning.
also believe it is the most powerful Stock LS1 at present
especially in auto trans format having lifted power by 83kw
at the back wheels , with a corresponding lift in torque
right through the whole rev range.
issue we will take the leap and see how a new Dominator
hi stall converter will affect the drivability of the car
and the 1/4 mile times - naturally slicks will now be required
as it should really push the engine into its meaty part
of the power curve. Then hopefully we will look at opening
the Motor up and fitting a head and cam package
Here for Part 3