Tuning the Singapore-Market EG9 Civic VTi
Mike has been a TOVW regular for many years. Recently on a business trip to
KL, he drove his black EG9 here. Once business matters are covered properly Mike
made an appointment with Aerotech here to dyno his car, principally to know the
power he is generating at the wheels.
Mike's SDM EG9
Mike's car is what can be termed moderately modified from stock. Mike
stuck with the more established brands for most of his aftermarket parts.
At the time of the dyno session, Mike's EG9 has a K&N FIPK, a full
Tanabe headers and exhaust system, a TRUST lightened flywheel, an
otherwise stock but ported engine head (done when he had to replace a
blown head gasket), a Field SFC controller, an adjustable fuel pressure
regulator, and an aftermarket ECU.
In addition, Mike also installed the Cheetah series of ignition
modifications, which includes adding an external ignition coil with a
modified distributor cap and silicon plug leads.
A chat with Mike before the dyno session revealed that all he expected was a
simple power dyno. The B16A in his generation Civic is spec'ed to deliver 160ps
at 7600rpm. Mike's EG9 has a manual transmission. For front-wheel drive,
Aerotech's guru Rennie Khoo told me this will incur a typical 13% - 15% power
loss. Using the worst case, this will translate to about 136ps at the wheels for
a stock 160ps B16A.
From previous dynos, Aerotech says a typical JDM B16A
will dyno between 125 to 135ps at the wheels, the variation probably due
to manufacturing tolerances as well as the engine's state of health at the
time of dyno. However I do have reports of dyno runs of 140ps or more from
owners. Due to engine age, Mike is merely hoping to dyno at least 160ps
from his engine. Assuming a gearbox at peak condition, this will translate
to around 136ps at the wheels. Based on the amount of mods done to the
engine, this should be achievable even though the engine is almost 7 years
Turning the Dyno session to a Tuning session
At the appointed time, I met Mike at his hotel and we drove to
Aerotech. After taking care of some logistics, the car was strapped down
to prepare for the dyno-run.
Upon opening the bonnet and examining Mike's engine mods, Rennie
offered Mike a tuning session instead of the plain power dyno. This
is because Mike has the SFC and adjustable fuel pressure regulator. When
installing these two mods, Mike had tuned them using the 'butt-dyno'
method, ie by feel and also by doing full throttle runs. A Dynojet
facility will actually allow them to be properly adjusted for optimal
power gains. Mike never realize that the Dynojet can be used for tuning
and immediately took up the offer.
The first dyno-run was to establish the current power of the engine. This
came out to 137ps at the wheels, ie as good as a brand new engine ! Subsequent
tuning will now build on this as the base-line, the objective being not only to
increase the max power but also the overall power delivery, ie the actual power
First to be done is the adjustable fuel pressure regulator. Finding the
optimal setting for the FPR involves first arbitrarily increasing the fuel
pressure by a half-turn and doing a dyno-run. This actually showed a loss in
power, ie the engine is now running too rich. Subsequently the FPR was set at
half a turn leaner than the original setting. This now showed a power gain. The
FPR was further adjusted and the results carefully dynoed to derive the optimal
fuel pressure setting.
The SFC controller was next adjusted. Adjusting the SFC is a more complex
task as it allows the MAP sensor signal to be modified for several 1000rpm
interval bands. In addition, the Honda stock ECU uses an averaging algorithm to
provide some smoothening effect so sometimes making an adjustment in one 1000rpm
band will have an impact on the adjacent bands. Knowing how much and
which band to adjust requires a lot of knowledge and expertise, including
the extremely complicated task of analyzing the dynoed power curve based on the
adjustment just made in order to decide which 1000rpm band next needs to be
tuned and by how much. The Field SFC is not an Aerotech product and thus Mike
was required to do the settings on the SFC based on directions from Rennie.
Finally ignition timing was adjusted. Adjustments were made in steps of
1 degree on either side of the stock timing and the Dynojet allows the
power gains or loss from each adjustment in ignition timing to be
The result of this tuning allowed Mike's car to finally dyno at 142.5ps
at the wheels. This is a big 5ps gain from the base dyno-run. This gain is
consistent across the top 500rpm band. More impressively, the tuning also
resulted in power gains all the way from 3000rpm up till the 8000rpm
redline. This represents a huge gain in overall power and driveability
especially for full throttle accelerations from medium cruising speeds
typically needed for expressway overtaking maneuvers.
As an interesting aside for this tuning session, I took the opportunity to
test for the repeatability of the results of my spark plug cable
test. Recall that a dyno test of three spark plug cable on a B16A engine; a
typical 8mm silicon cable, the NGK blue cable and a pair of 8 years old
stock cable; showed no difference in dynoed power all across the rpm
band. In fact, the generic 8mm silicon cable lost 1ps at the top end while both
this and even the much vaunted NGK blue exhibited misfiring characteristics at
high RPMs that the stock cables did not. I was eager to know if that exercise
was an isolated case. Though I did not ask for the dyno printout primarily
because I was not paying for the tuning session, changing the plug cables in
Mike's car back to stock also did not show any significant difference in
dynoed power. The power curve was almost identical while no misfiring was
evident. One big difference in this case is the use of an external ignition coil
together with an extra ignition cable from this coil to the modified distributor
cap. The effect of this part of the ignition mod is unknown.
Since Mike's adjustable fuel pressure regulator has a fuel pressure gauge
attached, I checked the fuel pressure before and after the tuning session. The
standard use of the FPR was to increase the fuel pressure primarily based on the
presumption that a richer air-fuel ratio means more power. In any case, this is
a misconception because max power usually derives from an optimized
air-fuel ratio and not an overly rich one. The original butt-dyno setting on the
FPR was more than 4 bar and the optimized setting from the tuning session reset
this to around 3.6 to 3.8 bar (loaded). However I would like to caution that
this pressure range is probably optimized only for Mike's setup because I
do have reports from other users of a higher setting of more than 4 bar for
their cars (also derived through a dyno tuning session).
Mike was indeed happy with this session especially with the discovery that
his car can be tuned using the dyno. In a discussion with Aerotech later, Rennie
did express the opinion that all he did was to re-tune the engine back to
original condition, cautioning that the use of the adjustable fuel pressure
regulator and the SFC controller may not be fully responsible for the
very impressive 5ps gain. Thus, the original settings arrived at using the
butt-dyno method was simply to 'de-tune' the car by making it run too rich - a
normal mistake made by owners. The tuning session on the dyno had actually
allowed us to regain 'lost' power by allowing the FPR and SFC to be reset back
to optimized settings.Note : Special
acknowledgement to ChongCH from Singapore who wrote in to correct my mistake in
quoting the FPR settings from psi to bar. According to Chong, the stock settings
for B16A are typically around only 3 bars. He also pointed out that there is a
difference between setting the FPR with and without load (ie with or without
attaching the vacuum hose).
Copyright 2002, Temple of VTEC