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 old.

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 curve profile.

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 accurately evaluated. 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).

Conclusion

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.

Copyright 2002, Temple of VTEC