Complementary Performance Mods

The performance of a car is not determined solely by its engine. The rest of the car is also crucial to its overall performance and like all knowledgeable enthusiasts, Lyonel pays equal attention to these parts as well.

First to come under attention is the suspension. Unlike later generation DC-Integra and EG-Civics, the DA-Integra is rather unusual in that it has a suspension that is not compatible with its "smaller" brother the EF-Civic. If fitted with EF or EF-compatible shocks/springs, a DA6 will ride so low that the wheel well rests on the tyres !

Lyonel fell back on properly designed suspension components for his DA6. Shocks are the popular Koni Yellow, adjustable for rebound only. Koni Yellow comes with a choice of spring perches, which allows a few levels of pre-tension of the springs to be set when they are installed into the shocks. Setting the pre-tension allows some mild adjustment of the car's ride height but more importantly allows the suspension compression rates to be adjusted as well. As expected from his track-usage, the springs are Neuspeed racing springs.

The suspension and chassis mods includes:

• - Koni Yellow adjustables
• - Neuspeed Race springs
• - Z-Speed front and rear strut tower bars
• - 16" Daytona Speed / 205/45 Toyo T1S for street use
• - 14" Volk Racing NRS / 195/60 G-Grids for track use

The strut tower bars are not installed in the car when the picture of the engine bay above was taken. Note the use of two separate set of wheels/tyres, one for street use and one for track-use. Stock tyres for DA6 are sized at 195/60 HR 14. This means the Daytona/Toyos street wheels used by Lyonel are a little bit oversized. But 16" rims will contribute significantly to the look of the car.

The cabin/interior of the car is also in immaculate condition and Lyonel have changed both the steering wheel and the gear shifter. The steering is what Lyonel describes as a "sport type", smaller in diameter and contoured for better grip. The shifter is a C's Sports Shifter; the shifting stick is shorter and the pivot point is moved, both leading to a shorter shifting distance. This effectively gives Lyonel a 'short-shift', standard issue for all super-cars and racing cars. The DA6 Integra XSi however does not come with a shifting mechanism designed for short-shifting, so a downside to the C's shifter is that shifting effort is increased. But in return, the shifting efficiency is improved since each gear shift requires less distance. In reality, this sort of mod for the DA6 can also be considered for track-use.

The Dyno Result

Lyonel dynoed his car during the same session as his friend Tamati, on the New Zealand designed Dyno-Pack dynamometer as explained in our previous article. So the conditions during the dyno-run will be similar to that for Tamati's car. To re-cap, it was raining at the time of the dyno, with ambient air temperature around 16-17 degrees Celsius. However I do not know if Lyonel dynoed his car with the bonnet closed or opened.

As explained in our first article on Tamati's car, the Dyno-Pack measures power through an electrical device mounted to the wheel mounting lugs. Although this method also measures power at the wheels but because the wheels are taken out for the dyno, it will also disregard the effect the wheels have on the measured power. I.e. the power loss due to wheel inertias are not measured in the result. As a result, after some reasoning, I thought it would be more accurate to use Tamati's result - 138ps at the wheel-lugs as the baseline for a stock 1G B16A when measured on a Dyno-Pack dynamometer. 138ps works out to around 14% power loss, so for Lyonel's car, I will use this value as the power loss benchmark instead of the 15% value that we have been using for Dynojet results.

This article is our first look at bolt-on modifications to a B16A engined Honda. As a result we do not have any reference figures to work out some power expectations for Lyonel's engine using theoretical calculations. Rather, Lyonel's car/engine will actually be the basis for us to work out a reference for expectations of power gains from bolt-on mods on a B16A in good working condition. In this case, in my opinion, we will get more of an upper bound for this reference level since Lyonel's engine has some mods that are biased towards racing use and not all owners who uses their car for purely street-use will be willing to adopt them.

The DynoPack result for Lyonel's car comes out to 112.6 kW which translates to 153ps. Using a 138ps baseline reference as explained above, this works out to a 15ps or 11% power gain. Using the 14% power loss value, 153ps now works back to approximately 178ps at the engine, 18ps gain from the 160ps spec'ed stock power of the 1G B16A !

While an ideal situation would be if Lyonel also did some fuel tuning using an air-fuel regulator like HKS' S-AFR or A'PEXi's S-AFC, nevertheless the DA6 PR3 ECU is quite flexible and would have largely compensated for the extra air-flow of the mods, leading to a very good increase in power. The use of the N1 straight-flow exhaust in particular, will really help in air-flow and therefore power increase compared to items which are designed to obey more domestic noise restrictions.

An interesting theoretical consideration will be to try to work out how much power gain removing the air-conditioning system have given. Even when not in use, there would be power drop due to parasitic losses from driving the compressor. How much parasitic power loss will be 'regained' by removing the compressor is an unknown factor. However I have personally witnessed an unusual case where a Malaysian Proton Putra (also sold as the Proton Coupe in the U.K.) was first dynoed without knowledge that the belt driving the alternator has snapped. Subsequently a new belt was replaced and the car re-dyno'ed again. On a Dynojet, the difference in power at the wheels was around 2ps. If we take this as representative, removing the air-cond compressor from the engine might probably also allow an extra 2ps gain (or more accurately, regain 2ps of lost power from the engine).

Conclusion

153ps measured on the Dyno-Pack works out to almost 178ps at the engine. All from a 1G B16A that is already 11 years old and with only bolt-on mods. This is a great achievement indeed !!

If we take a close look at all factors, three are particularly significant to Lyonel's very good power gain; the very favourable weather condition, the N1 straight flow muffler, and the removal of the air-conditioning components. These three combined can well attribute for quite a few of the large 15ps gain that Lyonel achieved.

Nevertheless, even though there are factors that worked in Lyonel's favour due to his biasness for track-usage, this case have allowed us to set a upper bound for expectations of power gains from a bolt-on mods package to the 1G B16A at 11% over the base reference power, which is a high figure indeed.

Wong KN
February 2002
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