Technical Information L15B Turbo Civic tuning
Recently added tuning capabilities
The related parameters and tables below are effective in software version 184.108.40.206. or later and represent the Hondata Engineering Team's newest developments for the L15B7 engine as of 02/08/2021. We have provided dyno charts for your reference and are committed to continuing the quality, development and updates that set our products apart, again here in the 10th Gen Civic.
Check back on this page, as we add dyno charts to illustrate injectors phase, cam angle and fuel pressure testing.
Artificial Knock retard
The base Civic has artificial knock control. When this is disabled the base Civic (non Si) gains power due to more ignition above 5250 RPM.
Stock, artificial Knock control
Artificial knock control disabled same car
In this example a base Civic running at maximum boost gains 18 hp. Gains are higher with bolt-ons.
Fuel Pressure tables
• There are two fuel pressure tables. MT vehicles and 2016 CVT models use only the low temperature table. Other CVT vehicles use the low temperature table when the ECT is below 0C, then interpolate between the low and high temperature tables until the ECU is 55C, when only the high temperature table is used.
• Some CVT vehicles have increased fuel pressure on the low temperature table at medium rpm and high load. Presumably this is for cold start emissions.
• Increasing the fuel pressure will shorten the injector duration, which may be advantageous if the injector duration is long enough to encroach on the spark event and cause a misfire.
• Increasing the fuel pressure will not increase the amount of fuel, because the maximum fuel delivery is determined by the mechanical fuel pump. By increasing the fuel pressure the HPFP volumetric efficiency decreases so the maximum fuel amount is decreased.
• Increasing the fuel pressure can improve atomization. We have sometimes seen top end power gains.
• Decreasing the fuel pressure can sometimes improve fuel flow due to the mechanical efficiency of the pump in cc/stroke as outlined above. We have sometimes seen mid-range improvements.
• The L15B runs 180 BAR DI fuel pressure stock. Increasing the pressure places more load on the pump, engine and DI camshaft lobe.
• For the Si the pressure relief operates at 240 bar. For the non-Si the pressure relief is at 230 bar. Above 230 bar for both Si and non-Si an error and pump noise is generated, which is to be avoided.
With a mechanical fuel pump the pump volumetric efficiency decreases with both rpm and pressure. So if the pump can flow 0.75cc per stroke at 100 bar it may only be 0.65cc per stroke at 180 bar pressure. So increased pressure will not give you more fuel, but increasing the fuel pressure will shorten the injector duration. See the injector phase section for why this might be a good thing at times.
The injector phase aka injector timing aka start of injection (SOI) tables determine when the injectors fire. Not how long they fire, but when they start and end injecting. For a direction injection engine the injection event is during the intake and compression strokes. You do not want to start injecting too soon, as some of the fuel will go out the exhaust. You do not want to inject too close to the spark event, because the fuel does not have time to mix completely in the combustion chamber and a misfire will result. The last problem is more serious than the first problem. As the injection duration in crank degrees gets longer (high rpm, high flow eg ethanol) the misfire possibility becomes a problem. In this case it is best to advance the injector timing to prevent a misfire.
We have added only the WOT injector timing tables. For people that need to advance the injector timing to prevent a misfire the table values are degrees where negative values advance. We have found that subtracting 40 or so degrees above 5500 rpm is beneficial for engines with a long injector duration misfire problem. We have also found that advancing the injector timing at lower rpm will delay turbo spool and reduce power.
We have added intake and exhaust cam angle tables at WOT. These tables become active at approx 60C ECT but we do not believe that anyone is going to try to tune WOT tables for when the engine is cold. For big turbos and higher rpm limits some gains can be made by preventing the exhaust cam from rolling back to 0 above 6900 rpm, which presumable was added by Honda to roll the power back even through this is past the stock rev limiter.
Knock Cylinder sensitivity
Paired cylinders 1+4 and 2+3 can now be tuned for sensitivity. Useful for built engines or where you suspect artificial knock. Must be used with the artificial knock control disable. Small numbers are high sensitivity.