Dyno Plots

January 1, 2004

This page displays the dyno runs that my 1990 JDM Honda Civic SiR has had. At the moment there have only been two dyno sessions. I wish I had done more prior to some of the modifications to see what modification have and haven’t worked. The seat of the pants dyno has always registered an improvement but the seat of the pants dyno is known to be inconsistent…

All of the B16A dyno runs have been 4th gear sweeps on the ATEC rolling road dyno at Shore Performance & Parts.

July 2002

This second and latest B16A dyno run was to check the fuelling and see what differences the Ford XF throttle body swap had made.

Modifications since the original dyno run

  • Overbored (66.5 mm) Ford XF Throttle Body Swap
  • Custom 80 mm cold air intake
  • Adjustable fuel pressure regulator
  • Vent to atmosphere catch can
  • Removed backpressure restrictor modifications from the first B16A dyno run in July 2001

Peak dyno numbers

    91.5 kW (127 HP) @ 169 kph
    259 Nm (190 ft-lb) @ 169 kph

Note that these readings do not compute. The 91kW seems pretty reasonable given the modifications, but the torque number doesn’t compute given that the peak for both readings occurred at redline (~8000rpm).

    HP = Torque * RPM / 5,252

If the HP reading is correct then the torque reading should only be a meager 83ft-lb. Something is horribly wrong somewhere… Oh well, at least the plots can still be used for comparison against the previous dyno runs. I may have to get some dyno readings taken somewhere else to verify what the actual numbers are. There are several shops in Auckland here that have Dynojet dynos so I may have to book a run on one of those.

July 2002 dyno plot

Below is the dyno plot that was recorded during the session after the fuelling had been checked. There were actually two runs done on this occasion, the second one being done after reducing the fuel pressure. Originally I had it set at 45psi until I knew that it wasn’t going too run lean. Since it was running very rich at low throttle angles on the dyno I dropped it down to 42psi without any problems. Now the car seems to be running fine without going through too much gas. In fact, I often get better mileage than what I used to.

July 2002 B16A Dyno Plot

Comparison with previous dyno plot

Below are the plots showing the comparisons with the previous dyno sessions. For some reason the torque and power curves represented by 001 don’t look much like the plot I got originally. I am not sure why that has happened, but the torque curve is much better at the VTEC crossover point and in the higher RPM range. I am not sure what reduced the torque hole near the VTEC crossover point, but I suspect the removal of the backpressure restrictor help. The backpressuer restrictor is basically half of venturi, so it’s essentially a cone pointing in the direction of flow to reduce the cross sectional area (from 62mm to ~32mm) thereby restricting flow and increasing back pressure. I think that this may have been causing some sort of bad resonance around the crossover point whilst also severely restricting exhaust flow.

The backpressure restrictor was originally put in by a local speed shop when I was having idle and hesitation problems after the swap, which they thought might have been related to a lack of back pressure. Later on it turned out to be because the oxygen sensors were installed the wrong way around. The PR3/PW0 ECUs use each oxygen sensor to determine the fuelling for two cylinders, so if they are the wrong way around all sorts of weird things can go on.

July 2001 vs July 2002 B16A torque comparison

July 2001 vs July 2002 power comparison

Latest impressions

The car pulls a lot better when VTEC kicks in as shown by the much improved torque curve near the crossover point. There is still a drop in torque at crossover, which probably overemphasizes the massive whack in the back that you get with the torque spike using a seat of the pants dyno. Passing cars on hills now is far better than what it used to be like. There has been a small reduction in torque down low, but not enough to be really noticeable. The car still accelerates in 4th gear at 60kph so I am happy with that.

July 2001

This first B16A dyno run was done after the second generation B16A engine swap. The dyno session was to primarily to check the fuelling to make sure the ECU was coping with the big new exhaust. It also served as a baseline for the future modifications I had planned.

Modifications to stock

Original dyno plot

Below is the dyno plot that was recorded during the dyno session after checking the fuelling.

July 2001 B16A dyno plot

Initial impressions

The car feels quite good except for the massive torque hole near the VTEC crossover point. It is really noticeable passing cars going uphill. You almost dread the VTEC crossover because you know you are going to start going backwards. It’s fine on a flat road, but anywhere where you really need the torque is just not fun at all.

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