Advanced tuning

Honda Tuning with the Hondata K-Pro

Compiled by Conrad H. Blickenstorfer

The notes below are a summary of the training videos posted at Hondata's website. In those videos, Hondata's Doug MacMillan describes the tuning process. You see moving K-Pro screen captures with Doug manipulating the cursor and explaining, in audio, what he is doing. Each of the files is quite large and sometimes the explanations are a bit brief. This is where my notes can help. They also include my own commentary and experiences.

1 VTC Basics
The K-Series engine uses variable cam timing (VTC) and this is one of the primary keys to getting optimal performance from this engine. Cam angles can vary between 0 and 50 degrees. A zero degree angle means no overlap between intake and exhaust valve openings. Medium overlap lets some exhaust gases back into the combustion chamber, which makes for more complete combustion and less unburned emissions. Maximum overlap makes most power in most of the rpm range. However, there are reasons why the cam angles are set certain ways in the low-speed and high-speed cam angle maps.

The first thing to understand tuning with the K-Pro ECU Manager software is what the columns in the K-Pro Tables represent:

Cam angle theory is explained in the Hondata training videos via a low-speed and hi-speed cam angle map. Note that the the example calibration used for all training slides are for a supercharged vehicle and quite different from maps for a normally aspirated engine.

Looking at the low-speed cam angle map, the cam angle in deceleration columns 1 and 2 should be zero or close to zero. That way there is no cam overlap which is good for emissions. At cruise range, columns 3 to 7 and 1750-4500 rpm, the cam angle is set to 30 degrees. This means some exhaust gas recirculation. This is good for emissions because it makes for a more complete combustion. In the power columns 7 to 10, the angles advance from 0 to about 30, and then to (or close to) whatever value it is at VTEC, so that the cam does not have to rotate much when it switches from low-speed to the high-speed cam.

Looking at the high-speed cam angle map, above 6000 rpm all columns, even the deceleration and idle columns 1-4, have very high cam angles. That's because when we shift, manifold air pressure (MAP) drops into columns 1-4 or so, and we don't want the cam to rotate all the way back during a gear change. So we keep the cam angle at the same maximum advance, which is very good for power.

2 Tuning setup
Comprehensive tuning requires tuning of all six low and high-speed cam fuel and ignition tables. Successively lock the cam angle from zero to 50 degrees in steps of ten degrees. Then tune first the fuel and then the ignition tables. To tune the low-speed cam maps you set the VTEC point to 7000 rpm for normally aspirated and turbo engines (at 98 kPa) so that the engine does not switch to the high-speed cam during the run. For supercharged engines you need to set it to 5500 rpm because they build boost pressure very quickly on the low-speed cam, which is not good for engine. Start with the zero degree cam angle map. When tuning the high speed maps, you need to set the VTEC point low so that the engine gets into it at a low speed.
3 Tuning Setup
Before setting the cam angle maps to fixed values, copy the low speed and high speed cam angle maps into a word processor so that the values will not be lost. You can do that by simply selecting the whole map and then copy the area and paste it into, say Microsoft WordPad.

By and large, tuning will concentrate on columns 8 and above, the full throttle columns. Columns 1 to 7 will be left pretty much stock because the Honda engine runs well enough under part throttle, and because in part throttle the engine runs in closed loop anyway.

4 Zero degree cam angle map
Set all cam angles to zero for both the high and the low-speed cam. That way, the engine will always be at cam angle zero during the dyno and road runs. This allows us to create an optimal fixed-angle fuel and timing map for cam angle zero. Once that is done, we'll do the same for 10, 20, 30, 40, and 50 degree tuning.
5 Fuel map editing
The fuel maps are tuned first because having the proper air-fuel ratios is very important for best power and also for engine health and durability. To start the process, do a dyno run and see what the air-fuel ratios are through the rpm band. Then adjust fuel to get to the proper target AF ratios. When tuning, always select and change rectangular areas in the tables. That way all fuel lines remain parallel. Smooth fuel curves run a lot better than bumpy ones. Once the curves are all done and the next dyno run shows the air-fuel ratios we want, first increase and then decrease fuel for the entire table by 5% and do additional dyno runs to see if we get more power.
6 Road and dyno tuning the 50 degree map
A comprehensive tune includes both dyno runs and road tuning. To get fuel right for, say, the fixed 50 degree table you may datalog a full throttle second and/or third gear run from 3000 to 8000 rpm. You then analyze the logs and may find lean spots and spikes due to special modifications on a car (in Hondata's example, the car has a Jackson Racing header, ITR exhaust and manifold, etc.). You then add fuel in the spots where the air-fuel mixture is lean (adding fuel for all columns, and flattening some lines), and do more runs to see the effect of the corrections. If the AF ratio is still not right you make additional changes until it is in the desired range. All in all expect perhaps three road runs and one dyno run.
7 Ignition tuning and knock:
The goal of ignition tuning is to have ideal ignition timing advance with minimal knock count.

Getting the optimal ignition advance is key to getting the most performance. For that, you highlight columns 7-10 for all rpm, then add two degrees of ignition advance and see if performance increases, and whether or not the engine is knocking. If power increases without knocking, add another two degrees. Once best power is found, reduce ignition advance by two degrees for optimal reliability. To be right at the point of maximum power puts substantial extra stress on components. Do this for each cam angle, both low-speed cam and high-speed cam.

Knocking is caused by too much ignition advance and bad fuel. It is also worst when going uphill when the engine gets hottest. The answer to knocking is to retard ignition or get better fuel. The Hondata training example showed a datalog of a supercharged engine with significant knocking in some areas. To eliminate that knocking, select a rectangle of data points at that area, then reduce ignition by 2% or so. Test to see if the knocking is gone. It is possible to eliminate knocking in certain spots while still advancing ignition?

What maps are we starting from? With the K-Pro, either with the factory maps or Hondata calibrations, if available. It is probably possible to create maps solely based on experience or knowledge of ignition timing principles.

8 On the Dyno
Once all fuel and ignition tables are optimized, set VTEC to 3000 rpm and do six dyno runs at fixed low-speed and high-speed cam angles of 0/10/20/30/40/50 degrees. The result is a dyno sheet that shows the torque and hp curves for all of those fixed cam angles. In general, the zero degree curve will show lowest power and the 50 degree curve highest power. When analyzing the results, concentrate on the torque curves because their resolution is higher and they are easier to follow. (Note that the resolution is higher for torque because they used a Dynapack where torque and horsepower are shown in two different windows so that torque min and max can be set separately from hp min and max.) Anyway, analyzing the runs tells you at which cam angle the engine makes most power at each rpm range.
9 Making composite cam angle map:
Now we can use the information from the fixed cam angle dyno runs to create a composite cam angle map. The idea here is to use for each rpm range the cam angle that produces the most power.

To create that optimized cam angle map, start with a stock high-speed cam map and then change it to the optimal cam angle values. In the Hondata example, up to 6000 rpm Doug MacMillan set the angle to 50 for columns 7 to 10 because the 50 degree cam angle provided best power. Then he noticed that 40 degrees made most torque to about 7700 rpm, again for columns 7 to 10. Above that 30 degrees made maximum power and he set columns 7 to 10 to 30 degrees. Now he commented that the steps may not be optimal and the curve could be smoothed so that the cam does not have to move in such big steps, You can also use the interpolate function to make the steps even smaller.

Next we want to see if we can squeeze a bit more power out of the top end. To do that we do two more dyno runs with 25 degrees and 35 degrees at the top end to see if power increases. Then he made more runs with 6250 up to 11000 plus and minus 5 degrees to see power. (He did not say what to do with columns 1 to 6, though it looks like he left the stock angles in high speed cam alone between 3000 and 5750, but set them all the same as for columns 8 to 10 above 5750. Also I am not sure if the same process applies to the low-speed map.

10 Putting it all together:
Once the high cam and low cam composites have been created, we set the best VTEC point, which is the point were the torque curves cross. In this example that point was at 4300, which becomes the lower VTEC boundary. Set the upper VTEC boundary pretty close to stock, i.e. something like 5800. This way, the car will go into VTEC at 4300 at full throttle. At part throttle, it will go into VTEC at higher rpm. In supercharged engines the VTEC point can be much lower, under 3000 rpm. Turbo cars, on the other hand, want a VTEC point of 5-6000 rpm. Now we have to make sure that the cam angle in the low speed map is close to the cam angle in the high speed map at the switch-over point. If that is not the case, the cam will have to rotate to go from a small angle to a much larger one. That takes time and can result in a power dip.
Wideband tuning:
Since the Type-S has a wideband oxygen sensor you can use a datalog to adjust the AF ratio. Run in closed loop (shouldn't that be open loop?). Set Tables to follow VTEC and cam angle. To examine the data, use a graph with RPM, A/F and K.Count. In the example, Doug found a lean spot and then adjusted a whole column 1 to column 10 rectangle upwards 5% fuel for a single table. Using % adjustment preserves the shape of all curves, so that they stay parallel and do not cross. On the high-speed cam Doug found a big difference between columns 10 and 11. Instead of adjusting column 10, he just copied column 11 and pasted it into 10, then decreased column 10 by about 7%. He found a knock at VTEC but commented this was not a problem and perhaps just some VTEC noise that the sensor picked up.
Tuning for fuel economy:
There are two ways to tune for fuel economy:
  1. Advance the ignition in the cruising area (columns 3-6 and 2250-5000 rpm). That way the engine makes a bit more power and we can give it a bit less throttle, which means less fuel consumption.
  2. Make it run leaner in the cruising area (columns 3-6 and 2250-5000 rpm). However, this only affects open loop. In closed loop the ECU will correct to 14.7.
Caution: you need to know what you're doing as car is very sensitive to knock. A real long cruise afterward such adjustments will show if the engine is knocking.
Nitrous/alcohol:
The K-Pro supports nitrous and alcohol injections, even in conjunction with supercharging. This is done via a Nitrous section in the parameters control panel. The K-Pro is also used to activate and disactivate nitrous (only, of course, after the overall nitrous system has been armed).

Enabling nitrous/alcohol in the Parameters control panel means that there is an input (K-Pro uses the power steering pressure signal) and an output (K-Pro uses the EVAP vent signal) for nitrous. If certain conditions are met (engine speed and load, throttle, vehicle speed), nitrous comes on. If it does, fuel will be added and ignition retarded. Assuming you use a dry system, start with adding a lot of fuel, then tune back.

Overall, with nitrous you want to add fuel and retard ignition. For a small (30-50) shot, retard by 2 degrees, for larger shots (75-100) retard 4-5 degrees. As for fuel, imagine this: If you have a 200 hp engine and you add a 100 shot, you have a 300 hp engine, and need to add 50% fuel. If the fuel value in column 10 is 2400, 50% of that is 1200. So you add that to "Fuel enrichment" in the Parameters>Nitrous panel. Typically, you need a good deal less, perhaps 400 to 600 more. Start rich, then tune back. The reason why fuel is added here and not in the fuel maps is because we only want the extra fuel when nitrous is activated. The ignition is retarded because nitrous burns much quicker, so if the same advance is used, the flame front hits the piston still on its way up.

Hondata recently commented on this: "If 4 degrees is too much timing in one part of the rev range, then retard the ignition more. Since this is nitrous and you want to be a little conservative, you add fuel based on the leanest point and likewise retard the ignition based on the most retard you need. Typically you're retarding 4-6 degrees on the ignition. The nitrous control was designed for a dry shot up to around 150 hp. It works fairly well using a set amount of fuel and a set ignition retard, with the engine running a little rich at first on bigger shots.

With alcohol, since it is a fuel, you actually subtract fuel and advance timing because alcohol is very knock-resistant.

Note: According to Mike Kojima in "Honda/Acura Engine Performance," the stoichiometric ratio for complete nitrous combustion is about 9.7, which means that the air-fuel ratio should be around 8.5:1 during spraying. It is easy to see why larger injectors are needed.

Questions/comments? Email me at cb@pencomputing.com