K20C1 Camshaft Testing - Unlocking the RPM, sound, and power we all love in a Honda Racing Engine
For 5 years now we have been supplying K20C1 racing engines for a variety of race series and sanctioning bodies worldwide. The trick with most of these is that they all have some sort of power restrictions to level the playing field of all the cars, and basic setups easily produce that limited power level that is typically around 300hp. However, one of these projects did give us the freedom to explore a higher rpm and higher output in an endurance application….although with some turbo size and boost pressure limitations. This set us down a path further exploring horsepower elsewhere in the engine and ultimately into what you see in our 4P CNC cylinder head paired with a racing camshaft.
Since a majority of our work is with race cars, they don’t have a lot of the factory systems, ECUs, intakes, and all of the challenges that come along with that. We decided to take some time and put what we’ve learned from the race programs into a basic street car application and see how they played out. Over the past three years we have worked with over a dozen different camshaft profiles to pinpoint characteristics that we want in a performance engine. For this particular test, we tuned both on an OEM ECU with aftermarket software and a motorsports ECU. This test took us 4 weeks to complete as we degreed all camshafts into engines to check clearances and map out VTC that could be achieved, then swapped the cams themselves into the engines that are in the cars. Each cam swap into the car took roughly 2.5 hours in the stock car, and 1.5 into the car that has less “stuff” in the way. For a first time swing at it, consider that it may take you an extra hour over that to do the install.
Note 1: Any time you read a dyno test, you need to keep an open mind and consider that dyno tests are only as good as the operator and the conditions that they are tested in. They are often used as marketing tools and best case scenarios are typically presented. Dyno numbers can be manipulated, period. We do take a lot of pride in how we test on our dynos and how the test parameters are controlled so that we see the true effects. Rather than taking the worst baselines and laying them over the best pulls from the cams, we tried to take the best averages so that we aren’t fooling ourselves (or you) on the results.
Note 2: We did make sure to control intake air temperature and our test conditions in the building to minimize variances. Although the dyno weather station does take care of correction, the less we rely on it the better. Intake Air Temperature (here forward referenced as IAT) affects these cars a considerable amount, so keeping that consistent was key.
Note 3: We tried to match before and after tests with equal boost pressure throughout the entire pull. In some cases this meant pulling the boost back so that we could better control the wastegate and more repeatable results. As much as we wanted to turn the power up as much as we possibly could….it’s a camshaft test and we are trying to show the gains from the camshaft alone and not simply maximizing the tunes. This was one of the bigger challenges. We did have to throw away some dyno pulls that were exceptional due to them having lower Intake Air Temperature or spikes in the boost control, which resulted in higher horsepower output.
Test Car 1: Stock Civic Type R
Test Car 2: Built 2.0L Engine, 4P Ported Head, Borg Warner 7163 turbo, XDI Fuel System, Motec ECU
About the camshafts
We narrowed this test down to the best performing “drop-in” camshaft of the bunch, and the best “mild race” camshaft of the bunch. What we consider a “drop-in” camshaft is one that you can install into a stock head using a stock valve spring. These cams still require limiting of the VTC gears so that piston to valve contact doesn’t occur. Even minimal changes in lift and duration in these engines require you to limit the variable camshaft so that you do not have valve to piston contact. We did all of the original testing on Motec to eliminate cams that didn’t perform, and keep the best performing profiles. I am most familiar with that software and we don’t have to work within the confines of some of the Bosch background programming to make sure we chose the best profiles. I will refer to the cams in this test as the names below.
TR2 – Drop in
TR3 - Mild Race Profile, Requires Valve Spring due to coil bind
TR4 – Race Profile (the TR4 test will be covered in another blog as it is more complicated to install and requires Motec or other motorsports grade ECU)
All Tests were performed on Pump Gas from our local Speedway Gas Station
Test Car 1 Tune Summary
BELOW: We did a baseline dyno pull on the stock car. It is a low mileage 2017….sort of our bubble wrap car. I only show this to give baseline reference for our Dynojet 224. This is 100% stock to 6800 rpm.
BELOW: We installed Hondata and an exhaust and made a baseline pull on the shelf mapping. This car for the remainder of this test has no other bolt-on modifications. Stock airbox and filter, stock intercooler, stock pipes, stock fuel system. The 339 with Hondata is a healthy gain over the 287 baseline. Rev limit was increased to 7200 rpm.
BELOW: The dyno below is after some tweaking of the tune from the standard basemap. We actually pulled some boost out to make sure we could match it with the camshaft later, and added a little timing for the small increase in power. Logged boost pressure is 24psi tapering to 21psi, compared to above where we saw spikes to 26-27psi. This is our base that we are able to match boost pressure and IAT for a pure back to back.
TR2 – Drop In Camshaft
Josh and Justin degreed the cam into an engine in the build room to map out the valve opening and closing events. This involves not only checking piston to valve and valve to valve clearances, but also verifying the valve timing events at various VTC settings.
As we do in all of our engines, we mechanically limit the VTC capability so that a tuner cannot physically damage your engine no matter what they type into the fields in the mapping.
BELOW: This is as pure of a back to back that we can show. We did not take the lowest power that was achieved on the stock cam and lay it over the highest peak that was achieved on the Drop-in cam. We took the best averages to try to show a clear representation of the differences. We also had to sift through some charts that had lower IATs and Higher boost to get the best back to back….and of course we had some higher glory pulls in both scenarios.
The end result is +25-35hp throughout the powerband with the TR2 Drop In Camshaft. Idling the car you can hear a slight difference….slightly more crisp feel and drivability is like stock. VTEC engagement is where you notice that something has changed. It’s a much more audible crack of VTEC and then it pulls much harder through the top. Driving the car, it is power you can feel and it continues to pull hard to the 7200 rpm redline. Boost builds similarly, not much has changed there, and then the car just pulls harder and smoother to redline. It was easier to get repetitive smooth dyno pulls with this camshaft over the stock cams.
Notes: If you simply drop in a set of these camshafts with the stock ECU and your existing map…whether that is a basemap or custom tuned, you will see nothing and you will get VTC failure codes. There is a lot going on in the background of the stock ECU, and you have to make sure you don’t have parameters that are holding you back from seeing the potential of the parts. This may sound like basic information for guys that tune these cars frequently, but at some point people are going to tackle this themselves and wonder why they didn’t see gains. There have been similar instances with cylinder head porting where people install the heads and then toss in a box tune that they use on every other car and they don’t see gains. The CFM has been increased dramatically from 158 CFM to 280 CFM and the volumetric efficiency of the engine is has changed. We have changed the combustion event, and it needs to be tuned differently. The same goes for the camshaft…we are changing the VE of this engine enough that you have to tune the engine.
You also have to adjust your VTC tables or you will see errors. It may not do it initially on the dyno, but it will immediately once you are off the rollers. These are easily overcome. Since we are limiting the VTC to avoid piston to valve contact, you need to make sure that the ECU isn’t targeting figures that it cannot achieve. After installing the camshafts, you can make a dyno pull, datalog the VTC angles that were achieved, and go back into all your VTC maps and change the values to these “achieved values”. You have to adjust ALL tables. You will have success and no faults….very simple.
After completing this test on the stock ECU we did put a Motec on the car just to see if we had extracted best power. We were able to make another 10whp pretty quickly, although please take a couple things into consideration. I think these differences can be attributed to the following; #1 Being able to stay on target AFR consistently…the Motec has better pump control and does not see the pressure loss and fluctuations that we saw on the stock ECU in the upper rpm range. It holds the pressure more steady. Target AFR is exactly what we ask for, and it reacts instantly to target this. #2 My experience and faith in the knock control may be a contributing factor, although this 10+hp was actually achieved with a logged half psi less boost pressure and 1.5 deg less timing. I’m not sure that the logged data between the 2 platforms can be considered valid side by side. #3 There is no MAF restriction on Motec since it does not use it. We pushed the rpm a bit further with this ECU as well.
Note: We were not able to use the same VTEC engagement point on the stock ECU and Motec. stock was smoother with a lower engagement point, and Motec was a smoother power curve with the engagement higher. The power curves are comparable, boost and fueling is as close as we could get them. We did target a touch richer on the Motec at .81 Lambda, which did not work on the stock ECU (yes it is the same o2 sensor). The only notable difference here is that with the higher VTEC activation….it is dramatic to the ears. MUCH more audible and classic Honda VTEC crossover with the higher engagement point on Motec.
Also, you can continue to push the boost on pump gas past what we did here. In fact we could push peak torque to 420 lb ft even on pump gas and not experience knock…however we needed a boost level that was repeatable and we needed to keep the stock rods in this thing to the end of the test. If you continued to call for boost as rpm increases, then you generate considerable heat and knock. We pulled the torque curve back in the interest of not punching holes in the block.
Testing on this car is to be continued….we are waiting on a couple bolt-ons that are hard to get ahold of right now. We are searching for a good race MAF solution and have some basis bolt-ons to put on the car with an XDI fuel system. Chime in if you have a preference for intake, intercooler, and anything else you’d like to see go on the car……we will reinstall the stock cams and the drop-ins the same day for that test. We landed over 75 dyno pulls in the 375-390hp range on pump gas with this car, and typically on this dyno we would be targeting 355-360hp on a car with stock cams at these boost and ignition timing levels.
Luke@team4piston.com for test related questions.
Test Car 2 Tune Summary
4 Piston 2.0L Longblock
4P CNC Ported Cylinder Head
BW 7163 Turbo
One of the benefits of Motec for testing purposes is that we really get to see the gains immediately with nothing going on in the background. Rather than trying to “fool” or overcome programming that already exists from Honda, we are simply telling the computer how to run the engine. If our VE is initially “off” the ECU is fast enough to make changes and stick to the target AFR no matter what. It performs better when optimized, but the ECU makes the corrections we need. This allows for you to see the actual return from the parts right away.
BELOW: Right off the bat first pull with the TR2 drop-in, we see 40+hp gained from the camshaft and the extended RPM range. As soon as the car starts building boost, and prior to VTEC engagement, power is up +30, climbs to +40hp gained at peak, and is at +60hp by 7000 rpm….keep turning rpm and the gaps are larger. Hit the EASY button. Again…noticeably smoother power through the pulls on the TR2 vs. the stock camshafts as we observed on the stock car.
BELOW: Speaking of RPM…..we decided on one of the early pulls in the tuning process to swing it up past 8000 rpm to see how the cam would drop off if overspun. It looks dramatic in terms of speed…. +80whp at 7300 on its way to a hard and consistent pull to an actual 8300 rpm that was logged. The TR2 drop-in cam holds power solid if you have the valve spring and fuel system to hold it. This is an XDI high pressure pump and 1650cc injector
Driving the car with the larger turbo and extended RPM range of the drop-in cam is night and day different. The extended rpm range gives you a sense of it having a touch of lag…but it doesn’t. It’s just building to so much more of a climax that it feels like that and never stops until the fake needle on your dash has lost function. No more going to 5th in the ¼ for you 600hp guys with this setup.
BELOW: The next test was the TR3 Mild Race Camshaft. Again, this was easily tested in a pure back to back thanks to the simplicity of the ECU. The graph below is the TR3 laid over the TR2. I’m only calling it a race cam because that’s what we have used it for….our road race engines. It still has perfectly tame street manners, it just requires a valve spring and more VTC limitations due to it size. Although the graph looks close in this view, you can see the gap at that cursor is another 15whp……and that’s achieved at 2.5psi less boost in this chart. The extra airflow from the cylinder head and large camshaft had this little turbo pretty tapped out.
This setup is my go-to for the track. The turbo is small enough to stay lit coming off low speed corners, and doesn’t make unusable power for a heated up track tire. The 8000 rpm powerband gives you extra long legs and makes a big difference for the driving experience. When you run these little turbos hard, the high rpm “fall off” is exaggerated at 6800 rpm. The head and cam clean that up and keep it pulling strong. You bury the needle at 8000 and it NEVER stops pulling.
The K20C1 Type R engine has many opportunities for more power to be made and for the shape of the power curve to be altered. If you run a turbocharger below its maximum capability, you can do a lot to shape these power curves. If you start pushing them to their limits, you now start to rely on the engine. Top end modifications have proven valuable in racing series that allow them. The bigger the turbo and the higher the power level, the more these camshafts will make a difference.
While we didn’t test any camshaft profiles that made less power than the OEM camshafts, we did test some that barely gained. We also tested camshafts that were large enough that they could not be run on any commercially available valve spring. It should be noted that with the drop in cam, we really recommend a 7200 rpm limit. We realize that some guys are turning these 7600, but short pulls on the dyno or quickly through the gears are not comparable to very long straightaway pulls at sustained high rpm. We have documented valve float and wire fatigue above 7200 rpm. A Ferrea Valve spring kit will allow you to run more aggressive profiles and turn over 8000 rpm with confidence.
Stay tuned for future blog entries and continued camshaft testing with various setups. Just to wet your appetite…..