BC Stage 2 vs Stage 3 Cams || Stock Block K24

Purpose: 

We've recently been testing bolt ons with this Honda K24 and we've certainly learned alot. For the next step in modifying this engine to make more power, we are diving into the cylinder head. Today we are performing a test on our engine dyno by first running the engine in it's stock internal form and then swapping in camshafts to find where we pick up horsepower and torque. With these camshaft upgrade we also also swapping in a 50 degree VTC gear vs the 25 degree version that comes in a factory K24a. This additional range should also aid in our making more power, typically shown more in the lower RPM. 

One thing to note in this process, is that while we upgraded the parts in the cylinder head, we also changed the oil pump from the OEM K24a balance shafted unit, to the "Type S" style that are known to provide higher oil pressure which we desire in this higher rpm style test. That will be listed as on of our "unintentional variable" in relation to testing power differences between the camshafts.

Intentional Starting Variables:

• Test 1: Stock Internal K24a
• Test 2: Stock Bottom End K24a w/ BC Stage 2 Camshafts w/ 50degree VTC
• Test 3: Stock Bottom End K24a w/ BC Stage 3 Camshafts w/ 50degree VTC
   

Constants:

• Bottom End: OEM Crankshaft, Pistons, and Rods
• Header: Skunk 2 Alpha Swap Header
• Intake Manifold: Skunk 2 Ultra Race w/ 2 Liter Spacer + 90mm TB
• Fuel: Gasoline 93 octane
• Lambda Target: .87
• Dyno:  Superflow SF-Powermark
• Engine Acceleration Rate:  500rpm/sec
• Start RPM:  2,500rpm

Unintentional Starting Variables:

• Engine Coolant Temperature: [T1: 182°F, T2: 178°F, T3: 176°F]
• Engine Oil Temperature: [T1: 194°F, T2: 193°F, T3: 201°F]
• Ambient Air Temperature: [T1: 96.4°F, T2: 91.8°F, T3: 83.3°F]
• Density Altitude: [T1: 2920ft, T2: 2507ft, T3: 2006ft]

Test 1: Stock Internal K24a

Results:

• Peak Horsepower: 254.6hp @ 7900rpm
• Peak Torque: 192.5tq @ 5200rpm

We have seen this same run before during our Intake Manifold Test which you can find  here.  In that test we looked for what would be the best manifold configuration for an unopened K24a longblock. Since were aiming to make more peak power with these camshafts, we elected to use the larger intake manifold from that line up. This run here is our baseline and will allow us to begin seeing differences in power easily when over laying the new graphs to the one seen below. In it's stock form we can see the power start to dive down at roughly 8000rpm and for that reason we had only revved our engine to 8200rpm.

Test 2: Stock Bottom End K24a w/ BC Stage 2 Camshafts w/ 50degree VTC

Results:

• Peak Horsepower: 275hp @ 7400rpm (↑ 8.01% from test one)
• Peak Torque: 198.6tq @ 5500rpm (↑ 3.17% from test one)

We increased our horsepower and torque not only in their peaks, but in nearly the whole graph. We shaded the increased areas in the graph below to represent that additional power gain. This type of whole powerband increase is extremely desirable to someone who is interested in autocrossing or similar styles of racing where your car wouldn't only race at a higher RPM range. You can also note that the power curve does not dive down at redline like the OEM K24 cams did. For that reason we increased the end RPM to 8600 from the original 8200 rpm.

 
Test 3: Stock Bottom End K24a w/ BC Stage 3 Camshafts w/ 50degree VTC

Results:

• Peak Horsepower: 279.0hp @ 8300rpm (↑ 9.58% from test one)
• Peak Torque: 198.6tq @ 6600rpm (↑ 3.17% from test one)

For this final test we installed the BC stage 3 camshafts. This was a fairly straight forward process on the engine dyno. Once the camshafts were installed, we re adjusted out valve lash and went in for the third test. Brian Crower suggests these camshafts for higher compression engines, but in the name of science, we had to try them! We did lose some lower end power, but gained some up top. We wouldn't suggest these for someone sticking with a stock block as the small high rpm gains don't justify the loss in the lower RPM. Down below we added the graph showing Stage 2 vs Stage 3 camshafts, and then all three. In this run we also increased the end RPM, now by another 100rpm vs the stage 2, which now put our end rpm at 8700. 

In Conclusion:

What have we learned here? The brief takeaway from this test procedure is the BC Stage 2 Camshafts are the perfect pick for your stock block K24a. To give a more detailed answer we would need to ask ourselves the following question:

What kind of racing do I want to do, and where does power matter most to me?

If you are exclusively a high RPM drag racer who will launch at a high RPM, shift gears at a high RPM and your gear ratios allow your shift change drop points to still keep you in high RPM, then maybe these Stage 3 camshafts will work well for you in a stock block configuration. The honest truth is that those are many ifs, and not what most people do. If you aren't worried about the extra 4hp in that very small high RPM area and more importantly care about your overall powerband, then the Stage 2 camshafts are a perfect choice for you. These camshafts not only picked up peak horsepower and torque but also improved the whole powerband, and in it's process surely make for a better overall driving experience.

What did you find most interesting about this test, and what would you like to see us do next? Reach out to us and we’ll make it happen.

Thanks for reading along, and we hope this information was helpful to you!