Power is not a piñata. You can't string up some effigy to performance then flail about madly swinging a stick, hoping to get lucky and bump the output of your engine. Making power is strictly science and experience. Science in that burning more fuel at the proper proportions will generate more horsepower. Experience in the enlighten-ment of knowing what parts will make a particular engine burn that extra fuel and produce those extra ponies.
Beyond basic bolt-ons, camshafts represent the next step in the modification chain. While capable of doling out dramatic gains it takes experience to select the right camshaft for the intended usage of the vehicle. It's not about peak power; it's about peak performance on the road where drivability and acceleration trump a big dyno number.
The test mule for this shootout is a 1995 Honda Civic with a D16Z6 SOHC VTEC engine. This is a great combination to run. EG Civics are cheap and the D16 single-cam engine is often overlooked as a powerhouse in favor of the more glamorous GS-R swap, so stock parts are plentiful. Speed Factory, a Honda savvy tuning shop in Tacoma, Washington, set out to test a bevy of D16 turbo cams and we followed along to chart the progress. Speed Factory modified the D16 in a manner representative of most commonly built turbo D16 setups in use by D16 enthusiasts today:
Vitara 75.5mm pistons
Skunk2 valve springs & retainers
Skunk2 Intake Manifold
RC Engineering 750cc injectors
Walbro 255-lph in-tank fuel pump
Mini-ram turbo manifold
57-trim T3/TO4E .63 A/R turbo
3-inch downpipe and exhaust
Chipped P28 ECU, Crome tuned
Testing was performed on Speed Factory's in-house Dynapack chassis dyno. The D16 was rev-limited to 8,500 rpm because most street driven cars do not rev higher. Testing was performed at 19 psi of boost as this is a common, safe boost level for this setup and 92-octane pump gas was used throughout.
Speed Factory started with the stock camshaft in place, and tuned the car with the GReddy PRofec B electronic boost controller. Speed Factory's James Kempf used the low boost setting with the low boost knob maxed out. This resulted in 16 psi of boost at 4,750 rpm, climbing slightly to a peak of 19 psi of boost at redline. James then changed camshafts and retuned it at the same 19 psi of boost for all cams. The boost curve remained the same for all camshafts; run time was kept the same for all camshafts. Engine coolant temps and intake air temps were kept consistent at the start of every pull on all camshafts. All cams were at 0-degrees unless otherwise noted.
Speed Factory decided to test the most commonly used, readily available camshafts on the market for this test. No one-off custom grinds, only mainstream available goods here:
(T)=turbo grind; NA=naturally aspirated
ZEX (Comp Cams) 59300 (T)
ZEX (Comp Cams) 59500 (T)
Crower 2 Turbo (T)
Blox Stage 3 (NA)
Bisimoto Engineering Level 2.4 (T)
Bisimoto Engineering Level 3.6 (T)
300 whp/254 lbs-ft torque (baseline)
Comments: Great idle quality, okay power; you gotta start somewhere.
Speed Factory put the hurt on their Dynapack, logging more than 150 dyno pulls during the test, and came to an easy conclusion after pouring over the data: the Bisimoto Engineering cams absolutely dominated. They sacrificed practically nothing to the factory cam other than stock idle characteristics, and delivered mind-blowing 70 to 80-plus-whp gains on the top end. These are the ultimate cams for Turbo D16 enthusiasts.
Jason was quick to point to the Bisimoto Level 2.4 as the best overall cam in this test for most street/strip D16 turbos. Nearly identical spool to the stock cam, with massive gains from 5,000 rpm up, a solid choice. The Bisimoto Level 3.6 is his top dog for a drag-only application, delivering 20-plus hp over the competition while continuing to deliver the goods above 9,000 rpm for super-high-revving applications most likely seen on purpose-built drag engines.
It's also clear that when you're generating 380-plus wheel horsepower from a single-stick D16 you are doing something right. This is a real world car that's street driven on pump gas and the results illustrated here are supremely attainable for any Honda enthusiast.
Comments: Very good idle quality, good overall power. Jason says, "The 59300 is a good overall cam for the average street car that may have some drag strip use in the cards." Identical spool to stock cam, no power loss anywhere, good gains from 5k rpm up. The 59300 comes off as a solid, well-balanced bumpstick. Note: An odd characteristic of this cam is that at 8,000 rpm there is a large drop in power. Volumetric efficiency drops significantly at this point, but it pulls through and regains efficiency at higher rpm.
Comments: Good idle quality, poor low-rpm power, good high-rpm power. Jason quipped that this cam is good for a drag application, but not recommended for a street driven car. Very comparable to ZEX 59500, but the 59500 makes more power from 6,800-8,100 rpm. Loss in power up to 5,300 rpm, equal to stock from 5,300-6,400 rpm, huge gains above 6,400 rpm. Also, this cam experiences a 350-rpm loss in spool time versus stock.
Comments: Decent idle quality, poor low-rpm power, good high-rpm power. Jason commented that this cam is more suited to a drag application, not recommended for a street driven car because it loses power up to 6,400 rpm then delivers huge gains above 6,400. Street engines spend a lot of time below 6,400 rpm and this cam's lack of punch will be felt on the road. Also, this cam experiences a 350-rpm loss in spool time versus stock. Note: This cam required 2 degrees of retard.
Comments: Good idle quality, poor mid-rpm power, good high-rpm power. This cam is okay for a drag application, not recommended for a street driven car. Note: Above 8,500 rpm, power dropped like a rock. Not recommended for applications that will rev above 8,500 rpm. Gains realized above 6,600 rpm up to 8,500; this narrow 1,900-rpm powerband is indicative of drag cams. Engine experiences a 100-rpm loss in spool time versus stock.
Comments: This cam is designed for street/strip applications with a mildly lopey idle, and idled at 15 in/vac. Jason says that this cam is his pick of the bunch for a hot street/weekend warrior strip car, and the slightly lopey idle sounds great and hints at the power lurking beneath the hood. Spool was within 100 rpm of the stock cam, with great gains above 5,000 rpm. This cam outperformed all other cams in the test up to 8,000 rpm with massive mid-range and top-end gains.
Comments: This cam is designed for pro full race applications with a very lopey idle, and idled at 15 in/vac. This is Jason's cam of choice for a full race build, and is what he uses in his own race motors. Spool was within 100 rpm of the stock cam, with huge gains above 6,400 rpm. This cam performs very similarly to its slightly smaller brother, but made superior high-rpm power above 8,000 rpm.