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For camshafts we chose Skunk 2’s Stage 2 Tuner Series camshafts. Tuner series cams are designed to keep the good idle and bottom end power characteristics of the stock cams with more mid range and top end. The intake cam has a primary duration of 247 degrees with a lift of 0.363″ with a secondary duration of 260 degrees and a lift of 0.407″. These are staggered to induce swirl at low engine speeds and loads for more complete combustion. The high lobe duration is 302 degrees with a lift of 0.527″. The intake cam centerline is variable due to the I-Vtec system. The exhaust cam has a primary duration of 256 degrees and a lift of 0.405″ and a secondary duration of 262 degrees and a lift of 0.407. Like the intake, the exhaust is staggered to help with scavenging the cylinders. The exhaust high lobe duration 306 degrees with a lift of 0.488″. The exhaust centerline is 111 degrees. We would probably prefer a little later exhaust timing on a turbo engine but with a long runner exhaust manifold and i-VTEC on the intake, it should not be an issue. The Skunk stage 2 cam is pretty healthy while still being very// streetable and we figure with the proper ECU tuning, it will work pretty well with a turbo system with a header type manifold.
The Skunk Tuner Series Stage 2 cams are ground on new chilled iron billets like OEM for good compatibility with the rest of the valvetrain and proper base circle dimensions. Chilling the lobes of the cam blank while casting produces a nice hard, wear-resisting lobe while keeping the rest of the blank soft for strength. Finger follower valvetrain engines are sensitive to base circle runout and it can greatly affect idle quality so this is important. They also have the correct flank profiles for roller rockers. Roller rockers require a different geometry. They cams are also phosphate coated which help them to break in properly.
Our head didn’t have any of the necessary parts to finish it so we had to buy brand new Honda Vtec rocker arms for the intake. The assembly has the primary, secondary and high rockers with the coupling for the hydraulics needed to lock them together when VTEC kicks in yo. The K series engine has friction fighting roller rockers.
The assembly taken apart shows the primary, secondary and high rockers.One of the biggest advantages of the new head is VTEC on the exhaust side of the engine. This should be good for a bunch of power. We think Honda eliminated VTEC on the exhaust as a cost cutting measure trading HP per liter for the nearly identical HP and increased torque of a larger engine. It is cheaper for an OEM to reduce parts count and enlarge an engine. The new head will give us the best of both worlds, high rpm breathing and the torque of a bigger engine.
The rollers pivot on shafts which makes for a very secure and stable valvetrain. No skidding rockers like the SR20. We had to buy brand new genuine Honda shafts at a pretty decent price. This is one of the reasons why having a spare parts engine can save a bunch of money even if you are starting with new block and cylinder head castings. The little parts can seriously nickel and dime you to death!
We used Supertech stainless intake valves. The Supertech valves are made from one piece forgings. it is common for valves to have the shafts spin welded to the heads which is inherently weak. Forging insures proper grain flow and a homogenous super strong valve. The valves have a flat nail head type contour and a reduced stem diameter near the head for the best flow. The valve stem tips are hardened for long life. The valves are also nitrided for surface hardness and slipperiness of the valve stem to valve guide interface insuring long wear and resistance to sticking.
11 comments
Very good write up I just wondered when you switched heads do you have to use k20 head parts or can you use the k24 parts in the new head ?
Yes you can.
What ecu did you guys use go run it i have hear that k pro cannot run it
It depends either K pro or K flash
Hey awesome write up but was there any modifications done to the k20z3 head for the oil passage or is it a straight up pug and play
You need to modify the front cover.
What exactly must be done to the front cover?
You have to weld a piece on to cover a place that is uncovered. It is pretty apparent when you put the cover against the block
How did u mofidy the sensor plates?
I am thinking to do the same for my Accord Euro CU2 (AUS). In US is called Acura TSX 2nd gen. Do you think the K24Z3 block will mate with K20Z3 cyl. head without any modification of the water passage?
Awesome write up, I would have loved to see dyno numbers of this swap. I also have a k24z2 and I’m trying to find the best head to swap too. I really don’t want to change out all the internals. I’m not finding a lot of write ups for our engine sadly.