The JUN AUTO 1033M-H011 is a Stage 2 camshaft kit for Honda B16A/B16B/B18C VTEC engines. Think of it as upgrading the engine’s “breathing timetable”—the camshafts determine when and how far the intake and exhaust valves open.
JUN specifically lists 1033M-H011 as Stage 2, with Type 0 intake/exhaust cams, uprated valve springs and Type 1 retainers.
🧠 What is actually happening?
A B16/B18 makes power by getting air into the cylinder and getting exhaust gases out.
The camshaft controls:
Crankshaft → timing belt → camshaft → cam lobes → valves
A more performance-oriented cam profile changes:
- Valve lift → how far the valve opens
- Duration → how long it stays open
- Overlap → period when intake and exhaust valves are simultaneously open
- Valve timing → when opening/closing occurs relative to piston position
The result is essentially:
More opportunity for the cylinder to breathe at high RPM.
But there is a trade-off: a cam designed for high-RPM airflow generally sacrifices some low-RPM smoothness and efficiency.
🔥 What makes 1033M-H011 special?
The key detail is that H011 is the Stage 2 “bolt-on” kit, not the more aggressive Stage 2R or JUN Advanced Type 4 configuration.
JUN specifies the Type 0 camshaft as:
|
Parameter |
Intake |
Exhaust |
|
Primary duration |
232° |
232° |
|
Mid duration |
292° |
284° |
|
2nd duration |
244° |
244° |
|
Maximum valve lift |
11.7 mm |
11.3 mm |
|
Valve clearance |
0.17 mm |
0.19 mm |
The Type 0 profile is also designed so that it can be used with the stock ECU, according to JUN.
That is an important distinction.
Type 0 ≠ gigantic race cam
Despite being called Stage 2, JUN’s Type 0 profile isn’t simply “maximum cam.”
It is more like:
OEM VTEC → JUN Stage 1 → JUN Stage 2 → Stage 2R → Advanced/high-power profiles
So H011 sits in the serious performance zone without being the most extreme configuration JUN offers.
🧩 What comes inside H011?
The kit contains four major components:
1. Intake camshaft
2. Exhaust camshaft
3. Uprated valve springs
4. Type 1 valve retainers
JUN’s catalogue confirms that the Stage 2 H011 uses the Type 0 intake/exhaust camshaft combination together with upgraded valve springs and Type 1 retainers.
That’s important because installing a high-lift cam isn’t simply:
“Remove OEM cam → install bigger cam.”
The valve train has to control the valves reliably at higher engine speeds.
⚙️ Why the valve springs matter
Imagine the cam lobe pushing the valve open.
At low RPM, the valve spring has plenty of time to return the valve.
At high RPM:
RPM ↑ → valve acceleration ↑ → spring control becomes increasingly important
If the spring isn’t capable of controlling the valve train, you can encounter valve float, where the valve no longer follows the cam profile correctly.
Therefore JUN doesn’t treat the camshaft as an isolated component—the H011 kit includes the appropriate spring/retainer hardware.
🧠 The clever part: VTEC + camshaft
This is where the B16/B18 becomes fascinating.
A B16/B18 VTEC cylinder head can effectively have different valve behaviour between lower and higher engine-speed operation.
Conceptually:
Low RPM
mild cam behaviour → good drivability
⬇️
VTEC transition
VTEC changes valve actuation
⬇️
High RPM
larger cam profile → greater airflow capability
The JUN cam therefore works with the fundamental philosophy of the VTEC engine rather than trying to turn the B16/B18 into a completely different engine.
📈 Where does the power move?
This is the most important concept.
A camshaft doesn’t magically create horsepower everywhere.
It changes the shape of the power curve.
A simplified comparison:
The performance cam’s objective is generally to improve the engine’s ability to produce power as RPM rises.
That makes it particularly attractive for an engine that is intended to rev and breathe at the top end.
🏁 Stage 1 vs Stage 2 vs Stage 2R
JUN offers three main kit levels for this B16/B18 application:
|
Kit |
Character |
Hardware |
|
Stage 1 - H010 |
Mild performance |
Cam + spring/retainer package |
|
Stage 2 - H011 |
High-performance sweet spot |
Type 0 cam + upgraded springs + Type 1 retainers |
|
Stage 2R - H012 |
More aggressive |
Type 0 cam + different retainer configuration |
JUN also offers versions using its Regular camshaft profiles, where the customer can select from Type 1–3 profiles.
So H011 is not the absolute wildest JUN B16/B18 setup.
It’s arguably more interesting because it gives you a substantial performance-oriented valvetrain package while retaining the Type 0 profile’s stock-ECU compatibility noted by JUN.
🔬 Why 11.7 mm lift matters
Valve lift is one of the easiest ways to understand the upgrade.
Imagine the OEM valve opening:
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versus a performance cam:
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More lift can expose more effective valve area and reduce the restriction to airflow—provided the cylinder head, valve size, ports and rest of the engine can actually exploit it.
But:
more lift ≠ automatically more horsepower.
The entire airflow system has to cooperate.
Think:
Camshaft → valve → port → cylinder → combustion → exhaust
If one part becomes the bottleneck, the benefit of the larger cam diminishes.
🧪 The real engineering equation
The interesting part isn’t simply:
“11.7 mm lift!”
It’s the combination of:
Lift + duration + opening point + closing point + overlap + RPM + compression ratio + cylinder-head flow
That’s why two cams with similar lift can behave completely differently.
For a naturally aspirated B16/B18, cam selection is essentially about moving the engine’s volumetric-efficiency peak toward the desired operating range.
🏎️ How about B18C GSR?
For your B18C GSR, this is particularly relevant.
The B18C already has the architecture that makes a performance cam attractive:
1. DOHC
2. VTEC
3. 4 valves/cylinder
4. High-revving character
5. Strong aftermarket cylinder-head support
So H011 makes much more sense on a properly built naturally aspirated B18C than on a stock engine where the rest of the combination cannot exploit the additional airflow.
Since it is B18C GSR, this is one of those modifications where the supporting combination matters enormously.
⚠️ One critical point
Don’t interpret “stock ECU compatible” as:
“No tuning is ever necessary.”
It means JUN identifies the Type 0 cam profile as usable with the stock ECU.
Once you start combining:
- high-flow intake
- larger throttle body
- ported cylinder head
- higher compression
- header
- freer-flowing exhaust
- different fuel system
- increased RPM
the optimal calibration can change substantially.
🧠 Summary
Think of JUN 1033M-H011 as:
A Stage 2 breathing upgrade for the B16/B18 VTEC that increases the engine’s ability to move air at high RPM while upgrading the valve train to reliably control the more aggressive cam profile.
The hierarchy is:
OEM B18C
⬇️
Performance intake/exhaust
⬇️
JUN Stage 1
⬇️
🔥JUN Stage 2 H011
11.7 mm IN / 11.3 mm EX Type 0 cams + uprated springs + Type 1 retainers
⬇️
Stage 2R
⬇️
Advanced/race-oriented profiles
The big idea is not simply “more lift.”
It’s:
better valve timing → better cylinder filling → higher volumetric efficiency → stronger high-RPM breathing → greater potential NA power.
And that is exactly where a B18C GSR starts becoming a very serious naturally aspirated engine.
