FAQ's

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System Set‑Up and Calibration
Set‑up duration will vary based on engine architecture, ancillary layout, and existing modifications. These kits are not universal in their final calibration, so expect to spend time performing mechanical and fuelling adjustments to achieve optimal operation. Fine‑tuning may require iterative adjustments to belt tension, bracket positioning, and carburetion.

We can supply the carburettor with jets pre‑selected to suit the most common engine configurations; however, final fuelling calibration must be carried out on a rolling road (dyno) with appropriate instrumentation. This process may require alternative jet sizes or additional tuning steps to achieve correct AFRs under load.

Please note that certain engine specifications—such as aggressive camshaft profiles, elevated static compression ratios, or other performance‑oriented modifications—may introduce compatibility challenges or require additional tuning considerations. Other variables may also influence installation and performance. In summary, while the kit is designed for straightforward mechanical installation, achieving optimal performance will require time, precision, and proper calibration.

Performance output will vary depending on the exact engine specification, but the following figures provide a reliable baseline. A stock 1600 cc twin‑port engine equipped with the factory crankshaft, camshaft, ignition system, and induction typically produces 40–45 hp in standard trim.

When equipped with the Ultimate Supercharger Kit, a healthy stock engine can be expected to deliver 90–105 hp, with torque output in the region of 160–175 Nm. Final results depend on carburettor jetting, ignition advance curves, fuel quality, and any deviations from OEM engine configuration.

The Sleeper Supercharger Kit typically produces 85–90 hp and is optimised for engines in the 1300–1776 cc range. Its compressor characteristics align well with the volumetric efficiency and airflow demands of engines within this displacement window.

From a technical perspective, the supercharger increases power by raising the mass airflow entering the cylinders. By compressing the intake charge, the supercharger increases the density of the air–fuel mixture, allowing a greater charge mass per cycle. As impeller speed increases, the compressor delivers a higher pressure ratio, resulting in elevated cylinder pressures and a more energetic combustion event.
In essence: increased charge density → higher cylinder pressure → greater torque and horsepower.

From a technical perspective, the supercharger increases power by raising the mass airflow entering the cylinders. By compressing the intake charge, the supercharger increases the density of the air–fuel mixture, allowing a greater charge mass per cycle. As impeller speed increases, the compressor delivers a higher pressure ratio, resulting in elevated cylinder pressures and a more energetic combustion event.
In essence: increased charge density → higher cylinder pressure → greater torque and horsepower.

Clutch Load Consideration
The torque increase generated by forced induction can be substantial. Engines operating near the upper end of the torque range may exceed the holding capacity of a worn or marginal clutch assembly, resulting in slip under load. It is the installer’s responsibility to assess clutch condition and suitability. Where an upgrade is required, a Kennedy Stage 1 clutch kit is recommended due to its proven clamping force and compatibility with moderate boost applications.

The AMR500’s maximum capacity is 500 cc of air per revolution, because it is a 500 cc‑per‑rev Roots‑type supercharger. This is confirmed by multiple technical sources, which describe it as a “500 cc displacement” unit designed for small engines.

📌 What “500 cc per revolution” actually means

• Every time the rotors turn once, the blower moves 0.5 litres of air.
• At higher RPM, total airflow increases linearly.
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Example:

At 10,000 rpm:

500cc x 10,000=5,000,000 =5,000 L/min

That’s 5,000 L/min of theoretical airflow (before efficiency losses).

📌 Practical engine size limit

Most builders and suppliers recommend the AMR500 for engines in the 1300–2000 cc range.
It can be used on engines up to ~2.0 L, but boost drops as displacement increases.

📌 Safe RPM limit

Most real‑world data puts the maximum limit around:

• 16,000 rpm (upper limit)

• Summary
• Maximum displacement per revolution: 500 cc
• Typical engine size supported: 1300–2000 cc
• Maximum RPM: 16,000
• Airflow at 10k rpm: ~5,000 L/min     

The kits are engineered for twin‑port cylinder heads using standard‑pattern inlet manifolds. Installation on single‑port engines is also possible; however, this requires single‑to‑twin‑port manifold adaptor plates, which are not included in the standard kit.

The following components are not supplied as part of the base kit. They are available as optional extras should you wish to have them included:

• Electric fuel pump (required to maintain consistent fuel delivery under boosted conditions)
• Crankcase breather system (to manage increased blow‑by and crankcase pressure associated with forced induction)

Brake System Advisory
Due to the substantial increase in torque and acceleration produced by the supercharger, it is strongly recommended that the vehicle’s braking system be upgraded prior to installation. Operating a forced‑induction engine with drum brakes is not advised. The elevated power output significantly increases kinetic load, and the braking system must be capable of dissipating this energy safely and consistently. A disc‑brake conversion or equivalent performance‑rated braking system is strongly recommended to maintain safe stopping distances and thermal stability.

A side draft carburettor is a device integral to the functioning of almost all internal combustion engines constructed prior to the 1980s. ... It is the task of a side draft carburettor to combine air with fuel in the correct ratio prior to its entry into the engine's combustion cylinders.

The Weber DCOE dual-throat sidedraft is considered by many to be the definition of a performance carburettor. The range of venturi (choke) sizes and the ease of changing jets make it the carburettor of choice for many performance upgrades. The 40DCOE size can be tuned to work with a wide range of engines, from 1500cc to 2000cc. Multiple carburettors can be used to feed engines up to 3 litres (150-300cc cylinder volume per throat) 

Every engine behaves differently and therefore the carburettors and timing will require tuning, some may only need minor adjustments, others may need more extensive adjustments and tuning.

Bogging is caused by a lack of fuel and there are components in the carburettor that may need to be replaced at your own cost.

Pump rod lengths can differ, they are not one standard size, the length of the pump rod dictates how much fuel is delivered in the pump shot .

Pump rod springs strengths can change the rate which the fuel is delivered, a softer spring will deliver fuel moderately where as a heavier spring will deliver a much more aggressive / faster shot of fuel, it will be the same volume as the softer spring but over a shorter period of time.

Spill jet which is fitted in the base of the fuel bowl bleeds some of the pump shot back into the fuel bowl, replacing this with a size 0 (zero) ensure all of the pump shot is used.

The standard size pump jet 40 can be replaced with larger jets, smaller jets will deliver a longer pump shot over a certain period of time where as a larger pump jet 45 will deliver a faster pump shot but over a shorter period of time.

Considering the above these are areas which you may have to consider when setting up and tuning the kit for final road / track use.

Although we do our best to dial the kit in based on your engine size before sending the kit it is not always the same result as you may see on your engine.

Supercharger Pulley, Boost Control, and Engine Safety Parameters (Advanced Technical Overview)

The supplied supercharger pulley is selected based on calculated compressor speed requirements for the intended engine displacement. For engines up to 1641 cc, the standard drive ratio is engineered to produce approximately 8 psi of boost under typical load and ambient conditions. Larger‑displacement engines may exhibit reduced boost pressure due to increased volumetric flow demand, reduced manifold restriction, and lower compressor pressure ratio at equivalent impeller speeds.

A reduction in supercharger pulley diameter increases impeller RPM, raising the compressor’s pressure ratio and mass airflow. This results in higher manifold absolute pressure (MAP) and increased cylinder filling. When targeting a specific boost level during an engine build, it is essential to verify that the selected pulley size aligns with the engine’s mechanical limits, fuel system capacity, and ignition strategy. Due to the wide variation in engine configurations, all boost figures should be considered approximate. Continuous monitoring is strongly recommended.

Critical Engine Parameters for Safe Forced‑Induction Operation

1. Compression Ratio

For boost pressures in the 8–10 psi range, a static compression ratio of 7.5:1 to 8.5:1 is recommended.
Lower compression increases detonation margin by reducing peak cylinder pressure and combustion temperature. Engines with higher compression ratios may require:

• Reduced boost levels
• Intercooling or charge‑cooling strategies
• Increased octane fuel
• More aggressive ignition retard curves

Failure to manage compression ratio appropriately can result in detonation, pre‑ignition, and catastrophic piston or ring‑land failure.

2. Fuelling Requirements

Under boost, the engine must operate at a rich air–fuel ratio to maintain combustion stability and control exhaust gas temperature (EGT). Forced‑induction engines typically require:

• Richer AFR under load to prevent detonation
• Increased fuel flow capacity
• Correctly sized jets and emulsion tubes
• Stable fuel pressure

Running lean under boost dramatically increases thermal load and can lead to piston crown damage, detonation, or valve overheating. While richer mixtures may reduce fuel economy, proper calibration of jetting and ignition timing can significantly improve efficiency and drivability.

3. Ignition Timing Control

Ignition timing must be actively managed as boost pressure increases. Elevated manifold pressure accelerates the combustion process, requiring progressive ignition retard to prevent detonation. Key considerations include:

• Boost‑referenced timing curves
• Retard per psi (typical forced‑induction engines require 0.5–1.0° of retard per psi)
• Avoiding excessive advance at mid‑range RPM under load
• Ensuring stable spark energy at high cylinder pressures

For these reasons, we strongly recommend the Bluetooth 123 Ignition Distributor or similar, which allows programmable timing maps tailored to forced‑induction operation. Before ordering, confirm compatibility with your engine’s compression ratio, camshaft profile, displacement, and intended boost level.

- The Sleeper Kit and Slammed Ultimate Kit are designed to fit the engine bays of Beetles, Karmann Ghias, and T1/T2 buses without requiring any modifications.

Ultimate Kit Fitment Notes

• T1 Split‑Screen:
  Fits within a standard engine compartment, although the clearance is tight. Minor modification to the upper engine‑bay panel (“roof”) may be necessary.
• T2 Bay Window:
  Fits a standard engine compartment with no modifications required.
• Access for Carburettor Jetting:
  On both Split‑Screens and Bay Windows, an access hatch in the upper engine‑bay panel may be required to allow carburettor jet changes without removing the carb.
• Karmann Ghia:
  May require deck‑lid raisers or a deck‑lid scoop depending on model year.
• Beetle:
  Will require deck‑lid stand‑offs to provide adequate clearance.

Cyclone Kit

The Cyclone kit is intended for open‑engine‑bay applications. The carburettor stack sits approximately 40 mm forward of the fan housing, so enclosed engine bays are not suitable without modification.

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We recommend servicing your supercharger kit every 6,000 miles or once per year, whichever comes first.

The supercharger features its own dedicated oil reservoir. To change the oil, the unit must be removed from the engine.

Our service kits include everything required to perform the oil change, along with all components of the kit that are subject to normal wear and tear.

- We only supply genuine Weber 40DCOE and 40IDF carburettors, and all units are brand‑new and unused.

• The S/Shorty carburettor included in the Sleeper Kit is not a genuine Harley‑Davidson component.
• Our serpentine pulley kits are genuine, new, and unused MST products.

All AMR500 superchargers we provide are Aisin OE‑spec refurbished units, as new units are no longer in production. Each supercharger is fully tested in‑house and supplied with a 6‑month warranty.

It is strongly recommended that you seek professional assistance when setting up ignition timing. Every engine behaves differently, so there is no single “correct” number that applies to all engines. The commonly quoted static timing of 7.5–10° BTDC may work for some 009 distributors, but not all, due to variations in their internal advance mechanisms.

Setting Maximum Advance

Warm the engine fully, then use a timing light to set the maximum advance at 3000+ rpm. Rotate the distributor to achieve 24° BTDC at 3000 rpm, and allow the idle timing to fall wherever it naturally settles.

Maximum advance is far more important than idle advance.
For air‑cooled VW engines using a 009 distributor, the correct maximum advance range is 18–24° BTDC at 3000+ rpm. The 009 typically reaches full advance around 2600 rpm, so setting timing at 3000 rpm ensures the advance is fully “all in.”

• If the engine pings at 24°, reduce to 23°.
• If it pings at 23°, reduce to 22°, and so on.
• Setting less than 18° will leave the engine under‑advanced at higher rpm.

Road Testing

Perform low‑speed acceleration runs:

• If the engine runs smoothly, your timing is correct.
• If you experience pinging or a flat spot, reduce maximum advance by ½–1° and test again.
• Always use higher‑octane fuel when tuning for maximum advance.

Keeping maximum advance within 18–24° helps reduce hesitation on acceleration and significantly lowers the risk of detonation.

Limiting or Locking Advance

This video may be helpful:
https://youtu.be/loA_MyJH19U

If you wish to limit or lock the advance for boosted applications, you can do so by removing the small plug, adjusting the two advance‑limit stops, and then re‑sealing the plug or spot‑welding the stops in place.

Spark Plug Temperature & Reading Plugs

Advancing ignition timing by up to 10° can raise spark‑plug tip temperature by 70–100°C. Reading spark plugs is an excellent way to assess mixture and timing:

• Black and sooty: Running too rich, timing too retarded, or low compression. (Running slightly rich helps keep temperatures down.)
• Oil‑fouled: Indicates worn rings, piston issues, leaking valves, or excessive oil level.
• Brown or light grey: Ideal—indicates correct mixture and timing.

We recommend NGK BP6HS spark plugs, as the correct plug can make a noticeable difference in performance and reliability.

Listening for Problems

During your first test drive, listen carefully through the gears:

• Pinking / valve rattle: Timing is too advanced—reduce maximum advance.
• Popping after shutdown with hot engine: Timing may be too retarded advance it slightly. This can also be caused by unburnt fuel igniting in the exhaust.

Our kits are designed to fit all T1 and T2 twin‑port air‑cooled engines up to 2155cc. They can also be used on single‑port air‑cooled engines; however, a single‑port to twin‑port inlet manifold conversion kit must be installed.
Please note that we do not supply these conversion kits.

For best results, we recommend using the 123 Bluetooth programmable distributors or similar. These units are relatively new to the market and have proven to be excellent for turbocharged and supercharged engines. Several of our customers use them and report that they are an ideal upgrade, offering full control of ignition settings directly from your phone, along with the added security of an integrated immobilizer.
https://123ignition.com/

A Bosch 009 distributor can also be used, provided it is fitted with a high‑quality ignition module and the advance mechanism is locked. The supercharger support bracket is designed around this style of distributor, although other types may also fit.

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Understanding Timing, Detonation & How to Protect Your Engine

Forced‑induction engines are amazing fun, but they’re also more sensitive to ignition timing. Getting the timing wrong—or guessing—can seriously damage your engine. Take your time, make careful adjustments, and don’t hesitate to get help from a professional.

What Is Pre‑Ignition?

Pre‑ignition happens when the air/fuel mixture ignites before the spark plug fires. This is extremely dangerous because the mixture explodes while the piston is still coming up the bore. The pressure spike is huge and can destroy an engine instantly.

Common causes of pre‑ignition

• Spark plugs that are glowing hot
• An overheated exhaust valve
• Hot carbon deposits inside the chamber

Any red‑hot spot inside the cylinder can ignite the mixture too early.

What Is Detonation?

Detonation (also called knock or pinging) happens after the spark plug fires. Instead of burning smoothly, part of the mixture explodes suddenly. This creates a sharp, hammer‑like shock inside the cylinder.

Signs of detonation

• A metallic rattling or pinging noise
• Damaged spark plugs or broken rings
• Piston or valve damage

Even one severe detonation event can cause major engine damage.

What Causes Detonation & How to Prevent It

1. Ignition Timing Too Advanced

If the spark happens too early, cylinder pressure rises too fast.
For supercharged engines, you must limit the distributor’s advance.

• Aim for 18–24° maximum advance
• If you hear pinging, reduce timing slightly
• Re‑calibrating the advance curve may be necessary

Professional help is strongly recommended.

2. Lean Air/Fuel Mixture

A lean mixture runs hot and increases the risk of detonation.

• Make sure your carburettor is correctly jetted
• A rich mixture runs cooler and is safer
• If you don’t have the tools, get a specialist to tune it

Forced‑induction engines need careful fuel control.

3. Too Much Compression

High compression creates heat.
A naturally aspirated engine built for high compression may not be suitable for a supercharger.

• Forced induction increases effective compression
• Lower static compression is often required
• High compression + boost = high detonation risk

4. Engine Overheating

Heat is the enemy. Air‑cooled engines rely heavily on proper airflow.

• Make sure all cooling tinware is in place
• Don’t remove the aluminium heater ducts—block them if unused
• Consider an external oil cooler
• Fit temperature gauges if you don’t have them

If the engine runs hot, detonation becomes far more likely.

5. Low‑Octane Fuel

Higher‑octane fuel resists knock better.

• Forced‑induction engines often need higher‑octane fuel
• Heavy vehicles (buses, campers) may also require it
• If the engine is under load, use better fuel

One bad detonation event can be enough to cause damage.

6. Too Much Boost

Boost increases pressure and temperature.

• Adjust boost by changing pulley sizes
• Or build the engine to safely handle more boost

Boost control is essential for reliability.

7. Carbon Deposits

Carbon build up increases compression and can hold heat.

• High‑mileage engines are more prone
• Deposits may indicate worn rings, guides, or oil issues
• Clean the chambers if necessary

Removing carbon reduces detonation risk.

8. Check Your Spark Plugs

Spark plugs tell you a lot about what’s happening inside the engine.

• Black/sooty: Too rich or timing too retarded
• Oil‑fouled: Mechanical wear or too much oil
• Brown/light grey: Perfect
• Damaged or yellowed: Too hot—use a cooler plug

Choosing the right heat range is important for boosted engines.