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VXR Logo
Garrett Upgrades
2.0 Turbo Z20LEx
Vauxhall Logo
What is a Z20LEx engine?

This refers to the 2.0 Turbo engines (Z20LET/Z20LEL/Z20LER/Z20LEH) used in Astra G, Astra H, Zafira A, Zafira B and VX220 including VXR models.

The first development was the Z20LET engine fitted to Astra G, Zafira A and VX220. Z20LEL and Z20LER engines were fitted to Astra H and Zafria B (and the Z20LER made its way into the Lotus Europa) and were basically the same as a Z20LET engine but with different Bosch management. The Z20LEH engine is that used in Astra H and Zafira B VXR models, and features under piston cooling.

For all 2.0 Turbo Z20LEx engines we are able to offer a range of upgrades to comfortable take power above the magic 300 bhp mark. We can supply all the required items for an engine build, cast exhaust manifold to accept a Garrett turbo, 76mm downpipe and we even offer a bespoke conversion supplied, fitted and mapped.

For any set up a big intercooler with good cooling and flow capabilities, a 76mm/3" free flowing sports exhaust and uprated fuel pump are mandatory. We can then advise on injector requirements and mapping as required. For tuning requirements above the 350bhp mark a replacement inlet manifold will be needed as the OE manifold does not allow enough flow and becomes a bottleneck, although we recommend our high flow inlet manifold is fitted to any car wanting to achieve over 300bhp. Our uprated high flow inlet manifold has been tested with excellent results and shows great top end power improvements without any loss of mid range torque.

For anyone who has undertaken their own build or conversion, we can bespoke map the ecu and carry out a full set up and map optimisation on our rolling road.

V Band Cast Manifold Z20LEx

For significant gains in performance above the OE Z20LEH K04 exhaust manifold for those wishing to fit a Garrett turbo, this new cast manifold offers an ideal solution. Developed in conjunction with our German Tuning partner Klasen Motors, this manifold offers the OE durability of a cast manifold, unlike stainless steel tubular manifolds which are prone to cracking, has a high quality finish, is manufactured from high quality materials and has been flow tested to 600bhp, although Stephan has produced a 689PS conversion with the manifold. Features a TiAL V-Band mounting flange for any suitable turbocharger plus external wastegate, again on a TiAL V-Band flange. This can be capped if an internal wastegate option is required.

The V-Band flange provides better security of the turbocharger to the manifold, and is less prone to backing off unlike traditional 4 bolt garrett flanges, and also allows for the retention of the air conditioning system.
  • D5S material with high nickel content
  • Turbocharger and waste gate have V-band flanges
  • TiAL 44mm external wastegate (water cooling possible)
  • TiAL exhaust housing with a V-band flange
  • Accepts the new Garrett GTx range of turbos. Gen2 Fitting
Z20LEx GT Kit
Example Z20LEx GT V Band Kit

Understanding a Garrett Turbo
Understanding a Garrett Turbo Click For Information
V Band Manifold £599.00 Buy Now Click Here!
TiAL MVR44 External Wastegate £396.00 Buy Now Click Here!

Full Garret Build and Install with V Band Cast Manifold is available in our workshop

We can supply any Garrett unit of your choice and specification to order - Just contact us with your requirements.

All parts from the V Band Kits are available separately. Buy Now Click Here!
Z20LEx Cast Manifold GTx V-Band Z20LEx Cast Manifold GTx V-Band Z20LEx Cast Manifold GTx V-Band Z20LEx Cast Manifold GTx V-Band
Z20LEx Cast Manifold GTx V-Band Z20LEH Cast Manifold GTx V-Band Z20LEx Cast Manifold GTx V-Band Z20LEx Cast Manifold GTx V-Band
Z20LEx Cast Manifold GTx V-Band Z20LEx Cast Manifold GTx V-Band Z20LEx Cast Manifold GTx V-Band Z20LEx Cast Manifold GTx V-Band

Astra H VXR V Band Manifold Garrett GTx3076R Conversion - 559bhp

Play Video
Duration: 1:50
V Band Cast Manifold, Garrett GTx3076R turbo 0.86 A/R, TiAL V-Band Flange, External Wastegate, Full Engine Rebuild, Steel Rods, High Flow 728cc Injectors, External Swirl Pot, High Pressure Pierburg Pump, Methanol Injection with 2 Injectors, 90mm Air Flow Meter, AEM Dry Flow Filter, Enlarged Plenum, High Flow Courtenay Klasen Inlet Manifold, Uprated Courtenay Klasen Inlet and Exhaust Cams, Courtenay Sport VXRacing Intercooler, 3" Full Exhaust System, bespoke mapping of the OE Bosch 7.6.3 ECU.

Astra H VXR V Band Manifold Garrett GT3076 Conversion - 479bhp

V Band Cast Manifold, Garrett GT3076 turbo, TiAL V-Band Flange, External Wastegate, Standard Z20LEH pistons (which are good for 500bhp), steel rods, High Flow Injectors, 90mm air flow meter, high flow enlarged plenum, high flow Courtenay Klasen Inlet Manifold, uprated inlet and exhaust cams, Courtenay Sport VXRacing intercooler, 3" full exhaust system, bespoke mapping of the OE Bosch 7.6.3 ECU.
View Graph Play Video
Video - Duration: 1:08

VX220 Turbo V Band Manifold Garrett Conversions - 398bhp and 689bhp!!

View Graph
398bhp VX220 Turbo
V Band Manifold, TiAL External Wastegate, Garrett GT2871R, Full Engine Rebuild, 3" Exhaust System, Chargecooler System - build for Road and Track use.
View Graph
689bhp Speedster Turbo
V Band Manifold, Garrett GT35, Methanol Injection, Solid Lifters - built for the drag strip.

 High Flow Inlet Manifold

Prototype Inlet Manifold
Prototype V1
Plastic Prototype V2 High Flow Inlet Manifold
Plastic Prototype V2
Plastic Prototype V3 High Flow Inlet Manifold
Plastic Prototype V3
CAD drawing of V4 High Flow Inlet Manifold
CAD Drawing - V4
Stephan Klasen, our partner and mapping engineer, has produced numerous high powered Z20LEx cars and for some time has had the most powerful Z20LEx engined car at 659BHP in his crazy Speedster. His various builds continually found that the standard inlet manifold starts flow inefficiently on high power applications over 350 BHP.

Using this knowledge gained from his Speedster and other builds, the high flow manifold is the culmination of a project Stephan started over 2 years ago. The aim was to design a manifold that fitted all versions & applications of the Z20LEx engine to produce good high end power whilst not sacrificing all the bottom and mid range end power.
Prototype Inlet Manifold Prototype Version 1 was a simple design with its squashed plenum it produced good high end bhp however more work was needed with the  plenum for more even air distribution.
Prototype Version 2 featured a dual plenum design this produced good air distribution and good bhp numbers due to is short inlet tract it was good for power to 8000+ rpm, however when tried with the plastic prototype V2 this power was at the cost of low end torque and mid range power. So was considered too extreme for most applications. Plastic Prototype V2 High Flow Inlet Manifold
Plastic Prototype V3 High Flow Inlet Manifold Prototype Version 3 was the beginnings of the manifold we ended up with. The inlet tracts were made longer to keep a good torque spread, whilst the pre-resonance chamber made larger and improved in shape for enhanced air flow. A costly plastic prototype was again made for testing.
This proved invaluable as the bottom end power and torque was vastly improved, however we felt that the top end power could be further enhanced with larger ports. This proved the best balance between low end torque and power and high end power, showing improved power / boost ratio at 455 bhp Flow Testing
(we did not dare run it at higher boost than this as it was making some nasty noises due it being made from plastic, whilst others in the workshop feared 1st degree plastic lacerations!!)
CAD drawing of V4 High Flow Inlet Manifold Version 4 was the final version with only subtle mods being made to the pre-resonance to port transition whilst externally some hardware mounting points altered.
The inlet manifold has so far been tested to 520 bhp. >>> Power Graph to 520bhp Gains on a car fitted with a K04-Race turbo. >>> Power and Torque Graphs when used on an engine with a K04 Race turbo.
Power Graph Click to Enlarge We have also tried the manifold on an engine equipped with a VXR K04 turbo whilst not expecting any huge gains with an engine already running 290 to 300 bhp we were pleased to see the inlet manifold fitted (red trace). Once mapped to suit the inlet manifold showed power gains from 5,700 rpm, with gains of 10 bhp at 6,000rpm, 23 bhp at 6,500 rpm and 29bhp at 7,000 rpm.

In the past this has only been achieved by fitting cams the result of this can lead to an unwanted lumpy idle, whilst fitting an inlet manifold and leaving the standard cam profile leaves the idle smooth as standard. (Figures shown on the graph are at the wheel figures)
High Flow Inlet Manifold High Flow Inlet Manifold High Flow Inlet Manifold
Images show High Flow Manifold fitted up to an engine with our Enlarged High Flow Plenum.

This manifold is not just for big power Garrett builds. It will produce excellent gains on a Stage 3 and 4 Astra/Zafira VXR, Astra/Zafira GSi and VX220 Turbo fitted with K04 and K06 turbochargers.

Our High Flow Inlet Manifold has been designed for ALL Z20LEx petrol turbo engines.

Designed to remove the restriction in the original inlet manifold that restricts air flow into the engine. This manifold will allow the engine to breathe fully, and has been designed to increase power but not at the expense of mid range power and torque (for example, a shorter inlet manifold will give good power at extremely high end rpm i.e. 8,500 rpm but will lose mid range torque).

Ideal for fast road and track use.

Gains can be seen on a Stage 3 300bhp Astra VXR set up, Stage 4 Astra VXR with K06 Hybrid Turbo with no loss in mid range torque and on a full Garrett build running a GT28/30/35 turbo unit, allowing the engine to continue to produce power well above 7,000 rpm.

From our experience we have found this to be a much more worthwhile upgrade to the Z20LEx engine than fitting a cams as an upgrade, as not only are the results better but there is no unwanted lumpy idle associated with high lift cams as this inlet manifold can be fitted whilst retaining the standard cams.

High Flow Inlet Manifold - £598.00 £500.00 Buy Now Click Here!
High Flow Inlet Manifold and Enlarged High Flow Plenum - £660.00 £562.00 Buy Now Click Here!

The power and torque graphs below show before and after graphs of a selection of vehicles that have had conversions both with and without our high flow inlet manifold and the benefits can be clearly seen.
Stage 3 Astra VXR
Stage 3+ Astra VXR
Before Without and
After With Inlet Manifold
Stage 4 Astra VXR K06 Turbo
Stage 3+ v Stage 4 Astra VXR
Before Without and
After With Inlet Manifold
Astra Z20LEx GT28 Build
GT28 Z20LEx Before and After
Before Without and
After With Inlet Manifold

A small selection of Garrett installs which we have carreid out......

Z20LEH Cast Manifold GTx V-Band
V Band Cast Manifold
Z20LEx Cast Manifold GTx V-Band
V Band Cast Manifold
Z20LEx Cast Manifold GTx V-Band
V Band Cast Manifold
GT30 Conversion
Tubular Manifold GT30
GT28 Conversion
Tubular Manifold GT28
GT28 Conversion
Tubular Manifold GT28
GT30 Turbo with Courtenay Cast Manifold
GT30 on Cast Manifold with Aircon
TT35 in VX220 Turbo
TT35 with Cast Manifold
TT35 in VX220 Turbo
TT35 with Cast Manifold

Nortech Tubular V Band Manifold

We can offer the Nortech V Band Tubular Manifold (shown right) £1020

Features a one-piece billet low angle merge collector, thick wall stainless steel and CNC machined head flange with V band fitment for additional security and strightforward fitment. For 44/45mm External Wastegate. Fits Nortech 3" downpipe. Non AirCon

Nortech Garrett Conversion Kit Z20LEx

Garrett installation kit with tubular V band manifold (supplied without turbocharger) £2462.40
includes V band tubular manifold, downpipe (dump tube in), crankcase breather tube, intake pipe, external wastegate, oil and water lines, clamps, manifold gasket, stud and nut kit and heatwrap.

Garrett turbocharger can be specified separately according to the individual power requirements. Specifications of turbocharger vary to suit application. Garrett turbo for V band application from £1250

Engine Strengthening (Z20LEx engines) when upgrading.......

As part of any Garrett conversion, for reliability and durability engine internal strengthening is required.

Z20LEH engines have strong pistons which are good for around 500bhp. Above 320bhp we recommend fitting steel rods.

The Z20LET/Z20LEL and Z20LER engines require stronger pistons when exceeding 310-320 bhp so a full engine rebuild is required using forged pistons and steel rods.

We can offer everything from parts supply, to a full engine rebuild. Pricing up of an engine build is again carried out for each individual customer and will vary according to requirements as well as current age and mileage of the engine we are being asked to work on.

Pricing up an engine rebuild is done on an individual basis depending upon what is required.

Example Prices:
Supply and fit steel rods to Z20LEH engine from £1415 inc new big end bearings, gaskets, head bolts and oil and filter change.
To carry out a suitable rebuild on a low mileage Z20LEH engine prices will begin at £1760
To carry out a full strip down and rebuild on a Z20LEx engine including removal from and refitting into the engine bay prices start from £3750 - £4500
To carry out a full rebuild on a Z20LEx (non LEH engine) already removed from the car prices start from around £2500

Additional Head Work and suitable high lift cams can also be specified depending upon individual engine build requirements.

What else is required?.......

Our recommendations for getting the best power:
A Full 76mm exhaust system from turbo back
A large full height intercooler for Astra/Zafira or extra large charge cooler system for VX220/Speedster
Minimum 80mm Air Flow Meter where not already fitted. A 90 or 100mm Air Flow Meter may be required depending on power requirements
High Flow Injectors to suit the type of conversion being carried out (fitted at time of mapping)
Uprated Fuel Pump, Replacement Map Sensor
Uprated Clutch Assembly and Replacement Flywheel
Our high flow inlet manifold and enlarged high flow plenum.

Head rework and high lift cams can be specified depending upon the conversion and required power, but required for above 400bhp.

High Lift Cams for Garrett Builds

Z20LEx Sports Cams Developed with our tuning partner Klasen Motors, after substantial testing, these high lift cams been specifically profiled to suit high power Garrett turbo builds sustaining power at the upper end of the rev range, ideally suited to large turbochargers capable of making high boost levels above 6,500 rpm.

They give a wide rev range up to 7500rpm and constant maximum power from 5,500 - 7,500 rpm where with the standard cams the maximum power drops at 5500rpm. Specially developed for turbocharged engines the exhaust cam gives good turbo response and less exhaust gas in the cylinder head reducing back pressure.
These cams are machined from blanks on a modern CNC-camgrinding machine and have a lift of 10.6mm. They can be fitted on standard cam settings, (you only need vernier pullies if the cylinder head has been machined.) With big Garrett applications we measured 70bhp more at 7000rpm compared to standard cams.

£569 per pair Buy Now Click Here!

Thermal Inlet Gasket - Z20LEx

Thermal Inlet Gasket (TIG) for Z20LEx engines - designed to reduce heat-soak from the cylinder head to the inlet manifold. Ideal for use with any engine, but especially big power builds.

Heat management is an area that is often ignored during engine modification. The Thermal Inlet Gasket will help prevent heat from conducting from the cylinder head casting into the inlet manifold, significantly reducing heat soak.

In theory, because of the cooler and denser inlet charge, a small and immediate power increase should be evident (if you can run a little more ignition timing before pre-ignition occurs then power should rise), but their main strength will be in helping to keep temperatures under control during and after prolonged engine use.
Thermal Inlet Gasket
This 4mm thick high performance composite gasket, designed for optimal heat insulation, is available for Z20LEx engines is paper coated on both sides to aid sealing.

Note: The TIG is paper coated on each side and designed to seal between two flat surfaces. If there is any doubt about the quality of either surface a thin bead of sealant should be used on both sides (not recommended unless absolutely necessary). If the paper gaskets are damaged during strip down/rebuild, they can be replaced with a pair of OE gaskets.

Gasket £45.00 Buy Now Click Here!

90mm Air Flow Meter Housing

90mm Air Flow Meter Housing for 400 - 650bhp conversions.
Requires a meter head from an 80mm Bosch (Astra VXR) Air Flow Meter.

Housing £90.00 Buy Now Click Here!

90mm Air Flow Meter Complete £228.00 Buy Now Click Here!
90mm AFM Housing
90mm AFM Housing
90mm AFM Housing
90mm and 80mm AFM

NGK Spark Plugs

NKG Spark Plugs Cooler running NGK spark plugs for big horsepower turbo applications

7EIX - £35.80 Set of 4 Buy Now Click Here! 8EIX - £35.80 Set of 4 Buy Now Click Here!

Bosch Map Sensors

We can supply a range of map sensors with a wider calibration scale to suit higher boost applications including 3 Bar, 3.5 Bar and 4 Bar. OE 2.5 bar are sensors are also available.

From £64.95 - £99.00 Buy Now Click Here!
Bosch Map Sensor

630cc High Flow Injectors

High Flow 630cc Injectors 630cc at 3 bar.

High Flow Fuel Injectors for high power engines 400bhp - 500bhp.

£395 Set of 4 Buy Now Click Here!

Uprated Fuel Pump

High Flow Uprated In Tank 340 Series Stealth Fuel Pump for most petrol turbo applications.

For Astra G/H and Zafira A/B Turbo models inc VXR running big horsepower and higher boost levels, fuelling is critical. The replacement Protec 340 Stealth high output in-tank electric fuel pump offers the solution. 340 lph at 40psi. Offset Inlet, Inline with Outlet. Will fit into original in-tank housing with slight modification. Suitable for cars from 300bhp up to approximately 450bhp. Features a vapour-purge port as on an OE pump, so less prone to fuel starvation at low fuel levels.

£99.00 Convoluted Flexi Fuel Hose also available
This 340 Fuel Pump is a high-output, in-tank electric fuel pump which is a compact, lightweight pump that bolts into the existing OE fuel pump assemby with just minor modification. This pump is ideal for applications requiring more flow while retaining the factory fuel lines and mounting provisions available in the Original Equipment (O.E.) configuration.

Features an offset inlet, inline with outlet.

• Fits Astra G/H 2.0 Turbo, Zafria A/B 2.0 Turbo, Corsa D 1.6 Turbo with minor modification to the OE fuel pump housing.
• Internal Check Valve
• Vapour Purge Port in base of pump
• Designed for in-tank use only
• Turbine pump mechanism increases durability.
• Suitable for standard and modified cars.

Flow Rate - 340 lph @ 40psi :: 300 lph @ 50psi :: 275 lph @ 60psi
Weight - 355 grams
External Materials - Black Steel Body
Inlet Fitting - Offset Inlet Inline with Outlet
Outlet Fitting - 8.5mm OD
Impeller Design - Regenerative Turbine
Terminal Post - Spade Terminal OE Fitment (6.2mm)
Min Voltage Input - 6 vdc
Max Voltage Input - 18 vdc
Current Draw - (40 psi) 12 amps (13.8vdc)

Pump Overall Height (including outlet) - 120mm
Pump Body Height - 80mm
Pump Body Diameter- 39mm
Outlet Length - 21mm
Outlet Diameter - 8.5mm
*All dimensions are approximate
Engine Rebuilding Options Engine Rebuilding and Components.

A separate page with details of our engine rebuilding services and components; Forged Pistons, Steel Rods, Balancer Shaft Deletion Kit.

Genuine Z20LEH Forged Pistons and Steel Rods Kit

Genuine GM/Opel/Vauxhall Z20LEH Forged pistons made by Mahle £650.00 per set
£1052 per Set with H Beam Rods. Details on our engine rebuild page. Click for Info

Wossner Forged Pistons

£606 per Set. Details on our engine rebuild page. Click for Info

Wossner Forged Pistons and Steel Rods Kit

£985 per Set with H Beam Rods. Details on our engine rebuild page. Click for Info

Uprated H Beam Steel Rods and Rod Bolt Kit

£402 per Set. Details on our engine rebuild page. Click for Info

Balancer Shaft Removal Kit

£148.80 Details on our engine rebuild page (not required on Z20LEH). Click for Info

Uprated Multi Layer High Performance Metal Head Gaskets

We have multi layer uprated metal head gaskets available for all high power builds.
High Performance 4 Layer Gasket - 1.3mm when compressed.
Ultra Performance 5 Layer Gasket - 1.9mm when compressed.

Price - £139.95 HP 1.3mm Gasket Buy Now Click Here!  UP 1.9mm Gasket Buy Now Click Here!

Engine Rebuild Components - Gasket Sets, Bearings, Head Bolts

Not only can we supply pistons and rods but for anyone carrying out their own engine build we can supply head gaskets, top and bottom gasket sets, big end bearings, main bearings, oil pumps, water pumps, cambelt kits and auxiliary drive belts. In fact everything you will need. Most parts are available for online purchase from our shop. For a list of components click on the button >>>>>> Buy Now Click Here!

Astra GSi Turbo Garrett Build GT2871

Courtenay Sport Garrett Astra GSi Turbo. Garrett GT2871RS turbo (built to our own spec), Courtenay Sport equal length tubular manifold, fully rebuilt engine, forged pistons, steel rods, lightened and balanced, under piston cooling installed, High Flow Injectors (550cc), 80mm air flow meter, high flow enlarged plenum, high flow Courtenay Klasen Inlet Manifold, uprated inlet and exhaust cams, modified head, Astra VXR (Courtenay VXRPC) VXRacing intercooler, 3" bespoke exhaust system with sports cat and custom mapping of the original Bosch 1.5.5 ECU (standalone management not required!!).
View Power & Torque Graph
Power Graph
Play Video
Duration: 2.21

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