It is for good reason that virtually every top professional engine builder relies on ARP Pro Series head studs for their all out competition engines. Simply stated, there's not a better stud setup on the market today.

ARP uses a premium grade 8740 alloy that is rated far superior to "aircraft" quality. Each stud is placed vertically in special racks and precisely heat treated to 200,000 psi. This procedure ensures complete and uniform heat penetration, giving far superior results to the more usual practice of placing them all in a basket and hoping for the best.

Following the heat treatment, each stud is centreless ground to make it as close to concentric as possible. This procedure involves about ten very slight cuts, and results in an exceptionally straight part to start from. They are then Thread Rolled which, due to being done AFTER the heat treatment, gives them around 2000% (20 times) better fatigue strength than studs that are threaded prior to heat treatment. It costs a lot more to do this way, because it is very tough on tooling, but the results are well worth the extra effort.

These ARP head studs have been specifically developed for the Vauxhall Z20 engines.

Full set including a sachet of ARP's assembly lube, for correct torquing.

Set of stainless bolts and washers to replace those terrible rusty Vauxhall ones.

Z20 stem seal and retainer combined.

For use with single valve springs only.

Piper Cams single valve springs with combined stem seal retainers for the Z20 LEx engine.

Uprated valve springs are a worthwhile investment for any Z20 engine intended for vigorous use, especially with regards to high revs / high load.

During the process of fitting springs, the stem seals are also accesible so it would be rude not throw a new set on.

This kit includes the combined stem seal retainer which allows you to kill two birds with one stone, replacing old worn stem seals and adding the support of the retainer body to help prevent failure. 

Klassen upgrade intake manifold system for Z20lex 

Designed to take the standard fuel rail and injectors , this manifold take some simple modifications to be installed.

Proven to increase power and torque across the RPM range and especially usefull if aiming for high power . 

We have run this manifold to around the 600 HP area , we believe around this sort of power a bigger intake manifold solution would aid power gains.  Below the 600 Hp region this manifold will improve power and torque in varying amounts depending what cams are fitted. 

We find these work especially well with the cat fast road cams and a GT28 frame turbo for the 450-500 HP region, for more than that aim for the Cat semi race cams and a GT30 frame unit and that will cover the higher output that is possible on this manifold 

Identical profile  to our semi race cams suited for the hydraulic lifter but modified with lash ramps for using solid lifters 

Installed seat pressure - 30kg 
Lift - 100kg@13mm
Max. lift - up to 13mm
Made from chrome-silicone steel SAE9254-V
16 pcs. outer springs
16 pcs. inner springs
16 pcs. titanium retainers
Fits Opel / Vauxhall 4 cylinder 2.0 16V Z20LET Z20LEH engines. 
With this set the risk of valve float and a possible engine failure is minimized.
Recommended for engines with series and racing camshafts and over 7600 RPM.
Titanium retainers are very light and strong, helps eliminate valve float. Weight is only 10g.

FCP Engineering lash cap used with solid lifter.
hardness HRC 55, inner diameter 7mm, over deck 5mm

Oversized lifter shim to be ground to suit applicalion 

Adjustable alternator bracket for the Z20 series engine using the standard type alternator.

This adjustable bracket allows the alternator to be rotated back approximately 20mm.

Includes all mounting hardware, all hardware is stainless steel except the  main spacer, this is aluminium and annodised black to prevent corrosion.

The bracket itself is CNC Laser cut from 4 MM thick stainless steel plate.