BLACK NITRIDE:

This is a hardening treatment that even though it is not widely used as the chrome coating, it has several benefits and is becoming very popular, mainly for European and Japanese applications.

The microhardness is higher than the stainless steel base material, keeping good ductility beneath the hard nitrided layer (microhardness is 800HV minimum).

Surface finish is smoother than with chromed stems, having less friction between stem and guide.

Valve seat surface is harder with the nitrided layer, lasting longer with lead free fuels, alcohols, nitro or other "explosive" mixes. Matches any kind of seats (nodular iron seats, steel powder metal seats, hard aluminum-copper seats or beryllium copper seats).

Higher rpm's engines take full advantage of all previous features. The higher the engine speed the bigger the power loss due to internal engine friction! The black nitride layer reduces this power loss due to less valve-guide  friction.

The nitrided layer is adhered to the base material at a microscopic level, so does not "flake" or break when the valves bend due to impacts with the pistons.

The Black Nitride applies to the whole valve while the chrome coating is only applied to the stem.

All valves are swirl polished, have stem undercut and a hardened tip.

Head Diameter 33mm  (+1.00MM )

Stem Diameter 5.96mm

Length 102.15mm

BLACK NITRIDE:

This is a hardening treatment that even though it is not widely used as the chrome coating, it has several benefits and is becoming very popular, mainly for European and Japanese applications.

The microhardness is higher than the stainless steel base material, keeping good ductility beneath the hard nitrided layer (microhardness is 800HV minimum).

Surface finish is smoother than with chromed stems, having less friction between stem and guide.

Valve seat surface is harder with the nitrided layer, lasting longer with lead free fuels, alcohols, nitro or other "explosive" mixes. Matches any kind of seats (nodular iron seats, steel powder metal seats, hard aluminum-copper seats or beryllium copper seats).

Higher rpm's engines take full advantage of all previous features. The higher the engine speed the bigger the power loss due to internal engine friction! The black nitride layer reduces this power loss due to less valve-guide  friction.

The nitrided layer is adhered to the base material at a microscopic level, so does not "flake" or break when the valves bend due to impacts with the pistons.

The Black Nitride applies to the whole valve while the chrome coating is only applied to the stem.

All valves are swirl polished, have stem undercut and a hardened tip.

Head Diameter 32.5mm +0.5mm 

Stem Diameter 5.96mm

Length 102.15mm

These Inconel valves are made from a Nimonic 751 alloy which has better resistance to heat then the stainless steel.  Inconel valves are only used on the exhaust side, it is the only side that it is required to use a higher temperature alloy. 

Head Diam: 30mm    (+1.00mm)

Stem Diam: 5.95mm

Length: 92.3mm

Material: Inconel

These Inconel valves are made from a Nimonic 751 alloy which has better resistance to heat then the stainless steel.  Inconel valves are only used on the exhaust side, it is the only side that it is required to use a higher temperature alloy. 

Head Diam: 29.5mm(+.5)

Stem Diam: 5.95mm

Length: 92.3mm

Material: Inconel

Timing belt kit comprising;

2 x steel idler rollers

Uprated Gates Racing Timing belt

Upgraded bolt for locking tensioner

OE tensioner

This kit is basically what we know to work best when the customer is wanting 450-500HP and the same in torque. 

From using many sets of these cams with different turbos across the range, we found what we term our "Fast Road" Cat Cams are about best in most scenarios. Generally speaking the fast road cams actually have a slightly saller exhaust cam and this seems to help in keeping the low end torque.   

We have run in excess of 500LBS of peak torque on these cams using the Owens GBT5471 style turbo, they also take the 500HP nicely too. If you are aiming for the 500-550HP region then what we call the cat semi race will be better suited. In most cases this setup is actually what people want for a fast road car. 

Supplied in a deal with everything that is required to do the job to a decent standard. This kit basically takes care of the whole top end with regards to parts that are changed for 450-500hp  



 

When upping the boost on a standard type engine , sometimes its a good idea to pull the compression back a little bit. This can be done easily with a thicker headgasket as one way of doing it without having your pistons machined. Going thicker in headgasket size is only a solution for a certain amount , if you end off needing a ludicrously thick gasket to get the compression you want then its probably time to start thinking about other options. The problem when you go too thick on the head gasket can be reliability. This area at the very top of the cylinder is where a lot of the really high pressure energy is made – its often a weak point on some engines prior to increasing the thickness. Increasing the thickness increases the surface area the chamber sees pressure over , meaning that the gas can now actually get more force into blowing the gasket out.

 

If building your engine from the onset for really high boost then we would recommend you ask about piston machining being involved in your build. If you maybe already have you engine built but are having some slight detonation issues then the RnD gasket could be ideal for you. Usually the heavier detonation on a z20 will always be around the outer ring of the piston , usually around the exhaust valve side.

The z20 engine tends to have quite a tight squish band . The standard tolerance of piston protrusion is 0.4mm , its acceptable to skim the block a few thou so piston protrusions can easily get into the 0.45mm area without piston correction. The standard headgasket is 1.1mm thick , the cylinder head is flat and has no recess for the piston. This leaves us with an area around the top of the piston that will come within 0.65mm of the head ( about 0.025" ) just turning the engine over by hand , a little closer maybe at 7000RPM . The RnD gasket is 1.6mm thick , this immediately bumps 0.5mm onto this size giving us 1.15mm ( about 0.045 ) - this size is certainly better for running more boost , if you have built a few engines for high boost then you will maybe still also think that this is still tight!

The 1.6 mm gasket is the thickest gasket we recommend for the Z20 engines for high boost reliability..

The RnD gasket has no rivets installed - do not mix up the gasket layers 

We also offer custom machining of z20 pistons via post

Custom machining on pistons available on new pistons £95 inc VAT set of 4 pistons.

We also have some developed Wossner Pistons arriving into 2020 , please get in touch if you are unsure what you need

We strongly recommend the use of ARP headstuds , we only use this in all our engines.

RnD Z20 Colidsbro Valve Guide Set 

CNC machined with depth stop 

Precision CNC turned, these guides are actually bored through with a boring bar and not just drilled.

• Manufactured from colidsbro material, very hard wearing material with high lubrication properties, these will last five times longer than any traditional bronze guide.

• Intergrated depth stop for easy fitting – if your head is OE spec then installing these guides to the depth stop will sit them just below the top tolerance of installed height (13.8 MM), if your cylinder head has had a bit of a hard time spring seat wise and needs the seat areas re machining, skimming this area by 0.2mm then fitting the guides will still leave them installed to standard spec.

• Valve stem seal barb grip technology, these valve guides will hold a traditional valve stem oil seal in place without a retainer type oil seal being used. 

• Relieved and radiused guide end to help improve air flow around the valve guide and reduce turbulance around the guide releasing them hidden horsepowers. 

• These guides need machine reaming after install , the valve seats will need recutting back concentric after the guides have been installed and reamed.

• Please contact us if you are interested in some extra heavy duty Chrome Nikel sintered valve seats. 

Upgrade Cam Cap Bolt kit

High tensile flange headed upgrade bolts for z20le* cylinder head cam caps

Most upgrade cam manufacturers recommend the use of upgraded bolts, not many actually know what to use – we use these every time we take the cams out of an engine , we have tested these bolts in the hundreds and we are finally happy to say they are fit for use.

We find that torquing these bolts into 10NM works well , always make sure the threads are clean, lightly lubricate the bolts with light oil before install.

These upgrade bolts require no modification to the cylinder head for install , they are a direct fit . They can be used if simply rebuilding the engine with standard cams or with our largest off the shelf performance cams.

RND Motorsport Z20let/r/l/h Single upgrade valve springs

Having pushed so far on the Z20 engine , we are using what we know to make the more normal power builds better. Learning more on the subject of how much valve spring you need for what you are doing lets you free up some HP in not driving an over sprung engine. Making the springs more accurately lets you drop the pressure back off a little bit because the real world average spring rate is much closer to what you want, on a less accurate spring you have to make them generally firmer to account for the soft ones still being OK to run. This potentially could mean you are over driving 15 valve springs just to make sure the one weaker spring is still doing its job well.

As with most of our high quality items that we sell, these are UK manufactured by a very reputable company, they are much more used to hitting a less than 1% deviation on spring to spring. This is key to being able to run a much closer to desired spring pressure without so much extra for the sake of it.

Wound from high quality steel , both ends ground flat , micro peened and coated , pretty much everything you can do to a spring to improve its performance and life.

These springs will give you in the region 20% more initial seat pressure than a stock spring , with 10mm of lift then they are about 13% stronger than the stock springs. In some cases the other springs we have measured are around 35% stronger with 10mm lift, fine in some applications but not needed in many others. These springs are set to be just right for most fast road cam applications. If you need a little more spring pressure then a 1mm shim will bump the pressure curve on by 10LBS , we have not required this option on anything we have tested so far.

Free length - 45mm

13.00mm lift before bind using stock valve spring retainer and stock seat.

Max lift recommended 11.5 mm

Installed seat pressure with 34mm install height – 79 LBS +/- 1%

pressure at 10mm lift with 34mm install height – 158 LBS +/-1%

Billet Steel Cylinder head hollow dowel pair - 

Replace the junky standard ones for some of these , proven to not crush down and allow the head to move so much