Factory Holden LC GTR Torana, HR X2, HK 186S GTS Monaro cast iron twin exhaust headers are pictured below. These factory style headers are good for a few extra horse power over std factory single outlet exhaust manifolds. The Holden 149 & 179 EH used a hot box style exhaust manifold to pre heat the cast iron inlet manifold. General Motors Holden changed to a water heated inlet manifold that was made from aluminum in the later engines.

Holden six
Holden 6 cylinder Yella Terra Alloy Cylinder Heads

The Legendary Holden six Yella Terra alloy 12 port cylinder head is back !!!
Yella Terra has reintroduced there aluminum 12 port Holden 6 cylinder head into the Australian market. Some of the new improvements include a revised port design with an increase of over 30% better flow than the factory 12 port cast iron head. This affordable new design has much more potential & higher flow figures can be achieved when professionally ported. This improvement in flow is due to many hours of research to develop to refine a taller, wider ports, low restriction to the area under the valve known as the short turn radius other improvements are larger valve throats & bowls. The streamline valve guide design allows for huge increases in port volume and airflow efficiency. The new Holden alloy head also has a near on 50% weight saving over a factory 12 port cast iron head, The cylinder heads are fitted with 2% nickel iron inlet valve seats and hard nickel alloy exhaust seats for extreme operating temperatures & unleaded fuels.

The new Yella Terra light weight Holden six aluminum cylinder head casting features further developed cooling passages for improved cylinder head cooling through the entire water jacketed area. The new Yella Terra Holden 6 alloy head is available with the choice of 2 combustion chamber sizes 56cc & 72cc low compression chambers for forced induction turbo charged or super charged Holden straight six cylinder engines.
This new performance product will transform your vehicle with more free revving power, improved performance and reliability with the following features:
• Excellent Flow figures:..240HP potential out of the box
• Average of .250” port wall thickness for custom porting
• Over 60% lighter than factor Iron Heads
• Flow over 30% better than the standard Heads
• Holden exterior design with totally revised ports and water
jackets for improved cooling, reliability and performance.
• Both Standard Compression and Turbo Versions


Material 356 Alloy Heat treated to T6
Chamber Volumes Standard Head- 56cc Turbo Head 72cc
Inner Runner 82cc
Exhaust Runner 71cc
Intake Valve 1.740”
Exhaust Valve 1,480”
Valve Guides K Liners

Valve Seats
Inlet Cast Iron 1.812”x .250”
Exhaust Nickel Chrome alloy 1.625” x .250”
Spark Plugs Tapered Seats
Deck Thickness 0.450”
Installed Height with Std Valves and .060” Valve Spring Insets/Shims 1.520”
Spring Seat OD. 1.250

Matching part # for yella terra roller rockers are listed below.
• Street Terra ST2030 Bolt On
• Street Terra ST 2031 Bolt On
• Yella Terra YT 5008 Stud Mount
• Yella Terra YT 5029 Platinum Twin Shaft in various ratios from 1.5:1 to 1.7:1

yella terra alloy holden 6 head

To view what is required in fitting a blue motor cylinder head to an earlier red motor block view the few story on the Kustombitz website

Supercharged Holden 6 fitted to EH Holden running straight LPG

Fitting a blue/ black Holden cylinder head onto a 186,202 red motor block.

There are a few tools you will need to do the mods to your red motor block to fit a black or blue motor Holden head to your red motor block..
Start by scrapping of the old gasket , grease & build up of shit that seams to get in.

Use a scrapper,old chisel or you can buy an air operated scraper. VHT gasket stripper is also very good but watch your eyes & wash ya hands before you go for a pee down the side of the shed as that stuff will burn ya pecker quick smart. an oil stone can be used with a bit of kero or wd 40 to give it a final clean.

You will need a black blue Holden 6 cylinder head gasket
felt marker to mark the holes.
A 6 mm drill bit
An electric or air operated drill,
A magnet or old speaker
A hammer & centre punch
Start by cleaning the block surface down with the scraper, removing all the old gasket, then use ‘wet and dry’ to clean the top of the block until you get a dull shine. Place you blue motor head gasket on the block and mark the holes that need to be drilled, as you stand in front of the engine they start at number 2 cylinder and finish at 5, down the right side of the block…there are 4 in total.

Centre punch the holes , This will make it easier to drill the hole in the right spot. You can drill a pilot hole then step up a few sizes until you get to the correct size.

Use the magnet to stop the drill swarf from entering the bores & water jackets.

Once the holes are drilled & clean, put a small amount of grease on the tap and plug the old coolant passages .

Clean up the face of the head, give it all a good clean, use a wire wheel on a bench grinder to clean up the threads on your old head bolts & put it all back together.

The Holden 6 blue motor ports are around 6mm larger in height than the red motor ports. You cant fit the red motor manifold so you will either need to stick with the std varijet manifold or use an aftermarket manifold like the AussieSpeed that is designed for a blue/black performance engine, other wise it is like running around with a plastic bag on ya head..

Holden Torana cylinder head casting numbers xu-1

cast number 2815843

date cast number: h252 25/8/1972

The Weber 40 or 45mm DCOE side draft carburettor is still a popular choice & in most cases is used with a 12 port head.pictured below is a set of triple webers fitted to a Warnerford 3 piece manifold.

The manifold pictured is a factory Holden VK commodore fuel injection over head type.These are to suit the factory 12 port cylinder head. The manifolds have been used for high performance Holden six turbo charging & LPG. The advantage of the Holden 202 late model engine is a factory electronic distributor can be regraphed for extra performance gains & the throttle body can be modified to run straight LP gas.

Bullet heads service recently got a factory blue twelve port cylinder head to flow
187.2cfm @ .550 lift, in a perfect world it works out to be 289 hp. Before the boys at bullet cylinder heads in Adelaide they gave it the once over. The previously modified blue motor commodore head flowed 169.4cfm@.550. now that equals 261hp flywheel horse power. Car was dynoed @204 rwhp had 9:1 compression ratio.
The compression has now been increased to 10.8:1 and will need to be retuned to suit.

Castlemaine Rods shop Have made a easy to install DIY supercharger kit to suit the Holden six cylinder. The kit will not fit the Holden 3.3 black motor, There are 2 carby options for the super charger set the first being a Holley 350 2 barrel & the 2nd carburettor that has been used is a 2 inch SU. The SU carb set up was the proven winner with better performance, easier starting, better engine idle, economy & more power. The std kit has 2 blower speed options. The Roots style super chargers are from a Toyota six cylinder engine, boost pressures run between 6 & 10 PSI.

Another rare early Holden Red motor item is a the Irving cylinder head.Designed by Phil Irving the Cylinder head had to be used with its own extractors & inlet manifold.Carburation was normally 48mm webers or mechanical Fuel injection. This engine pictured uses a magneto to supply spark.

Pictured below is some of the AussieSpeed range of performance manifolds to suit Holden 6 cylinders.

Yella Terra would have to be A name most Aussies know even if they are not real car buffs. The Yella Terra range of Performance products have made more of an impact on modified cars in Australia, New Zealand, the United States & many other parts of the world. There range of cast iron exchange Holden six & v8 cylinder heads with there trade mark Yellow paint has now gone to the next level with the release of the Alloy holden six performance head. The Yella Terra aluminum Holden 6 head is an affordable bolt on replacement head that will make more of an increase in power than any other bolt on hot up part. AussieSpeed have produced a true 12 port blue/ black motor triple weber & 4 barrel manifold that will boost performance on a factory cast iron head & even more gains can be found when used with the Alloy 6 cylinder Holden Yella Terra head. Other components like roller rockers made by yella terra & camshaft,lifter,valve spring & collet kits made by Crow cams offer some of the Best parts for you performance Holden six.

John Cain Holden 4 barrel Performance manifold to suit Holden 9 port red motor cylinder head. These Manifolds were good in there day & this wide runner version was 1 of many styles that Cain Manifolds made.

Holden six cylinder redline mk2 4 barrel manifold, the maker claims it will fit both red & blue motor cylinder heads.

The Thomas brand of Australian Speed Equipment that then ended up being Speco Thomas & latter just called Speco were a major part of of the performance industry in Australia.Pictured below is an early Holden six rocker cover that will fit Holden red motors from 149,161,179 & 186 Holden sixes. With the later bridge & rocker style rocker arms these rocker covers will not clear the valve train on 173 ,202 ,2850 & 3.3 Holden 6 cylinders.

AussieSpeed Street & Race Products & TTT Performance Offer Howler Super Charger Kits For Holden Straight Sixes

A combined effort between AussieSpeed,Kustombitz & TTT Performance Engineering will offer a range of super charger kits For Holden,Ford & Chrysler Slant 6 & Hemi 6 inline engines. AussieSpeed Have used there inlet manifold design with its even runner flow to the intake manifold that accepts the Yella Terra YT1500 M90 eaton style super charger. The super chargers are far more compact than the older style GM 3/71 & 4/71 & offer both carb on top & a rear entry style super charger for those wanting to keep as much as possible hidden under the bonnet. The first Kit to be offered under The Howler Forced Induction Brand is to suit the Holden black/blue 12 port cylinder head & includes Back fire valve, Idle by pass,Super charger, Drive snout, Idler bracket & pully, Blower drive belt, Supercharger top pulley, Crankshaft pulley, bolts & studs for installing the DIY kit or you can have it fitted & tuned for you. Other other components available with be modified 12 & 9 port cylinder heads, Camshaft Lifter & valve train kits, Reconditioned short motors with std or stroker style crank, Ignition system, Carburetors, Finned alloy dress up Rocker covers & sideplates & all other accessories for your performance upgrade.

The Best in Street Performance AussieSpeed dedicated Blower manifold to suit Holden inline 6 Cylinder 202 engines Using Yella Terra Terra Charger Supercharger. Picture of the proto type unit being developed Fitted & Tuned by TTT Performance engineering for Howler Forced Induction.

The Radial Style supercharger allows for Holley 4150 & 4160 4 barrel carb to be bolted on top of the super charger. A fuel injection throttle body in 4 barrel Holley or LPG dedicated gas system could also be used

The AussieSpeed manifold has a dedicated area on the back of the super charger manifold for the by pass valve the Super charger kit will offer different horsepower increases depending on engine combinations.

For More details on the Holden Straight 6 performance supercharger kits, modified cylinder heads & high performance long & short motors

AussieSpeed holden 202 Black & Blue Motor 6 cylinder 2 barrel performance manifold

The all new for 2010 AussieSpeed even flow 2 barrel Holden 202 suit 12 port head inlet manifold, The manifold offers hi velocity plenum & runners with even flow to all 6 cylinders. The unique plenum design over comes poor design in runner & plenum design when using 2 & 4 barrel inlet manifolds on inline engines.

To find out more about the all new AS0169 AussieSpeed 2 barrel Holden 6 manifold click on the link below