Subaru Cosworth Engine

Cosworth/Subaru Formula 1 engine

Racing History

The name Cosworth is amongst the most respected names in motorsport.
The company was officially founded by Mike Costin and Keith Duckworth (hence Cos-worth), in 1958. After initially providing engines for Lotus, the company expanded into manufacturing engines and parts for major auto manufacturers such as Ford and Subaru, and have enjoyed huge success in all areas of motorsport, from club racing all the way to Formula 1.

Cosworth manufacture highly engineered internal engine components, as well as peripheral components such as intercoolers, brakes, and electrical components designed to exceed manufacturer’s performance parameters.
Cosworth engine internals are tried and proven to increase strength and durability; thus providing an ideal platform for increased horsepower and performance.
Cosworth’s long list of achievements, the awesome power of their engines, and their reliability, have placed them amongst the first rank of motorsport players.

Cosworth/Subaru SC 400 WRX Impreza

Cosworth and

Cosworth have taken an interest in Subaru since Subaru’s early outstanding performances in world rallies and other motorsport events, and they now manufacture internal and external components for all Subaru models.
From the initial design stages to mass-manufacturing, Cosworth high performance forged pistons are engineered to withstand brutal punishment and still perform as designed. All Cosworth Subaru pistons are manufactured using the same stringent methods as their Formula One pistons and include features such as anti-scuff skirt coating, ultra-strong pins, polished tops and patented anti-detonation bands. Additionally, a unique forging process is implemented to minimize weight and results in the strongest possible piston.

The Subaru WRX or STI in stock form is already a potent machine, with finely balanced weight distribution, symmetrical AWD, and a high-output turbo charged boxer engine. Add the strength and F1 specific engineering of Cosworth engine internals, and you have the potential to generate some truly awesome power. You’ll find Cosworth pistons, rods, camshafts and cranks in most successful high performance Subarus on circuits or rally tracks. The outcome of Cosworth’s involvement in Subaru engines is the Cosworth built SC400 WRX STI, with a 0-100 time of 3.7 seconds landing it into exotic supercar territory.

and Cosworth

For the past ten years, All Drive Subaroo have been Australian distributors for Cosworth, and we have developed our own configurations of high-performance Subaru engines using Cosworth components. Our R&D has been driven by two needs: to produce increased power for our performance minded customers, and to address a number of notorious inherent weaknesses in the EJ255 and EJ257 engines, starting with the 2004 Forester XT, and the incorporation of this engine into WRX and Liberty STI. The mass production of these engines provided a big market for Cosworth components and their engineering evolved to meet demand. With the Cosworth components the EJ range of engines can now be all that they should have been from the start.

Inherent OEM Subaru engine issues (EJ205, 255, 257)

From our vast experience servicing and repairing all Subaru models over many years, combined with the advanced Subaru factory training undertaken by ADS workshop director, we have identified a number of inherent weaknesses and potential problems in the above engines, including:

  • Excessive oil consumption up to 1 litre per 1000kms
  • Head gasket coolant leak issues
  • Cylinder bore distortion
  • Timing belt dislodgement
  • Engine design associated turbo boost limitations
  • Piston failure
  • Engine bearing material issues
  • Engine Oil starvation
  • Catastrophic crankshaft failures
  • Lack of power at high RPM

All Drive Subaroo has the solution

With all those years of experience and research, combined with the strength and quality of Cosworth forged components, we can offer the very best Subaru engines ever made, and at competitive prices. Not only have we been able, with revised components, new techniques and Cosworth components, to address all these issues, but we have produced replacement engines that are cheaper to run, much stronger, more reliable, and longer lasting than a new OEM Subaru unit, with the added bonus of being ready for greatly increased power output if desired. When comparing our high quality engines and warranties you will find that Subaru Engines Australia is very competitive, especially for our Cosworth performance range. ADS have worked hard to produce engines that will satisfy the demanding performance driver and the most extreme applications. Whether you’re a professional racing driver, a keenly competitive enthusiast, or just looking for a strong, long lasting engine, our Cosworth setups give you the edge.

  • We can usually ship one of our high performance Cosworth engines within 5 days.
  • We offer two levels of engine for the EJ20 and EJ25, a total of four different assemblies.

ADS/Cosworth Engine Quote

1. SELECT ENGINE TYPE

The EJ20 and EJ25 Street Tuff setups are much stronger and more reliable than the factory engine, and have the potential to support big increases in power if desired. These are suitable for a daily driver who likes a stronger engine for robust reliability, or for an enthusiast on a tight budget who wants to tune his engine. Any performance boost will depend on the size and design of the turbo used, the ECU software configuration, and a range of other considerations such as intercooler, fuel injectors and exhaust setup.

EJ20/EJ25 Standard Stroke Cosworth Street Tuff Engines Include:

  • Brand new STI EJ207/257 semi-closed deck engine block
  • Brand new STI EJ207/257 induction hardened and cross-drilled crankshaft
  • New Cosworth forged billet 2618 pistons with ADS L.O.C design (8.5:1 or 9.2:1 CR)
  • New improved ADS low friction L.O.C piston ring set
  • New Cosworth forged EN24 I-Beam connecting rod set
  • New Cosworth H11 steel rod bolts (rated @ 260 000psi)
  • New revised race spec tri metal engine bearings (tested @ 1000hp)
  • Subaru genuine block bolt set
  • Measure combustion chamber volume to calculate actual compression
  • Completely recondensed cylinder heads with 3 angle valve cut
  • New genuine Subaru valve stem seals
  • Surface grind cylinder heads using diamond tool
  • Cam shaft and journal polish
  • Set all valve clearances to strict ADS specifications
  • AVCS cam pulley overhaul and adjustment (Model Dependant)
  • New ARP 11mm custom age 625+ SDF head stud kit
  • New Cosworth pre coated die cut stainless steel muti-layer head gaskets
  • New genuine Subaru seals, O-rings and sealing compounds
  • New genuine Subaru cast water pump (model suited)
  • New genuine Subaru timing belt and idler bearing kit with tensioners
  • New revised and improved 12mm h/d oil pump
  • New genuine Subaru water bi pass coolant hoses
  • Tested and checked genuine Subaru engine oil sump and pick up
  • Checked and cleaned timing covers set
Subaru EZ30 H6 engine

Cosworth Stroker Setup

Street/Strip Stroker Engines: The stroker engine has forged internals for increased strength and durability. The longer stroke effectively increases engine capacity and gives more performance straight off the rack, with the potential to handle much more. This is the perfect performance engine for customers who want the most on the street and at the track. This is the engine setup you need if you want to extract high RPM and maximum power.

EJ20/EJ25 Stroker Cosworth Race Tuff Engines Includes:

  • Brand new STI EJ207257 block.
  • ADS CNC Billet Alloy 6061 closed deck
  • Machine boring, honing, decking and torque plate
  • Drill, reem and tap 13mm head stud deep thread
  • Brand new induction hardened/Billet stroker crank shaft
  • New Cosworth forged billet 2618 pistons with ADS L.O.C design (8.5:1 or 9.2:1 CR)
  • New improved ADS low friction L.O.C piston ring set
  • New Cosworth forged EN24 I-Beam connecting rod set
  • New Cosworth H11 steel rod bolts (rated @ 260 000psi)
  • New revised race spec tri metal engine bearings (tested @ 1000hp)
  • New ADS high strength tensile block bolt set
  • Measure combustion chamber volume to calculate actual compression
  • Completely reconditioned cylinder heads with 3 angle valve cut
  • Tomei PonCams (IN:260 EX:254)
  • Tomei performance valves
  • Tomei nitride valve springs
  • Tomei titanium valve spring retainers
  • Tomei Adjustable cam gears (model suited)
  • AVCS cam pulley overhaul and adjustment
  • Set all valve clearances to strict ADS specifications
  • Measure cam timing and adjust for best outcomes (model suited)
  • New ARP super strong 13mm head stud kit
  • New Tomie centre folded super grommet design head gasket
  • New genuine Subaru seals, O-rings and sealing compounds
  • New genuine Subaru cast water pump (model suited)
  • New genuine Subaru timing belt and idler bearing kit with tensioners
  • New revised and improved 12mm h/d oil pump
  • New genuine Subaru water bi pass coolant hoses
  • Tested and checked genuine Subaru engine oil sump
  • Checked and cleaned timing covers set
  • New STI engine oil cooler
Subaru EZ30 H6 engine

EJ20 2.1l Stroker Cosworth Engines Includes:

  • Cosworth forged pistons and rings
  • Cosworth coated, tri-metal bearings
  • Cosworth high-strength head gaskets
  • New Subaru EJ20 STI engine case
  • New Subaru STI forged crankshaft
  • New forged connecting rods
  • New high-volume 12mm oil pump
  • New Subaru engine oil pick up
  • Inspected Subaru engine oil sump
  • Balanced to within .5 gram
Subaru EZ30 H6 engine

EJ25 2.6L Stroker Cosworth Engines Includes:

  • Cosworth forged pistons and rings
  • Cosworth coated, tri-metal bearings
  • Cosworth high-strength head gaskets
  • New Subaru EJ25 STI engine case
  • Cosworth 81mm billet crankshaft
  • Cosworth forged connecting rods
  • Cosworth head stud kit
  • Cosworth stainless valves
  • Cosworth high-rev valve springs
  • Cosworth valve retainers
  • Cosworth valve locks
  • Cosworth oil pump
  • New Subaru engine oil pick up
  • Inspected Subaru engine oil sump
  • Balanced to within .5 gram
Subaru EZ30 H6 engine

2. Select Performance Addons

ADS Spec Timing Belt

ADS Spec High Performance Timing belts are 300% stronger than original equipment timing belts

Billet Timing Belt Guide

ADS Spec Billet timing belt guide replaces the original sheet metal timing belt guide that can flex from belt deflection when subjected to extreme rpms causing the timing belt to skip one or more teeth on the crankshaft sprocket.

Head Stud Kit

Essential for high performance engine builds, heavy duty head studs reduce cylinder head movement in high boost or high compression engines optimising cylinder head to block sealing. ARP Ultra High Performance Head Studs

Oil Control Baffle

Killer B Baffled Oil Pan options have been engineered with diverters to control oil returning from the cylinder heads to the pan directing it away from the crankshaft. Additionally, one-way valves prevent oil from reentering

Engine Oil Pump

High performance engines dissipate a substantial amount of heat through the oil system. Maintaining oil pressure and control along with an increase in actual volume will help assist this process and stabilize oil temperatures.

Induction hardened Crankshaft 75mm (EJ20)

Increased engine performance often means increased engine speed and load. STi induction hardened crankshafts are designed to withstand the added stress.

Induction hardened Crankshaft 79mm (EJ25)

Increased engine performance often means increased engine speed and load. STi induction hardened crankshafts are designed to withstand the added stress.’

Destroked EJ25 (EJ25 De-Stroker)

Increased engine performance often means increased engine speed and load. STi induction hardened crankshafts are designed to withstand the added stress. Ask us about the various options to stroke and rod length.

Forged Connecting Rods

To ensure engine reliability in all conditions, original connecting rods should be replaced with heavy duty specification parts. Carrillo Forged Connecting Rods are manufactured from high strength 4340 (EN24) steel

ADS Spec ported Cylinder Heads with Camshafts (2.5lt Only)

Each Subaru cylinder head has been carefully evaluated and tested to establish what improvements are required to meet target performance levels. Hours of testing and flow bench validation are used to determine porting for each application

ADS Spec Camshafts (EJ20)

Kelford Cams designs are the most efficient in providing maximum usable power across the widest power band. Each cam is ground from a new blank and finished using the same procedures we use in our extreme level race engines.

ADS Spec Camshafts (EJ25)

Each cam is ground from a new blank and finished using the same procedures we use in our extreme level race engines. Kelford Cams are profiled to increase boost response thereby increasing engine torque and power.

ADS Spec Performance Valve Springs (EJ25)

Kelford & Ferrea Valve Spring Kits are engineered for use in situations that require valve control in extreme conditions. Each kit consists of single & dual valve springs with matched lightweight titanium retainers, keepers.

ADS Spec Performance Valve Springs (EJ20)

ADS Spec Performance Valve Springs are the result of countless hours of engineering, testing and validation ensuring the best possible spring for high performance applications. ADS Spec Performance Valve Springs are hand picked for thier application

Intake and Exhaust Valves

Large diameter valves are essential for improved air flow in larger setups. Ferrea race intake valves are produced from high quality stainless steel for maximum durability. Exhaust valves are machined from Inconel for tempreture resistance.

Intake Manifold

Subaru High Volume Inlet Manifolds are cast from aluminium featuring large tapered runners with radiused inlets for improved air flow. Plenum volume has been substantially increased and best for high power applications.

Grimspeed Phenolic Manifold Spacers

The Grimspeed Phenolic Manifold Spacers are designed to reduce inlet air temperature by isolating the intake manifold from the heat generated by the engine's cylinder head. Reducing the temperature of the inlet manifold.

Dry Sump Kit

The RCM Dry Sump Setup Kit for the Subaru EJ series engine is a must for race and performance applications. Dry sump oiling systems offer an unparalleled level of safety and reliability compared to factory Wet Sump systems. Complete

Air Intake Systems

Various Aftermarket High Flow Intake Systems feature increased diameter, large smooth radius bent aluminium inlet tubes for superior air flow management coupled with a high flow air filter for maximum air flow and performance.

ADS Air Pump Delete

ADS blanking plates are used to eliminate the air pump and related valves found from 2006 to current EJ Subaru Engines. Used for high performance applications, adapting later cylinder heads to early engines, or simply to effectively eliminate the secondary air valves.

Why trust Subaru Engines (ADS) Australia?

Increased Power

We are often asked for engines with more power, more strength, and less maintenance at an affordable price. While these might seem to be mutually exclusive outcomes, we have had our heads down and been hard at work to meet the challenge!

It’s taken a long time, but our patient research and development have resulted in multiple Cosworth based engine configurations with the strength to handle 250kw to 550 Kw. These packages range from options that that won’t break the bank, to complete competition race engines. Of course, if you don’t want one of our package deals, we can build a custom performance engine to your specifications; professionally assembled by highly trained ADS techs at our factory outlet at Peakhurst, NSW

Greater Durability

Of course, not everyone wants racetrack performance from their Subaru, but many owners do work their cars pretty hard; the man on the land, the traveller, anyone who covers a lot of ground, will want a strong engine. Our remanufactured Cosworth assemblies are perfect for demanding applications. They can operate under extreme loads while maintaining consistent strong output. Precision Cosworth engineering, using high-grade metals and processes, delivers excellent wear qualities. A Cosworth engine will be operating efficiently long after stock engines have worn out. If you and your Subaru work hard, you’ll want a hard working engine. You can’t go past Cosworth.

Best Quality

Very early on, we found that there are many performance parts suppliers and engine builders around the World who sell cheap, inferior products marketed as premium. It’s our philosophy to make sure that our products are truly the best available. In production too we aim to be the best. All Drive Subaroo don’t just put engines together like Lego blocks. We’ve carefully thought out all our setups, and spent hundreds of hours of building and testing to produce the optimum in performance potential and durability. Our Cosworth EJ20/25 Engine setups have gone through countless hours of dyno evaluation to determine the best combination of parts.

Service and Support

All Drive Subaru have assembled the most highly skilled group of Subaru techs in the country, together with the finest facilities available outside the dealer network. Our crew have been trained in different specialist areas, and we know more about performance engines than the dealers, who bring any such jobs to us. We don’t just sell engines, we also offer technical support and assistance throughout the process and afterwards. Before you commit to an engine, we can talk you though all the available options. Once you’re back on the road, we are ready to assist with any questions you might have about the running and maintenance of your new engine. Everyone at ADS is an experienced technician or an auto engineer.

Exacting Production standards

The Cosworth Subaru engine is designed for the demanding performance enthusiast. Each assembly is precision built by one of All Drive Subaroo’s specialist craftsmen using the finest components from our parts catalogue to ensure maximum reliability and performance. Starting with a new Subaru EJ257 semi closed deck block, we diamond hone each bore to guarantee perfect piston to cylinder wall clearance. The block is then assembled with Cosworth Forged Pistons, motorsport grade Forged H-Beam connecting rods along with Cosworth tri-metal bearings and a new STI forged crankshaft.

Installation or Delivery

We have one of the best equipped Subaru workshops in the country, and can handle any job, big or small. This means you can count on us to build and install your engine with seamless efficiency and the best warranty in the business. If we do the installation, the warranty covers both parts and labour, and we take particular care in fitting your engine. Our reputation depends on your satisfaction. We can also ship your engine nationally or internationally at very competitive rates to the repairer of your choice, using TNT Transport.

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