Recently there has been quite a bit of VQ35 work going on in the build shop here. The VQ35 has a lot of untapped potential from the factory. Simply bolting on a set of Cosworth CNC big valve cylinder heads, Cosworth camshafts (available end of summer), Cosworth Twin Plenum intake manifold, a set of headers, and a good remapping can increase horsepower from the factory 287bhp to 363bhp. That's an increase of 76bhp with just bolt on components!

Walking through the machine shop one day, I saw that Colin was balancing a factory VQ crankshaft for a special project. It turns out that the Cosworth piston, piston ring, rod, and bearing combination is approximately 110 grams lighter per cylinder. With this being the case, it was critical that the crankshaft gets rebalanced with the lighter component weights. Nearly 100 grams needed to be removed (48 grams front and 44 grams rear).  Any crankshaft that is not a flat plane design requires rebalancing with bob weights. If you do the math, that's 110g x 6 (6 cylinders of components) + 100g (crank) = 760g total weight savings.  That's 1.676 pounds or 26.81 oz. in weight reduction! It may not sound like a lot, but it is the weight reduction and the increased strength of the components that will allow an engine to last longer and spin to higher revolutions while doing so. The Cosworth rods and pistons are forged and the bearings are tri-metal so all of the Cosworth components are superior in strength. Every off the shelf Nissan VQ35DE short block built at Cosworth already has these same components


Bob weights are attached to simulate the weight of the components.


If a clutch and flywheel assembly is to be used, then it should also be balanced with the crank and indexed to the crankshaft. If your clutch and flywheel is already balanced, then it is not a major issue to balance the crank by itself. Most high performance or racing clutches are balanced from the factory.


Here the crank is almost balanced at 0.55 grams. We balance cranks to within 0.5 grams, but Colin is about to make the final adjustments. Precision is everything if you want excellent results.

During our extensive Subaru engine development program, the one thing we noticed is that the factory Subaru engine block's cylinder bore dimensions are very inconsistent right out of the box. This is fine with a factory cast piston because there is very minimal expansion in a cast piston. However, this can be a huge problem with forged pistons that are designed to expand when hot. If a forged piston is designed to have .003" of piston to cylinder wall clearance, what happens when the bore is oval by .002"? If you were to drop in a forged piston without honing the EJ257 cylinder block, the result is an eventual catastrophe.

First off, understand that the EJ257 cylinder block is more of a "case" than it is a block. Because it is virually hollow and its walls are quite thin, it is subject to severe distortion when head and block fasteners are torqued. Here are some tips for honing a Subaru engine block:

1. 1. Torque the case halves together with the fasteners you will assemble the engine with.



2. 2. Always bore and hone the cylinders with a torque plate and dowels in place. You should always use a head gasket (used ok) of the same make and model as your new gasket and also use the studs or bolts that you will be using in your final assembly. Steps one and two will allow the cylinders to be honed while "distorted" in its final assembled state.



3. 3. Always follow the piston manufacturer's recommendation for piston to cylinder wall clearance. If in doubt or if the engine will be used for severe duty, add .0005-.001" to the recommendation. It is generally safer to have more clearance than less with forged pistons.



4. 4. Always follow the piston ring suppliers recommendations for bore finish and crosshatch angle. Same with the piston ring end gaps.



5. 5. While a cylinder bore's perfection comes from the machinist's experience with your particular engine block, it is good practice to let the cylinder block cool before finish honing if there was a lot of material removed from the bore.

Follow these 5 simple tips and you should have a good running EJ257 if the engine is assembled correctly. If you haven't picked it up already, you should know that a "drop in" forged piston just will not last very long in a Subaru engine block without custom boring or honing from an experienced machinist.


Here is a factory EJ257 block straight out of Subaru's packaging with a custom designed Cosworth deck plate (available winter 2008) with the new Cosworth H-11 tool steel head studs.


Here is a measurement of the cylinder on axis with the crankshaft. You can see that it is .0011" from zero (the dial bore gauge was "zeroed" using the guage point on the piston).


Here is the thrust side of the cylinder bore measuring in at .0012" from zero. The cylinder bore is oval by .0023"! A "drop in" forged piston that called for a .003" piston to cylinder wall clearance definitely would not last very long in this cylinder block.

We are working on the new EJ257B from the 2008 Subaru Impreza STi and have one on the engine dyno at the moment. Some components we are planning on testing and developing are the dry sump oil system, CNC ported cylinder heads, valve train, camshafts, intake manifold, and a couple other goodies.

It is a long hard road to design components that work. This engine dyno installation took us nearly 200 hours to design, manufacture, install. The test engine is using a Garrett GT35R turbocharger, TiAL 44mm wastegate, and Cosworth/Pi ECU. Our engine dyno cells are complete with 18" thick walls, climate control (temp, humidity), barometric control, and are complete with many, many channels of data acquisition. I'll post a tour of a dyno cell in the near future. For now, the next time you purchase a Cosworth product, you can be confident that your Cosworth component has been tested thoroughly for reliability and horsepower.


2008 EJ257B dual AVCS custom dyno install with custom header.


Dry sump oil system in action. Also notice the huge intercooler in the background to the right.

The engineering department is hard at work finishing up the final prototype pieces of the Subaru EJ20/25 dry sump system. Many of our EJ25 engine customers are now winning in the various classes of Time Attacks and club racing events so we thought the next logical step would be a dry sump oil system. The EJ engine suffers tremendously from oil starvation due to high G turns and will pump out a significant amount of engine oil through the valve covers due to crankcase pressure (oil starvation + low oil level = disaster). While the Cosworth oil pan, oil control baffle, and high volume/high pressure oil pumps make great strides in oil control with a wet sump system, the absolute fastest cars at the track with sticky tires really should be using a dry sump oiling system for ultimate reliability.

A dry sump oil system not only eliminates oil starvation, but also produces a vacuum in the crankcase so that excessive crankcase pressure no longer becomes an issue. Also, there are small horsepower gains from vacuum being present in the crankcase since the laws of aerodynamics do not apply in a vacuum.

The Cosworth dry sump system is still in the prototype stage and will still go through several stages of testing. For this reason, there are no details regarding what the system will include or it's exact cost. Please wait until the end of summer before bombarding us with questions we have no answers for at the moment. I just wanted to share one of the more interesting things going on here in the building.


Here are the prototype parts fitted to an EJ25. The belt drive is designed to work with the factory dampener, but should also work with many aftermarket dampeners/pulleys with minimal hassle. The billet pump bracket is extremely strong and is designed to keep pump alignment perfect under any circumstance.


The pan will be machined from solid by CNC. This piece is still in the prototyping stage, but should be done soon. The best apart about product development is validation. I think I'll be offering my test driving services at the track!

The Cosworth NC Miata supercharger is now in the final stages of development. Soon we will be submitting a car to an EPA lab for CARB testing since our goal is to make this supercharger system 50 state legal. I got the chance to drive it around last Thursday and take some notes to refine the engine calibration. I was in boost just about the whole night and I can say that the supercharger system has given the Miata MX-5 a much needed boost in horsepower and torque. It feels like it has a nice broad, flat torque curve from about 2800-6500 rpm.

In its current configuration with a completely stock engine and exhaust, our car is currently making 210hp at the wheels which roughly translates in to 235-240bhp. The stock Miata made only 130hp at the wheels. With an increase of 70hp at the wheels, you can imagine how much quicker the car feels. That's a 53% increase in horsepower!

Please don't pick up the phone and call us just yet. The intercooled supercharger system is NOT available to the public yet. We are aiming for the end of summer as a release date. Calling us now would be a futile effort.



A clean OEM look was our goal from the very beginning. Some of the hoses here are not in their final routing positions as this is a first article installation.

Hello all. My name is Eric Hsu and I have been with Cosworth for almost two years now. I was hired to manage product development for the Performance Parts department. I work closely with the sales and engineering departments to ensure we supply the highest quality components for high end club racing and time attack vehicles.Our quest to supply the highest quality components and engine assemblies falls right in line with Cosworth's illustrious 50 year history of supplying the highest quality race engines and engineering consulting.

Check back regularly as I will be posting about random Cosworth related subjects. My posts will be mostly about product development, product testing, dyno sessions, component design, tech tips, etc. Whatever I post about, I hope you'll find it interesting. Thanks for reading!

Cosworth has been manufacturing motorsport grade engine components for 50 years. Very few companies can make the same claim and those 50 years of knowledge translate into experience producing in some of the finest components available for your engine including our crankshafts. Cosworth billet steel crankshafts are manufactured at our factory in Northampton UK. Machined from a solid piece of EN40B steel, hardened, precision ground and then Superfinshed for maximum performance each Cosworth crankshaft goes through the same manufacturing process as a Formula One crankshaft.

                                 

Crankshafts such as our Mitsubishi EVO 94mm stroker version (above) are designed in house using the latest CAD programs to ensure the strongest , lightest specification possible.

                                 

Factory 12 in Northampton England. Components for some of the most powerful engines in racing are manufactured here.

                                  

This crankshaft has had the main bearing journals rough machined. The rod journals have yet to be machined. This is very time consuming process.

                                    

The same style crankshaft  goes through the next machining process completing the final shape.

                                    

The finished Subaru crankshaft shows the detail and care that goes into each Cosworth crankshaft. Quality materials, precision design and manufacturing ensure maximum reliable performance.

Cosworth continues to develop high performance engine components for the Nissan VQ35.
Currently, we are testing a range of camshafts for normally aspirated performance. The engine was configured with our CNC ported Big Valve heads, 11:1CR pistons and Intake manifold producing approx 370hp at 7200rpm. Check it out the actual dyno run video below.