Astra VXR engine conversion

... installation of the TMS 400bhp Astra VXR engine into the Corsa SRI-R race car

Alongside my Corsa SRI race car I run a Corsa VXR Racing. As of October 2010 the power/torque output from my Corsa VXR Racing was 255.2bhp @ 6335rpm and 280.75ftlb @ 3415rpm.
My quest to achieve 300+ bhp led to more discussions with Thorney Motorsport as to my options.
Sticking with the Corsa VXR Racing engine (Z16LER) would require a bottom end and turbo upgrade, all possible but resulting in a more highly stressed engine.
Another option, proposed by Thorney Motorsport, would be to replace the Corsa VXR engine (Z16LER) with the Astra VXR engine (Z20LEH).
With the mods already carried out my car - larger front mounted intercooler and 3" stainless steel race exhaust power/torque figures of 300bhp/340ftlbs would be immediately available from the Astra VXR engine (with a suitable remap) in it's standard specification.
Also, already having the Quaife LSD and AP Racing Brakes fitted would ensure that all this extra power could be safely handled on both the road and track.
However, the exciting part of this option was, that by further modifying the Astra VXR engine (upgraded turbo - GT28, equal length exhaust manifold, uprated pistons & rods and uprated injectors), it would be possible to achieve at least 400+ bhp/380lb/ft.

So, my mind was made up and Thorney started work on the project, intially purchasing a brand new Astra VXR (Z20LEH) engine and gearbox.

The engine was then stripped down and rebuilt to TMS stage 5 specification which included:

• Garrett TMS GT28 Turbo (features Roller Bearings, Uprated Seals and Shafts)
• TMS forged lightweight pistons & conrods
• Bosch 650cc Injectors
• TMS equal length exhaust manifold
• TMS Oil Feed & Breather Pipes
• Uprated manifold studs
• Extra heat shielding
• New boost sensor
• All New Gaskets

With the engine build complete attention turned to a dry run installation of the Astra VXR engine. Initially, to minimise the time my Corsa VXR Racing would be off the road it was decided that this dry run installation would be carried out on Thorney Motorsport's own Corsa SRI race car.

The work progressed steadily with fabrication of new engine/gearbox mounts, modified alternator mounting bracket etc. necessitated to ensure that the driveshafts lined up and that the engine location was within Vauxhall's own strict specification. In reality the engine/gearbox assembly has been moved back and rotated rearwards slightly in order to ensure requisite driveshaft angles have been maintained.

At this stage an important decision was reached regarding the way forward. We concluded that, for both technical and commercial reasons, it made sense to complete the whole engine conversion in the Corsa SRI. I therefore agreed to purchase the TMS Corsa race car which now runs alongside my Corsa VXR Racing.

The Corsa SRI-R race car had been stripped down to the bare essentials, thus freeing up more space within the engine compartment. Ever conscious of the need to provide maximum cooling efficiency, bearing in mind the 400bhp expected to be available from the engine, a bespoke all alloy radiator and intercooler with rigid piping was designed and manufactured.
The high capacity front mount intercooler drops intake temperatures by over 45% compared to the standard car and 65% when running a higher boost map. This allows a more agressive map on the ECU to take advantage of these lower temperatures and yields resulting higher power with this power more useable more of the time.
In addition, the air intake system (again a one off design) will draw in cold air from the offside front foglight aperture.

Finally the tubular exhaust manifold, turbo housing and exhaust downpipe will all be ceramic coated by Zircotec.
Some of the advantages offered by Zircotec Performance Colours coating are:

• Significantly lower exhaust temperatures - surface temperatures reduce by ~33%
• Reduced heat loss from the exhaust resulting in lower engine bay temperatures - reductions of >50°C are possible
• Improved engine performance and reliability. Lower air intake temperatures lead to increased engine power, whilst keeping the heat inside the exhaust gas allows the gases to flow more easily increasing cylinder scavenging and allowing turbochargers to spool up more quickly.
• Rapid cooling of the exhaust when the engine is turned off - the surface temperature of the coating drops quickly when the engine is off

We may even consider fitting a carbon fibre bonnet (reduces weight also) with air vents to further improve the overall cooling performance.

To take care of the power and torque transmitted to the wheels a Sachs Organic Clutch Kit together with a lightened and balanced stock Astra VXR flywheel has been fitted.

By far the most challenging aspect of this project has been in the area of ECU's. In order to ensure that ensure both the engine management side of things together with ABS, traction control, power steering are all "talking" to each other it has been neccessary to combine various elements of both the Corsa VXR and Astra VXR ECU systems.
The aim has also been to minimise the use of bespoke wiring sub-systems so that standard Vauxhall diagnostic equipment can still be used.

As of today (12th March 2012) the installation is still ongoing albeit nearing completion. We hope soon to be on the rolling road, completing engine running in and setup.
Updates will be posted as important project milestones are reached.

Update 12 March 2012

Over the last couple of months Thorney Motorsport's attention has been focused on preparation for the forthcoming BTCC championship in which TMS are entering two Vauxhall Insignias. Fortunately for us this work is now becoming less demanding upon engineer resources and focus has shifted back to finishing off the Astra VXR engine transplant into the Corsa SRI race car.

As already mentioned by far the most challenging aspect of this project has been in the area of ECU's - making sure that all aspects of the Corsa's electronics and engine management systems are "talking" to each other. We believe this has been sorted and headway has been made - wiring looms extended, throttle body fitted, ecu brackets made, ecu fitted, wiring sleeved and in conduit. This good work will continue this week - updates and photos to follow ...

Update 7 December 2011
All of the major components (engine, gearbox, driveshafts etc.) are now back in the Corsa. Work is continuing on the fabrication of the numerous bespoke brackets required to mount things such as the ECU, various sensors, air intake system. In addition we will be manufacturing a full 3" bore race exhaust system. We already have produced the exhaust front downpipe and front sections, which have been ceramic coated (see below), so we need to concentrate on the rest of the system. We have selected a full 3" bore size for the system, this is to maximise peak power from the engine but also to keep torque levels high as well, it's the perfect solution. Secondly we have used only the highest quality of stainless steel for the construction and used only the highest motorsport specification catalytic converter (200 cell to ensure it meets MOT test standards and all UK emissions laws).
Photos will follow soon.

Update 19 October 2011
Due to motor racing commitments for Thorney Motorsport (Britcar 24 hours and BTCC Silverstone) work on the Z20 LEH engine conversion had to be put on hold. A little frustrating but fully understandable. Now that the racing season has drawn to a close TMS are back on the case with a vengance. The iterative process of developing the hybrid ECU system has necessitated stripping down various parts of the engine. This work is now complete so the task of rebuilding the engine is underway. The remainder of the underbonnet components - air intake system, intercooler rigid piping, oil pipework etc. can then be reassembled so that full ECU testing can be undertaken prior to firing up the engine for the first time - heady days indeed!

Update 20 June 2011
Hopefully this week the Sachs organic clutch, lightened and balanced stock flywheel together with a brand new gearbox/Quaife LSD should be fitted. The rigid intercooler pipes are promised in this week. The tubular exhaust manifold, turbo housing and exhaust downpipe are all going off to Zircotec to be ceramic coated - metallic black

Things are moving forward very slowly but surely. More updates are due later this week together with more photos.

A blog has been set up where updates and info will be posted. To visit the blog click here

Update 6 July 2011

Attention has turned to the suspension set up. Currently the Corsa is fitted with KW 2-Way Competition Suspension. The extra weight and slight relocation of the Astra VXR engine within the engine bay will probably mean the front springs will need changing to compensate. A range of different rated springs have been supplied by Eibach so once the Corsa is up and running we will be able to play around with the suspension set up to achieve an optimum fast road/track day set up.

15 July 2011

The components sent off to Zircotec for ceramic coating have returned. The items in question are the equal length tubular manifold, the exhaust downpipe and front section together with the turbo housing. Ceramic coating not only significantly lowers exhaust temperatures and reduces heat loss from the exhaust resulting in lower engine bay temperatures. Being coated in a metallic black finish they also look good!!

10 August 2011

The task of integrating the Corsa VXR and Astra VXR ECUs is ongoing - proving more challenging than first thought. The aim is for the resulting hybrid ECU to be as "standard" as possible enabling normal diagnostic tools (tech2 etc.) to be employed whenever required. The engineering solution is very eloquent and ingenious - more details to follow ....

19 October 2011

Due to motor racing commitments for Thorney Motorsport (Britcar 24 hours and BTCC Silverstone) work on the Z20 LEH engine conversion had to be put on hold. A little frustrating but fully understandable. Now that the racing season has drawn to a close TMS are back on the case with a vengance. The iterative process of developing the hybrid ECU system has necessitated stripping down various parts of the engine. This work is now complete so the task of rebuilding the engine is underway. The remainder of the underbonnet components - air intake system, intercooler rigid piping, oil pipework etc. can then be reassembled so that full ECU testing can be undertaken prior to firing up the engine for the first time - heady days indeed!

9 November 2011

Great progress has been made - we're at the stage where numerous bespoke brackets and mounts have to be fabricated to mount all of the various engine components. This is a time consuming task but essential if the resulting Astra VXR engine transplant is to look professional. We have decided that a full 3" stainless steel race exhaust system will be specified to fully capitalise on the 400+ bhp being pumped out by the stage 5 Astra VXR engine. We will probably utilise Scorpion Exhausts, the same Company that are producing exhausts for the Thorney Motorsport BTCC Insignia - so we know they are going to be of the highest quality and performance.
Watch this space for more details ...

4 January 2012

With the Christmas break out of the way work continues on finalising the design and fabrication of the numerous bespoke mounting brackets and protective covers for the various sensors and ECU components. This is taking longer than anticipated but it is vital that all of the additional sensors and ECU peripherals are well protected from physical damage and water ingress. As soon as all of these components are mounted and protected the air intake system layout can be finalised and the various rigid pipes and silicon hoses manufactured. Progress is not rapid but we're getting there slowly but surely!

10 April 2012

Attention has turned to the cold air intake system. We have decided to use the Pipercross Viper VFC244 sealed unit cold air intake. The unit will be tucked away down inside the nearside front wing away from the heat of the engine bay. It will draw cold air in through the nearside front fog light aperture.

Using 'velocity air force', the Viper air intake directs cold air directly into the engine. The cold air feed takes air from the area of cold, dense air straight into the Viper's inlet, swirling it through a unique Pipercross reverse-flow air filter contained within a carbon fibre heat shield, then into a ram pipe to increase the air pressure before feeding it into the induction system.

The carbon fibre heat shield protects the air charge from under bonnet heat keeping it cool -and therefore more dense -thus introducing more oxygen into the combustion mixture,giving increased power.
The reverse flow technology filter and 150mm ram pipe make use of the physical phenomenon of air tending to move towards surface area's, creating more air flow on the edge rather than in the centre of the inlet. The unique design of the filter cone and the inlet 'tune' the moving air flow to increase its speed and therefore its pressure maximising the laminar air flow into the engine, again resulting in increased power.

Throughout the transplant process we have incorporated several sensors into the engine management system so as to provide vital feedback data. Where necessary we have manufactured covers to protect the sensor from physical damage as well as affording protection from the elements.

30 April 2012

This week we intend to finish off tidying up the ECU / various aux wiring harnesses as well as finalising the air intake system. The guys from Pipercross are on site to measure up and layout the cold air intake system.
More details to follow ...