Astra H VXR Sprint

Late 2013, and in the quest for even more useable power on track, the next step was to add a high flow inlet manifold (more in a later post) and a set of H-Beam steel rods with ARP rod bolts. The steel rods are being added for strength and safety (in case of an over-rev) and to take advantage of the extra power available at the top end afforded by the already fitted K06 turbocharger and the soon to be fitted Inlet Manifold. The steel rods will allow the engine to rev to around 7,500 rpm. The factory fitted pistons are a Mahle forged piston and are very strong for a factory piston capable at up to 500bhp so more than adequate for this track day application.

The H-Beam steel rods were taken to my local engine machine shop (who do a lot of motorsport engine prep) and have been balanced end to end to within 0.5 grams. Once returned it was time to fit them.

The engine was opened up; airbox removed, turbo removed, inlet manifold removed, cambelt removed, rocker cover off, camshafts and lifters out then the head was removed and placed on the workbench. At the bottom end the sump and upper sump carrier were removed, the baffle plate, oil pickup and bridge came out and then the big ends could be removed and the pistons and factory rods could be lifted out from the top, ensuring the bearing caps and rods were dot punched to identify them and keep them together should the engine ever go back to standard.

The news was good when everything came apart. The engine has had regular oil changes and the bores are in excellent condition (which to be honest was what was expected), not showing the mileage it has covered (which is currently a shade over 87,000 miles) and with the original hone marks in the bores still visible and the pistons are also in excellent order. The cams are also showing no signs of wear.

Once removed the factory pistons and rods were also taken to the workbench where the OE rods were swapped over for the steel rods and the piston rings were checked and repositioned to ensure they were in the correct orientation. At the same time all 16 of the Valve ten Oil Seals, some of which were leaking on the exhaust side, were replaced and when the exhaust side stem seals were replaced 8 valve stem oil seal retainers were also fitted. These help prevent the stem seals from lifting off and leaking in future.

Whilst apart the cylinder head, cam shafts, oil pick up pipe, oil pan carrier, sump pan, baffle plate and bridge were all put into the Safety Kleen tank and thoroughly cleaned prior to being refitted.

The pistons and rods were then refitted into each bore with new Mahle big end bearings and the big end bearing caps fitted and then secured with the ARP rod bolts, torqued up to 55 lb/ft with ARP Assembly Lube. The engine was then put back together with new gaskets, seals and new head bolts and timed up ready to go.