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2512cc Opel 8V CIH Competition EngineThis page will be regularly updated as the engine building progresses. Check out the Latest News below. Initial Short Engine Build
The initial engine build to check the piston valve pocket sizes/depth and piston dome volume is now complete. As it happens the valve cut-outs in the pistons are big enough in depth and diameter for the valves we are using. In fact the depth is too big, as is the exhaust valve cut-out diameter. The piston dome volume including valve cut-outs has been measured at 4.88cc, and the piston deck height above the block deck is 0.10mm. We will therefore need to skim 0.35mm from the block deck to get the squish height down to 0.95mm. We have already measured the cylinder head combustion chamber volume which is 61.2cc. The compressed head gasket is 1.4mm thick and its bore diameter is 98.3mm, which gives a gasket volume of 10.62cc. The piston dome volume, combustion chamber volume, gasket volume and piston deck height above block deck, are all required to determine what we will need to do to the pistons and head to get the compression ratio up to 11.5:1. The pistons have been modified as described above, and the piston dome volume has been reduced to 2.28cc. This information has all been combined to tell us that about 6.5cc must be removed from the combustion chamber volume to get our required compression ratio of 11.5:1. As it happens, skimming 1.0mm from the head has removed about 5.8cc from the combustion chamber volume, giving a compression ratio of 11.43:1, which is close enough. Combustion Chamber Shape
Short Engine BalancingI took the block, crankshaft, crankshaft pulley, con rods, flywheel, clutch, clutch cover, camshaft and camshaft pulley to Steve Smith at Vibration Free (www.vibrationfree.co.uk) at the end of May for dynamic balancing. I had a very interesting chat with Steve, and a tour around his workshop, and saw some of the projects he was working on. After all the work that I have had done on the crankshaft and pistons, I was shocked to find that Steve was unable to balance the Con Rods, which had never been touched since being supplied by the manufacturer in 1999. Balancing the Con Rods consists of weight matching the rods to within 0.1g of each other. Each pair of rods, in this case 1-2 and 3-4, for a 4 cylinder engine, are spun up on a spindle, with the big ends on the spindle. If there is any end-to-end weight mismatch, then this can be seen by monitoring the vibration on the spindle. According to Steve this method is far more accurate, and repeatable, than other static methods. Anyway, rod pair 1-2 gave such a massive mismatch, that he ended up weighing each part of all the rods, bolts, rod and rod cap. What he found was that rod 1 was not matched to the other three. The rod part weighed almost 10g more than the rest of the rods, and the rod cap weighed almost 10g less than the rest of the rod caps. Obviously, Steve was not willing to remove so much material from each rod to correct the problem, as he may have weakened the rods significantly. He suggested that I contact the manufacturer, and see what they had to say. I contacted the con rod manufacturer, who were somewhat shocked, and said that I should send the rods back for re-working by their quality department. I have now received the rods back from the manufacturer. A visual inspection by me, shows that material has been removed from the rod part of No. 1 rod, and from the rod caps of the other three rods. I sent the rods back to Steve at Vibration Free to have the balance re-checked, and shot-peened if required. The rods are now back, properly balanced to within 0.1g. Everything is now set to start the second (final hopefully!) build of the engine. Journal and End Float Clearance
The first job is to install a new set of main bearing shells and the crankshaft, and at the same time check the main journal/bearing clearance. You place a length of Plastigauge across the journal and then tighten the bearing cap down onto it. This compresses the Plastigauge, the width of the compressed Plastigauge is checked against a measuring card which gives you the clearance. As you can see from the pictures, the main journal/shell bearing clearance is 0.0020-0.0025" which is within tolerance. I also measured the Con Rod Journal//Shell Bearing clearance which was again 0.0020-0.0025". After installing the bearing caps, it is time to check the crankshaft end float and install the rear crankshaft oil seal. I checked the crankshaft end, and guess what?..... .... that's right it is only .001", and should be .004 - .008". After much debate and discussion, it turns out that the lack of end float is caused by the newer type Vandervell one-piece thrust bearing being oversize compared to the original Opel three-piece thrust bearings. The choice you face is either using Wet&Dry Emery Paper to reduce the thrust bearing width, or putting the crankshaft onto a grinder and opening up the thrust bearing faces. Since the crankshaft needed polishing, also done on a crankshaft grinder, I decided that grinding the thrust bearing faces would save a lot of grief now and in the future. Anyway, after grinding and polishing, the crankshaft end float is now 0.005", which is within tolerance. Final Short Engine Build
I had to purchase a new set of piston rings from Omega Pistons Ltd, as I had found some problems when I visually inspected the original set which came with the pistons. The piston ring gaps have been set, .012"-.014" top ring, .010"-.012" middle ring, and .008-010" scraper ring, as per the manufacturers recommendation. Then the crankshaft, con rods and pistons were installed in the block without problems, as were the timing cover, modified water pump cover, heavy duty oil pump and oil pick-up pipe.  
A replacement for the long elusive sump finally arrived, together with a nice bottle of wine for my trouble, followed the very next day by a brand new Manta sump from Opel at Russelheim. I had ordered a new sump from my local Vauxhall dealer about 4 months previously, only to be told a few days later that Opel could no longer supply Manta sumps. so I naturally assumed (foolish, very foolish!) that the order was cancelled. Anyway, I now have a spare Manta sump. I decided that I should fit an extra oil temperature sensor into the sump, so that I can switch oil temperature monitoring between the sump and the oil cooler return line. The oil temperature sensor in my original 2.0L competition engine was located in the sump, and always gave good temperature reading, but I never knew what the temperature of the oil was as it entered the engine. On my 2.4L engine, I relocated the sensor to the oil cooler return line, which with hind-sight, or any thought at all for that matter, was a bit pointless as it didn't tell me what was really happening to the oil at the sharp end, but only that the oil was cool when it went back into the engine. I new from the 2.0L engine that its 10 row oil cooler was not able to maintain a reasonable oil temperature during sustained high speed motorway driving, as the temperature in the sump kept on climbing. My 2.4L engine had a 13 row oil cooler fitted without thermostat control, and showed no oil temperature problems, although it never saw any high speed motorway driving in the 500 miles (800Km) it covered before I threw the cylinder head away (read all about it in my 2000 engine pages) . This time, I shall be using the same 13 row oil cooler with thermostat control and a 30% higher flowing oil pump on this new 2.5L engine, and cast iron oil pump cover, from the Opel Diesel engine, which should give much more accurate oil pressure control. Initial Cylinder Head Build
A trial head build, in April 2003 with the new roller rocker arms, showed that my original valve spring caps were unsuitable, because they fouled the roller tips on the new rockers. Due to the required installed height of the valve springs (43.5mm), we were unable to find a suitable flat-topped spring cap replacement. After five weeks of trying to source a shorter set of single valve springs with a shorter installed height and suitable spring rate, we came across a set of suitable dual valve springs from Comp Cams Inc in the US. The new valve spring caps, exhaust valve seats, and the machining of the head for the inlet valve seats is now complete. The initial test build of the head to check the rocker arm alignment/angles, and the valve spring installed height checks are now complete. I have now received suitable 0.015" and 0.030" shims for the inlet valves from the USA, would you believe no such thing is available in the UK off the shelf. I'm ready to build up the cylinder head. Cylinder Head Final Build
I began by fitting the valve stem seals, which come from a Peugeot 1.9D, which didn't go very well. I damaged a complete set of eight seals in the process, because I had to guess how far to push the seal onto the guide. The problem was that the length of guide above the flange is longer than the seal locating area, so I couldn't just push the seal down until it met the flange on the guide. At this stage, I decided that I had better check the gap between the bottom of the spring cap and the top of the seal. Yes, you guessed it, the gap is too small. Valve lift for this engine is 12.6mm, and the gap is 13.6mm when the valve is in the closed position, giving a gap of 1.0mm when the valve is fully open. Unfortunately, you need a gap of at least 2mm (0.080") when the valve is fully open. Fortunately, the guides need cutting down by about 2.5mm (0.100") so that the seal will butt up against the flange. I guess, the guy who decided the design for the guides, didn't know which seals would be used so left some extra material on the top of the guides, so they could be cut down later when that decision was made. Thankfully the fix is easy, and the guides will be milled down to size in the next few days. I also now know that I should be able to go up to 14mm (0.551") of valve lift on any future roller camshaft I decide to fit. 
The machining was completed and the valve stem seals fitted. The head has now been put together and installed on the block. I have also installed the camshaft and timed it in. Having completed the timing in of the camshaft, I then installed the roller rockers, and set the lash to 0.015" (0.38mm). Finally, I fitted the blanking plates to the head, and then installed the modified 2.4L CIH rocker cover with its rubber gasket. Maybe the rubber rocker cover gasket will be less prone to leaking than the older cork gaskets, as used on the 2.2L, and lower, engines (pigs might fly too!). Exhaust Manifold Coating
I decided that the spray-on ceramic coating, on my exhaust manifold, wasn't going to be up to the job of significantly reducing the under-bonnet temperatures, or be very long lasting. There were already rust spots showing through on some of the welds, and a couple of minor scrapes had gone through to bare metal, and that's before it was even offered up to the new engine. The mechanic for a local Rally driver, with a 4x4 Ford Puma (with Ford Escort WRC engine and running gear, yum!!) put me onto another company, Zircotec who do a much more robust and effective insulating coating for exhaust manifolds called Thermohold GP™. As you can see from the pictures this new coating has a distinctive white colour, which should become a tan colour once the exhaust starts getting heat cycled. Air Filter Box
I have made up an air filter box, in fibreglass, which will be located just behind the head light. It is not really a box, but a shroud which will protect the air filter from the warm air in the engine bay. You may think the filter box is rather large, but so is the filter which is good for up to 400+ BHP. I started by making it in cardboard, which is very easy, and cheap, to work with. When I was happy with the shape, it was strengthened by filling box sections with expanding foam. The relevant areas were covered with aluminium tape, and the whole prototype was polished twelve (yes, 12) times with mould release polish to ensure that the fibre glass mould will release from the prototype. The prototype was now complete and we were ready to make a fibreglass mould from it. Construction of the mould, was done with two layers of fibre glass, and was easier to do than expected. The two parts of the mould were bolted together and polished eight times to ensure that the final product would release from the mould. I made up the final air filter box using a single layer of fibreglass matt. All I need to do now is clean it up and paint it black. It is held to the bodywork using Dzus fasteners, for easy removal. I will use something like the boot seal from a Manta to make a seal between the bodywork and the filter box. The upper seal will be made to the bonnet, which I have still to sort out. Air will get into the air filter box via the original air filter hole in the bodywork, which has been opened out, and via a hole in the inner wing just behind the headlight. I have piped this hole to the valance below the headlight. Not a very good explanation, I know, but the pictures should make it clear. 2002 Engine Build Finished
The engine is now complete. I have test fitted the inlet and exhaust systems, including the throttle bodies (yes, now painted red!) and the air box.
Cam Chain Tensioner Oil Leak Problem 
We finally determined the oil leak was coming from the modified Cam Chain Tensioner. The Tensioner is filled with oil, and maintained at full engine oil pressure, when the engine is running. So, oil was leaking from the 80x6mm bolt thread. I tried various methods to seal the leak, including copper washer and silicon sealant, none of which worked. In the end I machined up a replacement locking nut from 19mm hex steel bar, and installed an o-ring to make the seal, see the sketch. The new locking nut is 10mm deep, to help reduce the chance of leakage up the bolt thread again. If anyone has a better idea, please let me know? Engine Installation/Running
We dropped the engine into the car on Wednesday 3/3/2004. Over the next two weeks I fitted the ancilliaries, and sorted out most of the electrics. I also decided to move the Throttle Potentiometer from the back of the engine to the front, where it won't be so close to the exhaust manifold. During the third week I drained the fuel tank, connected and flushed the fuel pipe work, and replace the fuel filters. We eventually got the exhaust system fitted on Wednesday 24/3/2004. We finally decided to start the engine on Wednesday 31/3/2004. It started first time, and ran for about 15 minutes, at about 2000RPM. From this run we found a water leak from a weld in the thermostat housing which has now been fixed, and an oil leak from the front of the engine which I have still to sort out. The engine was again run on Saturday 3/4/2004. After some minor changes to the ECU maps and temperature correction settings, I drove the car around the yard at the workshop. Even though the ECU maps still need setting up correctly, the engine is showing some impressive torque and is very crisp. Rolling Road ECU MappingWe finally got around to mapping the ECU on the rolling road on Friday 16/4/2004, delayed due to the oil leak problem and work load. We started off with the fuel and ignition map from my 2000 2.4L engine. From an initial careful run on the rolling road, we immediately found the the timing was far too advanced, and the fuelling too weak, as the engine immediately began pinking as we started loading it. The engine timing only wants 21° at full load, and 6° advance at tick-over (about 1000 RPM), which maybe suggests too much compression for the 98 Octane fuel, or a very efficient engine, a bit of both I think. After getting the fuel and ignition maps a bit closer to their optimum, we started pushing the engine much harder. We made one run with a sustained 170BHP at the wheels at 5200 RPM. The engine has quite a lot of torque and pulls very well from tick-over. It also revs nice and freely. We pushed it a bit more, and saw 190BHP at 6000RPM but with weak fuelling and a bit too much advanced ignition. As we brought the engine back down towards tick-over, so that we could make corrections to the maps, we heard a very loud clunking noise from the engine, and at tick-over the oil pressure warning light came on. We stopped the engine immediately. Engine Problems from Rolling Road SessionUpon investigation, we found that the camshaft pulley had come loose, and was damaged. The loud clunking noise was one of the cam pulley bolts hitting the cone shaped plate which locates the camshaft laterally. We think that I hadn't tightened the three bolts correctly, when installing it. Fortunately, we caught it before the camshaft pulley fell off and damaged the whole engine. We could immediately see that I would need a new camshaft pulley, pulley bolts, and dowel pin for the camshaft. Upon removing the roller rockers, in preparation for removing the camshaft, to get the cam pulley dowel pin replaced, we also found grooves worn in some of the valve stem tops, and possibly excessive wear on the flat-topped cam lifters. There is no damage to any of the roller rockers. This problem is to be investigated further, but at the moment there are two possibilities. Firstly that the valve stem tops and lifter tops have no been hardened adequately, or that the dual valve spring rate is rather higher than the manufacturer specified. Valve Stem & Lifter Top DamageI've had the dual valve springs tested and it turns out they are almost exactly what I specified when ordering them. I specified 95lb seated pressure at an installed height of about 41mm, and spring rate of 250lb/in. From testing, the seated pressure is 93lb at 40.6mm installed height, and the spring rate is 255lb/in. So the springs are not the cause of the valve stem tip damage. The markings on the lifter tops is a polished round circle, which my machinist calls a Witness mark. Both my machinist, and Bob Legere assure me this is normal. It appears that the valve stem tips were not hardened by the manufacturer, as he thought that a Cam In Head (CIH) engine was an Over Head Cam (OHC) engine, so hardening the valve stem tips wasn't necessary. So, a Communications cock-up! Nothing new there then. The damage to the valve stem tips can be repaired by grinding them flat again, and then hardening them, by using a Stelite coating, which should give them a hardness rating of 65 Rockwell. Valve Stem Tip Repair ProblemsThe Stelite coating was put on the end of the valve stems, this is done by heating up the Stelite and dripping it onto the valve stem top, rather tricky and not very scientific. However after re-grinding, it was found that not enough Stelite was laid down and some voids have been left on the stem tops on six of the eight valves. Unfortunately, the Macro facility on my digital camera is just not up to taking such a close up picture. Why has it taken nearly 5 months to get this far, I hear you asking? Well, it took nearly six weeks to get a 'stick' of Stelite. It came from the USA, I believe. It was then nearly one month before the engineering shop were able to get around to grinding the damaged part of the valve stems down. It then took another two weeks to lay down the coating of Stelite on the valves. From this point, it took until the second week of September before the Engineering Shop were willing to admit that the job was complete, but unsuccessful. Anyway, basically the valves are now definitely scrap. I am not willing to risk fitting them to the engine, as there is a risk that the voids could cause a problem with the roller rockers. I contacted G&S Valves, a UK valve manufacturer, during the first week in October. I sent them one of each inlet and exhaust valve. A few days later they contacted me, they can make me a new set of valves, to the same profiles, with Stelite stem tips. They came back saying it would be about 8 weeks before my valves would be ready, costing about £350 including VAT and delivery. I received a fax on Monday 01/11/2004, the valves are ready, cost £343.72, three weeks early. Sent my cheque off immediately, and the valves arrived about a week later. I have been dragging my feet a bit, due to the cold weather, etc. The new valves were lapped in last week, and I expect to start rebuilding the head next week (starting 14/3/2005). Latest NewsFinally the engine was completed at the end of June 2005. It was tested on the rolling road at Motoscope, and performed quite well, although it was a very hot day, 30°C +, and the air temperature in the rolling road bay was in excess of 40°C. The ECU was showing the air temperature at the engine inlet at 80°C, so we only got about 170BHP at the wheels out of the car, as the ECU was retarding the ignition due to the very low air density and high coolant temperatures. We were unable to get enough cool air to the engine bay, even though we had two huge fans on the job.
 What can I say, "jobs fcuked", at least until I've saved up enough money to rebuild the engine, which could be a very long time. So far I will need the following, Opel 2.0S block bored to 97mm
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For problems or questions regarding this web contact [Project Email].
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Basically, only the modified water pump cover, dip stick,
oil pump and cover, alternator,
starter motor, flywheel & crank pulley appear to have survived, the rest of the short engine is scrap.
The modified alloy bell housing for the gearbox is holed and cracked, and the
gearbox input shaft may be bent.
Surprisingly the cylinder head is completely undamaged. There is not a
mark on the top of the pistons or valves, which is utterly miraculous.