Practical Engine Building: Step 1: Initial Preparation
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Step 1: Initial Preparation
09.16
| 00:00 | - In this worked example we're going to be covering the build of an SR20 DET fitted with a late model P11 VVL cylinder head. |
| 00:09 | This is commonly referred to as an SR20 VE engine. |
| 00:13 | Although Nissan never actually developed a turbocharged version using this cylinder head. |
| 00:18 | The engine's actually being built for our own race car and as part of this we're using the engine for endurance race events. |
| 00:26 | Now this provides us with some challenges. |
| 00:28 | What we want is an engine that can be run on pump gas due to the fuel economy benefits versus fuels such as E85. |
| 00:37 | With this sort of fuel we want to be able to achieve somewhere around about 500 flywheel horsepower. |
| 00:43 | At the same time we also intend to use the car for sprint events where we are not going to be limited by fuel load and for these events we would be using E85 fuel. |
| 00:54 | This will allow us to run more boost and optimise the ignition timing further and on E85 we're expecting to be able to make somewhere in the region of 650 horsepower at the flywheel. |
| 01:05 | Now these power aims are definitely not extreme for the SR20 VE builds. |
| 01:11 | So we're not really trying to reinvent the wheel here and we're not really trying to set any records. |
| 01:16 | This also means that the parts that we're going to require aren't anything particularly special. |
| 01:23 | So we'll cover off the parts we've chosen and the reasoning behind some of these parts. |
| 01:28 | Now the build here starts with requiring two base engine donor components. |
| 01:33 | The engine block that we're using has been sourced out of a rear wheel drive Nissan S14 so this is a conventional SR20 DET short block. |
| 01:42 | It is a well used short block, but really we're not too interested in many of the components out of that block though. |
| 01:49 | We'll be replacing the pistons and connecting rods. |
| 01:51 | Really what we're most interested in is making sure that the factory crankshaft is in good condition. |
| 01:57 | This is because we will be retaining the factory crankshaft and reusing it. |
| 02:00 | As far as the cylinder head goes, for the VE conversion, we can use either the P11 or P12 Primera cylinder heads. |
| 02:08 | Both have pros and cons, we've selected the P11 because it is a little bit easier to find and it's much cheaper than the P12. |
| 02:16 | The P12 cylinder head arguably has better cams and slightly superior flow, but again because we're not trying to really push the limits of what this engine is capable of producing power wise, we feel that the P11 is going to be more than adequate for our aims. |
| 02:32 | In order to ensure reliability with our built engine, we're going to be replacing most of the rotating assembly starting with the pistons. |
| 02:40 | In this case we are going to be fitting a set of JE forged pistons. |
| 02:44 | These are a 2618 forging, really suited to high horsepower applications, particularly with turbochargers fitted. |
| 02:52 | Now we are going to a first oversize here so the stock bore diameter on the SR20 DET is 86 millimetres so we've gone to an 86.5 millimetre bore diameter. |
| 03:03 | This allows the engine block to be bored and honed, this ensures that we can remove any existing wear and our machinist is going to be able to achieve a nice fresh bore that's perfectly round and perfectly parallel from top to bottom. |
| 03:17 | Choosing the piston also requires us to decide on a compression ratio and this is an area with this particular build that is a bit tricky. |
| 03:25 | Because we are intending to run on both pump fuel and E85, we are a little compromised on our selection of compression ratio and here we've gone with a 9:1 finished compressiion ratio. |
| 03:37 | This is still going to allow us to run reasonable boost pressure on pump gasoline without running into detonation problems however we'll still be able to run a lot of boost on E85 and make more power due to the properties of that fuel. |
| 03:50 | If on the other hand we were building a dedicated engine solely to run on E85 we'd be much more likely to increase that compression ratio further and I'd be likely to be choosing a compression ration in the order of about 10.5:1 or thereabouts. |
| 04:06 | Now to match with those pistons we're also using a set of K1 Technologies h beam connecting rods. |
| 04:13 | Now actually the stock connecting rods in the SR20 DET aren't a bad thing but given the ultimate power level we're aiming for as well as the fact we're likely to run this engine to 8000 RPM, or potentially above, it makes sense to fit a superior conrod. |
| 04:30 | So these are an h beam design, they're chromoly conrod and they're also fitted with a set of ARP rod bolts so these should be more than adequate for our aims. |
| 04:40 | I've already mentioned that we will be retaining the stock crankshaft and these have proven to be really reliable at the sort of power levels we're expecting and in fact well above this. |
| 04:50 | We are however replacing the factory bearings with a set of King Racing performance engine bearings. |
| 04:57 | Now with the SR20 this is an area where we do have a couple of options. |
| 05:00 | The SR20 engine came out in both the Silvia as well as GTIR variants. |
| 05:05 | And there is one difference in terms of the engine bearings used. |
| 05:09 | Particularly for the main bearings that support the crankshaft. |
| 05:14 | Now a modification we can use here is to fit the GTIR bearings into the non GTIR SR20 DET, these have shown to provide superior oiling to the crankshaft, however these aren't a direct fit changeover part, they actually require some modifications to the engine block that we will be dealing with through our engine machinist to ensure that there is a steady supply of oil to the bearings. |
| 05:40 | We're also going to be holding the crankshaft into the engine block using a set of Mazworx ARP based fasteners. |
| 05:47 | These are actually different to ARP's normal shelf stock part for the SR20 DET. |
| 05:52 | Mazworx found that the shelf stock part doesn't fully engage in the threads in the block, it's actually shorter and this has been attributed to some block cracking in high power SR20 DETs. |
| 06:06 | Mazworx have addressed this by designing a longer fastener, it's got more threads that can fully engage and it also has an extension that bottoms in the block. |
| 06:15 | On top of this these fasteners are also made out of a slightly superior material. |
| 06:20 | Instead of the normal SRP 8740 material, these are a slightly stronger ARP 2000 based material. |
| 06:28 | We're matching these main studs with a set of Mazworx head stud kits as well. |
| 06:33 | It's also important to note here that with the head studs there are different head studs sizes for the normal SR20 DET and the GTIR. |
| 06:41 | We're not really pushing things here too far and aren't expecting to run a lot of boost pressure in the engine, even on E85 so we've chosen to stick to the standard 11 millimetre SR20DET head stud size. |
| 06:56 | Matching with those Mazworx head studs we are also using a Tomei MLS head gasket. |
| 07:02 | This is a 1.2 millimetre thick head gasket, and it also has an 87 millimetre bore size, so this gives us a little bit of leeway with our 86.5 millimetre size pistons. |
| 07:15 | Now these MLS gaskets are well proven in high boost turbo applications. |
| 07:19 | So we're confident we're not going to have any problems here. |
| 07:23 | Now there are a couple of other aspects that need to be addressed with the SR20 VE conversion. |
| 07:30 | One of them is the oil pump and the stock DET oil pump isn't sufficient to provide oil flow to the VVL or variable valve lift mechanism. |
| 07:40 | This is essentially a VTEC style mechanism which has two pairs of lobes on each camshaft that can be switched using oil pressure. |
| 07:48 | What we've chosen to do here is go with the genuine Nissan VVL oil pump assembly which is suited to this particular application. |
| 07:57 | Now particularly when it comes to having the engine block machined, because the oil pump is part of the front housing assembly, this also needs to be sent off to our machinist as it will be fitted when the engine block is decked. |
| 08:11 | Failing to do this can provide some problems with our head gasket seal. |
| 08:15 | Now when fitting the VVL oil pump to our DET engine, we also need a spacer. |
| 08:22 | This is just a small spacer that goes behind the oil pump and it prevents the oil pump from being damaged when the crank pulley is tightened up. |
| 08:32 | Another small subtle aspect that's required for one of these conversions is that there is an oil gallery in the engine block that needs to be blocked, and again we're using a special Mazworx part to block that off. |
| 08:45 | Making this all work in a rear wheel drive application also requires a modified oil pickup. |
| 08:52 | Again we've sourced this from Mazworx, and this is just a modified version which has the oil pickup adjusted to suit the SR20 VVL oil pump. |
| 09:03 | So at this point we've introduced the project and we've got a good idea of what we're trying to achieve, we've also seen all of the parts that will be fitted into the engine. |
| 09:11 | We can now move on with the next step of our process. |
