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Practical Engine Building: Step 1: Initial Preparation

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Step 1: Initial Preparation


00:00 - In this worked example, we're going to be taking you through the build of a 2.2 litre stroked Mitsubishi Evo 9 4G63.
00:08 Now while we are dealing with the Evo 9 engine here specifically, and there are a few peculiarities with the Evo 9 variant, given that it does have continuously variable cam control on the inlet camshaft, most of what we're going to be discussing is completely applicable to the wider range of 4G63 engines, definitely the 7 bolt variants from Evo 1 through to 9.
00:32 However a lot of what we're going to be covering here will also be completely applicable to the earlier 6 bolt 4G63 engines.
00:40 Now what we're going to do is start by talking about the various options when it comes to building a stroked 4G63.
00:49 Because there are seemingly a confusing number of variants and options available and I just want to talk through what's out there, what's commonly used and why we've gone down the path we've gone down.
01:00 To start with, if we're talking about a standard 4G63 then the crankshaft is 88 mm in stroke and it also uses a 85 mm bore to get 2 litres of displacement.
01:13 A very common way of building a larger capacity 4G63 is to steal the crankshaft out of the 4G64 Mitsubishi engine.
01:23 Now that is a 2.4 litre engine and the crankshaft out of that engine has 100 mm of stroke.
01:31 Now confusingly, if we put that 4G64 crankshaft into the 4G63 block and it fits absolutely perfectly, for all intents and purposes, it is identical except for the additional stroke.
01:42 What we're going to end up with is an engine that displaces about 2.3 litres.
01:48 The additional 100 cc of capacity that the 4G64 block gives us comes from the fact that the 4G64 block has a larger bore diameter, it's 87 mm compared to 85.
02:02 There is one other key difference with the 4G64 block though and that is the deck height of the block.
02:10 The distance from the crankshaft centreline to the top of the block, on the 64 block, this is 6 mm taller than the 4G63.
02:18 Now why that's important is that this takes into account the additional stroke of the crankshaft coupled with the existing 150 mm centre to centre conrod length and the factory or stock compression height of the piston.
02:32 Basically what this means is that when we assemble the 4G64 block with the 100 mm stroke crankshaft, the piston doesn't stick out the top of the block at top dead centre which is exactly what would happen if we put all of those components into the 4G63 block.
02:48 So the key point here is if you are going to use a 100 mm stroke 4G64 crankshaft in a 4G63 block, we need to purchase a set of pistons designed for this application.
03:01 And how that's dealt with is that the compression height of the piston is simply reduced.
03:07 Compression height is the distance between the centre of the pin or the wrist pin and the top of the piston crown.
03:12 So basically the wrist pin is simply moved higher in the piston by 6 mm, that'll also have it intersect through the oil control ring and that's how we can build a 2.3 litre combination in the 63 block.
03:27 Alright so that's the basics there.
03:29 However, when we look at the different combinations, while yes the 2.4 or 2.3 litre variants to give us more capacity, that's really helpful for improving our low end torque and also spooling up a larger turbocharger, in my own experience I find that they don't rev particularly well.
03:48 So particularly if we want to build a combination that's going to happily rev to 8000 or more RPM, then the 64 crankshaft, is not in my opinion ideal.
03:59 Yes it absolutely can be done but again just not a perfect combination in my personal experience.
04:06 So what we've done here for our build is we've gone somewhere in between.
04:09 The aftermarket now provides crankshafts at stock stroke, 88 mm, 4G64 stroke, 100 mm and my own personal preference for a stroker engine, one we've chosen here has a 94 mm stroke.
04:24 If we use this particular crankshaft in our 63 block, this gets us an engine capacity of approximately 2.2 litres.
04:32 We do still need to account for the additional stroke with the compression height of the pistons so again this will require a special piston design around that 94 mm stroke so that our piston still sits flush with the deck surface of the block at top dead centre.
04:47 So again, in my experience, the 2.2 litre gives us a really nice compromise between increased capacity and giving us the ability to produce more bottom end torque, spool those larger turbochargers quicker but it still gives us great ability to rev and in this combination we're building an engine that's going to be red lining at around about 8000 RPM.
05:08 So this should be pretty well ideal.
05:11 I will talk very quickly about some other variants that are used in the 4G64 block because this still is a very popular basis for a build.
05:22 Given that the 64 block has that taller deck height, there can be some advantage gained from this by using a longer connecting rod.
05:31 It's quite common to use the 64 block with a 156 mm long connecting rod and this gives us a small improvement with the rod to stroke ratio when we are using those stroker crankshafts so again there's a little bit of a combination there we need to consider that comes into effect here, the compression height of the piston, the length of the connecting rod and also of course the stroke of the crankshaft and again various combinations depending on exactly what crankshaft you are using in there.
06:00 Also common to use the 4G64 block wtih a stock 88 mm stroker crankshaft and this builds us what's referred to as a long rod 4G63 and basically that will displace 2.1 litres.
06:15 Given that we can fit a much longer rod in the 64 block with the stock 88 mm stroker crankshaft, this also means that the rod to stroke ratio is greatly improved over the stock 4G63, giving an improvement in high rev capability.
06:30 Now, lot of information that's just gone in there, basically I just wanted to get a rundown on the common combinations in there but here we are just going with the 63 block and the 94 mm stroker crankshaft.
06:46 I also will just mention, one of the downsides in my opinion with the 64 block is that larger bore diameter, 87 mm bore diameter that it uses.
06:55 This gives us a lot less material between adjacent bores, it gives us a lot less material for the head gasket to seal on between adjacent bores and particularly this gets worse when we're also typically going to be over boring the engine block to first oversize when we are building it so 63 block with the smaller bore, gives us a little bit more material to work with and in my opinion, a stronger overall result.
07:21 It is important to mention here that there is no right and wrong way to build a 63/64 combination.
07:28 A lot of this really just comes down to personal preference and what you are trying to achieve and there are all of these combinations out there producing great power and torque and great reliability so it's a case of understanding the implications of the path you've gone down and making an informed decision which is hopefully what I've just been helping you make.
07:49 Alright let's get into our particular engine now we've got that background information out of the way.
07:55 Now to start with, we actually had a little bit of trouble sourcing a donor engine.
08:00 Evo 9 engines here in New Zealand are not exactly thick on the ground so we ended up having to piece and engine together from two parts.
08:08 We bought a low kilometre short block and then separately from another supplier, we sourced an Evo 9 cylinder head.
08:15 The important part here is that both of those components do appear to be in good condition and are relatively low km so again we'll be looking at this in a little bit more detail as we move further through the worked example.
08:27 The parts that we are dealing with here, we've already looked at our crankshaft briefly but this is a Manly billet crankshaft.
08:35 These are available in 94 mm stroke from a range of suppliers these days but the billet crankshaft is a great option.
08:43 It's more than strong enough for what we're going to be aiming for, 700 to 800 horsepower, 8000 RPM, these are capable of going well over 1000 horsepower.
08:52 One of the nice features is the design of the counter weights, the way that they are tapered.
08:57 So this helps reduce windage losses with that crankshaft rotating inside of the engine block.
09:03 The real key to the combination is our pistons and in this case we are using a JE forged piston.
09:10 We have gone with an 85.5 mm piston, so that's first oversize and this is my typical go to.
09:18 It allows our machinist to bore and hone the block to first oversize, making sure that we aren't going to be sacrificing anything with excessive wear that we may find in the block.
09:29 It allows us to basically start with a fresh bore that we know is going to be perfectly true, perfectly round and of course we've got that fresh hone pattern that's important to allow us to bed in the rings.
09:41 These pistons do have a few features on them as well.
09:44 First of all, as I mentioned, they are designed around that 94 mm stroker crankshaft so the compression height there critical so that our piston does sit flush with the block at top dead centre.
09:54 We also need to decide on a compression ratio for this engine.
09:58 And here we have made a bit of a compromise.
10:00 The engine will be flex fuel so it's going to be running on ethanol or probably E85 for the majority of the time, particularly when we are aiming for high power.
10:10 If we were building a dedicated E85 engine, I'd be inclined to run a compression ratio around about 10.5:1 or there abouts.
10:19 Because we aren't likely to be knock limited on that fuel.
10:22 However, given that we are going to still need to run this engine on pump gas, we have had to pull that compression ratio back a little bit so we are sitting at 9:1 which is still going to be perfectly acceptable on pump gas and it's obviously going to be more than adequate for E85 so really important to just understand the implications.
10:42 If we went with a higher compression ratio piston, we'd really struggle to avoid knock, particularly on lower octane fuels.
10:49 A couple of other features with those pistons, we can see the gold thermal barrier coating that is on the piston crown, designed to reject heat or reflect heat back into the combustion chamber rather than into the piston crown.
11:01 And there is also a friction reducing skirt coating which again is pretty common these days so nothing much more to talk about with our pistons.
11:09 We've also got our connecting rods here and these are a BoostLine rod from Wiseco.
11:15 More than up to the task again of our 800 horsepower maximum target and we're probably going to be turbo limited so I don't even know if we'll quite get to 800 horsepower with this engine.
11:26 But plenty of really strong conrod options available for the 4G63 in that 700 to 800 horsepower vicinity.
11:36 Now there are a few other components that we need to factor in here.
11:38 We're using ARP studs throughout this build so we're using a 10 mm ARP 2000 stud for the main studs holding the crankshaft girdle or cradle in place in the block and we're using a stock size 11 mm stud for the cylinder head.
11:56 This is one area that the 4G63 does have some problems.
12:01 As do most high boost turbocharged engines and this is around cylinder head sealing.
12:06 There are a variety of options here, I'll talk about the heat gasket we've chosen shortly.
12:10 But particularly with the studs, we can get an advantage in cylinder head clamping by moving up to a stronger material.
12:17 In this case we are using ARP's custom age 625+ material.
12:22 Really important when we are dealing with any of these more advanced materials, they do suffer from hydrogen embrittlement if we handle them with our bare hands.
12:31 So really important, for L19 and custom age 625+, make sure that we are using gloves while we are handling those.
12:39 So we've talked about our head studs and this also works in conjunction with the head gasket of course.
12:44 Now there are again a variety of options for head gaskets.
12:48 Well proven is the actual factory Evo 9 MLS or multi layer steel gasket.
12:54 This is more than up to the task of handling the power and boost levels that we're expecting to run so we see no need to swap from that.
13:01 There's also a pleasant surprise there, quite cost effective.
13:05 Moving into the cylinder head, this is really the key to where we're going to be making power, nothing wrong with the stock Evo 9 cylinder head in itself but we will be benefitting here from a CNC port job as well as a set of 1 mm oversize Ferrea valves.
13:21 Now to fit those stainless oversize Ferrea valves, we will also be using a set of bronze valve guides and everything there is going to be actuated by a set of GSC power division S2 camshafts.
13:35 These are not a really wild camshaft, given that this engine is still going to be built to be streetable but it is a well proven combination in the power levels that we're aiming for here.
13:46 Given that the 4G63 Evo 9 engine does include MIVEC or continuously variable cam control on the inlet cam, we're retaining this and we'll be using a single HKS vernier adjustable cam gear on the exhaust side only so that we can degree the exhaust cam into GSC's specifications.
14:06 We're coupling that with an HKS cam belt which is a little bit stronger than stock.
14:11 The rest of the components that will go into this build, we've got a set of GSC Power Division valve springs that are suited to their cams.
14:21 These will be coupled with a set of titanium retainers as well so really important when we are choosing cams to make sure that we are using matched components that will be adequately able to control the valve motion, otherwise we risk losing control of the valves which can end up really expensive at high RPM.
14:39 The rest of the components on the build will consist of ACL race series bearings, we're going to be using a new OE oil pump straight from Mitsubishi along with the rest of the ancillary components, the idlers, tensioners, water pump etc.
14:56 The sump is one other area we will be making a change, we're going to be sending the existing factory Evo 9 sump to Race Fab here in New Zealand and Race Fab's going to be modifying that, adding a little bit more capacity and a baffle box around the oil pickup, just to help reduce the chances of oil starvation when we end up with this car on the racetrack.
15:19 As part of this build, we will also be deleting the balance shafts that the 4G63 engine has.
15:24 This is something we'll be detailing as we go through the build but it is something that's really important to understand.
15:30 There's a couple of ways that the balance shafts can be removed and they're not all created equal.
15:37 So if we want reliability, it's important to understand the implications of how the balance shafts are removed and do it the right way, otherwise we can end up with an expensive oil pump failure.