Okay, first let me state that this idea certainly won't be for everyone. Also, the reason I'm using this idea is because I'd like to make a high-hp, bigger displacement engine that will make power up to about 9500 rpm. The things that I was concerned with are rod-to-stroke (R/S) ratio, as this affects piston acceleration because I want to keep piston speed down, bore-to-stroke (B/S) ratio, component weight, and parts availability. I'd rather the engine be square or oversquare than under. Also, just to note, my numbers are all in mm's because that's what I'm used to dealing with with Japanese engines. It's easier for me to work the numbers.
Anyway, this idea certainly isn't cheap, but it doesn't require using the Darton wet sleeves (though I'd love to use those). Starting with a 3UZ block, I'd be using a custom Scat crankshaft. Bore the block .030" or even just .020" (would be about .5mm for the .020" or .7mm for the .030"). Use Mitsubishi 4G63 rods, with custom pistons.
The reason is, the Mitsu rods have a big end diameter of 48mm as opposed to the UZ's 52mm. If we were to offset grind the crank, we'd effectively gain 8mm of stroke with the same crank! That would be 90.5mm stroke, and with the 3UZ overbored, 91.5mm bore. Really nice B/S ratio, and the Mitsu rods are 150mm (3mm longer than stock, if I remember correctly?) which gives a very decent 1.66 R/S ratio. The extra 3mm will be taken up by moving the wrist pin up 3mm, which is good because I wanted to move the pin up anyway. Then I could shave a bit more weight off the custom pistons, which I wanted to do anyway since it's all-motor.
So we end up with a 91.5mm bore and a 90.5mm stroke giving us a displacement of 4.76L, so I'd call it a 4.8. Now, the custom crank is required because the Mitsu rods are 1.140" thick at the big end... quite a bit bigger than the UZ rods. This is a good thing. STOCK Mitsubishi rods have been known to handle over 500 hp from a 2.0L 4-cylinder, so if we went with stock rods, we could use them up to 1000 hp safely. But, we can't use stock rods with aftermarket pistons because they use a different type wrist-pin. Otherwise I'd just grind the stockers down and use the stock crank. A pity too, because the wrist pin diameter is the same 22mm for those stock rods. Not to mention, everyone and their brother are dumping them off cheap for better rods. AND I already have four of them.
I'm not about to buy an aftermarket set of rods and grind them down. Unfortunately, 4g63 rods ARE a bit more expensive, typically ~$400 a set, though the prices have gone down a bit recently. Groden makes awesome aluminum rods for the 4g63 ($699) which weigh over 100 grams less than the stockers, which weigh about the same as the stock 3UZ rods. But that's $1400 for 8. That's the price for power though.
So I figure, if we're going to spend decent money to get awesome rods, we might as well spend the money on a brand new Scat crankshaft with all the goodies... lightweight, knife-edged, micropolished, etc. Though at this point, with new crank, rods, and pistons, I'm tempted to save an initial bit on the engine and just go with the Darton sleeves. What will that net us for displacement? Well first, let's check what the 1UZ would give us, since I'd personally rather use the 1UZ heads and the engines are far easier to obtain. 88mm bore (.5mm over) and a 90.5 stroke gives us 4.4L. This engine is undersquare. But remember, we have 3mm of rod to play with, so we COULD go down to 88mm bore with 87.5mm stroke. That only gives us 4.25L but with a R/S ratio of 1.71. I like the ratio, but I'd like more displacement.
Alright, so if we can use a 99.5mm bore with the Darton sleeves, and a 90.5mm stroke, that will get us 5.6L! With an engine that will rev to 9k and be bullet-proof! The cost of the Darton sleeves at this point would also be pretty small compared to the rest of it. So it becomes something to seriously consider. Let's say we want that 1.71 R/S ratio, and take the stroke back down to 87.5. We still get 5.4L, with an engine I'd be willing to try to rev up to 10k (assuming the camshaft profile isn't TOO aggressive). Note that we can get a lot more displacement with a small change in bore compared to a small change in stroke. The thing that worries me about the Darton sleeves is that the heads were designed with an 87.5mm bore size. Overboring it half a mm is nothing, but stepping up to the huge Chevy pistons might screw up the flame front. Also, what do we do about the head gasket?
So how much will this all cost? I have no idea how much Scat charges for their cranks, but since they're ultra-light (no sense in doing things half-ass
), I would guess above $1000. The Groden rods are $1400. Custom Ross pistons would probably run around $700-$800, based off their web site. And of course the Darton sleeves, which were mentioned in the other thread and I believe it came to about $2200 for parts and labor. Realistically, $5400. But you now have a bottom end that's nearly indestructable (I believe those Groden rods are rated above 800 hp, for a 4-cylinder, and I know the pistons are too), and if you look at some of the more common, high power engines, you'll see that this is not too bad a price compared to those even on ebay. I was looking into the BMW 8-series V12, and that's over 5 grand, and it's only a 5.0L SOHC engine with 300 hp. Viper engines go for well over $10k. I realize this isn't a Viper engine, but with another 5 grand in a twin-turbo setup you could DEMOLISH a Viper.
Anyway, since I'm going the N/A route, I'd be using a high compression ratio, probably 13:1 using methanol injection to combat detonation on pump gas (did I mention I want to make the car a daily driver?). I can do my own porting and polishing, valve seat grinding, and pretty much everything else on the head. I'd probably use the AE86-based ITB setup (sorry, forgot the company name at the moment) or possibly look into an even bigger custom setup. Even with 4.8L, I feel that this engine could possibly make 500 hp. As much as I love turbos, I'd love to spank some supercharged Mustangs with a naturally-aspirated import V8 (at the track, of course).
Anyway, I realize this isn't the most cost-effective idea, but it's got a few advantages. The custom crank gives the opportunity to have all performance mods done to it. The thicker rods allow for better strength, and since they are aluminum they are much lighter than stock. Custom pistons are a given anyway, and the Darton sleeves are purely a personal preference option. Does anyone have a picture of the bottom of a 1UZ head? I'm interested to see what kind of quench pads it uses.
Well, that's my idea, and I know it sounds rather crazy but it seems to suite my needs pretty well, other than cost!
Anyway, this idea certainly isn't cheap, but it doesn't require using the Darton wet sleeves (though I'd love to use those). Starting with a 3UZ block, I'd be using a custom Scat crankshaft. Bore the block .030" or even just .020" (would be about .5mm for the .020" or .7mm for the .030"). Use Mitsubishi 4G63 rods, with custom pistons.
The reason is, the Mitsu rods have a big end diameter of 48mm as opposed to the UZ's 52mm. If we were to offset grind the crank, we'd effectively gain 8mm of stroke with the same crank! That would be 90.5mm stroke, and with the 3UZ overbored, 91.5mm bore. Really nice B/S ratio, and the Mitsu rods are 150mm (3mm longer than stock, if I remember correctly?) which gives a very decent 1.66 R/S ratio. The extra 3mm will be taken up by moving the wrist pin up 3mm, which is good because I wanted to move the pin up anyway. Then I could shave a bit more weight off the custom pistons, which I wanted to do anyway since it's all-motor.
So we end up with a 91.5mm bore and a 90.5mm stroke giving us a displacement of 4.76L, so I'd call it a 4.8. Now, the custom crank is required because the Mitsu rods are 1.140" thick at the big end... quite a bit bigger than the UZ rods. This is a good thing. STOCK Mitsubishi rods have been known to handle over 500 hp from a 2.0L 4-cylinder, so if we went with stock rods, we could use them up to 1000 hp safely. But, we can't use stock rods with aftermarket pistons because they use a different type wrist-pin. Otherwise I'd just grind the stockers down and use the stock crank. A pity too, because the wrist pin diameter is the same 22mm for those stock rods. Not to mention, everyone and their brother are dumping them off cheap for better rods. AND I already have four of them.
I'm not about to buy an aftermarket set of rods and grind them down. Unfortunately, 4g63 rods ARE a bit more expensive, typically ~$400 a set, though the prices have gone down a bit recently. Groden makes awesome aluminum rods for the 4g63 ($699) which weigh over 100 grams less than the stockers, which weigh about the same as the stock 3UZ rods. But that's $1400 for 8. That's the price for power though.
So I figure, if we're going to spend decent money to get awesome rods, we might as well spend the money on a brand new Scat crankshaft with all the goodies... lightweight, knife-edged, micropolished, etc. Though at this point, with new crank, rods, and pistons, I'm tempted to save an initial bit on the engine and just go with the Darton sleeves. What will that net us for displacement? Well first, let's check what the 1UZ would give us, since I'd personally rather use the 1UZ heads and the engines are far easier to obtain. 88mm bore (.5mm over) and a 90.5 stroke gives us 4.4L. This engine is undersquare. But remember, we have 3mm of rod to play with, so we COULD go down to 88mm bore with 87.5mm stroke. That only gives us 4.25L but with a R/S ratio of 1.71. I like the ratio, but I'd like more displacement.
Alright, so if we can use a 99.5mm bore with the Darton sleeves, and a 90.5mm stroke, that will get us 5.6L! With an engine that will rev to 9k and be bullet-proof! The cost of the Darton sleeves at this point would also be pretty small compared to the rest of it. So it becomes something to seriously consider. Let's say we want that 1.71 R/S ratio, and take the stroke back down to 87.5. We still get 5.4L, with an engine I'd be willing to try to rev up to 10k (assuming the camshaft profile isn't TOO aggressive). Note that we can get a lot more displacement with a small change in bore compared to a small change in stroke. The thing that worries me about the Darton sleeves is that the heads were designed with an 87.5mm bore size. Overboring it half a mm is nothing, but stepping up to the huge Chevy pistons might screw up the flame front. Also, what do we do about the head gasket?
So how much will this all cost? I have no idea how much Scat charges for their cranks, but since they're ultra-light (no sense in doing things half-ass
), I would guess above $1000. The Groden rods are $1400. Custom Ross pistons would probably run around $700-$800, based off their web site. And of course the Darton sleeves, which were mentioned in the other thread and I believe it came to about $2200 for parts and labor. Realistically, $5400. But you now have a bottom end that's nearly indestructable (I believe those Groden rods are rated above 800 hp, for a 4-cylinder, and I know the pistons are too), and if you look at some of the more common, high power engines, you'll see that this is not too bad a price compared to those even on ebay. I was looking into the BMW 8-series V12, and that's over 5 grand, and it's only a 5.0L SOHC engine with 300 hp. Viper engines go for well over $10k. I realize this isn't a Viper engine, but with another 5 grand in a twin-turbo setup you could DEMOLISH a Viper.Anyway, since I'm going the N/A route, I'd be using a high compression ratio, probably 13:1 using methanol injection to combat detonation on pump gas (did I mention I want to make the car a daily driver?
). I can do my own porting and polishing, valve seat grinding, and pretty much everything else on the head. I'd probably use the AE86-based ITB setup (sorry, forgot the company name at the moment) or possibly look into an even bigger custom setup. Even with 4.8L, I feel that this engine could possibly make 500 hp. As much as I love turbos, I'd love to spank some supercharged Mustangs with a naturally-aspirated import V8 (at the track, of course).Anyway, I realize this isn't the most cost-effective idea, but it's got a few advantages. The custom crank gives the opportunity to have all performance mods done to it. The thicker rods allow for better strength, and since they are aluminum they are much lighter than stock. Custom pistons are a given anyway, and the Darton sleeves are purely a personal preference option. Does anyone have a picture of the bottom of a 1UZ head? I'm interested to see what kind of quench pads it uses.
Well, that's my idea, and I know it sounds rather crazy but it seems to suite my needs pretty well, other than cost!
