cranks, LONG rods, and stroker pistons
Dec 29, 2006, 12:32 AM
#16
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Well just to add somewhat of a conclusion to this, it looks like custom rods are going to be too expensive to be worth the tiny increase in rod/stroke ratio. Since the pistons used for the 4g64 crank strokers is already custom, even though they're so common it's not really custom anymore, that it would be very easy to move the pin 1.5mm lower. So it looks like that's the way I'm going to go. But if anyone feels like spending a ton of money on a theoretically great combo, I'd be interested to see how it turns out. Maybe even the 4g64 block 94mm crank/159mm rod combo with a gt42r to make the ultimate street/drag motor, that would be cool.
Dec 29, 2006, 12:43 AM
#17
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OMG... Why reinvent the wheel?
JUN Auto in Japan is and always will be the No.1 4G63 tuner in the world (period).
They use a 94mm crank, why? Maybe they just rolled two dices and made a crank with what ever stroke there number suggested.. Or NOT! R&D is what it's called.
No offense, but you will never be able to redo there work, nor get there experience.
I know I will get lot's of **** from this post from n00bs but I COULDN'T CARE LESS!
It's of a reason JUN is ranked No.1 tuner.
It's of a reason the fastest Evos uses there parts (and no I'm not talking 1/4 mil cars).
And one more thing.. No one uses a 85mm bore in a built 4G63 block, that's stock bore. Always, Always go to the first over dimension (85.5mm) and hone the cylinders to make sure you get a perfect surface.
If there is anything you like to know about JUNs products I can tell you the most as I have worked with all engine parts they supply to the 4G63.
If I had to choose another brand of stroker kit I would go with Cosworth, they make a replica (almost) of the JUN kit. Cosworth manufactures JUNs pistons after JUNs specs.
There are some differences between the JUN and Cosworth cranks, if you call Cosworth they will tell you exactly what it is, but it's also a slight price difference to Cosworth advantage.
JUN Auto in Japan is and always will be the No.1 4G63 tuner in the world (period).
They use a 94mm crank, why? Maybe they just rolled two dices and made a crank with what ever stroke there number suggested.. Or NOT! R&D is what it's called.
No offense, but you will never be able to redo there work, nor get there experience.
I know I will get lot's of **** from this post from n00bs but I COULDN'T CARE LESS!
It's of a reason JUN is ranked No.1 tuner.
It's of a reason the fastest Evos uses there parts (and no I'm not talking 1/4 mil cars).
And one more thing.. No one uses a 85mm bore in a built 4G63 block, that's stock bore. Always, Always go to the first over dimension (85.5mm) and hone the cylinders to make sure you get a perfect surface.
If there is anything you like to know about JUNs products I can tell you the most as I have worked with all engine parts they supply to the 4G63.
If I had to choose another brand of stroker kit I would go with Cosworth, they make a replica (almost) of the JUN kit. Cosworth manufactures JUNs pistons after JUNs specs.
There are some differences between the JUN and Cosworth cranks, if you call Cosworth they will tell you exactly what it is, but it's also a slight price difference to Cosworth advantage.
You only need to overbore if the walls need it. The engine sizes were given as examples as to how the size changes with differant strokes.
I know you have a JUN stroker, and I wasn't saying JUN sucks, I'm the type of person who thinks about differant ways to do things. I wanted some peoples opinions on my thoughts. So, if that's the way you took my idea, dont.
As far as Cosworth I had thought about using their stroker a while back, but couldn't justify the cost, as they really have NO experience with the 4g63 besides their recent cache of parts.
So, dont get worked up, it's not worth it.
Last edited by Frenchy4g63; Dec 29, 2006 at 01:38 AM.
Dec 29, 2006, 01:28 AM
#18
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Wait, I'm a confused noob here. How much displacement are you planning on ending up with? Will this be basically a 2.3L stroker kit with lower piston speeds for higher RPM potential? So by decreasing the stroke and increasing the rod length this will be achieved?
Dec 29, 2006, 01:44 AM
#19
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Well depending on the stroke it's gonna end up being somewhere between a 2.2L and 2.3L with stock bore a 100mm stroke crank will give you a 2.3, it's accually closer to 2.25 but rounded up it's a 2.3. With a 94mm stroke crank it would be a 2.2L if you round up. The 97mm stroke crank would be somewhere in between, probly a 2.2L, but a large 2.2. If you increased the bore you could make it round up to a 2.3L.
http://www.bgsoflex.com/displacement.html
That's the displacement calculator I use. It tell you ci, cc, and litres. Just make sure to change it to mm or you'll get a crazy huge motor.
http://www.bgsoflex.com/displacement.html
That's the displacement calculator I use. It tell you ci, cc, and litres. Just make sure to change it to mm or you'll get a crazy huge motor.
Last edited by Frenchy4g63; Dec 29, 2006 at 01:48 AM.
Jan 3, 2007, 11:45 AM
#21
late to the party... higher rod length/stroke ratios are very overrated. Increased rod length is a good thing, but the payback is very small in terms of power: ~1% on a 500 hp NA engine is what I've seen on back to back dyno tests going from realistically worst to best case possible. This was on a small block chevy V8 engine. to put it into perspective 1% is ~ the same gain as was shown as changing from a conventional to synthetic oil.
Jan 3, 2007, 12:21 PM
#22
While I don't know the specifics of the test in question, I should toss out that changing the rod length with no other changes doesn't really constitute an A/B test, simply because it doesn't take into account the obvious changes in effective cam specs and ignition timing that result from changing the rod length, which changes piston position with respect to crank angle. Likewise, changing the rod/stroke ratio may or may not present a benefit, depending upon the characteristics of the engine.
Nevertheless, I'll reiterate what I said above in saying that where a boost in power is concerned, a 15% change in displacement (e.g. 2.0 -> 2.3L) will make a more pronounced difference than the rod/stroke change, even if the latter is regarded as moving in an unfavorable direction.
Nevertheless, I'll reiterate what I said above in saying that where a boost in power is concerned, a 15% change in displacement (e.g. 2.0 -> 2.3L) will make a more pronounced difference than the rod/stroke change, even if the latter is regarded as moving in an unfavorable direction.
Jan 8, 2007, 12:57 PM
#23
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Hey i am just curious,i hope i am not getting off topic here,but what is your opinions on the following mix on a 20,5L 4g63: Omega pistons 85,5mm 8.8compression,Manley conrods,HKS Crankshaft,HKS metal gasket 1mm.
Jan 8, 2007, 01:56 PM
#24
late to the party... higher rod length/stroke ratios are very overrated. Increased rod length is a good thing, but the payback is very small in terms of power: ~1% on a 500 hp NA engine is what I've seen on back to back dyno tests going from realistically worst to best case possible. This was on a small block chevy V8 engine. to put it into perspective 1% is ~ the same gain as was shown as changing from a conventional to synthetic oil.
Jan 8, 2007, 06:28 PM
#26
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So I've been doing some thinking lately about stroker motors. With all the cranks available now, K1, Eagle, Jun etc.. It seems there's a ton of options out there. I'm trying to find that perfect mix of quick spool and high rpms, as I'm sure a lot of you are as well.
So here's what I'm thinking, using the 4g63 block, what about using a 97mm crank with the stroker pistons from a 4g64 crank stroker, and then using a 1.5mm longer rod? this would help with spool and help with top end. Or take it one step further and use a 94mm crank, same stroker pistons, and a 3mm longer rod? Both of these seem like great options, am I not thinking about something that I should be?
I calculated the rod ratio of both these combo's and they are pretty desirable.
97mm stroke/1.5mm longer rod = 1.56
94mm stroke/3mm longer rod = 1.64
I'm curious to see what EvoM guru's and engine builders have to say. This would also work with the 4g64 block, but the math would be differant obviously.
So here's what I'm thinking, using the 4g63 block, what about using a 97mm crank with the stroker pistons from a 4g64 crank stroker, and then using a 1.5mm longer rod? this would help with spool and help with top end. Or take it one step further and use a 94mm crank, same stroker pistons, and a 3mm longer rod? Both of these seem like great options, am I not thinking about something that I should be?
I calculated the rod ratio of both these combo's and they are pretty desirable.
97mm stroke/1.5mm longer rod = 1.56
94mm stroke/3mm longer rod = 1.64
I'm curious to see what EvoM guru's and engine builders have to say. This would also work with the 4g64 block, but the math would be differant obviously.
Jan 8, 2007, 10:46 PM
#27
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And as far as the compination i wrote,is there anyone that can understand something?
Jan 9, 2007, 12:57 PM
#28
I don't know of anyone who uses Omega pistons, so it is not a problem with understanding, but is an issue of experience. No one here seems to use them, probably because there are too many other, proven choices that are very available here in the U.S. (where most in this forum live).
As far as the HKS crankshaft, no one seems to use that part either, probably because the price seems ridiculous. But then again, most here find that the factory crankshaft holds up well, so it isn't an issue. If you want to know what crankshaft the extremely high hp cars are using (e.g. AMS, Buschur, etc.), you'll need to ask them.
As far as the HKS crankshaft, no one seems to use that part either, probably because the price seems ridiculous. But then again, most here find that the factory crankshaft holds up well, so it isn't an issue. If you want to know what crankshaft the extremely high hp cars are using (e.g. AMS, Buschur, etc.), you'll need to ask them.
Jan 9, 2007, 05:01 PM
#29
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If your looking at a smaller turbo and stroking the motor, the FORGED 4g64 100mm crank works nicely. It's what pretty much every shop uses as part of their stroker kits. If you want something stronger look into K1 Technologies.
I think Omega makes the pistons for Mitsu in the 4g63 Evo motor. Dont quote me on that though. A more proven piston company to look at would be Ross, JE, or Wiseco.
Jan 10, 2007, 10:39 AM
#30
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I guessing your planning on stroking the motor since you mentioned the HKS crank? Weren't you building another 42r powered car? If so, stick with the stock 4g63 crank, it's plenty strong, and you dont want to be limited with the rpm's by going with a stroker motor.
If your looking at a smaller turbo and stroking the motor, the FORGED 4g64 100mm crank works nicely. It's what pretty much every shop uses as part of their stroker kits. If you want something stronger look into K1 Technologies.
I think Omega makes the pistons for Mitsu in the 4g63 Evo motor. Dont quote me on that though. A more proven piston company to look at would be Ross, JE, or Wiseco.
If your looking at a smaller turbo and stroking the motor, the FORGED 4g64 100mm crank works nicely. It's what pretty much every shop uses as part of their stroker kits. If you want something stronger look into K1 Technologies.
I think Omega makes the pistons for Mitsu in the 4g63 Evo motor. Dont quote me on that though. A more proven piston company to look at would be Ross, JE, or Wiseco.
Thanks anyway for advice.
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