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4 inch crank into a ls1

 
Old 10-23-2017, 11:02 PM
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Iíll go check out their store now 👍🏽
Originally Posted by CattleAc View Post
This explains it well...

There are a lot of connecting rod options out there...but, I bought some reasonably priced forged 6.125" rods from the WS6 Store.

Maybe [email protected] will chime in hear with a recomendation...
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Old 10-24-2017, 07:24 AM
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Originally Posted by Bobby Kelii View Post
So going with these pistons is fine? my compression ratio will still be in the 9.5 - 10 range? I thought going with these pistons and the 6.125 rods would bring the piston further up to the valves on the compression stroke and therefore raise the compression? eventually I will be boosting with a single turbo so I wanted to keep the compression down in anticipation of boosting in the future. So these forged pistons are good for my application correct? now Im going to search for a deal on forged rods with .927 pin diameter and a 6.125 length and that set up should keep my compression in the 9'ish range, is that accurate? thank you in advance for the advice.
I don't know what heads you're wanting to use, so I can't tell you what your compression will be. However, with these pistons, the 6.125" rods, and the stock 5.3L heads, like an 862 or 706 casting, you would be right around 10:1 but swapping to a 317 casting would drop it down to about 9:1. I use this online calculator to come up with compression ratios:

http://www.wallaceracing.com/cr_test2.php

IMO, the best bang for the buck rod would be the Scat I Beam. WS6Store has them for about $300 a set. They are forged 4340 steel, use 7/16" ARP bolts, and can handle a good amount of power. The pin bores are a little tight for a forced induction application, but that's an easy cheap fix for your machinist.
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Old 10-24-2017, 08:54 AM
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Originally Posted by KCS View Post
The pin bores are a little tight for a forced induction application, but that's an easy cheap fix for your machinist.

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Old 10-24-2017, 09:50 AM
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Originally Posted by KCS View Post
IMO, the best bang for the buck rod would be the Scat I Beam. WS6Store has them for about $300 a set. They are forged 4340 steel, use 7/16" ARP bolts

These are the ones I used...
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Old 10-24-2017, 12:24 PM
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They make Forged pistons for stock 6.098" rods, too. So if you're not wanting to purchase rods, there's a few options out there for you without replacing your OE rods.
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Old 11-06-2017, 04:37 PM
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How's it everyone, so my build might take a slightly different direction depending on the extent of the work that needs to be done, I had no intensions of changing out my stock crank for a 4" but I might be able too get a LS7 crankshaft for less than a third of what it would cost to buy a new Eagle 4" stroke crank so thats why I am now considering this option, my question is what machine work will need to be done, supposedly the front needs too be machined down which seems logical being that the LS7 is slightly longer but will I be able to stick with the wet sump or will I have to convert to dry sump. My major parts acquisition is almost complete but luckily the only parts I have for the rotating assembly is the Mahle 3.903 pistons, I haven't ordered the rods or any of the bearing because I wanted to get the block into the machine shop and have them clean it up and check for clearances then order accordingly. Thanks for the replies!
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Old 11-06-2017, 04:55 PM
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Thats a very handy link thank you. I have the stock 862 heads which have been redone, 3 angle, new larger stainless intakes and exhaust, new seals seats retainers and a set of PAC springs. A friend of a friend did a mild porting and it looks pretty smooth. I wish I had done a little more research on my build before sending out the 862 heads had I known that the 317's would have been a better candidate too get redone for the lower compression, Ill make due with my 862's and maybe look into upgrading them in the future. I might possibly do a different direction on the crank shaft. I may have a line on acquiring a LS7 crank for less than 1/3 the cost of a new Eagle 4" stroke crank so Im considering going the 4" stroke route if the work involved is not cost prohibitive.
Originally Posted by KCS View Post
I don't know what heads you're wanting to use, so I can't tell you what your compression will be. However, with these pistons, the 6.125" rods, and the stock 5.3L heads, like an 862 or 706 casting, you would be right around 10:1 but swapping to a 317 casting would drop it down to about 9:1. I use this online calculator to come up with compression ratios:

http://www.wallaceracing.com/cr_test2.php

IMO, the best bang for the buck rod would be the Scat I Beam. WS6Store has them for about $300 a set. They are forged 4340 steel, use 7/16" ARP bolts, and can handle a good amount of power. The pin bores are a little tight for a forced induction application, but that's an easy cheap fix for your machinist.
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Old 11-06-2017, 05:23 PM
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Originally Posted by Bobby Kelii View Post
How's it everyone, so my build might take a slightly different direction depending on the extent of the work that needs to be done, I had no intensions of changing out my stock crank for a 4" but I might be able too get a LS7 crankshaft for less than a third of what it would cost to buy a new Eagle 4" stroke crank so thats why I am now considering this option, my question is what machine work will need to be done, supposedly the front needs too be machined down which seems logical being that the LS7 is slightly longer but will I be able to stick with the wet sump or will I have to convert to dry sump. My major parts acquisition is almost complete but luckily the only parts I have for the rotating assembly is the Mahle 3.903 pistons, I haven't ordered the rods or any of the bearing because I wanted to get the block into the machine shop and have them clean it up and check for clearances then order accordingly. Thanks for the replies!
The LS7 crank is a trap for many people. It's a cheap 4" stroke crank, so many think they can just add some cheap rods and pistons and have a cheap stroker. The problem is when it comes time to balance everything. The LS7 uses lightweight titanium rods so they're balanced for a very light bobweight. In order to get the crank to balance with heavier steel rods, you may end up paying $400 or more to have heavy metal added to the counterweights, thus negating the cheap initial cost of the crank.
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Old 11-06-2017, 05:34 PM
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Originally Posted by KCS View Post
The LS7 crank is a trap for many people. It's a cheap 4" stroke crank, so many think they can just add some cheap rods and pistons and have a cheap stroker. The problem is when it comes time to balance everything. The LS7 uses lightweight titanium rods so they're balanced for a very light bobweight. In order to get the crank to balance with heavier steel rods, you may end up paying $400 or more to have heavy metal added to the counterweights, thus negating the cheap initial cost of the crank.
Thanks for the reply KCS, that is and interesting point balancing might turn out too be the prohibitive cost factor along with the other mods required too complete the install since its not a simple take out put in swap. I'm still considering a 4'' stroke but if I do it will be with the Eagle engine specific 4" stroke crankshaft. Many thanks
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