4 inch crank into a ls1
 

soooo from what i have read.... i can trow a 4 inch crank in a ls1 block with out having to do any machine work? is this right or am i not reading the right stuff? i know u have to get the sleeves honed for the bigger pistons for a 383 but is there any machine work that needs to be done to an ls1 to fit a 4 inch crank? thanks!

No, just need the pieces and your block torque plate honed to 3.903", 3.905" No grinding or clearance issues at the base of the cylinders like some strokers, (that's 4.00 stroker) You will need to space your windage tray away from the crank by the thickness of a common 8mm washer though.

ok so if i just want to throw a 4inch in there i could do it no problem? im not trying to make a 383 because i just put new heads on and then thought of this so im trying to stay away from tearing everything apart haha

Just get the entire kit from Tsp or similar. You will need more than just the crank.

"swapping" a 4-in crank in an LS1 will result in a 383. you will also need new rods, pistons, rings, bearings, etc... its basically a full rebuild with new parts.

Does this apply to the 6.0 iron blocks as well??? Don't mean to thread jack, jus curious...

yes. at a minimum the pistons need to be changed to accommodate the longer stroke. most cases the rods as well. this applies to any engine.

You may have to do some clearance grinding on the iron block.

I made a quick image to illustrate. If you increase the stroke, the height of the pistons must decrease to compensate. that is why you need new pistons. New rods are also typically required as the factory rods will clash with the filleted radius on aftermarket stroker crankshafts.

https://ls1tech.com/forums/attachmen...ine=1357255482

so all of this can be done with out tearing the block completely down? really trying to stay away from redoing everything that i just did. thanks guys

See above.

No way. Remove engine, disassemble, reassemble with stroker kit, install your new 383.

op that is a nice visual picture of the piston rod clearance. Thats why I love this site I have learned so much and continue to learn. The next thing I want to do is take some classes and learn how to take apart and rebuild engines. for me visualizing I can only learn so much. I have thought about doing a 383 stroker someday seems you gain a shit load of torque

Piston question
 

Bring back a tread that hopefully you guys can help me with. I don’t want too change my crank but I do want too change my pistons on my 03 LM7 5.3 engine build. My question, when I take the bottom too the machine shop, the crank will remain stock with the 3.622 stroke but I wanted too bore for bigger pistons, I can get a new set of 3.903 forged plugs for a good price but I noticed on the websites description on the pistons that the stroke was good but the rode length was 6.125, but I’m not buying the rods from them so why does it say that? I was planning on buying forged rods that are the same length, 6.098, is that a mistake? Is the rod length of 6.125 that the website say already factor in the pistons size and adjust the length accordingly to make it stock? Any help on this would be greatly appreciated 🙏🏽6.125fQUOTE=RezinTexas;17027715]I made a quick image to illustrate. If you increase the stroke, the height of the pistons must decrease to compensate. that is why you need new pistons. New rods are also typically required as the factory rods will clash with the filleted radius on aftermarket strokerhttps://ls1tech.com/forums/attachmen...ine=1357255482[/QUOTE]

This was the information on the pistons

Yes, the compression height is adjusted to use the 6.125" rod length. Pistons for stock length rods are usually about 1.340"ish. As you can see, the ones you listed have a thinner compression height for the longer rods, which will keep the piston from protruding too far above the deck. Going to a 6.125" rod length will give you more options to choose from, as 6.098/6.100" rod choices are limited.

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.

LS Block Rod Bolt Grind
 

Hi Bobby, I have only assembled the AL LS-1 GEN III (Late) a few times with a 4.00" Crankshaft AND ALWAYS had to "grind" the bores for Rod Bolt clearance.

I will NOT use the "early" GEN-III AL Block due to the block breathing hole between the Main Journal/Camshaft.

I can supply the Forged Rods/Pistons (offset pin).

Lance

Hi Lance, I’m not doing the 4” crank swap I was just inquiring about using 3.903 pistons with.927 wrist, ( I have a LM7 5.3 truck motor that I will be boring out) I wanted too know what length con rods too look for, the Mahle discription of the piston list 6.125” but my stock ones are 6.098 so I was asking if these longer rods would raise the compression which I did NOT want, I want too have a stock compression of 9.5’ish for future forced induction QUOTE=Pantera EFI;19753025]Hi Bobby, I have only assembled the AL LS-1 GEN III (Late) a few times with a 4.00" Crankshaft AND ALWAYS had to "grind" the bores for Rod Bolt clearance.

I will NOT use the "early" GEN-III AL Block due to the block breathing hole between the Main Journal/Camshaft.

I can supply the Forged Rods/Pistons (offset pin).

Lance[/QUOTE]

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 tech@ws6store will chime in hear with a recomendation...