Notices
Generation III Internal Engine 1997-2006 LS1 | LS6
Sponsored by:
Sponsored by:

4 inch crank into a ls1

 
Old 01-01-2013, 10:22 PM
  #1  
SCAMMER ALERT!!!!
Thread Starter
 
Join Date: Oct 2011
Posts: 14
Likes: 0
Received 0 Likes on 0 Posts
Default 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!
Maroboy_Jimmie is offline  
Old 01-01-2013, 10:44 PM
  #2  
TECH Fanatic
iTrader: (4)
 
64post's Avatar
 
Join Date: Nov 2011
Location: Sonoma Co. Ca.
Posts: 1,033
Received 0 Likes on 0 Posts
Default

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.
64post is online now  
Old 01-01-2013, 10:50 PM
  #3  
SCAMMER ALERT!!!!
Thread Starter
 
Join Date: Oct 2011
Posts: 14
Likes: 0
Received 0 Likes on 0 Posts
Default

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
Maroboy_Jimmie is offline  
Old 01-02-2013, 04:04 AM
  #4  
12 Second Club
iTrader: (49)
 
bww3588's Avatar
 
Join Date: Sep 2005
Location: Chillicothe/Lima, Ohio
Posts: 8,134
Likes: 0
Received 0 Likes on 0 Posts
Default

Just get the entire kit from Tsp or similar. You will need more than just the crank.
bww3588 is offline  
Old 01-02-2013, 05:28 PM
  #5  
TECH Fanatic
 
RezinTexas's Avatar
 
Join Date: Jun 2011
Location: Katy, TX
Posts: 1,330
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Maroboy_Jimmie View Post
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
"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.
RezinTexas is offline  
Old 01-03-2013, 03:40 AM
  #6  
Teching In
 
Join Date: Aug 2009
Location: Philadelphia
Posts: 16
Likes: 0
Received 0 Likes on 0 Posts
Default

Does this apply to the 6.0 iron blocks as well??? Don't mean to thread jack, jus curious...
palaSS is offline  
Old 01-03-2013, 05:15 AM
  #7  
TECH Fanatic
 
RezinTexas's Avatar
 
Join Date: Jun 2011
Location: Katy, TX
Posts: 1,330
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by palaSS View Post
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.
RezinTexas is offline  
Old 01-03-2013, 06:51 AM
  #8  
TECH Junkie
iTrader: (18)
 
LS1MCSS's Avatar
 
Join Date: Jan 2006
Location: Dover, Arkansas
Posts: 3,830
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by palaSS View Post
Does this apply to the 6.0 iron blocks as well??? Don't mean to thread jack, jus curious...
You may have to do some clearance grinding on the iron block.
LS1MCSS is offline  
Old 01-03-2013, 05:24 PM
  #9  
TECH Fanatic
 
RezinTexas's Avatar
 
Join Date: Jun 2011
Location: Katy, TX
Posts: 1,330
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Maroboy_Jimmie View Post
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
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.

Attached Thumbnails 4 inch crank into a ls1-pistoncompressionheight_zpsc8eb7d7c.jpg  
RezinTexas is offline  
Old 01-06-2013, 01:00 AM
  #10  
SCAMMER ALERT!!!!
Thread Starter
 
Join Date: Oct 2011
Posts: 14
Likes: 0
Received 0 Likes on 0 Posts
Default

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
Maroboy_Jimmie is offline  
Old 01-06-2013, 01:13 AM
  #11  
12 Second Club
iTrader: (49)
 
bww3588's Avatar
 
Join Date: Sep 2005
Location: Chillicothe/Lima, Ohio
Posts: 8,134
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by RezinTexas View Post
"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.
See above.
bww3588 is offline  
Old 01-06-2013, 05:11 AM
  #12  
Launching!
iTrader: (4)
 
Join Date: Feb 2006
Posts: 272
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Maroboy_Jimmie View Post
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
No way. Remove engine, disassemble, reassemble with stroker kit, install your new 383.
mypoorLS1 is offline  
Old 01-06-2013, 06:38 AM
  #13  
Launching!
iTrader: (3)
 
Join Date: Nov 2012
Posts: 298
Likes: 0
Received 0 Likes on 0 Posts
Default

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 **** load of torque
dhctss is offline  
Old 10-22-2017, 11:59 PM
  #14  
Teching In
 
Join Date: Oct 2017
Posts: 15
Likes: 0
Received 0 Likes on 0 Posts
Default Piston question

Bring back a tread that hopefully you guys can help me with. I donít 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 Iím 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 stroker[/QUOTE]
Bobby Kelii is offline  
Old 10-23-2017, 01:14 AM
  #15  
Teching In
 
Join Date: Oct 2017
Posts: 15
Likes: 0
Received 0 Likes on 0 Posts
Default

This was the information on the pistons
Attached Thumbnails 4 inch crank into a ls1-d36ff2f9-13fb-4729-9229-0b1973da13f2.jpeg  
Bobby Kelii is offline  
Old 10-23-2017, 08:43 AM
  #16  
KCS
Moderator
iTrader: (19)
 
KCS's Avatar
 
Join Date: Mar 2005
Location: Conroe, TX
Posts: 8,484
Received 8 Likes on 8 Posts
Default

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.
KCS is offline  
Old 10-23-2017, 04:09 PM
  #17  
Teching In
 
Join Date: Oct 2017
Posts: 15
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by KCS View Post
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.
Bobby Kelii is offline  
Old 10-23-2017, 05:55 PM
  #18  
FormerVendor
iTrader: (1)
 
Join Date: Nov 2008
Location: Santa Ana, CA. USA
Posts: 2,166
Likes: 0
Received 1 Like on 1 Post
Default 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
pantera_efi is offline  
Old 10-23-2017, 07:44 PM
  #19  
Teching In
 
Join Date: Oct 2017
Posts: 15
Likes: 0
Received 0 Likes on 0 Posts
Default

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]
Bobby Kelii is offline  
Old 10-23-2017, 10:46 PM
  #20  
TECH Resident
iTrader: (7)
 
CattleAc's Avatar
 
Join Date: Dec 2007
Location: Dakota Territory
Posts: 885
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by KCS View Post
Yes, the compression height is adjusted to use the 6.125" rod length. Going to a 6.125" rod length will give you more options to choose from, as 6.098/6.100" rod choices are limited.

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...
CattleAc is offline  

Thread Tools
Search this Thread

About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: