Offset grinding crankshaft questions...
Thread Starter
Teching In
Joined: Mar 2002
Posts: 39
Likes: 0
From: Minneapolis
Offset grinding crankshaft questions... I'm having a new engine built using a LS6 short block(got at great price). A friend suggested I should have the offset grind the crankshaft which could increase the stroke from 3.62 to maybe 3.75. By doing so, I imagine that I would need longer or shorter connecting rods? Would I also need new pistons? 
I appreciate everyone's advice.
I appreciate everyone's advice.
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
Posts: 4,983
Likes: 13
From: Texas
Originally Posted by DRM C5
I'm having a new engine built using a LS6 short block(got at great price). A friend suggested I should have the offset grind the crankshaft which could increase the stroke from 3.62 to maybe 3.75. By doing so, I imagine that I would need longer or shorter connecting rods? Would I also need new pistons?
I appreciate everyone's advice.
I appreciate everyone's advice.
Also check with Valvegod@aol.com he had one 3.778 stroke billet crank lying around, new never used for like $1000. One of the cranks that GM used to mess around with 360ci stuff.
10 Second Club
Joined: Jun 2002
Posts: 1,884
Likes: 4
From: H-town
i got my stock crank off set ground locally to a 2.00" rod journal and 3.71 stroke for $150. the guy that did it said that it was the exact same process then a SBC crank which he has done plenty of. now he charges $200. the pistons will have to be custom but with my motor, i can just use a 350 SBC piston for a 6.0" rod. it ended up beeing the same compression height of 1.26" but i got a custom set anyways since i was going to spray it. if you got money, then just buy a stroker crank from eagle. in my case, i dont really like spending money in my car so i always find a cheap way out to go faster 
.
in the end, i ended up getting 380 cubes out of a 6.0L block for cheap. you also have to add the fact that with a smaller rod journal diamater, you lose rotating mass from the crank, bearings, and rods. and since the bearings have less surface area on them, you will have less friction then a standard 2.10 rod journal bearing. this all adds to that little bit more HP you can get out of it.
.in the end, i ended up getting 380 cubes out of a 6.0L block for cheap. you also have to add the fact that with a smaller rod journal diamater, you lose rotating mass from the crank, bearings, and rods. and since the bearings have less surface area on them, you will have less friction then a standard 2.10 rod journal bearing. this all adds to that little bit more HP you can get out of it.
Last edited by taqwache; Aug 3, 2004 at 10:53 PM.
TECH Enthusiast
Joined: Feb 2004
Posts: 743
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From: Foley, Alabama-southern Alabama
If you cut the rod journals down .100 you can only gain .050 in stroke,if you take off .100 from the side closest to mains you only move the center of the rod journal over ..050. .050 gain is it! 
On a 4 inch bore you"ll gain about 5.0 cu in.
On a 4 inch bore you"ll gain about 5.0 cu in. 
FormerVendor
Joined: Nov 2001
Posts: 3,065
Likes: 6
From: Houston, Tx.
Originally Posted by FASTONE
If you cut the rod journals down .100 you can only gain .050 in stroke,if you take off .100 from the side closest to mains you only move the center of the rod journal over ..050. .050 gain is it! On a 4 inch bore you"ll gain about 5.0 cu in.
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