View Full Version : Piston rock @ BDC in LSx OEM 6 liter iron block 4 inch strokers??


B'klyn9C1
04-28-2012, 06:38 PM
I want to build a 415 ci stroker out of a LSx 6 liter OEM iron block e.g. LQ4/9 or LY6, because the iron blocks are more plentiful, wicked cheap and are stronger than the aluminum LS blocks. But I have been told to be concerned about the piston rock at both BDC and TDC. Especially BDC because with the 4 inch stroke most pistons are pulled so far out of the cylinder sleeve with iron blocks which have a shorter sleeve than their aluminum block counterparts and also a shorter deck.

Who makes is best 4 inch crank rotating assembly combo for a LQ4/9 based stroker?? Or even the LY6 based stroker??

How much shorter are cylinder sleeves on the Gen III/IV iron blocks as compared to the LS2 or LS3/L92 blocks??

Can the "piston rock problem" be gotten rid of or avoided altogether with the right 4 inch crank rotating assembly combo??

This is for a daily driven '95 Caprice 9C1 with occasional autocrossing and road racing.

Thanx for your advice in advance!

litle88
04-28-2012, 10:44 PM
Just call a sponsor ----->
Get a combo within your budget that will meet the way your going to run it NA OR FI and they'll get you the right piston. Piston design has come along way. Just my .2

fastazzls1
04-29-2012, 01:46 AM
all lsx being aluminum or iron have the same deck height unless its a tall deck lsx from gmpp

KCS
04-29-2012, 10:58 AM
I want to build a 415 ci stroker out of a LSx 6 liter OEM iron block e.g. LQ4/9 or LY6, because the iron blocks are more plentiful, wicked cheap and are stronger than the aluminum LS blocks. But I have been told to be concerned about the piston rock at both BDC and TDC. Especially BDC because with the 4 inch stroke most pistons are pulled so far out of the cylinder sleeve with iron blocks which have a shorter sleeve than their aluminum block counterparts and also a shorter deck.

Who makes is best 4 inch crank rotating assembly combo for a LQ4/9 based stroker?? Or even the LY6 based stroker??

How much shorter are cylinder sleeves on the Gen III/IV iron blocks as compared to the LS2 or LS3/L92 blocks??

Can the "piston rock problem" be gotten rid of or avoided altogether with the right 4 inch crank rotating assembly combo??

This is for a daily driven '95 Caprice 9C1 with occasional autocrossing and road racing.

Thanx for your advice in advance!

BDC piston rock with 4" strokes are no longer a problem in even the iron LQ4/9 engines. They were nearly a decade ago, but the piston manufacturers have long since realized the solution and rectified the problem in the piston design. Now, 4.125" stroke cranks are going into the iron blocks pretty regularly, and even 4.250" strokes are going into standard deck height sleeved blocks, however these are not exactly off the shelf kits.