I know the iron 6.0 block has a shorter length then the LS2 block, Im wondering if the cylinder wall is longer on the LSX block then the 6.0 or the LS2 block, Im trying to fight bad piston rock at BDC with my 4.1" crank. I have gotten mixed reports on cylinder wall length on the LSx block. I hope one of my sources are wrong the LSX is longer then the iron 6.0 block.

 

I've read about this and have questions , too . Something about the standard deck LSX not allowing 3 rings after a certain stroke , due to piston pin height . Does this mean my 511 will never happen ?

 

It is the same as a stock block

Robin

 

Robin, Are you experiencing any piston/ring related problems with the 454 LSX that you built? As I recall you used a 4.125" stroke crank.

D.J.

 

So how are the motors with 4.1 and 4.125 stroke cranks lasting and not burning oil? I have had two different sets of pistons in my iron 6.0L block with my 4.1 stroke crank and both burn oil. The first motor burnt oil to the tune of 1 quart every 80 miles, the second motor burns a quart every 200ish miles. First set was JE's second set are wiseco's. Im running a 6.125 rod, is there something Im missing here?

 

Robin,

Which stock block? LS2? LS7? LQ9?

Do you have an exact length?

I thought I've read they're about 5.6" long?

 

I think he means the same as the iron blocks because I have heard the LSX and the 6.0 iron block have the same length cylinders. The LS2 block has a .2" longer sleeve.

 

the LSX line will be ble to go to 511ci but thats the tall deck version, which i think is due out sometime early nex year. at least i think so anyways

 

The LSX and the LS2 are both about 5.6, the LS7 is around 5.9 top to bttom on the thrust wall.


Kurt

 

So what kind of stroke can go into the LS7 ? What about C5R ?

 

The LS7 should have no problem with a 4.125 stroke. We have built one 4.25 stroke LS7, but the piston noise is pretty high.

Kurt

 

Does piston noise equal " boom " ?

 

Not boom, but shorter life for sure. It will be harder to keep a ring seal.
If you can keep the piston supported at the bottom of stroke when it makes its direction change, the whole engine will be happy!!


Kurt

 

What is the length on the darton dry sleeves???

 

They come in different lengths. They have them listed on their website.

 

All the stock OEM cylinders on LS1 type engines (including iron 6.0 and LS1, LS2, L92 etc.) are only 5.500-ish besides the LS7 which is much longer at 5.900-ish.

Most people aren't measuring the cylinders correctly and the LS2 has aluminum casting that goes further down but the cylinders are still as short as an iron block.

The LSX bowtie block is also only 5.500 so far on all the ones we have worked on. It is undercut at the bottoms of the cylinders for honing overtravel and core shift.

Again if you stuck a tape measure down any you will get an incorrect measurement as you aren't measuring the cylinder but rather the casting only.

The older original Darton MIDs are 5.625 long but the newer ones are 5.800 including the dry sleeves.

 

Something else is wrong or whoever is doing this isn't as competent as you think. I have not had these problems and we have done tons of engines over the last 5 years with that crank? The pistons are probably wrong for the bore or even more is wrong. Also remember it could be using that much oil for other reasons that have absolutely nothing to do with your stroke etc.

 

We installed Weisco pistons that had a ring package that allowed a sliver of the pin bore to protrude past the upper oil scraper. I was told by Weisco that there would be no problem running these. We prepped the cylinder bores very carefully making making oil consumption a high priority. The engine burned a quart every 200 miles. It also filled the catch can. We'll have the engine back this week and take a closer look at it.
Below is a pic of the relationship between the oil ring land and the pin bore. We used a napier second ring in this ring package.
I'd appreciate any comments about this.




Richard

 

hmm.. seems more like a basic flaw in the piston design. id be willing to bet the oil is getting in behind the oil rings at the pin. if the pin was just a little lower there probably wouldnt be a problem.

 

Richard,

Whats the cylinder bore length and the ring stack and the CH? Thats a huge top land? I've done hundreds of engines with absolutely no problems but I don't have any pistons that look like that although I use Wiseco and Diamonds all the time. Your break point might be outside the bore at the bottom allowing the piston to suck oil past the rings on the intake stroke at BDC when the cylinder pressure is low and the crankcase pressure is higher which it always is on a normal engine. If the pistons are excessively rocking down there the rings may not stay sealed.