vt2vx

We are finding cars using excessive amounts of oil in low K or in your case mile cars. that it is due to one or more of the bores being out of round, even new blocks turn up as replacements and are also out of round.

Since we get them from the same place you do, are you also finding this in a lot of motors ?? Of course it is all hush hush over here, dealer doing the most to cover it up with whatever. if you use most of your oil between changes they may open the motor and look.

GeorgeC

Excessive oil consumption does seem to be an issue over here, but this is the first I've heard of out of round bores... I think most of the problems have been related to the piston ring design, hence the redesign on the newest year models...

LS1derfull

VT2VX, i really doubt bore out of round is the core of problem.This would also show excess blow by, lack of power, unusual bore and ring wear. I have heard of none of these problems showing up.
Oil consumption is mostly if not completely related to large air delivery to pcv ports. This appears to be from hi vacuum pcv flow rates and improper valve cover baffling(oil separation from vapors) How do i know this, because changes made to correct this system have made dramatic improvements in oil consumption in lots of cases.

vt2vx

Thanks haven't heard of it strange... I'm aware of the poor PVC system. best fix for this is the Ls6 valley cover system.

I know of 6 motors with out of round bores. heard rumours of a lot more. Symtoms on these motors are high oil usage and piston slap. The motors are found to have a couple of bores out. As i said in one case the dealer ordered another new block in, measured it up, out, got another same thing. So gave up in this case and dropped in a new 2002 motor.

Since we import the motors from Gm, thought you may get the same problems showing up in bigger numbers (you have a lot more ls1s than we do). Maybe you send us the good ones <img src="gr_stretch.gif" border="0">

Thanks anyway, just wondering just how widespread this was. maybe thats it, althogh many people complain of piston slap noise and are told thats normal. of course its normal all motors do it, kidding...

LS1derfull

How out of round are we talking about? LS1 piston to bore clearance is from.0005" to.0029"
Any significant out of round would cause piston scuffing and or siezing. I believe piston slap is probably from pin placement in piston, one position makes assembly quiet other makes more power but is noisy. What are the out of round bore specs. im curious?

Trevor @ Texas Speed & Perf.

iTrader: (3)

That's definitely a new one for me. My SS has a LOT of piston slap but doesn't use any oil. On cold start-ups, it sounds exactly like I have a set of forged pistons. Like I said though, I can't get this car to use oil. <img src="gr_stretch.gif" border="0"> My '98 T/A would burn 1/4-1/3 qt. every time I went to the track.

LS1derfull

TREVOR D, all the more reason i dont think what are AUSSIE friend is talking about is the propblem. The piston pin placement in relation to center of piston can have a leverage advantage but at the cost of being noisier, the engineers know this. I think its a good trade off, there are so many kick *** design improvements in these LS1's! I dont think your average fan can appreciate everything going on with these.
Here is a list of what i think its advatages are:
1. 15 degree valve angle(STRAIGHT FROM RACE R+D)
2. Optimized plug location (BEST SO FAR,look at low timing figs. that make great power)
3. Phenolic intake(RACE TECH.)
4.Hypereutectic lite weight,positive deck, pistons
(BEST ALL AROUND COMPROMISE)
5.GM kept larger bore than most modern v-8 designs
6. Excellent bore to stroke ratio(TRITON IS A FAILURE!)
7. Excellent rod to stroke ratio(RELIABLE)
8. NO expensive OHC,street motors dont utilize extra rpm potential of these cam set ups(AND THERE SURE DOWN ON LOW SPEED TORQUE!)
9. Large cam core(ALLOWS MUCH MORE RADICAL PROFILE POTENTIAL)
I could just keep going! <img src="graemlins/fluffy.gif" border="0" alt="[Fluffy]" />

Pro Stock John

iTrader: (34)

I've seen the innards of like 15-20 LS1s, some of which had seen excessive nitrous usage (HackerJoe), and all of them looked great one had some oblonged(?) wear. Could have been from spray too.

99WhiteSS

[QUOTE]...it sounds exactly like I have a set of forged pistons.[QUOTE]

What exactly do forged pistons sound like? What's different than a stock engine? Sorry for my ignorance.

LS1derfull

99WHITESS, forged pistons(most) have more running clearance to allow for expansion which means their loose fitting cold and noisy until engine warms up.

LS1derfull

99WHITESS, forged pistons(most) have more running clearance to allow for expansion which means their loose fitting cold and noisy until engine warms up.