I have a resleaved block 84 1/2 bore with forged rods and pistons stroked with an ls crank in a B16. Piston 3,4 was cracked at 7-8 o'clock and 2-3 o'clock on the dome of the piston. Piston 1,2 has the line for the crack but it hasn't been broken off yet. I am running a turbo setup with a T3. I don't think boost had anything to do with this though you can rock the piston (3-4) back and forth with too much play and (1-2) you can rock but not as much I was thinking may be the skirt of piston 2,3 may be bent in or broken to cause it to rock or the bore is just to big.
I have no detenation marks on anything. Please help has anyone seen anything like this? No I have not taken out the bottom yet Until I talk to the shop I got the bottomend from.

[img]B16 bottomend 001[/img]





[Modified by StageIIIhb98, 4:18 PM 1/1/2003]

 

This is a picture of StageIIIhb98's pistons

http://www.we-todd-did-racing.com/we...MxeTU0MQ%3D%3D

 

Sounds to me that you have to big a bore or the pistons are smaller than they were supposed to be, which I've seen happen before.

 

I was thinking the same thing but I don't remember the pistons moveing like that when I first got the block now I am wondering if after a while will it start to do that with an over bor or the piston skert being bent or something.

 

the problem is this:
the weight of that 84.5mm piston with the shitty r/r from a 89mm stroke in a b16a block, and its on boost ... suprised it didn;t come out the side of the block.

greg

 

These pistons were run too lean and got too hot. They began rocking because they are colapsing and now have too much clearance. I also see what looks to be a slightly blown head gasket between 3 and 4.
Who built the block, what brand of pistons are they AND who did the compression holes on top of the pistons? Very unusual for most imports. This does not look like a street motor to me. Only cure now is rebore and new pistons.

 

Hard to tell from this picture but looks like end gap too tight caused by a lean cond maybe or excess fuel not burning completely and working its way under the ring land and then igniting.Slight pinging could do this too even if you don't hear it ,it doesn't take much.


[Modified by tk, 11:36 AM 1/2/2003]

 

I did have a problem on pressure getting into the coolent so I figured it was the head gasket or the head so that is why I was going to replace the head and headgasket. That is when I seen the pistons I never ran It lean also I kept the egt at about 1200 I never tried to push the car hard untill the dyno. I was trying to fix the headgasket first. And I told the shop I went through I needed a setup for daily useage but good enough to run a high 12 without too much trouble.

Just to know why would you consider this setup crap I am not on the defense I need to know so I can make my argument to them.

 

He isn't calling the setup crap, just the rod ratio.


[Modified by GreenR, 12:08 PM 1/2/2003]

 

I never said anything about a crap set-up. I actually like it. Compression holes on top of the pistons is something I have wanted to play with for a long time. You usually only see it on all out race motors as it seals the cylinder so strong that will wear out cylinders quicker.
That's not the problem. Something is wrong with the tuning. The heat generated by a blown head gasket will not hurt your pistons. Only lean conditions will hurt the pistons. You need to rebuild (pistons, rings and bore only) BUT you need to find out what is failing in your tune-up to cause this or will happen again.

 

Hey I have a Q. at worst case if they do not want to take this block back and fix it with only 900 miles on the motor can I just get a new set of pistons and hon the walls and install new pistons and just call it a day I am just so damn tired of all this

 

The company has decided it had nothing to do with detenation the releif cuts made the area of the pistons weak. He said because 1,2 has the cracks in it but not broken off yet if I was running lean then I should have blown a hole in the piston or through the sleave before something like that and still have the piston ring still in place.

 

Untrue

 

you need to deal with someone else. imho the setup is "interesting" to say the least. and yes it was also tuned very "interestingly"

 

my guess it that you are reving your motor too HIGH. your rod ratio could be too high for the high revs. since you have strong rods and sleeved block the only thing the engine put the stress on is the pictons. did you downshift when you were going like 100 in to 2nd? is your block sleeved? what are you reving to? the LS crank was made to rec at 7k, since you went with custom rods and all you reved your motor too high for what the crank was made to handle. this is y LS/VTEC and B20/VETC dont last as long because people rev them high because their power is @ 8500 rpm but their crank was never desiged to do that. you should of went with a gsr crank. it makes good tourque and revs high