Forged Piston to bore clearance?
08-22-2010, 09:33 PM
#21
Your pistons will rock back and forth a little. That is how you messure for out of the hole @TDC.
This is something that should have been checked during the biuld I wish you luck man I hope it all gets worked out. I have met you, I hooked you up with the sparkplug wire. GL keep us posted.
PS you said your bore was 3.912 your getting close, if your pistons were ordered for a(stock)LS1 that is allot smaller.
This is something that should have been checked during the biuld I wish you luck man I hope it all gets worked out. I have met you, I hooked you up with the sparkplug wire. GL keep us posted.
PS you said your bore was 3.912 your getting close, if your pistons were ordered for a(stock)LS1 that is allot smaller.
08-22-2010, 10:28 PM
#22
Your pistons will rock back and forth a little. That is how you messure for out of the hole @TDC.
This is something that should have been checked during the biuld I wish you luck man I hope it all gets worked out. I have met you, I hooked you up with the sparkplug wire. GL keep us posted.
PS you said your bore was 3.912 your getting close, if your pistons were ordered for a(stock)LS1 that is allot smaller.
This is something that should have been checked during the biuld I wish you luck man I hope it all gets worked out. I have met you, I hooked you up with the sparkplug wire. GL keep us posted.
PS you said your bore was 3.912 your getting close, if your pistons were ordered for a(stock)LS1 that is allot smaller.
08-22-2010, 10:35 PM
#23
Car is running fine but I have not had it down the track yet so we will see. Sorry to see your problems. I hope you get taken care of. If you need me to talk to anyone in ABQ let me know.
08-23-2010, 12:46 AM
#25
Mahle pistons are a 4032 alloy so their suggested piston to wall clearances are tighter than comparable 2618 pistons. I'm sure they suggest under .004".
08-23-2010, 08:28 AM
#26
Where did you measure on the piston? You need to measure at a specific point on the piston to get the true diameter, since the side profile is more of a barrel shape rather than a straight cylinder.
Mahle pistons are a 4032 alloy so their suggested piston to wall clearances are tighter than comparable 2618 pistons. I'm sure they suggest under .004".
Mahle pistons are a 4032 alloy so their suggested piston to wall clearances are tighter than comparable 2618 pistons. I'm sure they suggest under .004".
08-23-2010, 08:44 AM
#27
Also, if it was torque plate honed, you may not see a nice round cylinder without a torque plate bolted on.
08-23-2010, 01:04 PM
#28
Talked to Mahle this morning. He says the measuring point is .400" up from the bottom of the skirt. He also says that they don't even make pistons for a 3.912" bore and that the biggest he has is for a 3.908" bore. He also said recommended Piston to wall clearance is .003". but one could get away with .005". One thing I haven't checked yet is main bearings so I am gonna do that tomorrow and make sure my problem isn't a main bearing.
08-23-2010, 01:12 PM
#29
Where did you measure on the piston? You need to measure at a specific point on the piston to get the true diameter, since the side profile is more of a barrel shape rather than a straight cylinder.
Mahle pistons are a 4032 alloy so their suggested piston to wall clearances are tighter than comparable 2618 pistons. I'm sure they suggest under .004".
Mahle pistons are a 4032 alloy so their suggested piston to wall clearances are tighter than comparable 2618 pistons. I'm sure they suggest under .004".
08-23-2010, 01:13 PM
#30
Well you just confirmed the pistons are wrong! It takes a good machine shop to really check the bottom end properly. You could inspect everything but without properly measuring and checking the crank how are you going to know if the crank is straight and the align bore is straight. There are so many things that need proper attention.
Without a DOUBT they made a huge mess out of the piston bores. Now you need custom pistons or another block. You could grab a 5.3 block and reuse your pistons and rods.
Without a DOUBT they made a huge mess out of the piston bores. Now you need custom pistons or another block. You could grab a 5.3 block and reuse your pistons and rods.
08-23-2010, 01:24 PM
#31
Well you just confirmed the pistons are wrong! It takes a good machine shop to really check the bottom end properly. You could inspect everything but without properly measuring and checking the crank how are you going to know if the crank is straight and the align bore is straight. There are so many things that need proper attention.
Without a DOUBT they made a huge mess out of the piston bores. Now you need custom pistons or another block. You could grab a 5.3 block and reuse your pistons and rods.
Without a DOUBT they made a huge mess out of the piston bores. Now you need custom pistons or another block. You could grab a 5.3 block and reuse your pistons and rods.
08-23-2010, 04:41 PM
#32
http://www.jegs.com/p/Mahle/Mahle-LS...57295/10002/-1
08-23-2010, 05:15 PM
#33
The only thing that is keeping me from confirming that my pistons are wrong is the fact that to properly measure a cylinder I need to have a torque plate on because the cylinders were torque plate honed. I'm not sure how much of a difference it will make and if it will make a .004" difference or not but yea I have a feeling the pistons are wrong.
08-23-2010, 05:50 PM
#35
They make the power pack pistons in both alloys. Most of their flat top power pack pistons now are 4032. CORRECTION......ALL of them are. I have their 2010 revised catalog in front of me. Unless you custom ordered them in 2618, they are all 4032.
FYI 4032 will mean a little less PTB clearance. IMO it is way too much but hard to tell NOW since the pistons have been run.
FYI 4032 will mean a little less PTB clearance. IMO it is way too much but hard to tell NOW since the pistons have been run.
08-24-2010, 08:59 AM
#36
Staging Lane
iTrader: (19)
Join Date: Oct 2008
Location: MI
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
They make the power pack pistons in both alloys. Most of their flat top power pack pistons now are 4032. CORRECTION......ALL of them are. I have their 2010 revised catalog in front of me. Unless you custom ordered them in 2618, they are all 4032.
FYI 4032 will mean a little less PTB clearance. IMO it is way too much but hard to tell NOW since the pistons have been run.
FYI 4032 will mean a little less PTB clearance. IMO it is way too much but hard to tell NOW since the pistons have been run.
08-24-2010, 09:14 AM
#37
Wrong. Most are 4032 but there are some even in the Power Pak Series that are 2618. Normally they are the dished pistons for boost. I guess even they know that the bigger boys are going to need all they can get.
Last edited by Beau@SDPC; 08-24-2010 at 09:20 AM.
08-24-2010, 01:01 PM
#39
Pistons do not "get shrunk". They are what they are. They can expand from cracking/breakage/warpage, but not the other way around. You would have to wear off an obscene amount of material to make them small. It could have been mixboxed and not the right size, but that is more likely than anything else. But still highly unlikely.
08-24-2010, 02:31 PM
#40
Pistons do not "get shrunk". They are what they are. They can expand from cracking/breakage/warpage, but not the other way around. You would have to wear off an obscene amount of material to make them small. It could have been mixboxed and not the right size, but that is more likely than anything else. But still highly unlikely.