Go Back   LS1TECH > LS1-LS2-LS3-LS6-LS7 PERFORMANCE > Generation III Internal Engine
Sign in using an external account
Register Forgot Password?
Search

Generation III Internal Engine
1997-2006 LS1 | LS6
Sponsored by
Texas Speed & Performance

Welcome to LS1Tech.com!
Welcome to LS1Tech.com.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join LS1Tech.com today!


Reply
 
Thread Tools Search this Thread
Old 08-21-2010, 06:28 PM   #1
Launching!
1989 Chevrolet Camaro
 
89L98T56's Avatar
 
Trader Rating: 8
Join Date: May 2008
Location: Albuquerque
Posts: 260
Send a message via AIM to 89L98T56
Default Forged Piston to bore clearance?

Good day,

So my 383 LS1 was knocking pretty bad, I tried all the valvetrain parts I could think of, didn't fix the problem.

So I decided to tear it down and get to the bottom of this. The shortblock was balanced, and assembled by the machine shop. So I pulled a rod cap off, bearings looked cherry. Pulled the piston out and find this.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Is this kind of scoring normal after 5k miles???

So I started measuring things.
Pistons-3.900"
Bores-3.912"
Clearance-.012"

This is a .010" feeler gauge....
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

This is a huge clearance as I can rock the piston back and forth considerably while it is installed and torqued down.
So I would like to know what the average clearance for forged pistons to bore clearances are. These are Mahle 383 pistons.
And do you guys think the machine shop should be responsible for this? I have a 12 month warranty on the engine.

WOULD THIS CAUSE AN AUDIBLE 'KNOCKING' or 'TAPPING' NOISE???

BTW Every single piston is like this...
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
__________________
"YAHTZEE"
89' Mustang Coupe LSX/9.50@144 SOLD
91' Mustang Coupe LSX/9.20@155 SOLD
89' Camaro Hardtop LSX/11.51@123 got my Mullet back
13' NMKOTS #3
TX2K12 Street Class Winner
12' All Out Call Out Runner up


Last edited by 89L98T56; 08-21-2010 at 06:33 PM..
89L98T56 is offline   Reply With Quote
Old 08-21-2010, 07:35 PM   #2
TECH Enthusiast
Garage is empty, add now
 
nysbadmk8's Avatar
 
Trader Rating: 0
Join Date: Apr 2002
Location: Lehighton Pa
Posts: 537
Default

Looks normal for a stroker motor. Piston rock at BDC is responsible for most of the scuffing. As for piston bore to cylinder bore clearance I dont know.
__________________
01 C5 Z06 Ls2 Swapped, Tricked, Stroked, Drugged.
05 Gixxer 1k
02 Gixxer 750
nysbadmk8 is offline   Reply With Quote
Old 08-21-2010, 07:36 PM   #3
9 Second Club
Garage is empty, add now
 
Trader Rating: 0
Join Date: Aug 2008
Posts: 463
Default

what does mahle recommend?
__________________
Next project 1999 SS Camaro. Lose weight and maximize all good.
butler is offline   Reply With Quote
Old 08-21-2010, 08:04 PM   #4
On The Tree
Garage is empty, add now
 
Trader Rating: 4
Join Date: Oct 2009
Posts: 181
Default

It seems a little large especially since its an iron sleeve ally block, which has a bit more of an expansion rate than an iron block. You're also missing some of the coating, so your measurement will be big.

Piston material also plays a part in clearance, a 2618 alloy expands more than same piston of 4032.

Where on the piston did you measure?
The_Rizzle is offline   Reply With Quote
Old 08-21-2010, 08:10 PM   #5
Launching!
1989 Chevrolet Camaro
 
89L98T56's Avatar
 
Trader Rating: 8
Join Date: May 2008
Location: Albuquerque
Posts: 260
Send a message via AIM to 89L98T56
Default

Quote:
Originally Posted by butler View Post
what does mahle recommend?
I don't know, and I don't know where to find out.

Quote:
Originally Posted by The_Rizzle View Post
It seems a little large especially since its an iron sleeve ally block, which has a bit more of an expansion rate than an iron block. You're also missing some of the coating, so your measurement will be big.

Piston material also plays a part in clearance, a 2618 alloy expands more than same piston of 4032.

Where on the piston did you measure?
I measured from skirt to skirt, middle, bottom, top, and the top part of the piston. Anyone know what material Mahle uses for their pistons?
__________________
"YAHTZEE"
89' Mustang Coupe LSX/9.50@144 SOLD
91' Mustang Coupe LSX/9.20@155 SOLD
89' Camaro Hardtop LSX/11.51@123 got my Mullet back
13' NMKOTS #3
TX2K12 Street Class Winner
12' All Out Call Out Runner up

89L98T56 is offline   Reply With Quote
Old 08-21-2010, 10:02 PM   #6
11 Second Club
1995 Nissan 240SX
 
indeed's Avatar
 
Trader Rating: 4
Join Date: Apr 2010
Posts: 18
Default

Wiseco can have as little as 0.004". I would guess that Mahle would be about the same. Check your part number, its got to be a 3.908" piston.

Last edited by indeed; 08-21-2010 at 10:07 PM..
indeed is offline   Reply With Quote
Old 08-22-2010, 06:16 AM   #7
On The Tree
Garage is empty, add now
 
khaotic's Avatar
 
Trader Rating: 2
Join Date: Jul 2007
Location: Warrenton, VA.
Posts: 157
Default Clearance

Depends on the build you were doing for a N/A motor.
Street use should be .004 to .006 for a forged piston

Competition use should be .0055 to .0065 max for forged

Last edited by khaotic; 08-22-2010 at 08:19 AM..
khaotic is offline   Reply With Quote
Old 08-22-2010, 08:09 AM   #8
9 Second Club
Garage is empty, add now
 
Trader Rating: 0
Join Date: Aug 2008
Posts: 463
Default

Mahle says .0025 to .005. So you have twice that amount. Bore should be 3.905. My 383 has similar scuffing and you measure the clearance at the piston skirt.
__________________
Next project 1999 SS Camaro. Lose weight and maximize all good.
butler is offline   Reply With Quote
Old 08-22-2010, 08:10 AM   #9
Old School Heavy
1965 Buick Skylark
 
speedtigger's Avatar
 
Trader Rating: 14
Join Date: May 2010
Location: Florida
Posts: 5,549
Default

You should get your piston to wall clearance specs from the piston manufacturer. Only they know the materials and design details that determine what their products require. They can vary from design to design.

I do not know you, or your abilities, so do not take this as directed at you. But, also required is a high quality bore gauge with a very experienced operator. This way you can check the cylinder from top to bottom for roundness and bore taper. A cheap bore gauge or an inexperienced operator can both contribute to inaccurate measurement results and have you looking in the wrong direction for solutions.
__________________

65 Skylark My Build Thread - LQ9, 3.90 Gears, TH200-4Rr w/4000 ~ 2013 BMP NMCA Nationals True Street 12.00 Winner
Best on motor 11.05 @ 121.31 ~ 10.04 @ 133.35 on spray ~ 10 second pass track video
speedtigger is online now   Reply With Quote
Old 08-22-2010, 08:42 AM   #10
TECH Enthusiast
Garage is empty, add now
 
nysbadmk8's Avatar
 
Trader Rating: 0
Join Date: Apr 2002
Location: Lehighton Pa
Posts: 537
Default

Quote:
Originally Posted by speedtigger View Post
You should get your piston to wall clearance specs from the piston manufacturer. Only they know the materials and design details that determine what their products require. They can vary from design to design.

I do not know you, or your abilities, so do not take this as directed at you. But, also required is a high quality bore gauge with a very experienced operator. This way you can check the cylinder from top to bottom for roundness and bore taper. A cheap bore gauge or an inexperienced operator can both contribute to inaccurate measurement results and have you looking in the wrong direction for solutions.
Ditto.
__________________
01 C5 Z06 Ls2 Swapped, Tricked, Stroked, Drugged.
05 Gixxer 1k
02 Gixxer 750
nysbadmk8 is offline   Reply With Quote
Old 08-22-2010, 11:14 AM   #11
On The Tree
Garage is empty, add now
 
Trader Rating: 4
Join Date: Oct 2009
Posts: 181
Default

I don't know where some of you are getting your measurements from, since we don't even know the material used for the piston.

Also, what tools do you have to measure the bore?

Lastly, give the engine builder a call. He'll know what mahle wanted for clearances, and you obviously want to do something about this excessive piston rocking/slapping.
The_Rizzle is offline   Reply With Quote
Old 08-22-2010, 12:42 PM   #12
Banned
Garage is empty, add now
 
Trader Rating: 0
Join Date: Mar 2010
Posts: 337
Default

.010 is insane! Of course its going to knock like box of rocks. You should have 1/2 of that MAX!

How much you wanna bet someone thought they had it at .005, when actually they were at .010 because they doubled the measument.

That thing must knock like hell.

take the block and pistons back to the machine shop and make um check it in frt of you then school um!

Last edited by HotSilverBird; 08-22-2010 at 12:59 PM..
HotSilverBird is offline   Reply With Quote
Old 08-22-2010, 04:50 PM   #13
Launching!
1989 Chevrolet Camaro
 
89L98T56's Avatar
 
Trader Rating: 8
Join Date: May 2008
Location: Albuquerque
Posts: 260
Send a message via AIM to 89L98T56
Default

Quote:
Originally Posted by speedtigger View Post
You should get your piston to wall clearance specs from the piston manufacturer. Only they know the materials and design details that determine what their products require. They can vary from design to design.

I do not know you, or your abilities, so do not take this as directed at you. But, also required is a high quality bore gauge with a very experienced operator. This way you can check the cylinder from top to bottom for roundness and bore taper. A cheap bore gauge or an inexperienced operator can both contribute to inaccurate measurement results and have you looking in the wrong direction for solutions.
I have built a few engines, but I am not an engine builder. I used a dial indicator and micrometer. Measured in the middle of the cylinder.
I need to call Mahle on Monday and get their opinion and then call the machine shop who built this.

This sucks because I am in the military and had the shortblock built while I was overseas, when I got home I put the motor in my car and drove out to CA where I am now stationed. So I am about a 12hr drive away from the machine shop who built this engine.

Quote:
Originally Posted by HotSilverBird View Post
.010 is insane! Of course its going to knock like box of rocks. You should have 1/2 of that MAX!

How much you wanna bet someone thought they had it at .005, when actually they were at .010 because they doubled the measument.

That thing must knock like hell.

take the block and pistons back to the machine shop and make um check it in frt of you then school um!
It sounded like my valves were slamming into all my pistons but it ran fine!!! Made 420hp!
__________________
"YAHTZEE"
89' Mustang Coupe LSX/9.50@144 SOLD
91' Mustang Coupe LSX/9.20@155 SOLD
89' Camaro Hardtop LSX/11.51@123 got my Mullet back
13' NMKOTS #3
TX2K12 Street Class Winner
12' All Out Call Out Runner up


Last edited by 89L98T56; 10-01-2010 at 01:07 AM..
89L98T56 is offline   Reply With Quote
Old 08-22-2010, 05:41 PM   #14
Banned
Garage is empty, add now
 
Trader Rating: 0
Join Date: Mar 2010
Posts: 337
Default

Hell yeah it made good power cause LOOSE is FAST! It also makes for loud knocking sounds ans worn rings and oill consumption. You can't have pistons rocking constantly like that in the bores!

.010 clearance is INSANE!
HotSilverBird is offline   Reply With Quote
Old 08-22-2010, 05:48 PM   #15
Banned
Garage is empty, add now
 
Trader Rating: 0
Join Date: Mar 2010
Posts: 337
Default

This is gonna **** you off........

PISTONS: Cast Eutectic Aluminum, +'03 have coated skirts
Weight = 434 grams
Piston OD: 98.964-98.982mm / 3.8962-3.8969"
Piston to Bore Clearance(P): 0.018-0.054mm/0.0007-0.00212"
Piston to Bore Clear. (SL): 0.018-0.054mm / 0.0007-0.00212"
(Maximum)
Piston Deck Height in Operation: 0.203mm / 0.008"
(Above Deck Surface)
Top Land Thickness: 34mm / 0.177"

thats stock but still you are not even close!
HotSilverBird is offline   Reply With Quote
Old 08-22-2010, 05:54 PM   #16
Banned
Garage is empty, add now
 
Trader Rating: 0
Join Date: Mar 2010
Posts: 337
Default

Even ay at the max .005 i wouldn't be happy...why start off so loose? Loose does make more hp but it also causes a list of other troubles. At .010 the pistons are basicly rocking and floping back and forth. Did you call the builder before you tore it down?

I'll bet you at .010 you could of rocked the pistons in the bores with the heads off with your hands!. I've seen it already...on engines with 200k on um!

I know exactly what your machine shop did, they figured .005 clearance all the way around the piston! so that equals .010.

Last edited by HotSilverBird; 08-22-2010 at 05:59 PM..
HotSilverBird is offline   Reply With Quote
Old 08-22-2010, 08:20 PM   #17
Launching!
1989 Chevrolet Camaro
 
89L98T56's Avatar
 
Trader Rating: 8
Join Date: May 2008
Location: Albuquerque
Posts: 260
Send a message via AIM to 89L98T56
Default

Quote:
Originally Posted by HotSilverBird View Post
This is gonna **** you off........

PISTONS: Cast Eutectic Aluminum, +'03 have coated skirts
Piston to Bore Clearance(P): 0.0007-0.00212" (Maximum)

thats stock but still you are not even close!
Yea 7 ten thousandths for stock is tight because those pistons don't expand with heat.


Quote:
Originally Posted by HotSilverBird View Post
Even ay at the max .005 i wouldn't be happy...why start off so loose? Loose does make more hp but it also causes a list of other troubles. At .010 the pistons are basicly rocking and floping back and forth. Did you call the builder before you tore it down?

I'll bet you at .010 you could of rocked the pistons in the bores with the heads off with your hands!. I've seen it already...on engines with 200k on um!

I know exactly what your machine shop did, they figured .005 clearance all the way around the piston! so that equals .010.
It's funny you would say that......
http://www.youtube.com/watch?v=Vja9KnZmPK8

I have called them before I knew it was the pistons. I thought it was a spun bearing and asked if they would warranty it and they said if it wasn't caused by lack of oiling. So I am pretty sure they will own up to this mistake. only problem is that they are in Albuquerque NM and I am in San diego....

I'm thinking if I were to do it myself which I would rather do than to trust someone else again. It would be cheaper to buy a standard block and hone each cylinder to the pistons I already have since this rotating assembly is already balanced, and the pistons are about $750. The only problem would be the clearancing for the 4.00" stroke crank. Anyone know how hard it would be to clearance the block myself?
__________________
"YAHTZEE"
89' Mustang Coupe LSX/9.50@144 SOLD
91' Mustang Coupe LSX/9.20@155 SOLD
89' Camaro Hardtop LSX/11.51@123 got my Mullet back
13' NMKOTS #3
TX2K12 Street Class Winner
12' All Out Call Out Runner up

89L98T56 is offline   Reply With Quote
Old 08-22-2010, 08:38 PM   #18
On The Tree
Garage is empty, add now
 
Trader Rating: 9
Join Date: Jul 2010
Location: Gadsden AL
Posts: 104
Default

Im no expert(not even close) but it would seem to me that with the scuffing on the piston you have on each one, timed by 8 pistons that your rotating assembly wont be balanced anymore. BUT I could be wrong
1baaadz28 is offline   Reply With Quote
Old 08-22-2010, 08:55 PM   #19
Banned
Garage is empty, add now
 
Trader Rating: 0
Join Date: Mar 2010
Posts: 337
Default

Call um and tell them what they did! They owe you ALOt of expensive parts!
HotSilverBird is offline   Reply With Quote
Old 08-22-2010, 08:56 PM   #20
Launching!
1989 Chevrolet Camaro
 
89L98T56's Avatar
 
Trader Rating: 8
Join Date: May 2008
Location: Albuquerque
Posts: 260
Send a message via AIM to 89L98T56
Default

I'm sure its not perfect but its way closer than if I bought new pistons.
__________________
"YAHTZEE"
89' Mustang Coupe LSX/9.50@144 SOLD
91' Mustang Coupe LSX/9.20@155 SOLD
89' Camaro Hardtop LSX/11.51@123 got my Mullet back
13' NMKOTS #3
TX2K12 Street Class Winner
12' All Out Call Out Runner up

89L98T56 is offline   Reply With Quote
Old 08-22-2010, 08:56 PM
LS1Tech
Pontiac Firebird




Paid Advertisement
Reply

Tags
010, 2618, bore, cheap, check, clearance, coated, cylinder, forged, good, ls1, mahle, piston, pistons, ptw, roundness, skirt


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off



All times are GMT -5. The time now is 09:18 AM.


Powered by vBulletin® Version 3.7.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Advertising - Terms of Service - Privacy Statement - JOBS
Emails & Contact Details