Piston slap issue? (gen3 LS 5.3 SBC) - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 06-30-2013, 09:53 AM
Registered User
 
Last photo:
Join Date: May 2009
Location: Wichita KS
Posts: 261
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
Piston slap issue? (gen3 LS 5.3 SBC)

Working with a gen 3 SBC 5.3. 8.6:1 CR on E85. Basically stock with the ring gaps opened up to .028 and .030. OEM bore/stroke etc... OEM LS9 cam. (nothing radical).

So leaning over the engine bay blipping the throttle lightly in neutral from idle to say 1800rpm or so. I'm getting a audible piston slap sound. Sounds just like forged piston slap briefly, then disappears at higher revs. (engine is up to temp)

I'm running a standalone engine management computer so I can alter timing/AFR etc. Currently timing in that range is around 30* AFR's are around 13:1.

The bore was in great shape and well within specs. Oem pistons and rods went right back in their mated holes on reassembly. Even used the same bearings as they all looked great. Oil pressure is nice and high. around 40psi warm.

Any suggestions? Think raising or lowering the timing would have any effect? I'm assuming it's not knock of any sort because of the E85 and low compression.

Thanks!

Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-30-2013, 12:48 PM
ProStreetRob's Avatar
Blown 502
 
Last photo:
Join Date: May 2011
Location: Selden NY
Age: 53
Posts: 168
Wiki Edits: 0

Thanks: 0
Thanked 28 Times in 24 Posts
I had something similar happen to me on a Gen 2 Ford 5.4L Supercharged Lightning Motor. The Builder knew I was going to be spraying it so he built it a little loose and I had piston slap from that point on. As you say you would only hear it on idle and low RPM and not hear it under load and in the upper RPM range. I know many other 5.4L owners that had the same piston slap and many even had it on a bone stock 5.4L motor. If it's just that (piston slap) then it'll be fine and there really isn't much you can do.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-30-2013, 03:36 PM
Registered User
 
Last photo:
Join Date: May 2009
Location: Wichita KS
Posts: 261
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
Thanks for the input! Dont' those 5.4's come with forged pistons from the factory thou?

I took the car out out and beat on it pretty good. Cranked it up to 12 lbs, it's a beast in this tiny car! After I got it home I popped the hood and tried to replicate the same slap noise and it was gone. Pulled all the plugs again and it all looks great.

I'll test it again when it's cold next time I play with it. Hope this $220 JY dog short block stays together!

Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-30-2013, 04:01 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 7,954
Wiki Edits: 0

Thanks: 13
Thanked 218 Times in 207 Posts
GM had a bunch of warranty problems with the cold knock of the new style short skirt Hyper style pistons. Cure was a tighter piston to wall dimension. You will see a lot of .0005" clearances.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-30-2013, 05:03 PM
Slammedsi's Avatar
Registered User
 
Last photo:
Join Date: Feb 2013
Location: Vernon, TX
Posts: 248
Wiki Edits: 0

Thanks: 117
Thanked 3 Times in 3 Posts
Quote:
Originally Posted by BOBCRMAN@aol.com View Post
GM had a bunch of warranty problems with the cold knock of the new style short skirt Hyper style pistons. Cure was a tighter piston to wall dimension. You will see a lot of .0005" clearances.
Agreed, I had a 5.3 silverado at one point. Thing always had piston slap on cold starts.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-30-2013, 06:43 PM
ProStreetRob's Avatar
Blown 502
 
Last photo:
Join Date: May 2011
Location: Selden NY
Age: 53
Posts: 168
Wiki Edits: 0

Thanks: 0
Thanked 28 Times in 24 Posts
Kick *** Car Bro
Ya the 5.4's come with decent Pistons & Crank but unfortunately really ******* cast rods. If you want to pump them up to 6, 7, or 800 RWHP you need to redo everything in there.

PS
You may be able to soften the noise with a oil thats thicker when cold, what oil are you running now ?

Last edited by 68NovaSS; 06-30-2013 at 07:29 PM. Reason: Bypassing the profanity filter
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-30-2013, 06:56 PM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 56
Posts: 6,745
Wiki Edits: 0

Thanks: 236
Thanked 619 Times in 602 Posts
was the mazda 20-B too expensive? just wondering why the LS?
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 06-30-2013, 06:57 PM
KVP's Avatar
KVP KVP is offline
Registered User
 
Join Date: Jan 2012
Posts: 11
Wiki Edits: 0

Thanks: 8
Thanked 4 Times in 4 Posts
5.3 piston slap

I have a 2002 GMC Sierra with cold start piston slap. The dealership said it was a piston skirt issue. No warranty work was done as they said it wouldn't affect the life of the motor. I owned it for several years. The truck now has 130,000 miles and still runs great with very good oil pressure.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 07-01-2013, 02:05 PM
Registered User
 
Last photo:
Join Date: May 2009
Location: Wichita KS
Posts: 261
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
Went with the LS because of initial price and availability. This is my 3rd Rx-7 motor swap. Went with a Gen1 SBC the first time, and a grand national motor the second time. Nothing against rotors though. If someone wants to sponser me I'd love to build a nasty boosted 3 rotor.

Thanks all, I feel a bit better about it now. I'll just run it till she blows.

Running 10w40 weight rotella at the moment. Was thinking of switching over to the VR1 50w when I crank the boost up.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 07-01-2013, 02:49 PM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 56
Posts: 6,745
Wiki Edits: 0

Thanks: 236
Thanked 619 Times in 602 Posts
I like the wankel and the LS. I think even a partial bridge port 13-b with a turbo would be fun. I agree the LS is a good engine,I just dont see the advantage at lower power levels? either way I love those cars.Handling is very forgiving and the brakes very nice considering the year of the car
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 07-01-2013, 03:12 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,239
Wiki Edits: 0

Thanks: 12
Thanked 221 Times in 206 Posts
Quote:
Originally Posted by vinniekq2 View Post
I agree the LS is a good engine,I just dont see the advantage at lower power levels?
durability and off idle torque. Not to mention very controllable power band, about as peaky as Kansas.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 07-01-2013, 03:19 PM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 56
Posts: 6,745
Wiki Edits: 0

Thanks: 236
Thanked 619 Times in 602 Posts
the 13-b rotary is extremely smooth. The torque is lower than the LS,but so is the engine size.The third gen mazda turbo has a very flat torque curve from the factory,feels like a perky 327
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 07-01-2013, 06:37 PM
Registered User
 
Last photo:
Join Date: May 2009
Location: Wichita KS
Posts: 261
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
Comparing the Dollar per total HP/TQ output the LS has the rotary beat hands down. I'll be pushing 700hp with this setup if all goes well. I've seen over 900 at the wheels with a totally stock unopened 5.3 long block. When a rotary does that, let me know!

I paid $220 for this engine. I can go to any local junk yard and get another for about the same. No ones even heard of a rotary at the local yards here in podunk KS.

This sucker went 8.60 @ 167.9 mph. Untouched JY long block... Springs/cam/headgasket/boost.

Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 07-01-2013, 09:16 PM
Member
 
Join Date: Apr 2004
Location: Cassville,MO
Posts: 751
Wiki Edits: 0

Thanks: 15
Thanked 33 Times in 29 Posts
Quote:
Originally Posted by BOBCRMAN@aol.com View Post
GM had a bunch of warranty problems with the cold knock of the new style short skirt Hyper style pistons. Cure was a tighter piston to wall dimension. You will see a lot of .0005" clearances.
GM's first solution was to say that's normal. My truck has 245,xxx miles on it . It's only been slapping for 225,000 miles and it hasn't started burning oil yet.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 07-01-2013, 09:44 PM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 56
Posts: 6,745
Wiki Edits: 0

Thanks: 236
Thanked 619 Times in 602 Posts
rotary?

Quote:
Originally Posted by ForceFed86 View Post
Comparing the Dollar per total HP/TQ output the LS has the rotary beat hands down. I'll be pushing 700hp with this setup if all goes well. I've seen over 900 at the wheels with a totally stock unopened 5.3 long block. When a rotary does that, let me know!

I paid $220 for this engine. I can go to any local junk yard and get another for about the same. No ones even heard of a rotary at the local yards here in podunk KS.

This sucker went 8.60 @ 167.9 mph. Untouched JY long block... Springs/cam/headgasket/boost.

Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
SBC Piston Ring Issue Dougie Engine 2 04-22-2011 06:59 PM
Possible piston slap problem demitristewart Engine 11 08-01-2005 07:53 PM
Piston Slap 4onthefloor 2 Engine 7 12-08-2004 09:01 PM
PISTON SLAP in Detroit USA1 Hotrodders' Lounge 4 11-22-2004 07:10 PM
What could this knock be? Piston slap? 70bird Engine 8 09-19-2004 04:05 PM


All times are GMT -6. The time now is 02:17 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.