Sonic testing for wall thickness - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• Sonic testing for wall thickness by subsonic on 26 Feb, 2007 22:24
• I've heard of this, but have never seen it done.  Anyone offer a brief bit of information on how it works? Can this tell you how much you can bore out the cylinders before you get to thin? How accurate is it?  Do you do it before you start the bore job, or when you are getting close?
  
  Thanks jim
• #1 by BruceM31 on 27 Feb, 2007 17:18
• It works by sending a sonic signal through the material being tested.  It is accurate to the thousand.  I would test it before you begin boring this way you know how much to remove for your max.  a good rule of thumb is to have a min. of .100 cylinder wall clearance.  if you need more info let me know,  I work at a carquest with a large machine shop and they do this quite often.
• #2 by subsonic on 28 Feb, 2007 01:11
• Cool.  The only info I've found on the net had to do with big blocks and such.  I am interested in this as I am planning to bore out a 1.6TD to take 1.7 pistons. It will be a bit over the 3rd overbore limits.  OK, perhaps more than just a bit over.  79.5 I think.  I would be interested in talking to you more about this.  Presently it is 0115 local time.  I am getting up in two hours to drive my ass off up to Canada to pick up 2 1.6TD's and a 1.9 head.  Filling up every thermos I have and hitting the highway.  Night night.
• #3 by malone on 28 Feb, 2007 09:41
• It would be great if you can share your findings here. I've been thinking of larger pistons in a 1.6 block too.
• #4 by BruceM31 on 28 Feb, 2007 10:30
• You can actually measure more than just cast iron.  from glass to plexiglass, tin brass aluminum pretty much everything you just have to calibrate the tool for what you want to test.  I'll take the tool home probably on thursday. i have a couple 1.6na blocks with the heads off i can test them out and see just how much meat there is.
• #5 by subsonic on 28 Feb, 2007 23:52
• GOT THEM!  OMG!!! 20 freaking hours.  Truck didnt start so I took the Golf.  Yes, VW now has a 12 cylnder rear engine sports coupe.  Set up for high speed with a specially designed low riding rear end.  Will post a pic when I figure out how to do it.  
  Customs was a nightmare.  I spent about 4 hours there going back and forth with inspectors.
  "These engines don't say the conform with epa standards"
  "OK, Where would I find that information?"
  "It's in the engine compartment"
  "UHHHHHH....there is no engine compartment.  There sitting in my trunk, in pieces."
  "I need that info, and the vin, and the registration from the vehicle they came out of."
  "WHAT! Man, those vehicles are in little pieces somewhere in a smelting pot, probably in Tiawan!  These things are like 15 years old!  Let me pull the numbers off the blocks."
  "Sorry, you need to return them to Canada."
  "WHAT!!!!! :evil:  :shock: Thats crazy! I'll tell you what the emissions equipment is!  Air cleaner to exhaust pipe to muffler!  Thats it!"
  "So sorry, next"
  "AAAARRRGGGGGGGGG!!!!!!!!!!"
  It was like the beginning of the Brokevw.com clip.
  
  Time for a nap and a tranquilizer :roll:
  Jim
• #6 by burn_your_money on 01 Mar, 2007 07:35
• How did you manage to get through? That sounds like a horrible experience
• #7 by subsonic on 01 Mar, 2007 08:30
• I sat around looking miserable enough for an extended period of time, the shift change happened, and an older more experienced inspector came on shift who took pity on me and dug through the regulations until he found an exception buried deep in the regulations. Thank god
• #8 by BruceM31 on 01 Mar, 2007 10:08
• Sounds like quite the adventure!!!
• #9 by BruceM31 on 01 Mar, 2007 13:05
• Well the good news is i'm going to test the wall thickness, but the bad news is the ultrasonic grease couplant that i have to use is empty.  We ordered more today, so i won't see them until next week..............
• #10 by subsonic on 01 Mar, 2007 19:25
• I would be very interested in the repeatability of the numbers you get.  Meaning, if you measure three blocks, will thin and thick spots generaly be close in number for the same locations.  I know there can be a bit of difference in castings.  How many locations do you need to check per cyl. to get a accurate "map".  What do people here consider for thickness guidlines?  What is way to thin, what is marginal, standard etc.. for running more power than stock. Because after all, is'nt that what this is all about
  Jim
• #11 by BruceM31 on 02 Mar, 2007 10:00
• i have 2 blocks i can measure without ripping everything apart.  As soon as i get more of the grease i'll will measure.  Normally to get a good map you measure 4 sides of the wall and about an inch down for every location you test.  This gives you a good reading for the total bore for how much metal there is.  My foreman in the machine shop says .100 thousands is as thin as you want to go, and they build alot of racing chevy 350 motors that are pushing WAAAAAY more power than we could ever dream about.
• #12 by SMOKEYDUB on 02 Mar, 2007 20:44
• well you have to remmeber that we are pushing 23:1 compression ration without boost. If you were to go wild boost then you would have majour flexing in the cylinder walls and probably just blow the boost/compression past the rings. A diesel engine is alot different then a 350.
• #13 by BruceM31 on 05 Mar, 2007 19:27
• i measured 2 1.6na blocks and got pretty much the same results.  The top of the bore is quite thick over .300  all around and between cylinders is about .440   But where the BIG problem is further down between the cylinders.  There the most i saw was .160  Every where else is down the bore is a little over .200 on all sides.  Now to answer the question of this post can you fit the 1.7 pistons in this block?  Personally i would not because stock bore is 76.5mm  1.7 is 79.5mm.  That in terms of thousands is .120, or .060 each side that would need to be removed.  It wouldn't leave enough meat between cylinders in my opinion.  You could do it but your wall would be pretty damn thin.  Now in my research i found that the 3/4 of and inch down and up is the thickest part. This is where i got readings of .300.  The casting is slightly thinner futher down after the 1st 3/4 of an inch.  After studying my readings i have come to the conclusion that the casting is slightly egg shapped so that coolant can pass/circulate between cylinders.  
  
  I would bore to fit 1.7 pistons at your own risk!
• #14 by burn_your_money on 06 Mar, 2007 05:36
• Is it accurate to say that the upper parts of the cylinders are the areas that need to be meatier because that is where most of the compression and action is?