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Old 10-25-2012, 01:20 PM   #26
oem
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Aboothman please don't muddy up this thread.

Spackyscooby, Crystal is using 2(pi)R1 - 2(pi)R2 = circumference difference between a cylinder with a torque plate and one without it. He simplifies this equation by stating distortion difference x pi = true circumference difference. This equation would work if the cylinder did not distort and only the radius changed.

When Crystal applies this equation incorrectly he is exaggerating the effect of a torque plate. This exaggeration leads members on this site to believe they need to buy a torque plate to set their rings. Torque plates are only needed for boring and honing where exact tolerances are required. Setting ring gaps is not exact enough for the slight distortion to effect the rings.

Builders in this forum that are only setting ring gaps do not need to waste money on a torque plate.
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Old 10-25-2012, 02:01 PM   #27
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Alright, thank you.
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Old 10-25-2012, 03:03 PM   #28
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The guy who consistently attacks board members who contribute, without actually contributing any information himself, should not talk to me about "mudding" up a thread

I will help you out. The formula for the area of an ellipse = Pi*(2*Square Root((1/2 Long Axis)Sq)+((1/2 Short Axis)squared)

Lets use 3.937 as an undistorted bore size.

For the ellipse's long radii we can use 3.938 and 3.937 as the short, as the testing we are referring uses .001 as the distortion between a torque plate bore and without. I realize that this assumes the distortion is only on one axis, but this will give us an extreme. We are, after all, talking about extremes and what if situations, are we not?

But more on this in a minute.

I will spare you the math:

The ellipse circumference = 12.37001072
Circle circumference = 12.36843983

Difference between the ellipse and perfect circle bores = 0.001570895

So I just got off the phone with JE tech support. First, I asked whether they recommend using a torque plate to set ring gaps if one was used to hone. They said yes, that would be ideal. I went on to explain this math question of whether the calc for a circle is correct when a distorted bore becomes an ellipse, or oval. This is where things got interesting.

The tech said the ellipse formula is NOT applicable, as the head bolts/studs will not affect the entire cylinder directly. They actually create smaller "bumps" in the cylinder near the head bolts/studs. Think of small radii circles being introduced into the cylinder.

So a cylinder that is circular (NOT plate honed) before a torque plate is installed WILL have gaps in the ring/ cylinder contact. It then becomes a question of whether the "bumps" push into or out of the cylinder. If they push out, then end gap should not be affected much if at all. This was the opinion of JE tech.

A cylinder that has been honed WITH a torque plate should account for these "bumps" and become circular when a plate or head is installed. Therefore a plate should be used to set end gaps...otherwise the bore will distort out of round without the plate.

In either scenario, I cannot grasp why anyone would recommend against using a torque plate to set ring gaps. Whether one was used to hone or not, and I sincerely hope one was, you will be better off using one to simulate cylinder distortion with the head one. This has been discussed to death, so I will say the same thing I told a buddy recently. You can do this one of 2 ways; the right way that takes more time and is more expensive, or the half assed way that is quick and cheap.

This also brings up an interesting question regarding the Team Scream test, so I will have to ask him. I do not recall whether the test used many different bore radii, or just a few. The reason I ask is because one of these "bumps" could have given false results that would not have shown in a different orientation. It occurs to me that many radii need to be measured and charted, NOT averaged.
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Old 10-25-2012, 07:25 PM   #29
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^ very nicely laid out. I am in total agreement on the 2 ways to do something point. If someone does not want to use a plate that is fine its their time/money and maybe everything will be fine, it probably will actually especially if we are talking about a fairly low power motor. But for me and my $$ I just purchased a tq plate and will be using it while setting the ring gaps because the little extra time it takes is of no concern to me and a couple hundred dollars to buy my own since no shop I could find within a 100 mile radius of me has one is a small investment for piece of mind when talking about the thousands that go into a built motor.
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Old 10-25-2012, 07:32 PM   #30
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That is my take as well. I too live in a rural area with a limited number of machine shops that are ALWAYS busy, and the mechanics suck. So I do my own work. I also have 3 EJ engines in the build process now and others planned in the next year, so the $2k investment in mics, gauges, torque plates and other tools will be returned many fold.

But for the guy in a city with many options, who has all machining and other related work done already, who JUST needs to grind rings, and does not plan on building many engines... I would not recommend getting a torque plate. I would recommend having the rings done by the person that did the machining with a torque plate on
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Old 10-25-2012, 09:21 PM   #31
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Great thread! Subscribed for sure. Question: if one was to hone the cylinders would you really have to worry about the "distorted circle" issue? Theoretically it each cylinder shouldn't have the bumps.... right?
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Old 10-25-2012, 10:57 PM   #32
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The idea is to hone the cylinder with a torque plate, so that regardless of the type or shape of the distortion, the cylinder is honed to account for this. You want to have as close to a circular cylinder as is possible when the heads are on.

Keep in mind this was just what a JE tech told me, but it made sense, so I thought I would share it
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Old 10-25-2012, 11:00 PM   #33
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Quote:
Originally Posted by aboothman
The idea is to hone the cylinder with a torque plate, so that regardless of the type or shape of the distortion, the cylinder is honed to account for this. You want to have as close to a circular cylinder as is possible when the heads are on.

Keep in mind this was just what a JE tech told me, but it made sense, so I thought I would share it
Exactly
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Old 10-26-2012, 12:19 AM   #34
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Aboothman, thanks for agreeing with me and showing the problems with Crystal's torque plate assumptions.

Now I will explain why torque plates are not needed for gaping the rings.

aboothman calculated .0015" as the max circumfrence difference so I will use that number.

Ring gaps are measured with a feeler gauge (thickness gauge), which is a go/no go gauge. Feeler gauges come in .001" increments and do not measure the gap. The user can only tell if the gauge fits or does not fit. i.e. a .015" gauge fits too loose, a .016" gauge fits ok, and a .017" gauge does not fit. For this example, that means the gap is greater then .015" and less then .017". Only by feel can one determine how close the gap is to .016". So with practice one can get closer to feeling what he believes is .016" but it is not exact.

So now when a max circumference difference of .0015" is used the most the ring gap will be off is one feeler gauge. If it is not the max the difference will be between a tight .016" and a loose .016". If we were building F1 engines, this would matter. But for 99% of the Subaru engines built here by members, the difference will not matter.

Just because a process is more complicated does not make it right.
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Old 10-26-2012, 09:28 PM   #35
chris keefe
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subscribed! love when facts are brought to the table!
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Old 10-26-2012, 09:33 PM   #36
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Couldn't agree more. Not to mention, setting up a slightly looser gap is fine on a high-boost engine.


Quote:
Originally Posted by oem View Post
Aboothman, thanks for agreeing with me and showing the problems with Crystal's torque plate assumptions.

Now I will explain why torque plates are not needed for gaping the rings.

aboothman calculated .0015" as the max circumfrence difference so I will use that number.

Ring gaps are measured with a feeler gauge (thickness gauge), which is a go/no go gauge. Feeler gauges come in .001" increments and do not measure the gap. The user can only tell if the gauge fits or does not fit. i.e. a .015" gauge fits too loose, a .016" gauge fits ok, and a .017" gauge does not fit. For this example, that means the gap is greater then .015" and less then .017". Only by feel can one determine how close the gap is to .016". So with practice one can get closer to feeling what he believes is .016" but it is not exact.

So now when a max circumference difference of .0015" is used the most the ring gap will be off is one feeler gauge. If it is not the max the difference will be between a tight .016" and a loose .016". If we were building F1 engines, this would matter. But for 99% of the Subaru engines built here by members, the difference will not matter.

Just because a process is more complicated does not make it right.
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Old 10-26-2012, 10:35 PM   #37
aboothman
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Quote:
Originally Posted by oem View Post
Aboothman, thanks for agreeing with me and showing the problems with Crystal's torque plate assumptions.

Now I will explain why torque plates are not needed for gaping the rings.

aboothman calculated .0015" as the max circumfrence difference so I will use that number.

Ring gaps are measured with a feeler gauge (thickness gauge), which is a go/no go gauge. Feeler gauges come in .001" increments and do not measure the gap. The user can only tell if the gauge fits or does not fit. i.e. a .015" gauge fits too loose, a .016" gauge fits ok, and a .017" gauge does not fit. For this example, that means the gap is greater then .015" and less then .017". Only by feel can one determine how close the gap is to .016". So with practice one can get closer to feeling what he believes is .016" but it is not exact.

So now when a max circumference difference of .0015" is used the most the ring gap will be off is one feeler gauge. If it is not the max the difference will be between a tight .016" and a loose .016". If we were building F1 engines, this would matter. But for 99% of the Subaru engines built here by members, the difference will not matter.

Just because a process is more complicated does not make it right.
This is THE BEST thing you have posted to date, and it makes real sense!! But it is making an assumption based off theoretical numbers that I pulled, for the most part, from my arse. I should not have said max, because it is completely possible to have a bore distortion of .001 or greater. Without EXTENSIVE testing we do not really know how much bore distortion is possible, or what shape it will take.

With out actually having YOUR block in front of you, with all of the required tools, before and after a plate hone, it is pretty much pointless to speculate too far...but I was bored This is why I finished with "Do it right (hard/expensive way) or do it wrong (easy/cheap way). We could extend the "it will be fine" mentality to no end.

Furthermore the .001 used to derive everything I posted above, used as the difference on ONE AXIS of a theoretical distorted bore, is based off of a test with completely different methodology. That piece of math alone has so many variables and possible error to discount ALL of the math I posted.

I wouldn't really call what either of us posted fact...more like armchair engine building. I simply wanted to fill in the gaps in OEM's statement that Crystal's math was wrong since he cannot be bothered to support any of his statements.

And then the JE tech's statement that ALL of it is wrong Considering what the tech said about "bumps", and how they can affect the cylinder, it becomes clear that a cylinder honed WITH a torque plate must be gaped WITH a torque plate (old news). In my mind these theoretical bumps will take the cylinder out of round negatively (inward) when the cylinder is relaxed without the plate, which actually could affect the end gap more than on a cylinder that has NOT been plate honed. Such a cylinder would have a positive flex (outward) with a torque plate as the tech suggested, which would not affect the end gap as the rings do not follow minor changes in cylinder wall diameter. More speculation for thought....and hopefully verification!!

In my opinion, if you are not that concerned with getting the tolerances as close as possible, then buy an OEM block and drop in some pistons. That is an attitude that has been taken advantage of by crappy engine builders for years, especially in Subaru land... which is why you see so many built engine horror stories. Now that we have some engine builders taking the time to get it right, and rightfully charging a little bit more for their time, it seems ass backwards to revert to the "its good enough" attitude now...especially if you are building it yourself. It can affect parts of your build: Cleanliness, main tolerences, PTW clearances, EVERYTHING.

This discussion is clearly aimed at those of us building engines at home...even in our kitchens on occasion!! Personally I have all the time in the world to do things the hard way. If the results are the same, great!! But why take the chance, when you have the time to spare, because "it is complicated"? If I did not have the time, I would have paid someone else to build it for me with the money I spent on tools and measuring instruments.

As for "more end gap on higher boost engines" it assumes that we are all building high boost engines. What about higher compression engines, whether turbo or N/A?

Last edited by aboothman; 10-26-2012 at 10:54 PM.
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Old 11-08-2012, 09:21 AM   #38
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I am setting ring gaps tonight with cosworth rings/pistons... I don't have micrometers or anything but I will test the ring gap differences if any with and without the torque plate before I grind them. I will post results here
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Old 11-09-2012, 12:52 AM   #39
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ok, I am halfway through the process and its already 1am... going to be a long night.
Before I say this, let me say that I am going to use the torque plate while sizing my rings and honing... and I feel it is ABSOLUTELY good practice and the right thing to do to be as precise as possible. I looked at the recommendations from cosworth on the ring gaps and the range was quite large... lets take the top ring gap for example, the RECCOMENDED range was from .012" to .018" (cosworth rings 8.2 comp 99.75 bore)... If you are sizing the rings without a torque plate and the block was honed with a torque plate, (I THINK the difference would be a maximum of around .002 w/ vs w/o) then you should be safe sizing the rings to .015... that way you will still be within the range.
I am using a torque plate however and will be setting all the ring gaps as close as humanly possible because of how important the rings are and because I can. BUT for someone who doesn't have access to a torque plate ect. the cylinders may have slightly different ring gaps... but they should all be within the recommended spec
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Old 11-09-2012, 01:56 AM   #40
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ok, so before the torque plate the top ring was in between .012 and .013 and after the torque plate the .014 feeler gauge fits perfect... roughly .0015 difference... by the way the cosworth rings didn't need filing
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Old 11-09-2012, 03:53 PM   #41
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good info!!
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Old 11-26-2012, 07:11 PM   #42
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nice frkn writeup.. doin my 100mm build with the same pistons and was happy to see some time saving techniques using the piston upsidedown to get the ring evenly in the cyl down an inch. Excellent. I was sittin there measuring an inch all around to be sure they were straight takin forever... wanted to double check the calculated gaps with what other people were running so.. high five!
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Old 02-02-2013, 01:55 PM   #43
champ125
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Default which rings is the top and which is the second?

im assuming the top one is silver and the black carbon nitrate one is second?
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Old 05-06-2013, 06:24 AM   #44
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Thanks for the info, will share
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