IT Piston Rules - Overbore

Originally posted by GregAmy@Dec 13 2005, 01:31 PM

To not change the application of the rules as they have been done for over 20 years. - GA
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Then we will let others continue the debate because like Joe, I respectfully think you have been assuming something without dissecting it for a lot of years.

We will agree to disagree. I hate that because I know you Greg, and I know you are trying to run your program as I am, legal and fast. I respect you and your interpretation of the good book...how can two sane people read it so differently? Maybe the real answer is that I am f-ing crazy. Crap.

:023:

AB
 
Originally posted by Andy Bettencourt@Dec 13 2005, 02:29 PM
... Let's make the distinction between 'no longer' available and 'NEVER' available.  No .040's WERE NEVER available from Mazda for my configuration.........no dice in making them from scratch. ...
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Okay, if I buy the initial premise - that one can't make an exact duplicate of something that never existed - the suggestion is now that one CAN make an exact duplicate of something that might no longer exist?

Can that be documented with a part or is it necesssary to have engineering drawings to for provenance purposes?

If a part is acceptable (I'm picturing the shelves in Joe's office), what documentation is necessary to make a case that the model for the no-longer-available parts is in fact correct?

This is kind of academic (because that's really where we've collectively taken this question, at the cost of untold hours of productivity for our employers) but a few more questions, please:

If oversize pistons ARE available for a model, is is allowable to use aftermarket alternatives instead, or is the implication that this option is only a last resort?

If that is OK, and if AVAILABLE factory-available oversize pistons for whatever reason are not "identical" in all dimensions besides bore to stock-sized pistons (say they have a different valve pocket design for some reason), do aftermarket replacements have to be identical to the OE oversize units, or may they be identical (besides diameter) to the original pistons? MUST they be only one or the other?

For that matter, are the factory-available oversize pistons legal, if they are NOT identical to the originals in all respects besides bore (e.g., they have a super-secret coating, where the original ones did not)?

If diameter is a variable that can be controlled by the builder, then where factory 40-over pistons are available is it permissable to make "undersize," oversize, forged pistons that are small enough to allow them to grow into a bore that is bored .040 over?

Is it illegal - regardless of any other consideration - to bore a block +.0401"? To +.041"? There are industry conventions here, given that the spec goes to three decimal places - do they apply?

If we are going to tackle this problem by trying to set precedent in the protest/COA judiciary, we should try to get it all taken care of in one shot. It does not solve the problem to simply find one way of falling afoul of this bundle of snakes illegal and have the protest upheld.

K
 
To not change the application of the rules as they have been done for over 20 years. - GA
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Haha there you go making it sound like everybody has read the rule the way you do. I am hunting for the earliest books I can find. I believe that the bold print was normally found in the second printing of a rule change. That would lead me to believe if I remember correctly that those 2 words may have been added in 1991. Again relying on memory only... NOw to the .040 deal. In domestic stuff most of the replacement pistons stopped from the factory at a .030 overbore. The import stuff didn't seam tomess around with .010 and .030 stuff. most of it was .005 .020 and .040 for replacement pistons. A little more worthless historical automotive info.

Have fun guys.
 
Originally posted by Knestis@Dec 13 2005, 01:39 PM
Okay, if I buy the initial premise - that one can't make an exact duplicate of something that never existed - the suggestion is now that one CAN make an exact duplicate of something that might no longer exist?

Can that be documented with a part or is it necesssary to have engineering drawings to for provenance purposes?

If a part is acceptable (I'm picturing the shelves in Joe's office), what documentation is necessary to make a case that the model for the no-longer-available parts is in fact correct?

This is kind of academic (because that's really where we've collectively taken this question, at the cost of untold hours of productivity for our employers) but a few more questions, please:

If oversize pistons ARE available for a model, is is allowable to use aftermarket alternatives instead, or is the implication that this option is only a last resort?

If that is OK, and if AVAILABLE factory-available oversize pistons for whatever reason are not "identical" in all dimensions besides bore to stock-sized pistons (say they have a different valve pocket design for some reason), do aftermarket replacements have to be identical to the OE oversize units, or may they be identical (besides diameter) to the original pistons? MUST they be only one or the other?

For that matter, are the factory-available oversize pistons legal, if they are NOT identical to the originals in all respects besides bore (e.g., they have a super-secret coating, where the original ones did not)?

If diameter is a variable that can be controlled by the builder, then where factory 40-over pistons are available is it permissable to make "undersize," oversize, forged pistons that are small enough to allow them to grow into a bore that is bored .040 over?

Is it illegal - regardless of any other consideration - to bore a block +.0401"? To +.041"? There are industry conventions here, given that the spec goes to three decimal places - do they apply?

If we are going to tackle this problem by trying to set precedent in the protest/COA judiciary, we should try to get it all taken care of in one shot. It does not solve the problem to simply find one way of falling afoul of this bundle of snakes illegal and have the protest upheld.

K
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Kirk, I would have to say that this is another part of the issues created when the CRB accepted the alternate process of manufacturing. Lets take the L24 engine since I do a bunch of them. The factory spec is 3.267 to 3.269 std bore replacement pistons with a 3.308 for .040 over size spec. The actual bore spec 3.2677 (+.0020) with a wear limit of (.0097) so my guess is the spec would be to the 4th digit in this case. SO lets add it up. 3.2677+.0020=3.2697+0097= 3.2794+.040=3.3194 max. 3.3194is the throw away point...Now for 3.308 sized piston in a maxed out bore says .0114 side clearence would be more than enough for any piston I can think of.

OH and BTW the 1970 factory manual I pulled that out of has .060 pistons as the 5th oversize listed in the FSM.. B)
 
Originally posted by GregAmy@Dec 13 2005, 07:10 PM


This seems all fine and good, but it does not explain one simple point: why allow aftermarket pistons in the first place, and why feel compelled to specify exactly which characteristics must be met on thee parts, and then not mention bore?
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Greg, I agree. Why does it mention every other characteristic but the bore size? That doesn't make sense to me either. It says factory equivalent, then goes on to mention everything else BUT bore size. I don't get it.

Andy,
I really think you're splitting hairs here man. That extra .020" of bore on a 1.8 amounts to next to nothing. Are you really going to lose a race because you have 10cc less of displacement? At NHIS no less? And to boot you're racing in a regional class. In all likely hood you're going to be running against someone who is outright cheating anyways. And you know what, if there is a guy out there (hondas/acuras are great examples) running with a .040" piston where one from the factory wasn't available, it's not lightweight and has all identical characteristics, then fine. I don't think he was trying to cheat nor do I believe that that extra .020" of bore is what helped him to beat me. So, I think you're making too much of this.

Now the business where people are making lightweight forged slugs is a whole 'nother story in my book. That needs to be dealt with. I'm willing to bet that if you did protest someone and there was no .040" overbore available from the factory, but the weight was more than the factory STD piston, they would beat the protest based on the fact that MANY people have read the rule that way for a LONG time. Instead of trying to get to the bottom of this and waste all this time and energy, why don't we just add in some wordage to clarify the rule? Let everyone go to a max of .040" overbore. If it's not available from the factory, the replacement must weigh no less than a STD bore size factory piston.

All this other discussion is just a waste of hot air. We may never know the intent. But I agree with Greg. I believe it was meant to limit it to .040 over to keep from being more. And if .040 over isn't available, then let it be.

And in all likely hood if you do pop your motor, chances are the block won't be usable anyways. That's usually only the case if you rebuild it BEFORE somethig bad happens.

steve
 
Originally posted by stevel@Dec 13 2005, 02:09 PM
Greg, I agree.  Why does it mention every other characteristic but the bore size?  That doesn't make sense to me either.  It says factory equivalent, then goes on to mention everything else BUT bore size.  I don't get it. 

Andy,
I really think you're splitting hairs here man.  That extra .020" of bore on a 1.8 amounts to next to nothing.  Are you really going to lose a race because you have 10cc less of displacement?  At NHIS no less?  And to boot you're racing in a regional class.  In all likely hood you're going to be running against someone who is outright cheating anyways.    And you know what, if there is a guy out there (hondas/acuras are great examples) running with a .040" piston where one from the factory wasn't available, it's not lightweight and has all identical characteristics, then fine.  I don't think he was trying to cheat nor do I believe that that extra .020" of bore is what helped him to beat me.  So, I think you're making too much of this. 

Now the business where people are making lightweight forged slugs is a whole 'nother story in my book.  That needs to be dealt with.  I'm willing to bet that if you did protest someone and there was no .040" overbore available from the factory, but the weight was more than the factory STD piston, they would beat the protest based on the fact that MANY people have read the rule that way for a LONG time.  Instead of trying to get to the bottom of this and waste all this time and energy, why don't we just add in some wordage to clarify the rule?  Let everyone go to a max of .040" overbore.  If it's not available from the factory, the replacement must weigh no less than a STD bore size factory piston. 

All this other discussion is just a waste of hot air.  We may never know the intent.  But I agree with Greg.  I believe it was meant to limit it to .040 over to keep from being more.  And if .040 over isn't available, then let it be. 

And in all likely hood if you do pop your motor, chances are the block won't be usable anyways.  That's usually only the case if you rebuild it BEFORE somethig bad happens. 

steve
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So stevel if that's the belief then why stop at .040? Why not any factory piston or is exact equivalent. The reasoning that says all manufactures are not created equal so we should make it that way is bunked by the fact that I now have to throw blocks away at 040 when Nissan offered a 060 replacement piston in the FSM. Am I as a Nissan competitor now being unfairly treated? Where does it stop? I admire the fact that Andy wants a proper reading and will acept 020 if that's what all the Mazada's get. I have not seen him say that since nissan gets them we should also.
 
Originally posted by Joe Harlan@Dec 13 2005, 09:17 PM
So stevel if that's the belief then why stop at .040? Why not any factory piston or is exact equivalent.
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because i'm assuming (yes, dangerous i know) that the .040" was mentioned to set a limit. I think we do need to set a limit.

by the fact that I now have to throw blocks away at 040 when Nissan offered a 060 replacement piston in the FSM.
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which you have to do right now anyways, since .040 is the max? Correct?

Am I as a Nissan competitor now being unfairly treated?
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I think you would be treated the same as everyone else. Bore up to .040, no more than that is allowed.

Where does it stop?
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At .040 like the rule reads now. No matter what is available from the factory.

I have not seen him say that since nissan gets them we should also.
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I didn't either. But sure, give everyone the same allowance. i'm fine with that.

And Joe, I'm sure you're going to come back with a bunch of counterpoints. I know you have a lot more experience with all this stuff than me. And I'm sure you're counterpoints are going to be some good pieces of knowledge that I didn't think of or are not even aware of. I concede that you do know more than I and rightly so.

I just proposed what we could do. I say allow everyone .040" as a max, and make sure to include a hook for a minimum weight of the piston. If there are too many holes in that, let's add at least some wording to at least bring some clarity to the rule, because as it stands there's a difference in opinion. I don't think the rule is as clear as some think and it seems like I'm not alone.

steve
 
Originally posted by stevel@Dec 13 2005, 03:22 PM
because i'm assuming (yes, dangerous i know) that the .040" was mentioned to set a limit.  I think we do need to set a limit.
which you have to do right now anyways, since .040 is the max?  Correct?
I think you would be treated the same as everyone else.  Bore up to .040, no more than that is allowed.
At .040 like the rule reads now.  No matter what is available from the factory.
I didn't either.  But sure, give everyone the same allowance.  i'm fine with that.

And Joe, I'm sure you're going to come back with a bunch of counterpoints.  I know you have a lot more experience with all this stuff than me.  And I'm sure you're counterpoints are going to be some good pieces of knowledge that I didn't think of or are not even aware of.  I concede that you do know more than I and rightly so.

I just proposed what we could do.  I say allow everyone .040" as a max, and make sure to include a hook for a minimum weight of the piston.  If there are too many holes in that, let's add at least some wording to at least bring some clarity to the rule, because as it stands there's a difference in opinion.  I don't think the rule is as clear as some think and it seems like I'm not alone.

steve
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No actually a lot of counter points are not needed. My main point is that not every rule is gonna be equal for everyone. The allowance limits to .040 if there is a factory equal. Then add the new line I referenced in the ITCS and you have a case even if accidental for not creating a part that never existed...The other point is just because you believe it does not make it so. (even in my side of the argument) I will share may hand on this deal. When I write the protest on Andy's .040 mazda I am going to require a factory replacement .040 piston for his motor be supplied at my expense to the court as evidence. When the factory part cannot be supplied for comparison I win the protest. This is one of the reasons I keep a know good example of a factory part. The book says it will be up to the competitor to prove the legality of the protested part.
 
Joe-

In most cases I would think that the SOM's will only accept your parts if both parties agree that it is a stock part. Just an FYI, I am sure it doesn't much matter to you, as you use them in your building process... Good Idea IMO.

Greg and others with this potentialy illigal modification-

Many people seem to think you are illigal. You have spent thousands on your motor development... go in with some of the others and get a 13.9. If you are not willing to put up the $10.00 - $20.00 I would think that it would represent your fear of having illigal parts. $10 - $20 is a drop in the bucket for 90% of the people on here... $250.00 is expensive and I can understand a hesitation but this could be an inexpensive group effort and all this wasted time could be ended... As far as I am concerned you/we all have wasted far more than 10 hours on this debate; I am worth at least $25 an hour... thats the $250. I am sure most of you are worth more than I am :119:

Good luck everyone, and stop being soooo cheep... may santa bring each of us super fast motors with or without the .040 pistons!!!

Raymond
 
Joe,

Is it correct to add the wear limit to the total max bore size? The way I see it, it says 040 over standard bore size. To me, that would be w/in the published tolerences (3.2677 - 3.2697 in your example. So, your throw-away point is 3.3194 - 0.0097 = 3.3097. Your 3.308" piston now has 0.0017" clearence. That's a tick tight for a cast piston, and is flat out too tight for a forged piston, given that both would be 3.308" in diameter.

I'm not a professional engine builder, but to me, standard bore, is standard bore, w/in stated tolerences, for a new block. The wear limit is essentially the point where you have to go to the first stated oversize. I don't think you get that, on top of an 0.040" overbore.



Here's a side question for Kirk, and anyone else that was around when this whole thing got started. How was '68 determined as the cutoff year?
 
I don't have old GCRs to nail this down, but I can confirm that the piston rule was changed around 1987. Until it was rewritten, there was no mention about weight or ring thickness. I believe it mentioned dome configuration and pin and ring location.
Taking full advantage of this, I had forged Venolias made for my Volvo which were 25g/piston lighter tqan stock, had tapered pins and narrow (.0625" vs 2.0mm) rings. How do I remember this so well? The next year, they closed these loopholes and out came the pistons. What to do with $600 worth of esoteric stuff? Build a hot street motor for my 4 door-the one that broke a very thin piston crown (no-it wasn't detonation!) near Sacramento while towing the 2 door from Sears to PIR in 90. Switched cars, towed tow car w/racecar to PIR. Realized then that tow vehicles were uneccesary. Built 4 dr and bought a Coleman camper. Funny how thigs are connected!
PS: just my 2 cents, but my feeling is that since the original IT rules were generated (duplicate?) from 1963 production rules, and all prod cars were allowed to have .040" overbore then, that the intent was for all IT cars to have that option.Most people have always considered that if an exact equivalent piston grew .040", whether at the oe's factory, or elsewhere, it was legal. I'd be pretty POd if some boneheads changed that "interpretation" and although +.040" equilavent pistons that met all other prescriptions of the rule (including weight), were readily available, and were in my motor-became de-facto illegal. That woul cause me, and many others, to basically throw away our motors.
when I had my lightweight pistons made 17 yrs ago, I KNEW I was going through a loophole, and when they closed it, It really didn't bothe me. This would.
Phil Hunt
 
Originally posted by Bill Miller@Dec 13 2005, 04:20 PM
Joe,

Is it correct to add the wear limit to the total max bore size?  The way I see it, it says 040 over standard bore size.  To me, that would be w/in the published tolerences (3.2677 - 3.2697 in your example.  So, your throw-away point is 3.3194 - 0.0097 = 3.3097.  Your 3.308" piston now has 0.0017" clearence.  That's a tick tight for a cast piston, and is flat out too tight for a forged piston, given that both would be 3.308" in diameter.

I'm not a professional engine builder, but to me, standard bore, is standard bore, w/in stated tolerences, for a new block.  The wear limit is essentially the point where you have to go to the first stated oversize.  I don't think you get that, on top of an 0.040" overbore.
Here's a side question for Kirk, and anyone else that was around when this whole thing got started.  How was '68 determined as the cutoff year?
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Ah Bill I knew either you or Kirk would catch that....That presents a whole new group of issues but since my FSM shows it as part of the factory bore spec. I have to run at the moment but I will be bcak and relook at the specs. I think I have typed a min/max spec. wrong. I will get you the correct clearance.
 
Originally posted by Joe Harlan@Dec 13 2005, 04:34 PM
Ah Bill I knew either you or Kirk would catch that....That presents a whole new group of issues but since my FSM shows it as part of the factory bore spec. I have to run at the moment but I will be bcak and relook at the specs. I think I have typed a min/max spec. wrong. I will get you the correct clearance.
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And Phil the converstion goes alot better without the Bonehead reference.
 
Originally posted by RSTPerformance
Greg and others...go in with some of the others and get a 13.9.  If you are not willing to put up the $10.00 - $20.00 I would think that it would represent your fear of having illigal parts
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Wait a sec: my lack of giving you money to "prove myself legal" represents that I believe I have illegal parts? Good try, son, but as I told Joe some time back, I don't respond to threats or dares unless it's a "triple-dog-dare-you".

This is all pretty interesting, given that you have no freakin' clue what I've done to my engine(s) or what the manufacturer offers to me OEM. You automatically assume I'm arguing from a position of bias, not with a long history and interest in the class's future? I had given consideration into joining in on you and your brother's idea, but this pretty much sealed it. Good luck with your investigation(s), I'll be interested to hear how it works out. - GA
 
greg-

Bad assumption on my part... I assumed (made an ass out of me I guess) that you have fully developed your car to the max of YOUR interpretations, thus you had pistons that may be interpreted illigal by some. (To be honest I don't remember what you may have stated in the first 5 pages if your car offer bigger pistons or not, and or if you had any made).

I want to make myself clear in that I fully think that you are 100% well founded in your interpretation no matter what you have or have not done to your car... and I do not mean anything I said in a negative way.

I can't afford $250.00 and I don't have and I am not intending to build a .040 motor anytime soon as I don't have the funds... I would however invest a few dollars to get a clarification on the rule for the interest of everyone who is or may plan on bulding a motor as well as for folks like yourself who apparently only have an interest in the future of IT.

I think that this is an important rule that needs clarification, and it has nothing to do with my development. I would think that you are in the same boat as you state that you are interested in the future of it.

Sorry if I came across negatively sarcastic in anyway, not ment to be. This entire debate has done only one thing... prove that we need a clarification on the rule!!! I think that instead of debating we should all work together, follow the proper chanels that SCCA has set up for us, even if we like that process or not.

Sorry Gregg for any hard feelings :(

Raymond

PS: as far as my investigation(s) I am not interested for myself nor do I have $250.00 to spend on something that I would only be able to use protesting someone else (and I don't think that someone will beat me just casue they have .040 pistons and I don't), thierfor I am not investigating, but would be happy to help someone else financialy.
 
Originally posted by pfcs49@Dec 13 2005, 06:23 PM
I don't have old GCRs to nail this down, but I can confirm that the piston rule was changed around 1987. Until it was rewritten, there was no mention about weight or ring thickness. I believe it mentioned dome configuration and pin and ring location.
Taking full advantage of this, I had forged Venolias made for my Volvo which were 25g/piston lighter tqan stock, had tapered pins and narrow (.0625" vs 2.0mm) rings. ...
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Damn. I was off by a couple years but I knew it. You are the reason they added that text. :)

K
 
If someone spent $250 for a (possibly bonehead) ruling, and the consequence of that ruling was that any number of reasonable men, operating with reasonable (perfect?) expectations that it was legal, had built 40 over motors, would now have to spend collectively many thousands of dollars to bring their engines into compliance with this new interpretation of the rule-would that be reasonable? absolutely not! This is amateur club racing. we race for ashtrays! I always hope we can be a community. This is not the debating club (aaaaah? maybe it is!) This seems like BS to me. Advocating to make a somewhat contrived interpretation of traditionally accepted custom (everyone gets the 040 option), is counterproductive and not in the spirit of club racing (did I relly say that?!) and would hurt a large number of good guys who have integrity. All of this, just to get to be right! Maybe someone should send it in to the comp board under errors and omissions, that they never clarified this. I expect their decision would be reasonable-make no bones about it.
Phil
ps Joe-I don't think of you as a bonehead and don't know how you made that association. In fact, you seem like an OK kind of guy who's shop I'd like to hang in.
 
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