IT Piston Rules - Overbore

[Banzai240]

Originally posted by Turfer@Dec 13 2005, 05:05 AM
...somehow during all this Darin stumbled over the rule and here we are.

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Just to be perfectly clear... I rarely "stumble" over anything...

I was looking specifically for what was and wasn't allowed, as far as pistons go, and posted what I found... Had nothing to do with classifying cars...

Don't kid yourselves, guys... if the difference in HP between a .020 and .040 is only 2hp... there is NO WAY we can get within that kind of accuracy, given the resources we have... Heck, that's less than the dyno inaccuracies in most cases

Now, back to the regularly scheduled piston debacle, now in progress....

 

[Greg Amy]

Let's take a couple of trips down Logical Lane; I think you could imagine it going something like this…

Fade to a bar some place in the outskirts of Englewood Colorado (home of 'the largest shopping mall west of the Mississippi'). It's 1983. There's a bunch of guys discussing a new racing category that came out of the Pacific Northwest that's caught on. Michael Jackson's "Billy Jean" is blaring out of the jukebox with Kenny Rogers and Sheena Easton's "We've Got Tonight" and Men At Work's "It's a Mistake" queued up right behind it. The Tandy TRS Model III computer was about to be released and the only computer "networking" around was an occasional dial-up connection on your new 300-baud "MODEM" to a local Wildcat server sitting in some nerd's bedroom (a scary thought in itself).

SCCA regions are ecstatic with increasing entries in this new category, and these guys in the bar have been tasked with merging a few regions' slightly-differing rulesets in order to create the very first Nationally-published rules standard for a Regional-Only class, called "Improved Touring." Let’s listen in…


"OK, now we're down to engine prep rules. We've already agreed that these cars must be prepped to shop manual specs (they called 'em 'shop manuals' back then, not 'factory service manuals'). We OK with overbores per the manuals?"

"Sure, no problem, but shouldn't we limit it? I mean, what happens if some manufacturer offers a 1-inch overbore! I'd hate to have to run against a Datsun 320ZX!!" (The boys still called them "Datsuns" back then, even though "The Name is Nissan" commercials were all over the TV.)

"Yeah, good idea; let's stick to industry standards, and make it .040" max. So, we'll make the rule read 'Engines may be bored to a maximum of .040 inch over standard bore size.'"

"Sounds good to me. Hey, what if the manufacturer only offers 20-over pistons?"

"Too bad for them! I don't think we want to get into letting folks go above and beyond the shop manual. Besides, where are they gonna get pistons? We don't allow aftermarket parts."

"That's true...hey, wait a sec, here’s an idea: why don't we allow aftermarket pistons…?"

Scenario 1:

"Aftermarket pistons?!? What, for the guys that don't get to go 40-over? We don't allow aftermarket parts for anything."

"No, no, no, just as replacements for what the factory already offers."

"Why? Who cares? If the factory offers it as a repair part, you can install it."

"I dunno, maybe factory overbore pistons are expensive? Maybe them Datsun pistons are hard to get? Joe at the shop says there’s cheap sources for pistons, we can save folks some money or something." (insert WAG here)

"Sounds like a bag of worms, Clyde; we gonna allow aftermarket parts for anything else?"

"No, just pistons."

"Well if we did it, how do we make sure that they're the same thing?"

"We could make the rule read, 'Factory oversize replacement pistons or their exact equivalent shall be used.'"

"Well, so what does 'exact' mean?"

"Uh, well, it means 'exact' in every way." (Remember, this was before the national debate on the definition of the word 'is').

"Well, I think we should clarify it."

"Hey, 'exact' means exact, man; if it matches the factory pistons, it's good; if it doesn't, it's not."

"No, we need to clarify. You know that Smokey’s gonna find a hole in there somewhere."

"OK, OK. Let's add, 'Equivalent pistons shall provide the same dome/dish/valve relief configuration, ring thickness and spacing, pin height relationship, weight, and compression ratio as factory replacement oversize pistons.'"

"What about specifying bore?"

"Nah, that's fine. They'll know what we mean."

"OK, we got it! The rules reads, 'Engines may be bored to a maximum of .040 inch over standard bore size. Factory oversize replacement pistons or their exact equivalent shall be used. Equivalent pistons shall provide the same dome/dish/valve relief configuration, ring thickness and spacing, pin height relationship, weight, and compression ratio as factory replacement oversize pistons.'"

"Done. Now, on to suspension bushings…"

Scenario 2

"Well, wait a sec, here’s an idea: why don't we allow aftermarket pistons…?"

"Aftermarket pistons? What, for the guys that don't get to go 40-over? We don't allow aftermarket parts for anything."

"Yeah, but it doesn’t seem fair that some guys can overbore 40-over, and some guys can't."

“True, but it sounds like a bag of worms, Clyde; we gonna allow aftermarket parts for anything else?"

"No, just pistons, and only to make sure everyone gets to prep to the same level."

"So how do we make sure that they're the same thing except for bore?"

"We could make the rule read, 'Factory oversize replacement pistons or their exact equivalent shall be used.'"

“Well, what if there’s no factory equivalent piston to compare it to? What then? I think we should clarify it."

"Hey, 'exact' means exact, man; if it matches the factory pistons except for bore, it's good; if it doesn't, it's not."

"No, we need to clarify. You know that Smokey’s gonna find a hole in there somewhere."

"OK, OK. Let's add, 'Equivalent pistons shall provide the same dome/dish/valve relief configuration, ring thickness and spacing, pin height relationship, weight, and compression ratio as factory replacement oversize pistons.' Everything except bore."

"That makes sense. OK, so the rule reads, 'Engines may be bored to a maximum of .040 inch over standard bore size. Factory oversize replacement pistons or their exact equivalent shall be used. Equivalent pistons shall provide the same dome/dish/valve relief configuration, ring thickness and spacing, pin height relationship, weight, and compression ratio as factory replacement oversize pistons.'"

"Done. Now, on to suspension bushings…"


Now, you tell me: which scenario makes more sense...?

 

[Andy Bettencourt]

Very entertaining Greg. But at this point I don't really care what anyone remembers things were like when the Chevy Citation was around. All I care about is the way the rule reads now...and apparantly has read for as long as anyone can prove.

We rarely disagree but I can't make the connection between what I read in the GCR and what we have to assume is the way things went. I think scenario #2 doesn't make sense...FRP's are FRPs. If there is no .040 size made, you can't mfg an exact match to something that doesn't exist....

No worries. I hope the rule is meant to read the way you say it is intended to. I will personally get to the bottom if it.

AB

 

[Joe Harlan]

Originally posted by Andy Bettencourt@Dec 13 2005, 08:05 AM
Very entertaining Greg.  But at this point I don't really care what anyone remembers things were like when the Chevy Citation was around.  All I care about is the way the rule reads now...and apparantly has read for as long as anyone can prove.

We rarely disagree but I can't make the connection between what I read and what we have to assume is the way things went.

No worries.  I hope the rule is meant to read the way you say it is intended to.  I will personally get to the bottom if it.

AB

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Just as a point of interest Andy I may have a ITCS from the mid eightys in my shop. I will look around for it. If you want money kicked in for a ruling let me know.

 

[Greg Amy]

...I care about...the way the rule reads now...and apparantly has read for as long as anyone can prove.

Andy, this statement disturbs me, mostly because it's conflicting but also because it implies there's been a change in the rule, and thus its intent, since the inception of the class in 1984. The plus side of this is that I infer you're willing to accept my logic if no change in the rule is proven; thus I hope with much sinerity that Joe can find that old ITCS (In fact, I'd pay money for a copy of the 1984 or '85 ITCS...)

I think I've made my position clear, both logically and historically, and I'm going to stop beating this dead horse. I also recognize that, with the notable exception of Joe, no one else has come up and said, "hey, that's the way *I* have been interpreting that rule for years!" In fact, this "interpretation" was not even considered by you until someone found out that Mazda can't provide factory 40-over pistons yet some folks were building super uber-lightweight pistons for the Miata that cost mongo bongo dollars...it was at that point that you guys got all scared about engine builders micro-word-parsing the rules to their advantage, so you chose to micro-word-parse them in response.

This is silly.

The rule is what it is, and it is VERY important that it be considered in the historical context in which it was written, unless you want the rules to be some "living document" subject to change at the whims of society, the competitors, and how others define the definition of the word "is". When these rules were written -- yes, in the days of the Citation -- micro-word-parsing was not done to the level and to the volume that it's being done today. You're simply over-thinking this; the rules meant what they said, not what a linguistics teacher would say they could mean.

I firmly believe you can uphold your position with a micro-parsing of the rules, but you cannot uphold your position using logic and history. I've asked multiple times for anyone else to uphold your position using logic and history, and (granted it's only been since last night) no one has; the only response I've gotten is "but that's what the rule says!" If you wish to ignore context then you win, but until you can prove otherwise I encourage folks to build their engines with 40-over pistons, regardless of OEM offerings.

The rule has been this way for 21+ years. If you want to clarify it to read better, great. If you want to change it, then let's run it through the rules change process and membership input. Until then, I'm of the opinion that 40-over is good for the goose and the gander.

Greg

 

[Joe Harlan]

Originally posted by GregAmy@Dec 13 2005, 09:25 AM
Andy, this statement disturbs me, mostly because it's conflicting but also because it implies there's been a change in the rule, and thus its intent, since the inception of the class in 1984. The plus side of this is that I infer you're willing to accept my logic if no change in the rule is proven; thus I hope with much sinerity that Joe can find that old ITCS (In fact, I'd pay money for a copy of the 1984 or '85 ITCS...)

I think I've made my position clear, both logically and historically, and I'm going to stop beating this dead horse. I also recognize that, with the notable exception of Joe, no one else has come up and said, "hey, that's the way *I* have been interpreting that rule for years!" In fact, this "interpretation" was not even considered by you until someone found out that Mazda can't provide factory 40-over pistons yet some folks were building super uber-lightweight pistons for the Miata that cost mongo bongo dollars...it was at that point that you guys got all scared about engine builders micro-word-parsing the rules to their advantage, so you chose to micro-word-parse them in response.

This is silly.

The rule is what it is, and it is VERY important that it be considered in the historical context in which it was written, unless you want the rules to be some "living document" subject to change at the whims of society, the competitors, and how others define the definition of the word "is". When these rules were written -- yes, in the days of the Citation -- micro-word-parsing was not done to the level and to the volume that it's being done today. You're simply over-thinking this; the rules meant what they said, not what a linguistics teacher would say they could mean.

I firmly believe you can uphold your position with a micro-parsing of the rules, but you cannot uphold your position using logic and history. I've asked multiple times for anyone else to uphold your position using logic and history, and (granted it's only been since last night) no one has; the only response I've gotten is "but that's what the rule says!" If you wish to ignore context then you win, but until you can prove otherwise I encourage folks to build their engines with 40-over pistons, regardless of OEM offerings.

The rule has been this way for 21+ years. If you want to clarify it to read better, great. If you want to change it, then let's run it through the rules change process and membership input. Until then, I'm of the opinion that 40-over is good for the goose and the gander.

Greg

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(2006 ITCS)
Stock replacement parts may be obtained from sources other than the
manufacturer provided they are the exact equivalent of the original parts.
The intent of this rule is to allow the competitor to obtain replacement
parts from standard industry outlets, e.g., auto-parts distributors, rather
than from the manufacturer. It is not intended to allow parts that do not
meet all dimensional and material specifications of new parts from the
manufacturer

Greg, please break down how this would not apply to the .040 argument then. If the part was never made are you not breaking this rule? The may portion of the rule is only allowing it and based on the above sentence if the part was an option from the factory. I just don't see how that is splitting hairs. It is using the book as a complete document rather than just pulling out the parts I want to use.

 

[Greg Amy]

Originally posted by Joe Harlan
Greg, please break down how this would not apply to the .040 argument then.

Easy, Joe: that paragraph was added last year on the recommendation of the current ITAC and CRB, as a way to allow the use of aftermarket parts (brake discs, drums, body panels, etc). It therefore has no bearing on the original, historical, and logical intent of 17.1.4.D.1.j.

Are you implying that this noobie addition to the rules should supercede one that's been in place since 1984? Are you implying that because of this, anything that was done in regards to the discussion at hand is now considered suddenly illegal? Fortunately, the ITAC group that put this rule in place is still with us...maybe they'll be able to tell us if this is what they intended...?

Now that I've answered your question, Joe, where's your answers to mine from previous posts...? - GA

 

[Knestis]

EDIT - OOPS. Greg beat me to it.

K

EDIT EDIT - moved to a new post.

 

[Joe Harlan]

Originally posted by GregAmy+Dec 13 2005, 10:53 AM-->

<!--QuoteBegin-Joe Harlan

Greg, please break down how this would not apply to the .040 argument then.

Easy, Joe: that paragraph was added last year on the recommendation of the current ITAC and CRB, as a way to allow the use of aftermarket parts (brake discs, drums, body panels, etc). It therefore has no bearing on the original, historical, and logical intent of 17.1.4.D.1.j.

Are you implying that this noobie addition to the rules should supercede one that's been in place since 1984? Are you implying that because of this, anything that was done in regards to the discussion at hand is now considered suddenly illegal? Fortunately, the ITAC group that put this rule in place is still with us...maybe they'll be able to tell us if this is what they intended...?

Now that I've answered your question, Joe, where's your answers to mine from previous posts...? - GA

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[/b]

Greg, your gonna have to direct me to your question again. And please i can deal with logic but historical has little bearing here or we would still be racing with basicly SS cars with interior's. I look at your reading of the rule and I would contend that the writers of these rules never pondered the FI/ECU issues anymore than they considered some cars only having a .010 overbore. That really doesn't matter what they considered for the time. They likely never considered the use of a restricter but that dosen't mean we shouldn't use them. My reading of the rule is different than yours so maybe a COA ruling gets the rule either opened or closed but an answer is needed I guess.

 

[Andy Bettencourt]

Originally posted by GregAmy@Dec 13 2005, 10:25 AM
Andy, this statement disturbs me, mostly because it's conflicting but also because it implies there's been a change in the rule, and thus its intent, since the inception of the class in 1984. The plus side of this is that I infer you're willing to accept my logic if no change in the rule is proven; thus I hope with much sinerity that Joe can find that old ITCS (In fact, I'd pay money for a copy of the 1984 or '85 ITCS...)

I think you are getting this all backward. I actually was trying to say that nobody can prove that the rule has changed at all...so I am disptuting these historical 'assumptions of intent' that you are using as the basis for your position.

I think I've made my position clear, both logically and historically,

I disagree in both cases. Logically, I don't agree at all, and historically all you have to offer is the way 4 guys remember it.

I also recognize that, with the notable exception of Joe, no one else has come up and said, "hey, that's the way *I* have been interpreting that rule for years!" In fact, this "interpretation" was not even considered by you until someone found out that Mazda can't provide factory 40-over pistons yet some folks were building super uber-lightweight pistons for the Miata that cost mongo bongo dollars...it was at that point that you guys got all scared about engine builders micro-word-parsing the rules to their advantage, so you chose to micro-word-parse them in response.

Well the facts are simple. You have been doing this for many moons more than I. This off-season project is the first piston-based IT engine we will have built...so it is my first micro-analysis of the rules - for my benefit - in an effort to put a package together to compete with the likes of your program. In my journey, I asked Mazda for some 40-overs - sorry! 20-overs are all they make. OK, so a closer look at the rules was nessesary...what can I have made custom - and how the hell much is it going to cost me? After talks with a few people, you included, I concluded that 40's weren't legal for my application. The side issue was that there were others out there doing light stuff based on non-existant specification interpretation.

The rule is what it is, and it is VERY important that it be considered in the historical context in which it was written, unless you want the rules to be some "living document" subject to change at the whims of society, the competitors, and how others define the definition of the word "is". When these rules were written -- yes, in the days of the Citation -- micro-word-parsing was not done to the level and to the volume that it's being done today. You're simply over-thinking this; the rules meant what they said, not what a linguistics teacher would say they could mean.

Prove to me what the historical context was/is and I will ride your bandwagon. I have yet to see anything other than assumptions and hypothetical roundtables.

The ironic thing is that I am usually on the other side of these arguements. The GCR has a rule, it's intent is obvious, and some word-smith rips it to shreds with "it doesn't say that" nonsense. Double-secret irony is that my view on this HURTS the power potential of my build. I just don't read it like you do I guess. (and what scares me is that I know you are smarter than I am... )

I firmly believe you can uphold your position with a micro-parsing of the rules, but you cannot uphold your position using logic and history. I've asked multiple times for anyone else to uphold your position using logic and history, and (granted it's only been since last night) no one has; the only response I've gotten is "but that's what the rule says!" If you wish to ignore context then you win, but until you can prove otherwise I encourage folks to build their engines with 40-over pistons, regardless of OEM offerings.

See above. You have proven nothing to me other than what you THOUGHT and ASSUME. If the GCR hasn't changed since the GM X-Body, then I repectfully think that you have been reading the rule wrong for 22 years. I also think logic is fully on my side as I do not think the original intent was to allow everyone to overbore to 40-over or else there is NO NEED to reference a FRP at all. All you have to say is that you may use up to 40-over pistons with the same specs as stock. It could be that simple but it isn't. I could also be wrong about this, and if I am, a re-write of the rules is needed.

The rule has been this way for 21+ years. If you want to clarify it to read better, great. If you want to change it, then let's run it through the rules change process and membership input. Until then, I'm of the opinion that 40-over is good for the goose and the gander.

I hope you are right. It will allow me to rebuild using the same block when my .020 motor pops.

AB

 

[Knestis]

I've moved this down to a new post, since things zoomed along as I was pondering...

* * *

EDIT EDIT - Another historical consideration is the fact that "40 over" pistons were commonly allowed in budget-concious stock car classes of the '70s and early '80s. When we were working on our own IT rules in NWR (again before the National rules out of Denver but it goes to context), we had no second thoughts about allowing oversize pistons for rebuilds. It was just so much a part of the psyche of the time, and the quesiton of whether or not oversize pistons were available from the factory was never considered - because, for the cars with which were were all familiar, they just WERE.

I'm really beginning to understand that what we have here is another critical benchmark in the "anachronising" of IT - it's march toward becoming the "next Production." I haven't gone looking but I wouldn't be surprised that oversize pistons are essentially nonexistent for new cars simply because technology and consumer demands have made them obsolete. My newish Civic uses some freakin' sewing machine-weight oil in the crankcase and doesn't have any regularly scheduled maintenance for something like 30K miles. We turn over our cars in months rather than years and how many people would actually pay for a rebuild rather than just buy a new lump out of the boneyard?

Problem is, the bulk of IT grids are made up of cars from between the mid-'80s and the early '90s, when automotive technology was going through a pretty ugly pubescence. They are kind of stuck between the era when the rules were first written and that in which they are now being applied.

So the intepretation grounded in experiences of a whole IT generation are no longer rally valid, as time and technology marches on. This new context completely changes the implicit meaning of a paragraph in the ITCS, even if the explicit meaning of the individual words is exactly the same. Just like parents and little kids can now talk about how a particular movie "sucked," or the soccer team's defense "sucked," or whatever "sucked" without complicating their lives with any understanding of the root of the term - when I was a kid 35 years ago. Sheesh.

The real problem with Andy's well-intentioned solution is that any interpretation coming out of a modern protest and appeal is going to apply modern meanings made in modern contexts. Just looking at the words of the rule is NOT enough - historical memory matters. Luckily, just like it's totally OK for a mainstream comic strip character to say, "this sucks" in front of millions of kids and young mothers, I can say that what amounts to a historical re-write of the rules kind of sucks, too...

Old-ass Kirk

 

[Joe Harlan]

Originally posted by Andy Bettencourt@Dec 13 2005, 11:17 AM
I think you are getting this all backward.  I actually was trying to say that nobody can prove that the rule has changed at all...so I am disptuting these historical 'assumptions of intent' that you are using as the basis for your position.
I disagree in both cases.  Logically, I don't agree at all, and historically all you have to offer is the way 4 guys remember it.
Well the facts are simple.  You have been doing this for many moons more than I.  This off-season project is the first piston-based IT engine we will have built...so it is my first micro-analysis of the rules - for my benefit - in an effort to put a package together to compete with the likes of your program.  In my journey, I asked Mazda for some 40-overs - sorry!  20-overs are all they make.  OK, so a closer look at the rules was nessesary...what can I have made custom - and how the hell much is it going to cost me?  After talks with a few people, you included, I concluded that 40's weren't legal for my application.  The side issue was that there were others out there doing light stuff based on non-existant specification interpretation.
Prove to me what the historical context was/is and I will ride your bandwagon.  I have yet to see anything other than assumptions and hypothetical roundtables.

The ironic thing is that I am usually on the other side of these arguements.  The GCR has a rule, it's intent is obvious, and some word-smith rips it to shreds with "it doesn't say that" nonsense.  Double-secret irony is that my view on this HURTS the power potential of my build.  I just don't read it like you do I guess.  (and what scares me is that I know you are smarter than I am... )
See above.  You have proven nothing to me other than what you THOUGHT and ASSUME.  If the GCR hasn't changed since the GM X-Body, then I repectfully think that you have been reading the rule wrong for 22 years.  I also think logic is fully on my side as I do not think the original intent was to allow everyone to overbore to 40-over or else there is NO NEED to reference a FRP at all.  All you have to say is that you may use up to 40-over pistons with the same specs as stock.  It could be that simple but it isn't.  I could also be wrong about this, and if I am, a re-write of the rules is needed.
I hope you are right.  It will allow me to rebuild using the same block when my .020 motor pops.

AB

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Funny I found my 93 ITCS and it has he same wording except the words exact equivalent is in bold print. I will continue to look for the earlier book or start shopping E-bay, but I owuld contend that a few people have been reading this wrong for a few years and it was never an issue until we got cars with no .040 pistons.

 

[Andy Bettencourt]

Interesting piece of history there. So are you saying...

- When the rules were written, everything was available with a 40-over option so the need to write a specific rule was not needed.

Now that everything ISN'T available .040, how do we make the leap that you can go 40-over when the rules say you must use a FRP or is exact equivilant?

While I am coming around to this logic, what other items in the GCR, should you apply it too, would you be opening up pandoras box?

AB

 

[Knestis]

I'll bet a six pack that the "exact equivalent" wording went into the rule after the .040 allowance was well established, but before modern times. I would guess about 1990, in response to "clever" people who DID push the rules beyond the intent that I honestly believe was in place at their creation.

K

 

[Joe Harlan]

Originally posted by Andy Bettencourt@Dec 13 2005, 11:33 AM
Interesting piece of history there.  So are you saying...

- When the rules were written, everything was available with a 40-over option so the need to write a specific rule was not needed.

Now that everything ISN'T available .040, how do we make the leap that you can go 40-over when the rules say you must use a FRP or is exact equivilant?

While I am coming around to this logic, what other items in the GCR, should you apply it too, would you be opening up pandoras box?

AB

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AAndy to give you a little more to ponder. I will have to confirm the specs today but back in the day Nissan offered .060 and .080 pistons for the L24 engines. I believe the .040 was a desired maximum to prevent this much displacement increase. But that is also just guessing cause I was busy kicking Darin's butt everyday too get to work on time in 1984.....

 

[Andy Bettencourt]

Originally posted by Joe Harlan@Dec 13 2005, 12:43 PM
AAndy to give you a little more to ponder. I will have to confirm the specs today but back in the day Nissan offered .060 and .080 pistons for the L24 engines. I believe the .040 was a desired maximum to prevent this much displacement increase. But that is also just guessing cause I was busy kicking Darin's butt everyday too get to work on time in 1984.....

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This piece of data would seemingly support the way I read the rule (in modern times). There is a limit and you must use FRP or their exacts.

AB

 

[Joe Harlan]

Originally posted by Andy Bettencourt@Dec 13 2005, 11:46 AM
This piece of data would seemingly support the way I read the rule (in modern times).  There is a limit and you must use FRP or their exacts.

AB

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Up to a .040 max even of the factory offers more...

 

[Greg Amy]

I'm reading along with an open mind...

Andy, the only issue I have with your last post is that I'm inferring that you're assuming 40-over was removed as a result of some discretion or some rule intent change. Based on this discussion, however, I'd be more inclined to believe that:

- Pretty much every car at the time this rule was written had 20 and 40 overbore pistons (Kirk)
- 40-over was set as a maximum in order to limit the amount of displacement increase. (Andy/Joe)
- Thus, the intent of the rule was to allow anyone to overbore to 40 max (Greg)
- Some time along the way "exact equivalent" was added (though I dispute this), or bolded, to clarify the intent of the rule (Joe) Remember, we assume at this point pretty much all cars could do that with factory parts.
- Modern cars, especially Japanese, started only offering 20-over pistons, putting us in the position we are now.

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? Joe pointed out the same verbiage is in the '93 ITCS, and lacking the "revision bars" we can assume it was there in '92; we're now down to within 8 years of the original book.

This is where the leap of logic fails me. Up to this point, most people - myself included - have accepted the unique ability to use aftermarket parts as a signal that 40-thou overbore is open to everyone. The only rational explanation for allowing aftermarket pistons is for those vehicles that cannot get them from the factory...if you give me a reasonable answer to this, I'd feel a whole lot better...

OK, so we gotta figure out where to go. My suggestion is we dump the "factory equivalent", let everyone go 040-max, and make sure the replacement parts are comparable to stock (Joe's reference to the new ITAC paragraph above may provide guidance...)

I'd sure like to see some 80's ITCS books, though... - GA

 

[Andy Bettencourt]

Originally posted by GregAmy@Dec 13 2005, 01:10 PM
I'm reading along with an open mind...

Andy, the only issue I have with your last post is that I'm inferring that you're assuming 40-over was removed as a result of some discretion or some rule intent change.

I don't see where it was removed. It is still in there and says you may use UP TO .040 slugs. Not understanding you here.

Based on this discussion, however, I'd be more inclined to believe that:

- Pretty much every car at the time this rule was written had 20 and 40 overbore pistons (Kirk)
- 40-over was set as a maximum in order to limit the amount of displacement increase. (Andy/Joe)
- Thus, the intent of the rule was to allow anyone to overbore to 40 max (Greg)
- Some time along the way "exact equivalent" was added (though I dispute this), or bolded, to clarify the intent of the rule (Joe) Remember, we assume at this point pretty much all cars could do that with factory parts.
- Modern cars, especially Japanese, started only offering 20-over pistons, putting us in the position we are now.

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? Joe pointed out the same verbiage is in the '93 ITCS, and lacking the "revision bars" we can assume it was there in '92; we're now down to within 8 years of the original book.

Because you don't have to mention bore. Each spec by manufacturer is different per the factory repair manual. What are you supposed to do, write .001, .002, .003 etc? You allow FRP's with a max of .040. That is what the rule says!

This is where the leap of logic fails me.  Up to this point, most people - myself included - have accepted the unique ability to use aftermarket parts as a signal that 40-thou overbore is open to everyone. The only rational explanation for allowing aftermarket pistons is for those vehicles that cannot get them from the factory...if you give me a reasonable answer to this, I'd feel a whole lot better...

You are right, if you can't get them, you can have them made. If Nissan stops making .040's for your NX2000, you can source them from the aftermarket. 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.

OK, so we gotta figure out where to go. My suggestion is we dump the "factory equivalent", let everyone go 040-max, and make sure the replacement parts are comparable to stock (Joe's reference to the new ITAC paragraph above may provide guidance...)

I'd sure like to see some 80's ITCS books, though... - GA

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That is a clarification to you because you are leaning on your historical assumptions. To me, it's rules creep. Now I have to go and spend $800 on .040 slugs to be on par with every other IT 1.8 Miata getting built when that isn't what the rules currently (or seemingly ever) say.

What is best for IT?

 

[Greg Amy]

(Heavy sigh...)

We're each going in circles, my friend, and they don't intersect...one last shot before I stop flogging.

I don't see where (verbiage) was removed.

OK, so you're assuming, as am I, that the verbiage has not changed since 1984? Then we at least agree on that. Now we need to agree on the original intent.

Because you don't have to mention bore.

If you're using "exact equivalent" pistons, you also don't have to mention dome/dish/valve relief configuration, ring thickness and spacing, pin height relationship, weight, and compression ratio. If you are restricted to running pistons that are exactly the same as ones supplied by the factory, then they have to be exactly the same and then there is no need to be so specific, UNLESS...

...you are offering to let people run alternately-supplied parts that may be exactly equivalent to factory overbore pistons, except for bore, the one important characterstic of an alternate piston that is specifically not listed (the "elephant in the room").

That is a clarification to you because you are leaning on your historical assumptions.

Of course I am! To do otherwise would be to allow any new guy to come around and re-interpret the rules to fit his particular situation and biases!

To me, (your position is) rules creep.

On this we agree. I feel the same about your position.

What is best for IT?

To not change the application of the rules as they have been done for over 20 years. - GA