IT Piston Rules - Overbore

Banzai240

Banzai240

New member
OK guys... In researching some questions concerning IT pistons, I've come up with the following:

17.1.4.D.1.j - "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."

We can really stop there, and here is why...

"Engines may be bored to a maximum of .040 inch over standard bore size."

It doesn't say "shall", or "you have to"... it says you MAY...

"Factory oversize replacement pistons or their exact equivalent shall be used."

The "shall" MANDATES that you WILL, should you decide to overbore up to the allowed .040" over, use FACTORY or THEIR EXACT EQUIVALENT pistons... If factory pistons in .040" are not available, then this means you are out of luck in this department... You can only use an overbore that the factory supplies a piston for... PERIOD. That's exactly what the rule says...

Now, this is NOT affected by the allowance to obtain stock replacement parts from sources other than the manufacturer, because an overbored piston would NOT BE STOCK! It would NOT be a stock replacement part. That, again, is exactly what the rule says...



So, in my humble opinion, here is what I think:

1) You may bore your engine up to whatever size the factory supplies oversized pistons, up to the maximum of .040".

2) You may use either a FACTORY oversized piston, or it's exact equivalent... If the factory does NOT supply an oversized piston, or only supplies it up to .020", or .030", etc., then THAT is the maximum size you are allowed to use.

3) You may NOT have a .040" piston made if the factory does not supply one as well... If they do supply one, then you can make it's equivalent, but it must be an exact equivalent...

This is how the rules read. I see no allowance to create a .040" overbored motor in a case where the factory does not supply an oversized piston. Obviously, this means that not all car can take advantage of the full .040"... some may be limited to .020", .030", etc...

OK, fire away... show me where the holes are... I don't see any other way to read this... It is written... ;)
 
I don't see it that way at all. The key being "or their exact equivalent". If you couldn't use an alternate the rule should read, "Factory oversize replacements shall be used." To me that means if you go to .040 on the overbore and can find exact equivalent pistons that match factory specs you are good to go.
 
Originally posted by Banzai240@Nov 16 2005, 04:29 PM
OK, fire away...  show me where the holes are...  I don't see any other way to read this...  It is written...  ;)
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Okay, I'll bite. What car does this concern, it has to be a certain car somewhere for it to show up. I know it isn't the Jensen, even though I no longer have a factory I can still get 0.040" over factory pistons.

R
 
I agree with drew, when I read that rule my interpitation meant you could use a .040 overbore piston size that had the exact dome, valve clearance and specs as a factory replacement standard size piston.
 
Originally posted by Banzai240@Nov 16 2005, 11:29 AM
OK guys...  In researching some questions concerning IT pistons, I've come up with the following:

17.1.4.D.1.j - "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."

We can really stop there, and here is why...

"Engines may be bored to a maximum of .040 inch over standard bore size."

It doesn't say "shall", or "you have to"... it says you MAY...

"Factory oversize replacement pistons or their exact equivalent shall be used."

The "shall" MANDATES that you WILL, should you decide to overbore up to the allowed .040" over, use FACTORY or THEIR EXACT EQUIVALENT pistons...  If factory pistons in .040" are not available, then this means you are out of luck in this department...  You can only use an overbore that the factory supplies a piston for...  PERIOD.  That's exactly what the rule says...

Now, this is NOT affected by the allowance to obtain stock replacement parts from sources other than the manufacturer, because an overbored piston would NOT BE STOCK!  It would NOT be a stock replacement part.  That, again, is exactly what the rule says...

So, in my humble opinion, here is what I think:

1)  You may bore your engine up to whatever size the factory supplies oversized pistons, up to the maximum of .040".

2)  You may use either a FACTORY oversized piston, or it's exact equivalent...  If the factory does NOT supply an oversized piston, or only supplies it up to .020", or .030", etc., then THAT is the maximum size you are allowed to use.

3)  You may NOT have a .040" piston made if the factory does not supply one as well...  If they do supply one, then you can make it's equivalent, but it must be an exact equivalent...

This is how the rules read.  I see no allowance to create a .040" overbored motor in a case where the factory does not supply an oversized piston.  Obviously, this means that not all car can take advantage of the full .040"... some may be limited to .020", .030", etc...

OK, fire away...  show me where the holes are...  I don't see any other way to read this...  It is written...  ;)
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To me it's simple.
If the factory for example only has a .020" piston set, you can have pistons made to .040" as long as they are exactly the same as the dimensions of the factory .020" piston (other than the bore size). The rings must also be the same as the factory rings in all aspects.
dj
 
Originally posted by Banzai240@Nov 16 2005, 11:29 AM
17.1.4.D.1.j - "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."
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I think I see what you are getting at in that their refers to factory oversize replacement pistons. If no .040 factory oversized replacements were ever made and you take exact equivilant to mean all dimensions, including bore size, than a .040 over piston would not be legal. The big assumption is what exactly is the definition of exact? If it refers to every dimension including bore size than you might have something.

The bigger question is does this really matter? The standard interpretation up to this point seems to be anything up to .040 over is allowed. If you are trying to make a case for reigning that back in to only applications where the factory made .040" over than a few things happen. Some people suddenly realize they are illegal and have to go through a lot of expense to fix the issue (new pistons, block, rings, etc) and if the process that has been used for classification assumes overboring than suddenly every car is theoretically open to reclassification. I don't think we want to go down either road.

I think in actuallity the wording didn't quite match up with the intent which means change the rule or live with it based on the idea that most people already interpret the rule as desired. Some would say it is better to leave it as is rather risk new wording having unintended consequences. Unless there is a particular case you are looking at this seems like a non-issue, at least compared to the bigger fish the ITAC is trying to fry. Maybe you have too much free time? :)
 
Originally posted by Drew Aldred@Nov 16 2005, 04:48 PM
I don't see it that way at all.  The key being "or their exact equivalent". 
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How can you have an "exact equivalent" of a factory piston that isn't available? Not possible...


To me that means if you go to .040 on the overbore and can find exact equivalent pistons that match factory specs you are good to go.
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Same question as above...


So, if based on your interpretation, you are saying that the .040" piston would have to be dimensionally identical to the "factory replacement" with the exception of bore diameter??? That would include weight, ring sizes, etc..???

I don't see how you can compare something as to it's "equivalentness" to something that doesn't exist...

Again, I'm just going by the exact words in the ITCS, which says very specifically what is allowed...

And, to address the question of a factory not being available anymore (Jensen)... THAT is why the "exact equivalent" line is there, in my opinion... Find out what Jensen used to offer, and you can have THOSE made, based on the rules...

"May"... "Shall"... It's all very specific, and I still don't see how what you guys are suggesting "is" legal is legal...
 
It seems we have had this discussion before (along with one for forged replacements).

I also remember the argument whether the over bore could be bigger because a replacement piston exactly .o40 was available.

I would not worry about it. You can have a piston made to fit a .040 overbore (and even have it of a forged variety) that is otherwise dimensionally the same as the OEM piston. However, you may want to consider that if the factory did not go to a .040 replacement, perhaps they are telling you the block may not take it.

Cheers.
 
Originally posted by Banzai240@Nov 16 2005, 06:28 PM
How can you have an "exact equivalent" of a factory piston that isn't available?  Not possible...
Same question as above... 
So, if based on your interpretation, you are saying that the .040" piston would have to be dimensionally identical to the "factory replacement" with the exception of bore diameter???  That would include weight, ring sizes, etc..???

I don't see how you can compare something as to it's "equivalentness" to something that doesn't exist...

Again, I'm just going by the exact words in the ITCS, which says very specifically what is allowed...

And, to address the question of a factory not being available anymore (Jensen)...  THAT is why the "exact equivalent" line is there, in my opinion...  Find out what Jensen used to offer, and you can have THOSE made, based on the rules...

"May"... "Shall"...  It's all very specific, and I still don't see how what you guys are suggesting "is" legal is legal...
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Engines may be bored to a maximum of .040 inch over standard bores size.  Factory oversize replacement pistons or there exact equivalent shall be used.  Cast or forged equivalent pistons shall provide the same dome/dish/valve relief configuration, ring thickness and spacing, pin height relationship, weight, and compression ratio as the factory replacement oversize pistons.  Piston rings are unrestricted. 
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If what you're saying is the way the rule is supposed to read then it's not clear from the rule. I know it says exact equivalent but then it mentions that the "dome/dish/valve relief configuration" etc shall be the same as factory oversized pistons. It pretty much mentions everything but the bore size of the piston. If that's what the rule is supposed to mean why was it the only thing left out? IMO, I think there's a hole in that rule if that's the way it's supposed to read. If the bore size is NOT allowed to be bigger than what was offered from the factory then it would be a very simple addition. You could just add it in to the current things it mentions must be equivalent.

And while I don't think it's a bad thing that forged pistons are allowed, but I think that opens up the door to a lot of things also. Good luck ever getting a forged piston to weigh as much as a factory cast piston. It's always going to be lighter. And are guys building engines because they know the forged pistons are lighter? I would bet a lot on it. And though the rule does specifically say that the weight shall be equivalent, what exactly is equivalent? Is it within .0001 grams, 1 gram, 10, 100 grams? Would they win if someone protested and the forged piston was noticably ligther? Well, with they way the rule currently reads I think they should. Why/how? Well, a forged piston isn't available from the factory. You would be hard pressed to keep equivalent dimensions to a factory cast piston, so naturally the weight is going to be less. If you add to the dimensions to make the forged piston the same weight, you're breaking the rules because the dimensions are not equal to the factory cast. So, while it definitely strays from the intent of the rule big time, I bet the guy with the lightweight forged piston would win because with the ruleset there would be no way to get BOTH equal weight AND dimensions. This is another big hole I think and actually a good way to squeeze a few more ponies out of a motor. Do I think it should be that way? Absolutely not. Do I think the guy that does it would and should win a protest? Yes, based on the way the rule reads.

I realize how hard it is to plug all the holes in a rule, but when every dimension of a piston is mentioned except the bore size and the bore size isn't supposed to be larger than what the factory offered, to me that's a pretty obvious hole. If it's not supposed to be that way, add two words to the rule (, bore size, ) and you've plugged it. But, the forged piston is another hole.

I know you can't win, but i don't know the intent behind allowing forged pistons so I don't wanna argue against it without knowing the background, but i think it does allow an advantage.

Now, don't get me started on adding a resistor inline to a sensor rule. I don't even know why that one is there. Yes, I believe a wire is a resistor.

Darin, I don't mean this a shot to you at all in any way. I really support and advocate what you guys are doing. I consider myself straight as an arrow and always look for the intent of the rule instead of the way it reads. In my HONEST opinion, I would never have read that to mean that I CAN'T use .040 over pistons if they weren't made from the factory. If the aftermarket had a .040 over piston available with the same dome/dish, valve relief config, ring spacing etc I would totally assume it was legal and within the intent of the rule. While I may not agree with someone else's interpretation because they may have strayed from what I would consider the intent of the rule. I may agree that they should win a protest based on the wording. If there's a hole there and someone exploits it, which we know is going to happen and does, then they didn't necessarily doing anything wrong. They did inside what the rule said. Like I said I may not agree that they followed the intent of the rule, but the way the rule can read I would support that they win the protest. I think the holes need to be plugged.

I guess a good way to look at the rules is like tax laws. While the government doesn't always agree with the way someone uses the laws, they realize there may have been a hole in it and need to plug it.

steve
 
DJ,

I understand what you're saying. Change the rule to read, "Factory oversize replacement pistons shall be used." Period. That would end any confusion or gray area.

miss ya on the prod page....... B)
 
Originally posted by Drew Aldred@Nov 16 2005, 01:50 PM
Change the rule to read, "Factory oversize replacement pistons shall be used."
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I disagree.

I do not believe the original intent of the rule was to limit builders to what the factory offers or what the service manual recognizes. This is supported by the facts described above, where specific requirements of replacement pistons are offered. If the rule was intended to limit the rules to factory oversized pistons, then your recommendation would follow; the rule would read "Factory oversize replacement pistons shall be used", there would be no need for specifics and/or aftermarket allowances.

I am confident that the original intent of the rules was to allow anyone to overbore their engine to a maximum of +0.40". Recognizing that some manufacturers do not provide 40-over pistons, the rulesmakers allowed aftermarket sources (which was on of the only legal aftermarket replacement parts technically allowed in IT until this year) while specifically indicating via the specs requirements that this rule could not be used to install pistons that did not meet factory specs other than bore size. It's the only logical explanation for the wording of the rules.

There are some out there who believe that the lack of a factory .040" oversize factory piston to which to compare the aftermarket one thereby relieves them from the "equivalence" requirement. Hogwash. These folks then decide that since they are not required to be equivalent to a non-existent piston then they can make them super light and/or change the specs as listed in the ITCS; this makes absolutely no logical sense. The day that an engine builder tries to convince me that a larger, .040" overbore piston is allowed to be lighter and/or have different ring sizes than a factory standard piston is the day I laugh in their face and call them idiots.

Don't throw the baby out with the bathwater on this one. If you find guys making pistons with different ring sizes and/or lighter than the factory pistons, throw the book at them. But don't take away legitimate allowed modifications from the rest of the field because a select few people want to play word games with the rules.

Greg Amy
 
Originally posted by GregAmy@Nov 16 2005, 08:17 PM
I disagree.

I do not believe the original intent of the rule was to limit builders to what the factory offers or what the service manual recognizes. This is supported by the facts described above, where specific requirements of replacement pistons are offered. If the rule was intended to limit the rules to factory oversized pistons, then your recommendation would follow; the rule would read "Factory oversize replacement pistons shall be used", there would be no need for specifics and/or aftermarket allowances.

I am confident that the original intent of the rules was to allow anyone to overbore their engine to a maximum of +0.40". Recognizing that some manufacturers do not provide 40-over pistons, the rulesmakers allowed aftermarket sources (which was on of the only legal aftermarket replacement parts technically allowed in IT until this year) while specifically indicating via the specs requirements that this rule could not be used to install pistons that did not meet factory specs other than bore size. It's the only logical explanation for the wording of the rules.

There are some out there who believe that the lack of a factory .040" oversize factory piston to which to compare the aftermarket one thereby relieves them from the "equivalence" requirement. Hogwash. These folks then decide that since they are not required to be equivalent to a non-existent piston then they can make them super light and/or change the specs as listed in the ITCS; this makes absolutely no logical sense. The day that an engine builder tries to convince me that a larger, .040" overbore piston is allowed to be lighter and/or have different ring sizes than a factory standard piston is the day I laugh in their face and call them idiots.

Don't throw the baby out with the bathwater on this one. If you find guys making pistons with different ring sizes and/or lighter than the factory pistons, throw the book at them. But don't take away legitimate allowed modifications from the rest of the field because a select few people want to play word games with the rules.

Greg Amy
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Greg, I agree with everything you said. I read the intent as to allow .040 pistons no matter if the factory made them or not. Just wanted to clarify. In my post I meant if they're not supposed to be allowed the rule certainly doesn't read that way.

steve
 
Greg,

I totally agree with your above statement. I was trying to say if the rule was meant for only factory pistons, the part of "exact equivalent" should have been left off.

Good discussion, continue on.
 
Originally posted by Banzai240@Nov 16 2005, 11:28 AM
How can you have an "exact equivalent" of a factory piston that isn't available?  Not possible...
Same question as above... 

"May"... "Shall"...  It's all very specific, and I still don't see how what you guys are suggesting "is" legal is legal...
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So was this taken into account for the HP potential when a car is classed? An engine with no factory overbore sizes being allowed will definetly lower the potential that one can legally access by this interperatation.

James
 
Originally posted by Z3_GoCar@Nov 16 2005, 04:51 PM
So was this taken into account for the HP potential when a car is classed?  An engine with no factory overbore sizes being allowed will definetly lower the potential that one can legally access by this interperatation. 

James
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you mean like a rotary :D
 
OK so if the factory doesn't have a 040 piston as an example then how do you determine weight for the replacment? In a protest How do you determine ring thickness and spacing with no original replacement part to compare to? Believe it or not I have 1 stock rod 1 040 piston as samples for every IT engine I build. Maybe I am going to far to be legal?
 
Originally posted by Joe Harlan@Nov 16 2005, 03:50 PM
...then how do you determine weight for the replacment?
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I think a non-tortured, common sense measurement would be "no less than stock", especially given it's physically impossible to make a same-as-stock-but-larger piston weigh less.

How do you determine ring thickness and spacing with no original replacement part to compare to?
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That's pretty obvious, isn't it?
 
Originally posted by GregAmy@Nov 16 2005, 04:39 PM
I think a non-tortured, common sense measurement would be "no less than stock", especially given it's physically impossible to make a same-as-stock-but-larger piston weigh less.
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Is it? Your telling me I can't get a .040 weisco lighter than a stock KA24 piston?

That's pretty obvious, isn't it?
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Obvious to me, Yes Obvious to the COA,? Rules don't get written for me rules are writtenfor those that enforce them. As an SIT I can tell you the book says you enforce them as written.
 
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