48 replies to this topic

[Mike Collins]

It stops here.  I have been the Secretary for the SMAC for as long as I can remember.  Below is the rule set in question from the protest and appeal.  The SoM directed the CRB to address the rule as they felt it was unclear.  It is going to change.  We may have a chance to ask for how we would like the change addressed.  Comment below.  If your comment is not directly related to addressing the rule I will delete it.  There are others places on the forum for ranting or name calling.

 

The Red is what the Appeal was based on. The Green the Protest.

 

 

 

 

f. Cylinder Head

1. The gasket face of the cylinder head may be resurfaced provided the maximum compression ratio is not exceeded and the minimum height of the cylinder heads are main- tained. The minimum heights of the cylinder heads as measured in the factory service manual allowed are shown in the following table:

2. The cylinder head must not be ported, polished, or machined. The original casting must not be modified in any way or polished unless specified below.

3. The throat area of the port consists of the 90 degree angle at the very bottom of the cast steel valve seat as it transi- tions to the aluminum casting below. It is permitted to plunge cut the throats in order to correct for core shift that is commonly found in many cylinder heads. This cut cannot extend further than the specified number below from the bottom of the ferrous valve seat. There can be no tooling or machine marks in the head below this point. The area under the seat where the plunge cut ends and the casting resumes cannot be blended by hand, machined, or chemically processed to create a smooth transition. The 90 degree bend at the bottom of the valve seat and the aluminum directly below it will be measured with a gauge and must conform to the maximum diameters and depths listed below.

Model Year

Minimum Height (inches)

90-93 (1.6L)

5.245

94-05 (1.8L)

5.245

Engine

Maximum Intake Throat Diameter (inches)

Maximum Exhaust Throat Diameter (inches)

Maximum Throat Depth (from bottom of ferrous valve seat (millimeters)

 

1.6L                                     

1.095

0.948

12

1.8L

1.178

1.020

12

 

4. No aluminum in the bowl area (other than that specified for the plunge cut) or the ports may be removed, added, or manipulated for any reason. It is understood that heads may look slightly different from bowl to bowl due to casting irregularities. No material may be removed or added from the short turn radius in the port.

5. Unshrouding of valves is explicitly limited as follows: there must be a sharp edge where the valve relief cut meets the chamber. That edge must be present and unmodified. This area is not to be blended by hand, machined, or chemically processed to create a smooth transition. The maximum dimensions are listed below, measuring guide centerline to chamber edge:

Engine

Maximum Intake Valve Relief Cut radius (inches)

Maximum Exhaust Valve Relief Cut radius (inches)

1.6L

0.687 Radial

0.600 Radial

1.8L

0.760 Radial

0.675 Radial 

 

 

[Mike Collins]

Sorry for the table layout, they were correct in the preview....  They are not really relevant to this.  I may try to figure out how to edit it...

[Rob Burgoon]

Delete this line for starters. 

 

 No material may be removed or added from the short turn radius in the port.

 

 

 This line makes it redundant.

  No aluminum in the bowl area (other than that specified for the plunge cut) or the ports may be removed, added, or manipulated for any reason.

 

 

 Someone else can describe how to perform the plunge cut.

[Den]

 

there must be a sharp edge where the valve relief cut meets the chamber. That edge must be present and unmodified. This area is not to be blended by hand, machined, or chemically processed to create a smooth transition. The maximum dimensions are listed below, measuring guide centerline to chamber edge:

 

 

The more I read about it the more this seems to indicate that you are not allowed to deburr following the cut. Is this  correct?

[Glenn]

#4. No aluminum in the bowl area, short turn radius or the ports (other than that specified for the plunge cut), may be removed, added, or manipulated for any reason. It is understood that heads may look slightly different from bowl to bowl due to casting irregularities. To clarify: No material may be removed, added or manipulated from ANY part of the chamber other than the material specifically removed from an otherwise legal plunge cut.

[38bfast]

I believe two sections should be included with dementions and GD&T call outs for tollarance.

[Todd Green]

Apparently someone edited my post to the point it made no sense, so I've removed the rest of it.  But the main point was that I liked Glenn's wording, but I'm hardly an engine expert, so take this with a grain of salt.

[Bench Racer]

Mike, from my reading the .3. and .4. rules, it seems time to ask Mazda for the OEM plunge cut process. Why, because from my minimual looking at heads plunge cut, I visually see no massaging the edge of the plunge cut to the parrent material.  < I view that as a primary goal, other wise massage control at the edge of the plunge cut to the parrent material is lost at the get-go.There is also information we need with reference to the OEM diameter of the plunge cut. Is material during the OEM plunge cut always removed from the approx 1/8 inch below the valve seat at the short turn radius? < Very important in clarifying the plunge cut diameter. If the engine builders have this information, please share. The engine builders could also share a description/pictur of their plung cut tool. Mazda has a considerable amout of skin in this game. I have a call in to Mazda Motrosports at the moment. I also have a phone message to my son who is the OEM manager for Gurhing Drill (tool manufacture) USA. They provide round machiningg tools to many world wide auto engine manufactures.

I will contribute to the rule clarification after I obtain knowledge of the OEM plunge cutter, OEM diameter dimensions and the Mazda plunge cut process. Please, don't anyone believe me wanting this info is un-called for. I could TODAY plunge cut and the cut would fall within ALL the existing rules. Would be ta tad more costly, but the end job would meet all the rules. And the plunge cut would not be completed by hand or a rotating tool. The folks with an understanding of manufacturing metal parts know the process I'm talking about. Want to know the process, please send a pm. 

 

David Dewhurst

SCCA # 250772

[Ron Alan]

I like what Rob wrote. I like what Glenn wrote...either works IMO. I also feel the current wording is completely clear...though apparently that is just me

[Bench Racer]

I like what Rob wrote. I like what Glenn wrote...either works IMO. I also feel the current wording is completely clear...though apparently that is just me

And what do we do with the Spec Miata engine builders that massage the material at the edge of the plunge cut and the parent material. Or are we better off investigating for a plunge cut tool that functions as the OEM Mazda too and many other head manufactures world wide that plunge cut ( some call it throat cut) with zero massaging the material at the edge of the plunge cut and the parent material.

[Danny Steyn]

I like Glen's version.

[Glenn]

I like Glen's version.

So the BIG question is when we close this rule, what rule do the builders attempt to pervert next.........

[Jamz14]

Bench,

Head builders are perfectly capable of selecting a tool that does not violate the rules. Give them the parameters ( and they have been) and let them achieve it in the way the professionals best see fit. My opinion.

James

[Bench Racer]

Being I'm not a engine builder/machinest this information may come off a bit naive, so be it, it is presented as knowledge. Some items require detailed identification.

Within .4. of the rule, Short Turn Radius is used. Witin posts those words leave a lot of question marks. If one opens address   http://www.austincc..../headdesign.htm  and scrolls down to figure 2 there is a very good cross section showing a valve, the bowl, the Short Turn Radius and the intake runner. Within rule .3. the words 90* angle are used to partially identify the words Short Turn Radius. The correct trigonometry definition of the 90* angle which truly is not 90*, is the external angle (surface). Viewing figure 2 the bowl inside diameter surface extending from the inside diameter of the valve seat is one line of the external angle with the runner surface being the second line of the external angle.

 

My previously mentioned OEM tool source from my first post in this thread has provided a pdf file which shows a series of views showing the many different tools/head cross sections from OEM head manufacturing including the plunge cut tool which in the OEM world is called the throat cut. Have permission to, but don't have the skills to transfer the pdf file to this post. In the Runoffs thread folks were tossing about thoughts on tools. The tool used is a round tool shaped similar to the valve bowl with a double fluted tool with the flutes 180* apart and it leaves zero requirement to massage any head surface it has machined. No burrs remaining.............. No machining around the Short Turn Radius/external angle corner into the runner.

 

There are a couple high end engine manufactures that do machine around the Short Turn Radius/external angle corner into the runner.

 

It would seem when OEM throat cut maching is complete the throat cut is a full 360* diameter below the valve seat. Because the OEM throat cut is finished a full 360*, It would be logical that per our rule as long as the throat cut is machined to the maximum rule specification diameter and depth a full 360* cut would be legal.

 

Because of the technical capability of EOM throat cut tools to leave no burrs/loose machined material, after market engine builders should be capable of using a tool which leaves no burrs/loose machined material. Hence no massaging the machined finish line of the plunge cut and the parent material.

 

Hopefully there is added value within this post.

 

Mike, Glen, Whoever, use the info to clarify the existing rules .3. and .4. 

 

That's it untill Monday, the Miata needs attention for the weekend.

 

David Dewhurst

 

 

[Bench Racer]

Bench,

Head builders are perfectly capable of selecting a tool that does not violate the rules. Give them the parameters ( and they have been) and let them achieve it in the way the professionals best see fit. My opinion.

James

This is not a flame. ^ So says you. Because I'm not an engine builder and because engine builders are being very quite and secerative/protective with their tools and capabilities, my attempt is to provide info to support the rule clarity being worked on today. How many engine builders are on the surface/thread are being part of the rule process??? If one does not understand the throat cut process at the OEM level and why the OEM level heads have zero burr without massaging, where do we start. From posted info, Runoffs engines had massaged material at the throat cut/parent material. Was that massaging by engine builder because the engine builders have issues doing throat cut leaving burrs/loose material or was the material massaged for other reasons??? James, within this post there are two questions for you to answer.

 

As I stated in the previous post, my Miata needs attention for the weekend, say by untill Monday.

[bones240z]

I don't see the ambiguity of the rules as written but I like Glenn's version. My opinion, whatever rule set we come up with, don't let rule creep make non-compliant heads compliant. 

[Bench Racer]

A couple items to consider within the clarified rule .3. To eliminate some of the far out suggestions with reference to plunge cut tools/ machining process, insert into the rule, the plunge cut tool while preforminh it's function will rotate about the longitude centerline axis of the valve stem. Also, along with there will be no massaging the plunge cut machined finish line of the plunge cut and the parent material there will be no massaging within the the area machined by the plunge cut.

 

Defining/inserting furter during rule clarification will elinminate dark gray areas, less interpertation of the rule. Yup, more pages of rules, but the more pages of rule is brought to be by rules which are left opended and those that exploited the current rule.    

[Steve Scheifler]

This is from the second half of a post in the other thread, but since this is the unofficial rules topic I am duplicating those comments here.

As for exactly what should be done about the rules, I don't know that I have enough information yet. But something that has been said by others a couple times and rings true for me is, step back and set aside the issue of the Runoffs and all the questionable heads that may be out there, and focus on what makes the most sense going forward. That isn't to say the people stuck with those heads don't matter, but first craft the best possible rules, consistent with the spirit and goals of the class, clear, specific and documented so a conscientious car owner can check their own, and yet not so restrictive that a tired old stock head is at risk of failing. I honestly don't know if that's even all possible at the same time, but getting as close as possible seems like step 1. If it turns out that best possible rule leaves the class with hundreds of non-compliant heads then the next step is to deal with that. There aren't many options really: Accept that they are not compliant and leave everyone to deal with it as best they can; Let them run with a weight penalty; Deviate from the "ideal" rules to incorporate at least some of them.

I've never been particularly sympathetic to people caught breaking the rules, even if they have a degree of plausible deniability. I also realize that very few drivers are in a position to have even the remotest idea that something like this is in their engine. But I'll always end up having more sympathy for the poor schmucks that don't fuel the endless arms race by plunking down big money for magical pixie dust and blindly trust that whatever they are buying will pass tech one way or another. It certainly does not seem reasonable that the guys who did nothing wrong should end up with the short end of the stick on this deal.

So at the moment, pending more details of what's actually out there, I would craft the best rule possible going forward, and in my mind that is probably very, very minimal allowance for taking the edge off any cuts. Then I would estimate and write specs with a specific definition and dimension limits for this "blending" to cover most existing heads. Essentially write that rule as you would if the decision were to "make them all legal", but then assign a weight penalty as is done for an overbore. In this case though there must be no doubt that the penalty weight at least offsets the best-case gains from the allowed modification so as to avoid any chance that the builders will determine they can still get a net gain by pushing it to the limit and taking the weight.

That combination seems the only way to move the main rule set closer to the ideal, avoid placing any new burden on those who are following the rules, not reward those who have broken the rules, and give anyone who has unwittingly purchased a non-compliant head the option to race without additional expense if they are unable to work something out with their builder. There are no clear winners that way but also no clear losers, which I think is the best that can be achieved from this embarrassing debacle.

[john mueller]

I sent this out to the drivers registered for the 2014 NASA Western Champs.  It may not be the ultimate answer but for right now it works for NASA.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

SM Driver;

Given all that has happened in our community over the past 10 days, I just wanted to send a quick email to touch base.

 

The plunge cut protest at last week’s Runoffs has had my phone and email rather busy for days.  I’ve been gathering info and working with some great folks (thanks Craig) to come up with a way to make it work best we can given the time frame and complexity of the issue.  So, for the 2014 NASA Western Championship we’re leaning toward this:

• There will be an a moratorium on “plunge cut protests” for the Western Champs and the remainder of the NASA season.
• NASA Tech will still inspect the plunge cut just as we would normally when the valves are out of the head.  Tech will act accordingly based on NASA’s clarification of the rule.
• The Clarification will allow some deburring but not egregious blending.  My goal is to have illustrations and photos to help make our interpretation of the machining process less subjective.

 

I’m still working on the wording of NASA’s clarification and should have something out to you and have it published somewhere on NASA’s website and/or Facebook page(s) hopefully by the middle of next week.

 

Please feel free to reply to this email if you have specific questions about this or anything else regarding tech and this year’s Western Champs.

[Glenn Davis]

#4. No aluminum in the bowl area, short turn radius or the ports (other than that specified for the plunge cut), may be removed, added, or manipulated for any reason. It is understood that heads may look slightly different from bowl to bowl due to casting irregularities. To clarify: No material may be removed, added or manipulated from ANY part of the chamber other than the material specifically removed from an otherwise legal plunge cut.

 

Would this not start the head search again?  I would want that one in a thousand head where all the plunge cuts line up the best with the specific casting.  I think defining the cut boundary (45 degrees and </= 2mm?) would be a better way to equalize the vast majority of heads.