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January 2016 Prelims

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#1
pfrichardson

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are posted:

http://www.scca.com/.../cars-and-rules



#2
Johnny D

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http://cdn.growasset....pdf?1449506044

NOTE: This preliminary version of the Club Racing Technical Bulletin is provided at this time as a service to the membership. These items may be corrected and will not be official until published on the Fastrack page of the scca.com website on or about December 20.

Spec Miata
1. #17927 (Dan Tiley) Please Add Tolerance Specification to Engine Stroke Requirement
In SM, make the following changes:
Mazda MX-5 / Miata (90-93):
Bore x Stroke: 78.0 x 83.604 1597 or alternate 78.25 x 83.604
Mazda MX-5 / Miata (94-97):
Bore x Stroke: 83.0 x 85.004 1839 or alternate 83.25 x 85.004
Mazda MX-5 / Miata (99-00):
Bore x Stroke: 83.0 x 85.004 1839 or alternate 83.25 x 85.004
Mazda MX-5 / Miata (01-05):
Bore x Stroke: 83.0 x 85.004 1839 or alternate 83.25 x 85.004


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#3
Johnny D

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Recommended Items for 2016

SM
1. #18236 (Jason Isley) Update the Muffler Rule
Thank you for your letter. Change 9.1.7.C.1.m.4.c:
No expansion chambers. A single Up to two muffler(s) may be added. The muffler(s) shall not exceed a maximum length (parallel to the longitudinal centerline of the car) of 34 inches. The muffler(s) shall not exceed a maximum width of 24 inches (parallel to the lateral centerline of the car). In addition, the sum of the length and width of the muffler(s) shall not exceed 40 inches.


What Do You Think ?

SM
1. #18342 (Ralph Provitz) Allow Turn Signal Removal in the 94-97 1.8
The CRB is seeking feedback on the following. Please respond through the CRB letter system, www.crbscca.com.
Input is requested from racers on parity for the 94-97 model year cars. Is there a parity issue? Are the cars currently competitive?
Option of weight/restrictor plate adjustment, and/or allowing similar changes as the 1.6 cars recently received, but only if needed.


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We have a Winnah! - Won their 1st race... Congratulations! Beta-Tester - Assisted us with beta testing the website. Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver Novel Approach - When a paragraph simply won't do... Survive the 25, NASA Thunderhill - Survive the 25, NASA Thunderhill Instigator - Made a topic or post that inspired other Make it Rain - Made Paypal donation of $100+

#4
Johnny D

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In addition, the sum of the length and width of the muffler(s) shall not exceed 40 inches.


Ok, who's got their 40" wide muffler at home ready to go ??
J~
2011 NASA Western Endurance Racing Championship E3 Champ
We have a Winnah! - Won their 1st race... Congratulations! Beta-Tester - Assisted us with beta testing the website. Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver Novel Approach - When a paragraph simply won't do... Survive the 25, NASA Thunderhill - Survive the 25, NASA Thunderhill Instigator - Made a topic or post that inspired other Make it Rain - Made Paypal donation of $100+

#5
Erik Hardy

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Ralph - When Bruce ran both NA/NB cars, did the data suggest the NA1.8 needed some help on straight line performance? I really can't comment because my car isn't what it could be and well, yours is.


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#6
B(Kuch)Kucera45

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Im still going to ask Santa for a header ! Lol :)
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Kuch
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#7
38bfast

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From all the data I have collected the 1.8 seems to be in the same boat as the 1.6. Just a fuzz off par.
Ralph Provitz
V2 Motorsports

#8
RWP80000

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Spec Miata
1. #17927 (Dan Tiley) Please Add Tolerance Specification to Engine Stroke Requirement
In SM, make the following changes:
Mazda MX-5 / Miata (90-93):
Bore x Stroke: 78.0 x 83.604 1597 or alternate 78.25 x 83.604
Mazda MX-5 / Miata (94-97):
Bore x Stroke: 83.0 x 85.004 1839 or alternate 83.25 x 85.004
Mazda MX-5 / Miata (99-00):
Bore x Stroke: 83.0 x 85.004 1839 or alternate 83.25 x 85.004
Mazda MX-5 / Miata (01-05):
Bore x Stroke: 83.0 x 85.004 1839 or alternate 83.25 x 85.004

 

It looks like an intended "inch" tolerance spec allowance of 0.004 was mistaken in the above as being a metric (mm) specification.

 

A 0.004 mm allowance is less than .0002 inch whereas a 0.1 mm tolerance would be 0.0039 inch.  This would in reality round to .004 inches in all practical tech shed measurements (example 85.000=3.346447 inches, while 85.100=3.350384 inches and 85.004 mm = 3.346604 inches).

 

The 3.346447 would round to 3.347 (as would the 3.346604) while the 3.350384 would round to 3.350 for a net dial indicator tolerance allowance of 0.003 inches on the typical 0.001 inch graduated dial indicator found in tech.  Having a rule that only allows for a .0002 inch (rounded) allowance on a specification measured with a tool typically having 0.001 inch graduations does not make sense.

 

While 0.003/.004 may seem as a overly generous allowance, it is not out of the reality of what can and has been seen to occur in the field with the undersized crank journals which are allowed.

 

Rich Powers


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#9
Erik Hardy

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Woooo fuzzies. My estimate of a v2 fuzzz on a long straight is 0.7-1mph = 2.5-4hp = 2mm bigger restrictor? Howd I do :)
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#10
Marc Cefalo

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Ok, who's got their 40" wide muffler at home ready to go ??
J~

DDG probably still has a "suitcase" muffler lying around from the last time i was there.....


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#11
Johnny D

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DDG probably still has a "suitcase" muffler lying around from the last time i was there.....


I was thinking more folding card tableish, no legs  :)

 

Are they going to have a max thickness of 40" too :)

 

And it's a muffler, not a diffuser, those fins every 5" are to strengthen it.  :)

J~


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#12
Jim Drago

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.004 in stroke variance from Mazda barely covers what I have measured.. Never on all throws however. I have seen .002-003 over on several lobes on different crankshafts. IMO this should never result in a dq, however with the way tech is instructed to enforce the rules, there is no tolerance and there needs to be a tolerance if the rule is applied with no discretion.

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#13
Johnny D

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.002-003, .004 is inch or metric ?
2011 NASA Western Endurance Racing Championship E3 Champ
We have a Winnah! - Won their 1st race... Congratulations! Beta-Tester - Assisted us with beta testing the website. Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver Novel Approach - When a paragraph simply won't do... Survive the 25, NASA Thunderhill - Survive the 25, NASA Thunderhill Instigator - Made a topic or post that inspired other Make it Rain - Made Paypal donation of $100+

#14
Johnny D

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Official Jan

 

http://cdn.growasset....pdf?1450468295

Recommended Items for 2016
SM
1. #18236 (Jason Isley) Update the Muffler Rule
Thank you for your letter. Change 9.1.7.C.1.m.4.c:
No expansion chambers. A single Up to two muffler(s) may be added. The muffler(s) shall not exceed a maximum length (parallel
to the longitudinal centerline of the car) of 34 inches. The muffler(s) shall not exceed a maximum width of 24 inches (parallel to
the lateral centerline of the car). In addition, the sum of the length and width of the muffler(s) shall not exceed 40 inches.


"the sum of the length and width of the muffler(s) shall not exceed 40 inches."  :scratchchin:

 

J~


2011 NASA Western Endurance Racing Championship E3 Champ
We have a Winnah! - Won their 1st race... Congratulations! Beta-Tester - Assisted us with beta testing the website. Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver Novel Approach - When a paragraph simply won't do... Survive the 25, NASA Thunderhill - Survive the 25, NASA Thunderhill Instigator - Made a topic or post that inspired other Make it Rain - Made Paypal donation of $100+

#15
Chris D.

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Recommended Items for 2016

SM
1. #18236 (Jason Isley) Update the Muffler Rule
Thank you for your letter. Change 9.1.7.C.1.m.4.c:
No expansion chambers. A single Up to two muffler(s) may be added. The muffler(s) shall not exceed a maximum length (parallel
to the longitudinal centerline of the car) of 34 inches. The muffler(s) shall not exceed a maximum width of 24 inches (parallel to
the lateral centerline of the car). In addition, the sum of the length and width of the muffler(s) shall not exceed 40 inches.
 

 

 

OK, I'm a little slow......can someone explain the reason behind this a little more?   Just looking for some understanding as to what the benefits might be.


Chris Dilluvio

Farmington Hills, MI


#16
Jim Drago

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OK, I'm a little slow......can someone explain the reason behind this a little more?   Just looking for some understanding as to what the benefits might be.

A few years back, someone built a "muffler" that acted as a diffuser. It filled up the entire area in front of the rear bumper which acts like a parachute. So the next year, the muffler dimensions were spec'ed

Jim


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NASA Champs Winner - NASA Champs Winner Hoosier Super Tour points Champion - Hoosier Super Tour points Champion ARRC Champion - Won the ARRC Race in a Spec Miata Series Champ - Won a points based series in a Spec Miata BFG Supertour Winner - Majors Winner - Circuit of the Americas Winner - We have a Winnah! - Won their 1st race... Congratulations! June Sprints winner  - June Sprints winner June Sprints winner  - June Sprints winner June Sprints winner  - June Sprints winner June Sprints winner  - June Sprints winner SCCA National Champion - Won SCCA Runoffs at Road America SCCA National Champion - Won SCCA Runoffs at Road America

#17
Chris D.

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Ok, got it. Thanks for the explanation Jim.
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Chris Dilluvio

Farmington Hills, MI


#18
Dan Tiley

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Spec Miata
1. #17927 (Dan Tiley) Please Add Tolerance Specification to Engine Stroke Requirement
In SM, make the following changes:
Mazda MX-5 / Miata (90-93):
Bore x Stroke: 78.0 x 83.604 1597 or alternate 78.25 x 83.604
Mazda MX-5 / Miata (94-97):
Bore x Stroke: 83.0 x 85.004 1839 or alternate 83.25 x 85.004
Mazda MX-5 / Miata (99-00):
Bore x Stroke: 83.0 x 85.004 1839 or alternate 83.25 x 85.004
Mazda MX-5 / Miata (01-05):
Bore x Stroke: 83.0 x 85.004 1839 or alternate 83.25 x 85.004

 

It looks like an intended "inch" tolerance spec allowance of 0.004 was mistaken in the above as being a metric (mm) specification.

 

Rich is correct.  My intent was to add 0.004in (0.1mm) to the stroke spec, which currently calls for the factory nominal spec of 85.0 & 83.6 as an absolute maximum with no tolerance.   Here's the letter to the CRB:

 

 Please Add Tolerance Specification to Engine Stroke Requirement Request:

 

SMAC & CRB Members,

Our current engine stroke specification is outlined in the GCR on page 752 as 83.6mm for a 1.6L and 85.0mm for all 1.8L.  Page 185 states that "unless otherwise specified" stroke is an "Absolute Maximum", defined as follows:"Absolute maximum means tolerances of+0.000 inches or +0.00 millimeters."  Therefore, a 99 miata with stroke of 85.01mm is technically non-compliant.Realistically, the 83.6 and 85.0mm specs are nominals from Mazda, which have a small tolerance.  Very little discretion is being given in the tech shed (ie. 3rd place runoffs car being disqualified for 1 out of 16 relief cuts slightly oversize).  As such our rules need proper tolerancing built in to protect ourselves from ourselves.  Mazda cranks are VERY repeatable.  Allowing for just  +0.004" (+0.10mm) is enough to capture every OEM Mazda crank I've personally measured.  Note, our bore spec is already defined with a tolerance of up to +0.006" over nominal.  

 

Thanks,

Dan Tiley


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#19
Tom Sager

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Calling all NA 1.8 owners/drivers.  For those that have not seen the request for input in the January SCCA Fastrack regarding the competitiveness of these cars, there is a window for us to submit our requests to bring these cars up to a competitive level with the more powerful NB cars and the lighter 1.6 cars. 

 

Here is the text from Fastrack:

The CRB is seeking feedback on the following. Please respond through the CRB letter system, www.crbscca.com. Input is requested from racers on parity for the 94-97 model year cars. Is there a parity issue? Are the cars currently competitive? Option of weight/restrictor plate adjustment, and/or allowing similar changes as the 1.6 cars recently received, but only if needed.

 

IMO these cars are very nearly competitive with the others and only need a very small adjustment to close the gap.  Weight and restrictor plate adjustments are the easiest for the SMAC and CRB to approve and are also the simplest and least expensive for competitors to adopt.

If you own or race one of these cars, NOW is the time to submit reasonable and well founded requests.  It might be wise for those of us who still own or race these cars to pool our thoughts and information and submit it with some collaboration.  Anyone that wants to share their thoughts can send me a private message and we can get a group effort started.  Time is probably of the essence as the next Fastrack will be published in 2 weeks or less and it’s best to submit requests while we are still on this month’s watch.   


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#20
Brandon

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I've heard rumor the 47mm plate is nearly no longer the intake bottleneck of a pro-built NA1.8, thus implicating the airbox and intake piping.

I'll have my setup on the chassis dyno this off-season to confirm (yanking the plate outright) but it may not be as simple as we've thought to get "more" out of these motors as others.

 

None of the allowances for the 1.6L would be a detriment to the NA1.8 IMO and their influence would be minimal in upsetting any apple carts.


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