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NA 1.6 updates summary

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#1
jfeniello

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I know i'm setting myself up for the "Pay attention" or "search is your friend" replies, but i'll ask anyway...

Does there happen to be a summary of the changes/mods given to the NA 1.6's over the past few years?  Sticking with one, and want to see what i can do.

 

thanks!



#2
chris haldeman

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This is from memory so I might miss a thing or 2.....
Allowed to remove drivers side marker light
Allowed to grind the welds inside the header and weld outside
Allowed to use heat reflecting meterial on Intake tube
Allowed to use comp diff or nb torsen
Allowed na or nb 5 speed trans
Allowed to shim the steering rack

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#3
Bench Racer

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As Chris mentioned, eliminating the left turn parking light for ambient air to air filter locate by the master cylinder ia a large deal in getting ambient air to the airflow meter and wrapping the plastic tube from the air flow meter to the throttle body keeps the tube/air from heating up.

How do I know, because contrary to some who disagree, I did complete thermocouple test along the complete path the incoming air takes form ambient air temp outside the car to the throttle body. There are advantages with the Mazda Comp L/S. Exhaust system is a factor. Cooling system to not over heat engine. My 1.6 engine on DynoPac 127 HP 109 ft. lb. If there is a great spacer between the steering wheel and the seat at specific tracks it'll get the job done.


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#4
Steve Scheifler

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Sorry, but first and best is just read the SM section of the GCR, line by line, and create a bullet point checklist with short descriptions. It’s fairly short if you weed out the very early suspension stuff. The very latest stuff is even in red for you.

But, a few notes on what’s already been mentioned. Chris meant left front running/signal light not side marker.

Differential options include a specific Cusco in addition to the old comp and Torsen choice.

I don’t recall ever seeing a rule on shimming the steering rack. The only reference I see is the original on depowering.

You can use 1/8” shims under each end of anti-roll bar mount brackets to reduce pinching.

Is it proposed or final to use NB rear hub/upright?

Splined transmission main shaft collar is fairly recent

Weld-on front subframe reinforcements (from Mazda)

Penske’s of course

Probably others, so read the GCR.
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#5
Tom Hampton

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Steering rack shim IS a NASA rule, but not specific to na6.

Other new (non na6 rules)

extended lower ball joints.
Offset bushings


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#6
Steve Scheifler

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Ah, NASA, shame on them. I didn’t realize they had deviated on that. And too bad is wasn’t just NA chassis since the NB rack is already spaced down further by design. Same deal as the R tie rod ends, it benefited both rather than closing the gap between them.

That reminds me of one of my favorite na6 non-rules. The na8 can use the na6 front bar but the na6 can’t use the na8 bar. Makes perfect sense.
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#7
Tom Hampton

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Just looked up the current rule.  Yes, its NA body specific, not just NA6.


16.3 Steering rack on 1990-97 cars may be shimmed between the rack and subframe at its two mounting locations. Each rack mount utilizes two bolts; both bolts must pass through each shim at that location. Shims must be the same dimensions and be made from aluminum or steel. Total thickness of shims can not exceed 12.70mm (0.50 inch) in thinness/width.


Here's another new one (new in 2019):
 

15.17 NA 90-97 cars may use the OEM Mazda 99-05 (NB) model year rear uprights. NA Cars upgrading to the OEM Mazda NB rear upright must use the NB rear upright on both sides of the car. Miss-matching of rear uprights is not allowed.

Both of these are from the NASA CCR. 


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#8
EMatoy

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Just to clairify- you can only clean up the internal welds 1” in from either end of the exhaust. No cleaning up the 4-1 collector. Welding on the outside is permitted to hold the flanges on.
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#9
Steve Scheifler

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Tom, so that’s NASA. I mentioned the rear uprights but wasn’t sure if it is official for SCCA.
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#10
Tom Hampton

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From October GCR:

t. NA 90-97 cars may use the OEM Mazda 99-05 (NB) model year rear uprights. NA Cars upgrading
to the OEM Mazda NB rear upright must use the NB rear upright on both sides of the car. Miss-
matching of rear uprights is not allowed.

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#11
Alberto

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Just curious.  What is the reason for allowing NB rear uprights on an NA?

I thought the NBs increased track width but apparently I was wrong.


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#12
Brandon

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Just to clairify- you can only clean up the internal welds 1” in from either end of the exhaust. No cleaning up the 4-1 collector. Welding on the outside is permitted to hold the flanges on.

 

There isn't a 1" rule that I'm aware of. That's in the IT ruleset regarding port matching.

 

To my understanding: the NA6 exhaust weld clean up was the ability to remove the globs and boogers that are formed by welding the respective flanges to each end.

Clean up the four ports mating to the head.

Clean up the 2" port at the downpipe flange.

 

Cleaning up the collector, where the four tubes merge (before the flange), and that's a paddlin' (or bouncin' from results).


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#13
Brandon

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Just curious.  What is the reason for allowing NB rear uprights on an NA?

I thought the NBs increased track width but apparently I was wrong.

 

Stock, the NB is 10mm wider on the rear track however the maximum track width numbers had previously not been able to be properly measured by tech in my understanding.

 

Early on there was a lot of presumed data about the total track width, along with speculation about the highest offset legally weighted wheels available at that time, which meant the disallowance. But if tech can now accurately and repeatably measure track width, the rationale for preventing update/backdate of the rear spindle/upright is no longer supportable. Kind of like the front sway bar bracket shim allowance & transmission clarity the SCCA has provided.

 

Whether running a 10mm wider rear track on an NA is favorable or not is left up to the various drivers and how they like their platforms.


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#14
Steve Scheifler

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I never thought it was a measuring issue, but either way, the max on all cars has always been the same (IIRC), but the NA required either different wheel offset or long studs with spacers to achieve what the NB did without. So whatever the reason, it is a welcome change for convenience with no meaningful change to final spec or performance.
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#15
Tom Hampton

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There isn't a 1" rule that I'm aware of. That's in the IT ruleset regarding port matching.

Its not very hard to actually look up the rule, instead of speculating. From the GCR, the nasa rule is identical:


1. 1.6L (1990-1993): The exhaust manifold internal factory welds may be ground from the inte-
rior of the OEM exhaust manifold up to 1” from the mounting surfaces of the cylinder head and
the collector.
A bead of weld or braze may be added to the outside of the exhaust manifold
inlet and outlet mounting flanges for the purposes of repair only. No coatings are permitted on
the exterior or interior of the manifold. Heat wraps may not be used.

-tch
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#16
Ron Alan

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I never thought it was a measuring issue, but either way, the max on all cars has always been the same (IIRC), but the NA required either different wheel offset or long studs with spacers to achieve what the NB did without. So whatever the reason, it is a welcome change for convenience with no meaningful change to final spec or performance.

Front track width on all cars has always been the same...1450mm.  Rear track width for years was 1465mm on NA cars and 1475mm on NB cars. At some point a few years ago the rear track for ALL cars was changed to 1475mm. Early on this year(end of last year?)I sent a letter to the CRB requesting the allowance of the NB upright...since the main reason for not allowing this in the past was the track width(and the NB upright is a 5mm difference per side)which was now equal. Plus I had way more NB uprights laying around than I had NA :)

 

So I'm 100% with Steve here!

 

AND...SCCA made this change and NASA followed as they should! Just as SCCA decided the ELBJ NASA allowed a few years back was ok! I still think the only real difference besides tires between the 2 orgs is the steering rack shim.


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#17
Bench Racer

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AND...SCCA made this change and NASA followed as they should! Just as SCCA decided the ELBJ NASA allowed a few years back was ok! I still think the only real difference besides tires between the 2 orgs is the steering rack shim.

Ok, so we need a few front enders to run shims, get caught and change the rule like occurred with other items.  :whistling:


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#18
Steve Scheifler

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Front track width on all cars has always been the same...1450mm. Rear track width for years was 1465mm on NA cars and 1475mm on NB cars. At some point a few years ago the rear track for ALL cars was changed to 1475mm. Early on this year(end of last year?)I sent a letter to the CRB requesting the allowance of the NB upright...since the main reason for not allowing this in the past was the track width(and the NB upright is a 5mm difference per side)which was now equal. Plus I had way more NB uprights laying around than I had NA :)

So I'm 100% with Steve here!

AND...SCCA made this change and NASA followed as they should! Just as SCCA decided the ELBJ NASA allowed a few years back was ok! I still think the only real difference besides tires between the 2 orgs is the steering rack shim.


Thanks Ron, once again my memory fails me. I have no recollection of the rule change for max on the 1.6, perhaps it was while we were away. Good to know.
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