Car Classing Guide + Help Thread

[Magner]

Original post updated with 2023 links and info.

[Lance_L]

Good evening,

Japanese Purchase BMW Z3 2.2

LHD

All options available in NA, except motor, has 2.2L, NA had the larger 2.5.

Added front strut bar.

Squared the wheels and tires:

factory front 7.5" 225-45-17, rear 8.5" 245-40-17

Now 8.5" 245-40-17 front and back.

Replacing the soft top as a project, driving with factory removable hardtop.Z3 build.pdf

I've attached the build, the only anomaly is that car has a manual and not an automatic, that is confirmed as factory from other services.

 

Thanks,

 

Lance

Z3 build.pdf

[Magner]

The correct class would be SSM-S if the tires are 200TW or higher. Locally we allow imported cars not originally sold in North America to run in Street Modified. Other clubs would be E-Modified. 

[Kilohertz]

Hi everyone,

I am just about to embark on my autocross journey and have just bought a 2000 Miata (NB) MX-5 to use. I just discovered it was brought into Canada from California sometime in it's life so it has 2 CATS, one at the header and one in the main pipe, in it's normal single CAT system location. Currently the car is bone stock and is class E as far as I can tell. Will it stay class E if I put the exhaust back to Canadian and Federal 49 state exhaust standards? i.e. plain exhaust manifold from an NB car and the original CAT in the mid pipe?

Thank you

PS I couldn't find anything in the 400 pages of SCCA rules that talk about changing California cars back to Federal 49.

PPS Might as well ask about wheels while I'm learning...I see all Miatas from 1990-2005 are classed ES, in stock form, even though HP ranges from 110-178 and suspension and so much else changes in that 15 year spread, not sure how that works or is fair, but for me shopping for new wheels and tires I need to know what is legal to remain in stock ES? The wheel sizes in the range of dates for Miata ES is 14x5 up to 17x7.  Does this mean I can run anything in that range, plus go up/down 1" in diameter which is allowed anyway? So if I wanted to use a 15x7, it should be allowed?

So much to learn. thx

Edited April 30 by Kilohertz

[S2KRob]

I believe so. We can also double check with @Magner who is always super helpful when it comes to classing details.

[Kilohertz]

Thanks Rob, 

I was hoping @Magner would see this and jump in with his wisdom.

I'll standby for a reply.

Cheers

[Magner]

On 4/25/2024 at 5:14 PM, Kilohertz said:

Hi everyone,

I am just about to embark on my autocross journey and have just bought a 2000 Miata (NB) MX-5 to use. I just discovered it was brought into Canada from California sometime in it's life so it has 2 CATS, one at the header and one in the main pipe, in it's normal single CAT system location. Currently the car is bone stock and is class E as far as I can tell. Will it stay class E if I put the exhaust back to Canadian and Federal 49 state exhaust standards? i.e. plain exhaust manifold from an NB car and the original CAT in the mid pipe?

Thank you

PS I couldn't find anything in the 400 pages of SCCA rules that talk about changing California cars back to Federal 49.

PPS Might as well ask about wheels while I'm learning...I see all Miatas from 1990-2005 are classed ES, in stock form, even though HP ranges from 110-178 and suspension and so much else changes in that 15 year spread, not sure how that works or is fair, but for me shopping for new wheels and tires I need to know what is legal to remain in stock ES? The wheel sizes in the range of dates for Miata ES is 14x5 up to 17x7.  Does this mean I can run anything in that range, plus go up/down 1" in diameter which is allowed anyway? So if I wanted to use a 15x7, it should be allowed?

So much to learn. thx

 

I believe the follow paragraph from page 74 of the 2024 SCCA Solo Rulebook applies to your question regarding the exhaust:

Option package conversions may be performed between specific vehicles
of a particular make and model, but only between configurations from
within a particular model year. Such conversions must be totally complete
and the resultant car must meet all requirements of this Section. These re-
quirements are not met by simply pulling a fuse to disable a feature which
distinguishes one model from another.

 

I believe this would be considered legal, however everything else about the California modification would need to be converted back to 49 State car.  This would be to follow the rules as written by the SCCA, however locally if you discussed some fellow local WSCC stock class competitors about only swapping the exhaust I don't think you would have any problems as there likely no performance gain from missing out on removing additiional California specific items, unique EGR, maybe? There's nothing in our local rules that would restrict US cars from competition either, however if you planned to run at an offical national SCCA event this could be a problem, hope that helps.

Regarding the wheels, your wheels are based on what the car originally came with from Mazda. For example if a 2000 Miata Sport (not sure which model you have) came with 14x6 +42mm offset. You could run a 13x6, 14x6 or 15x6 wheel. Offset can be +/- 7mm from the OEM size as well to accommodate some wheel models. Wheel width however cannot change from the originals wheels the car sold with new.  You cannot pick and choose from any other Miata year or model to select a wheel size. 

15x6 with 205/50/15 tires is like the most cost effective, best performing and most common wheel setup available for ES Miatas that came with 14x6, 15x6 or 16x6 wheels.

Regarding the 110-178hp Miatas on 14 to 17" wheels comment all running in the same class. SCCA car classing offers every car a class to participate, this however does not guarantee all cars will be competitive in their respective class.

 

Hope that helps!

[Magner]

Links on first page updated for 2024 season.

[Kilohertz]

Thank you so much for your detailed reply, it is exactly the info I needed before buying wheels, tires and exhaust. 

I have no interest in any SCCA official events, this is just a hobby for me and I want to keep legal but get the best setup I can for the car and stay ES. 205/50/15 is what I was planning, just wasn't sure what wheel width to buy.

Thank you again for the guidance, it's greatly appreciated.

Cheers

Edited May 3 by Kilohertz