SCCA STR Class
 

Anyone considering building a STR RX-7? If so, which platform FB or FC?

Neither? I've heard enough people talk about running a GTUs in STS that it must have some potential, but I don't see any way either chassis is going to catch an s2000 in str.

You're right. Neither chassis will be competitive against the NB Miata either. I'm still curious since I like to race my RX-7 at local autocrosses on occasion.

For the people that have not had a chance to see the Fastrack:



August Fastrack:

- Per the STAC, the following revised version of the STR proposal is published for member comment (significant changes are shown in italics):

“Street Touring Class R (STR)

Class requirements and restrictions:

- Only those cars listed below are eligible

Eligible vehicles are:

- Honda S2000

- Mazda Miata (except Mazdaspeed)

- Mazda MX5 Miata (’06-‘09)

- Toyota MR2 (non S/C, non-turbo)

- Toyota MR2 Spyder

- BMW Z3 (non-M)

- BMW Z4 (non-M, non-turbo)

- BMW M Coupe & M Roadster (1998 to 2000)

- Mazda RX7 (non-turbo)

- Porsche 924 & 944 (non-turbo)

- Porsche 911 (1984 to 1989 Carrera 3.2)

- Porsche 968

- Pontiac Solstice (non-turbo)

- Saturn Sky (non-turbo)

- Datsun 240Z & 260Z & 280Z & 280ZX (non-turbo)

- Nissan 350Z

Additional class notes include:

- Tire Allowances (add to 14.3):

AWD – 225mm

2WD – 255mm

- Wheel Allowances (add to 14.4):

AWD – 7.5”

2WD – 9”

- Catalytic Converters (add to 14.10.E):

Same as ST, STS allowance.

- Limited Slip Differentials (add to 14.10.K):

Aftermarkets units allowed per STX/STU rules.”

NOTE, per the STAC: Classing for STR will not be formula based, but will utilize a list of eligible vehicles. Cars *not* on this list

are not eligible. However, as in all subjective classing, cars may be petitioned by the membership for inclusion and will be

reviewed on a case by case basis.








I may well start slowly building my 1987 GXL up to the class from E Stock set up for local fun since my ASP FD probably won't see an autocross course again any time soon.

The clutch type dif was the only thing keeping my FC out of STS (old STS2 if you have not kept up for a year or so). When the STR was originally talked about I thought they would adopt STX's cat rule and I could get rid of the 3 cat set up. Now they are adopting the ST/STS cat rule so it will take some thinking and measuring about how to set that up.

I think an RX-7 could do fairly well in STR (not Nationally). I think it may do better than in CSP (not sure since my first autocross 1986 RX-7 I jumped from C Stock to F Prepared without any time in CSP-that was a waste of a good car ;-) -).

I think that the 1.6 Miatas are running megasquirt in STS (not sure on this just what I remember reading somewhere) so more than likely the RX-7s could too. The GSL-SE could be a very fun car to play with. We will have to see if anyone builds one to the class rules.

STR is an open ended class (though the STAC seems tied to N/A at the moment to keep from going down the STX/STU boost mess) and they seem to be open to member comment so if you have any comments write in. Initially I was hoping that the Mazdaspeed Miata and TII RX-7 would be in STR (and ALL N/A RX-7s regardless of stock dif would go to STS) but that did not work out.

Here is a thread with an open discussion about STR on SCCAforums.com with the newest info since the Fastrack rulling around 7/18/09:
http://sccaforums.com/forums/38/232170/ShowThread.aspx


Hopefully this tread will live on with people building to the class as I always enjoyed reading James Wilson's threads about his STS2 build a few years ago.

I was considering a GSL-SE shell or sticking with the S5 FC since most of my setup experience is with this chassis. I was also disappointed with the ST/STS cat rule. The S5 only has 2 cats, but 1 would be better for both S4 and S5 =). It would also allow a decent length aftermarket header as opposed to fabricating your own.

I definitely think the NA RX-7s would do better in STR than in CSP. It was nice to run 275 V710s and an open exhaust, but the CSP cars are making almost the same power while being 300 lbs lighter.

The Miatas are running Megasquirt ecus in STS, but the RX-7 can use the even friendlier Rtek7. It uses the stock case.

Now that I think about it, I'm leaning toward the GSL-SE (got a shell sitting in my backyard right now). I've got no money until I graduate, but I've got a little bit of time, so I'm probably going to look into the car's capabilities over the next few months.

No way I'm putting emmisions back on my car. That would be like nuetering the poor thing. I'll just stick around in CSP for a while, I think. :)

I was asking about cats on the sccaforum site and Andy Hollis posted this link that will be helpfull to RX-7 guys that are replacing cats.
http://sccaforums.com/linkthru.aspx?...%2f500spun.asp

We are all missing the best part of running a 7 in STR... We get to run a big ricer wing ;-).

Hi, I am racing an FC NA here in Spain (sorry for my English). I ignore if our rules are the same than SCCA ones, but this is my first year with racing licence and I am in 1st position into rwd class, beating some really well made BMW E30, Mercedes 190e 2.3 16v and other serious hillclimb - rally cars, with a little modified and stock ported homemade rx7 na. The main pros are the great chasis and low polar momment of inertia with the most of the wheight placed near the center of the vehicle, the worst is the difficult to find a shorter final gearing (I am already running 15" low profile wheels but it isn´t still short enought).

Here you have some videos if you want to see how it performs, any question/advise/recommendation are welcome. The car is a stock ported S4 GXL with miata Torsen LSD, s5 vdi, pinneapple inserts, intake and free dual exhaust, TB mod, removed all emissions stuff and lightened (2000 lb). Crappy ksport coilovers

http://www.youtube.com/watch?v=GXlipuIklno

http://www.youtube.com/watch?v=dRaCgEB7vW4

http://www.youtube.com/watch?v=aFfHMvZFkZc

http://www.youtube.com/watch?v=SxIh9_daoiU

http://www.youtube.com/watch?v=Ym84DoueSd0

Finky, your link goes straight to an add?

That's actualy pretty cool, those runs in th estreet. :icon_tup:

Riz.

It was meant to. Those cats are legal in ST/STS/STR. The smaller size and metal core make them perfect for the RX-7 precat replacements. RX-7+header+most aftermarket cats = blown out or melted cats. These will do well since you have to keep the replacement cats in the stock location. Us S4 guys are so lucky... we have 3 cats compared to the S5 guys with 2.

My FB knowledge is somewhat limited but I think the '79-80 guys can just replace the thermal reactor exhaust manifold with a header and run a straight pipe back. So they won't have to worry about cats for this class. Correct me if I am wrong.

I was considering a 2" pre-converter like this for a pre-cat replacement. They should definitely take the heat. Good find.

I'm starting to consider the FC over the FB again. I just realized that the FB doesn't have electronic controlled ignition. A decent amount of power can be found by tuning the FC's ignition maps with a Rtek7. I also think fitting 245s on 8.5" wheels in the rear of an FB will be difficult without panel modification; however, this is just a guess since I've only quickly looked at it and never tried it.

I'm running 8" wheels, and have plenty of room left over. I could easily have fit 9" wheels for the new 255 size race tires. Also, there are plenty of options for improving the ignition systems on the fb. And it's lighter, etc. :)

Thanks Riz! :gwink:

Good to know that 8" wheels fit without issues. Are these 8x13? I was considering running 8.5x17 with 245/40/17 tires since these are popular sizes that are easy to find. Not sure what street tire options are available in 16", and 15" sizes are a joke (that's what I'm using now).

You're getting some great rear rotation. What size rear anti-sway bar are you using?

Both front and rear anti-sway bars are stock 24mm front and 14mm rear. I am thinking about remove them because with hard set coilovers they might not be necessary.

About the rear rotation, I loosen a little the rear shocks because there have been removed a lot of weight from the rear, and I can´t go lower due to excessive rear camber (I have the rear adjusting bar already set to the limit). Are these settings ok or might I put attention to anything else?

Thanks for your attention

I've used these universal metal core cats with great success (on street) as well:
http://www.randomtechnology.com/products.html

If you don't have solid rear control arm bushings you can use the individual camber adjustment links in addition to your adjustable subframe link to remove a little more negative camber. For a little more money you can replace the rear control arm bushings with spherical bearings. Both individual camber adjustment links and rear control arm spherical bearings can be found at MMR Direct. The spherical bearings are illegal for any SCCA solo class that I'd be interested in or else I'd use them immediately since they allow individual camber adjustment at each wheel using the individual camber adjustment links.

Yes, they are 13x8 Revolution wheels. Nice and light. But, like I said, if I had it to do over again (for race wheels) I would go with a 8.5 or 9 inch wheel so I could run the new 255/13 Hoosiers. Nice 13 inch wheels keep the center of gravity nice and low, making the car very happy. :)


Also, I forgot to mention the differences in costs associated with suspension upgrades. Much cheaper on the fb I believe. Check out www.re-speed.com By far the best place in the world to deal with...



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Thanks mate! I will have a look