Why is the 12a so heavy in STL??
- Thread starter AS-RACER
- Start date
Can't give you the "official" reason for that weight (I don't know it) but I can tell you that from personal experience rotaries really wake up with porting (I built a Racing Beat/Holley-equipped and -ported RX that would keep up with a Porsche Turbo in a straight line to 100 mph). So that wold be why no porting is allowed (if you want porting, STU beckons).
And I don't buy the "no torque" argument, especially since the masses seem to think that STL will be a "Honda class", a manufacturer not exactly known for its massive torque output (what was my old sig line? "My Nissan's lugnuts have more torque than your Honda engine"...?)
Let's also not forget that it's perfectly legal to toss that engine into a Miata chassis...
Finally, note the car is legal in STU in IT prep and weight (but I recognize that's not really what you want).
Given that ST is pretty much on a clean slate right now (moving away from World Challenge VTS sheets and towards its own set of standalone prep rules) I'm not surprised there's some confusion and dissatisfaction vis-a-vis the Mazda 12A rotary. After all, it's a legacy engine and not really used by a high volume of competitors right now, so I'm guessing it's a low priority. However, if you're interested in seeing less weight considered, I'd recommend you submit a request with a reasonable weight that you think the engine should get (keeping in mind that Miata thing; in my mind all specific engine allowances/deviations should be done with the optimal chassis it could go into) with your support for that number (why you think that way). I'm confident it will warrant at least a reasonable consideration.
GA
And I don't buy the "no torque" argument, especially since the masses seem to think that STL will be a "Honda class", a manufacturer not exactly known for its massive torque output (what was my old sig line? "My Nissan's lugnuts have more torque than your Honda engine"...?)
Let's also not forget that it's perfectly legal to toss that engine into a Miata chassis...
Finally, note the car is legal in STU in IT prep and weight (but I recognize that's not really what you want).
Given that ST is pretty much on a clean slate right now (moving away from World Challenge VTS sheets and towards its own set of standalone prep rules) I'm not surprised there's some confusion and dissatisfaction vis-a-vis the Mazda 12A rotary. After all, it's a legacy engine and not really used by a high volume of competitors right now, so I'm guessing it's a low priority. However, if you're interested in seeing less weight considered, I'd recommend you submit a request with a reasonable weight that you think the engine should get (keeping in mind that Miata thing; in my mind all specific engine allowances/deviations should be done with the optimal chassis it could go into) with your support for that number (why you think that way). I'm confident it will warrant at least a reasonable consideration.
GA
Was that directed at me, Dick? I'm not sure what your question is...?
To summarize:
- The 12A-equipped RX-7 is allowed in STU in ITA trim (no porting) at 2280# (since the chassis was built through 1985).
- The 12A engine is allowed in STU with "street porting" at 2350#
- The 12A engine is allowed in STL with no porting at 2535# (changed Dec Fastrack).
If anyone thinks these should be lower, please do submit a request for the weight you think it should be to the CRB at http://www.crbscca.com.
GA
Because they make infinity horsepowers. We learned that back in the '80s, beat Mazda to death with our knowledge, and suffered their "death of a million Miatas" as a result. History. Know it or repeat it.
K
Quote of the Month, if not the year!
dickita15
New member
Not directed at you specifically Greg , although I applaud you taking the role of publicly furthering these discussions. The original posters question was why the 12a was so heavy in STL. In that class I have not found any allowances for porting of a carb change. As far as I know there are no allowances that would let the car make any more power that it does in ITA/IT7. Given that like the original poster I am not sure why the cars was speced in STL at 255 pounds more than the IT car. Hence my question, what am I missing.
Yea I was basically wondering why a 12a RX7 has to weigh way more then ITA trim if you run it in STL? I was looking at the 1.8 Integra GSR which is classified in ITS, it gets to lose more then 200 lbs in STL trim. I know you can put these engines into different cars (like the miata with the rotary or the crx with the GSR motor) but, it seems like the 12a is still way to heavy. That was basically my point. Unless I'm missing something?
What I would really like to do is run my ITS RX7 non ported 13B in STL or possibly build a 1st gen rx7 for STL but, if the 12a has to weigh 2600 then I'm just wondering what they would make the 13b run at? 3000 lbs. ?? I know this class is new and everything and not trying to bash the rules. Just trying to figure out what the thought process is on everything. Oh and I must have missed the weight change to 2535 lbs. but, it still seems a little high compared to other cars in the class.
What I would really like to do is run my ITS RX7 non ported 13B in STL or possibly build a 1st gen rx7 for STL but, if the 12a has to weigh 2600 then I'm just wondering what they would make the 13b run at? 3000 lbs. ?? I know this class is new and everything and not trying to bash the rules. Just trying to figure out what the thought process is on everything. Oh and I must have missed the weight change to 2535 lbs. but, it still seems a little high compared to other cars in the class.
Andy Bettencourt
Super Moderator
The rotards weights are WAY off. Just pull them from the rules if this is the best ya can do!
As has been pointed out, the car weighs a ton MORE in STL all while making no more power. When looking at the potential power to weights, it would make sense to allow the 13B WITH a street port - at 2600...and it still barely fits. Given the stock intake and AMD, around 190whp-200whp TOPS?
Probably a great place for ITS RX-7's but 250lbs of ballast in a Miata doesn't sound all that great for the trouble.
Suggestions:
12A - street port @ 2400
13B - street port @ 2600
As has been pointed out, the car weighs a ton MORE in STL all while making no more power. When looking at the potential power to weights, it would make sense to allow the 13B WITH a street port - at 2600...and it still barely fits. Given the stock intake and AMD, around 190whp-200whp TOPS?
Probably a great place for ITS RX-7's but 250lbs of ballast in a Miata doesn't sound all that great for the trouble.
Suggestions:
12A - street port @ 2400
13B - street port @ 2600
Rabbit07
New member
Short answer..... "We F'd Up!" Working at fixing it. Stay tuned!
dickita15
New member
Thank you Chris, that is the answer I was looking for, nothing else really made any sense.
I assume the fix would be to allow something for more power at the higher weight, some porting and or an alternate carb.
Anybody know what an unported 12a can make with a Holley and an Racing beat intake.
lateapex911
Super Moderator
Yea, I figured they hated the sound of the rotary up there in the STL rulesmakers offices.
It made no sense otherwise! An ITS car making 185hp, LOSES 200 ponds, while an ITA car making 125 (SIXTY less!) GAINS 320!! That's a 500 pound swing! So the ALREADY faster ITS car goes even FASTER, while the Slower than ITA car goes even SLOWER. Hahaha....somebody clearly hates the rotaries!!
In other SCCA classes they allow "street porting", and have a tightly controlled easily available template that is used. Power output is well known. I'd suggest contacting members of that AdHoc (The STAC will have the CRB liasons on the call who can facilitate this).
On this board, Steve Eckridge is familiar with the template and expected outputs, IIRC.
Further, I'd suggest classifying both the 13B and the 12A, as the 12A parts are very difficult to get these days. The 13B at a reasonable weight is going to be the better draw. I think the ITS 13B would be a good candidate as is. No porting needed. The 12A though, would require porting as nearly any Mazda chassis would be impossible to make weight with, IF the weight was to be competitive.
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lateapex911
Super Moderator
This last post has made me think.
HOW does the STAC set weight? here's a case in point:
We know the Integra will weigh 180 lbs or so LESS than it would in ITS. Fine. So it should be faster than ITS. We know it's power. (And it gets to make some other changes, but lets ignore those for now).
Now, take a ITS 13B rotary. What do you make IT weigh? Well, the engines are very close in curves/hp/tq. The 13B (in ITS/ST trim) comes a leeetle short, but, for giggles, lets make it a wash. So, it would weigh the same as the integra, right? Plus 2.5% for RWD.
So, whats the Integra in STL, 2420? 2420 + 2.5% = 2480?
Now, if understand it, the assumption of the rules makers is that somebody will put that engine in the corporations best chassis. So, that be the Miata. So, a 2480 lb Miata? Now we're talking.
Somehow, I see the PTB saying, "Hold on, don't think so". (*, and **)
Fine, but how will extra weight be added?
I HOPE the STAC comes up with a repeatable, empirical, documentable and systematic way of doing it.
Otherwise, they are headed for trouble.
If there's POOMAs going in, they better be ready to defend, and fix them.
*Also, just as a reference point, there IS an ITS Miata and, in some pretty competent hands, it hasn't set the world on fire. It's classed at 2375, and makes 160 hp in race trim.
** I say that because I assume they will want to add weight because I have a hunch they are creating a FWD centric class. Now, I hope I'm wrong, or that the results we've seen thus far are merely random, with no actual intent. Because it's a cool ruleset, and i'd like to see it be as open as possible, give as many formats/manufacturers/cars an equal chance, and not aimed at any one demographic.
HOW does the STAC set weight? here's a case in point:
We know the Integra will weigh 180 lbs or so LESS than it would in ITS. Fine. So it should be faster than ITS. We know it's power. (And it gets to make some other changes, but lets ignore those for now).
Now, take a ITS 13B rotary. What do you make IT weigh? Well, the engines are very close in curves/hp/tq. The 13B (in ITS/ST trim) comes a leeetle short, but, for giggles, lets make it a wash. So, it would weigh the same as the integra, right? Plus 2.5% for RWD.
So, whats the Integra in STL, 2420? 2420 + 2.5% = 2480?
Now, if understand it, the assumption of the rules makers is that somebody will put that engine in the corporations best chassis. So, that be the Miata. So, a 2480 lb Miata? Now we're talking.
Somehow, I see the PTB saying, "Hold on, don't think so". (*, and **)
Fine, but how will extra weight be added?
I HOPE the STAC comes up with a repeatable, empirical, documentable and systematic way of doing it.
Otherwise, they are headed for trouble.
If there's POOMAs going in, they better be ready to defend, and fix them.
*Also, just as a reference point, there IS an ITS Miata and, in some pretty competent hands, it hasn't set the world on fire. It's classed at 2375, and makes 160 hp in race trim.
** I say that because I assume they will want to add weight because I have a hunch they are creating a FWD centric class. Now, I hope I'm wrong, or that the results we've seen thus far are merely random, with no actual intent. Because it's a cool ruleset, and i'd like to see it be as open as possible, give as many formats/manufacturers/cars an equal chance, and not aimed at any one demographic.
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Dano77
New member
Yes Greg I know your one of the originals with rotaries. But there is just something about a motor with only 9 moveing parts thats cool. It does sound like crap though. Mufflers hide that.
I believe it was Kurt you were working with,long before I met Tan Dan Fisher,Brian Holtz and the other rotor heads. Do you think you can come up with the answer to our question on the carbs. Holly 2300 2 bbl 500cfm max or holly 4 bbl racing beat style. What would the expected output be. I havent tried either combo as the Nikki seems to be working the best right now,and there was no reason to try any others,but they are getting scarce as well as complete engines and housings.
I know what a bridge port and a Holly will do but thats a story for another date. Lets just say PDA had an issue with me at Lime Rock a bunch of years ago. Really,who waits for a point by from a 911. Thought he was gonna go faster than that.
Dan 77 IT7
I believe it was Kurt you were working with,long before I met Tan Dan Fisher,Brian Holtz and the other rotor heads. Do you think you can come up with the answer to our question on the carbs. Holly 2300 2 bbl 500cfm max or holly 4 bbl racing beat style. What would the expected output be. I havent tried either combo as the Nikki seems to be working the best right now,and there was no reason to try any others,but they are getting scarce as well as complete engines and housings.
I know what a bridge port and a Holly will do but thats a story for another date. Lets just say PDA had an issue with me at Lime Rock a bunch of years ago. Really,who waits for a point by from a 911. Thought he was gonna go faster than that.
Dan 77 IT7
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