updating / backdating engines

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AStaidle
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updating / backdating engines

Post by AStaidle »

i want to run a later model 13B engine in my FB mostly for two reasons, primarily is the higher output, but secondly the 12a engine is hard to find anymore and the parts for them are usually extremely worn. What kind of class bump am i going to experience with this? I was tossing around the idea of a higer gear ratio (4.77) in either stock rear end form or a better 7.5" rear end with the same gearing (junkyard upgrades). If the engine is going to shift me a notch higher, then i might as well go ahead with other modifications, right?
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Re: updating / backdating engines

Post by NJ 03Mach1 »

AStaidle wrote:If the engine is going to shift me a notch higher, then i might as well go ahead with other modifications, right?

Wow, if that sort of thinking right there hasn't gotten me in a LOT of trouble lol...


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Re: updating / backdating engines

Post by dspgti »

Let's go back to the basics.

You need to make a decission on the catagogy or preperation level you want to start with.

In Time trials, you are either SOLO type class which consists of Street Prepared or Streel Mod. These are classes that are typical full Street legal configuration, full Interiors, Roll "Bar" required, DOT tires.

The next are Road Racing, or Club Racing (CR) classes. They start with Show room stock, then Improved Touring (IT) then Production and on to GT. There are also Regional CR classes that cover the RX7. They include SpecRX7. Show Room Stock you can't do anything, IT allows lots of suspension changes, some tuning up grades (mostly exterenal) to the engine, stripped interiors. CR cars should have full cages but right now TT is allowing a bar onlt in SS and IT classes. Production and GT need full GCR Cages. Up dating and back dating can be done if the engine trans combination appears on the same line (I can explain that term later).

Time Trials also allows for purpose built specialty cars known as "Specials" but I don't think that is where you are coming from.

You need to pick a catagory, get a rule book, find the car you want in a class you want to run in and see what's legal. Getting a rule book and understanding it can be overwelming. You are looking at potentialy needing 3 books. Solo II, Time trials, Clug Racing GCR. Everything can be down loaded but that's massive as well. We are willing to help narrow that down, but you need to be more specific.

Do you have a catagory in mind where you'd like to start?

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Re: updating / backdating engines

Post by Mazdahead »

Adding a 13B definitely jumps you up a class over a 12A. What class were you thinking about? Steet prepared, Street Mod, IT, then I can advise you what class to put it in.
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Re: updating / backdating engines

Post by AStaidle »

well the car originally was a 13B engine (GSL-SE). Now that it in my possession, i can start working on it.

The biggest thing is where not using a GSLSE 13B will put me. They are not easy to come by. But they are only a stones throw away from the S4 engines. So im thinking either IT or the step above.
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Re: updating / backdating engines

Post by Joe Foering »

The IT rules state that you can update or backdate components within cars of the same make, model, body type and engine size as listed on a single improved Touring Specification Line. So I don't believe you can use the 13B engine in, say, a 12A car (different engine size, different model). The rules go on further to state that you can't "create" a car out of components from different models or engine sizes and stay in IT...sounds like a "Special" to me...
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Re: updating / backdating engines

Post by AStaidle »

so to be in IT i would have to run a GSLSE engine then correct?
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Re: updating / backdating engines

Post by AStaidle »

so i may almost HAVE to run the GSLSE in "special". but i do have a 12a powered 1982 that i could possibly run in another (cheaper) class. Both arent expensive builds really.

so the spec 7 might be good for the 82. or IT
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Re: updating / backdating engines

Post by Mazdahead »

Joe, Let me see if this is correct?
If I have a 1st gen RX7, I can use any parts that came from that make and body style.
If I use a part from a 2nd or 3rd gen this makes me illegal because they are different body styles?
I believe this is standard practice in racing especially when it comes to the rotors and flywheels from cetain models have lightened components from the factory.
So, if I use all components for my body style and have to run against cars in my class that are newer, but allowed and much stronger, or can I use the parts from one of the other generations because they are from the same make and model?
This kinda has me confused as well?
I was always under the impression that I could use whatever year parts I wanted from the same model?
The body style threw me a curve.
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Re: updating / backdating engines

Post by dspgti »

OK! Lets start here! Improved Touring, GCR Club Racing specs:
ITA - RX7 1978-1985, 2 rotor, 12A...... That's it. No motor up dates beyond that.

So what's next?

Solo classes: CSP is a start. 1978 to 1992 all non-turbo. That fits, right? You're starting with the 1985 if I remember, right? Now, the trans, differential combination? What is that coming from?

I know this might be a little frustrating, but it will all make sense in the end. No other racing organization does a better job of keeping the paying field level. The goal is to keep all cars running in the same class pretty even in performance. The challenge is amoungst drivers.

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Re: updating / backdating engines

Post by dspgti »

It would help if you guys stop using sub model letters and such and identify what class you are talking about each time you ask a question. Class, Year, model, engine size is what we need.

In CSP, the "line" for RX7 is 1978 to 1985. Any part that came on those cars can be interchanged in CSP. HOWEVER!!! the engine or trans must be swapped as a unit and only from a 1985 and older. I don't know RX7s but that is the oldest body style (1st Gen) right? The 85 had a 13B as an option and that is what you can use. Not a 1986 or new 13B or trans or any other part unless is is exactly the same as a 85 and older.

Is that any clearer?
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Re: updating / backdating engines

Post by Joe Foering »

Dave has it right...I do have a problem with using the 13B optional engine reportedly available in the '85 (and '84) in an ITA car...the rule says same make, model, body style (e.g. coupe) and engine size-the 13B is larger (and not listed on that spec line) so, theoretically, the only car you could swap parts with would be another '85 ('84) with a 13B engine. As to parts from later cars, the engine size will get you (78-85 w/12A)it's got to have the same size engine-along with meeting the other parameters. As Dave said READ the rules, choose a class, determine the allowable mods within a given class, and make your decisions based on that acquired knowledge If you don't, you may find yourself taking parts off the car before some eagle-eyed class competitor protests you!
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Re: updating / backdating engines

Post by Mazdahead »

I am planning on running ITS with my new car and it will be up against 2nd gen RX7's that have a larger throttle body and intake, can I use those components? These cars are both put into ITS because of the 13B engine, this is the only real difference.
The parts are from the same make model and body type (2nd gen vs 1st gen, but both coupes) and from the same engine type? This pushed the stock RX7 to 165 HP in 86 up from 140Hp in 84 & 85.
If not, I am at a definite disadvantage.
That was how Mazda added a little more horsepower to the 2nd gen to keep up with Nissan and other competition.
I read it as I could use these parts and only an RX7 guy could tell the difference. If this is illegal, then I am making changes back to stock very soon!
This is a good discussion because we are always faced with this type of situation when trying to find performance improvements and no one really wants to be illegal. We just want to find the most out of our cars.
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Re: updating / backdating engines

Post by dspgti »

Let me make a correction first. I had to get to my inventory control computer this morning to look a couple of things up. The 13B was available in 84 and 85. These and only these can be interchanged in a CSP 1978 to 1985 RX7.

Now ITS. This is where you got to get a rule book and study it. Yes, you must stay with the 84-85, 13B(1st gen) as well as every part on your car. That is what is on the same "LINE". 1986 on (2nd gen)is a different line. What you are not taking into consideration since you aren't reading a rule book is the 1st gen has a 330 pound advantage over the 2nd gen. Also, you have to keep the stock throttle body but some porting of the intake is allowed. Utilizing all the available modifications for IT can add a lot of performance. Is the 1st gen competitive in ITS? You'd have to talk to club racing RX7 guys to answer that.

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Re: updating / backdating engines

Post by AStaidle »

well being that i don't HAVE the engine for the GSLSE. So that IS going to be a problem unless that car is going to be a "special". Frankly, i have no qualms about running in a class where i have no chance in hell of winning as long as i have some fun.

So lets then look at my other car.

1982 Mazda Rx7 GS w/ 12a engine

she is basically complete less the carbs. From looking at the rulebook and classes, its seems i could go two ways with it. Spec7 and run in the CR(?) or Improved Touring (or i could always run in a near stock class).

a guy on my ohiorotaries forum runs "F prepared solo"...
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Re: updating / backdating engines

Post by Mazdahead »

The 12A and 13B engines place you automatically into another class.
Any 13B engine can be put into any model RX7 with slight engine cover changes, the engines are cosmetically identical, how would anyone be able to tell what engine or components were used?
There were so many pieces in the engines that were lightened or modified over the years by the manufacturer that it would be too difficult to figure out even during a tear down.
This is a very complicated topic and I have tried to read the rules.
It is not easy trying to figure out if I should use solo rules or club racing rules since both have different classes and requirements and both are allowed in Hillclimbs.
I was looking at the rules and see there is not a CSP class anymore in Club Racing, from what I can tell. Do I keep my car in CSP for this year?
It appears there is a B and D Street prepared only now?
It would be much nicer if Time Trials defined the classes they allow instead of stating that allowed classes are taken from this or that level of the SCCA?
There is so much back and forth to different rules and regulations, this is what is confusing, anyone want to try and simplify that one for me?
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Re: updating / backdating engines

Post by AStaidle »

it would be VERY hard to tell the difference between the 84-85 13b and a 86-88 13b because the only differences is the change from 3mm to 2mm seals, compression and i believe that to be about it for the actual block. Everything else is a bolt on change over. Plus if the transmissions had to come from the car with the same engine, that is almost impossible to determine as well without checking the 5th gear ratio.
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Re: updating / backdating engines

Post by Joe Foering »

I doubt if anyone can simplify the rules, but... PHA hillclimbs are based on Time Trials which is a part of Club Racing. PHA/TTR allows ALL the Club Racing classes found in the GCR-in fact, provisions must be made to allow ALL the classes to compete in events...as to trophies, that's another can of worms. We also allow cars from the SOLO classes Street Prepared and Street Modified-they are prepared to SOLO Rules and must meet TT safety rules. We also have Hillclimb Specials... As Dave said, there is an attempt in SCCA to even out the cars in a class-so to speak... For example, the only RX7s in ITA are the ones with the 12A engine; that is the only car listed in ITA-it does NOT list the optional 13B engine for that car or class, so... NO 13B engines in ITA. What I'm reading in this thread is how easy it would be to cheat! If one uses illegal parts out of ignorance, that's one thing; to deliberately use illegal parts, engines, etc. is another. There's an old saying in NASCAR: "The shame in cheating is getting caught" that says a lot for Nascar. I hope we are not emulating NASCAR. All that can be said is READ THE RULES, don't listen to someone else unless they're quoting the GCR or TTR or SOLO Rules and be legal! If you believe someone is cheating, PROTEST! I don't know what satisfaction one gets out of winning if you know you're illegal. Saying everyone else is cheating misses the point. Read the rules, choose your car and class based on the rules (if it doesn't say it's legal, it's not!), and be legal!
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Re: updating / backdating engines

Post by AStaidle »

AStaidle wrote:well being that i don't HAVE the engine for the GSLSE. So that IS going to be a problem unless that car is going to be a "special". Frankly, i have no qualms about running in a class where i have no chance in hell of winning as long as i have some fun.

So lets then look at my other car.

1982 Mazda Rx7 GS w/ 12a engine

she is basically complete less the carbs. From looking at the rulebook and classes, its seems i could go two ways with it. Spec7 and run in the CR(?) or Improved Touring (or i could always run in a near stock class).

a guy on my ohiorotaries forum runs "F prepared solo"...
so this is probably the right track then?
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Re: updating / backdating engines

Post by Mazdahead »

I am not talking about cheating intentionally, but say I get a 2nd gen engine out of a junk yard and put it into my 1st gen? Sometimes it's all that is available out there and they bolt right in if you use the covers from the 1st gen engine. This is what I did for my street 1st gen that I drive. They are interchangeable and honestly with all the engines I have lying around, I would be very hard pressed to tell you definitely what year they came out of when you are looking at the short blocks. I guess it ultimately comes down to our honesty, but I am never going to tear one down just to figure out which model it comes out of. I am going to throw it into the car and hope it runs! The rotary engines are becoming so difficult to get parts for the older ones because of the demand for drag race engines we just have to use what we can find in most cases. Knowing a little more now than I did before I will at least try to remain legal and I believe to this point I have been beyond legal and just barely competitive. I've been having way too much fun for an average kid tho! lol
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