The Super Cup and SP3 rules are intended to be identical though PCA does choose some different wording at times to conform more with their way of doing business. PCA defers to the corresponding series for related interpretations.

For Super Cup, the intention and interpretation is to allow for updating and backdating by specific model. I believe PCA's language on partial conversions is intended to refer to partial updating or backdating. If asked, that's how I would interpret the language.

There was a time when we allowed model jumping or Frankensteins as commonly referred to, but it became to difficult to oversee and ensure proper conversions so we eliminated the practice.

So if I am reading this correctly, the plethora of cars running as S2's that just so happen to have a 951 VIN are not legal? Not unique to SP3, there are E-stock cars running that way, as well (or have been in the past, anyway). Which basically means that the only backdating type of thing that would be allowed would be an SP2 2.7L/2.5L swap?

Is there a reason that the engines, which for all intents and purposes are the sole differentiator for the cars, aren't used as the sole criterion for defining "what" a car is?

I would begin a response to your question by saying that the engine is not the sole differentiater for the cars in all cases. For example,brakes can also be much different between models.

The reason why engines are not used as the sole criterion for defining what a car is by the 944 Cup is we for the most part followed the manner in which PCA defined a car, as their ruleset was our beginning point. Don't know why the founders of PCA club racing did it this way. Don't think its a bad way. There are as you point out, other ways. Club racing classes throughout the sport seem to favor this way. To this point, the consider the Cup series began employing a format to attract racers that allowed them to race their cars in Cup just as they were in SCCA and PCA, for which classifications were geared towards model and not engine classifications.

There was a time when the Cup was more liberal in the interpretation and allowed some mixing and matching. That did seem to bring about some chaos when trying to tech cars or determine what weight or power limits they should be running at. We went back to a more model specific manner of defining cars to help simplify the process of administering the rules of the series.

As we continue to free up the rules for Super Cup, we are begin to approach the idea which you are promoting. More like the NASA GTS classes which go even a step further.

I know there are differences, but the rules have basically made everything else even - brakes are free, wheels are free (that remain inside the fenders), etc. So we're really left with the engine and the VIN (and the 968's gearbox). Obviously the VIN won't have any impact. Besides, the S2 cited above only had one difference from any 951 - an M030 S2 had 7.5" wheels in the front, rather than 7" ones. Otherwise, identical.

That said, overall, I really like the format. I like that I can remove inconsequential stuff from my car (i.e. the whole HVAC system, the headlamp system, etc.), which makes it much easier to maintain and repair, as well as put the weight where I want it. It is a VERY GOOD system. I can simplify my car in ways I couldn't dream of by staying E-stock, and I don't have to build a $25K engine to be competitive in a GT class car. The attraction to me is really about being able to make the car simple to work on - so my paradigm is a bit different, and I'm sure that biases my perspective. But in that vein, it just seems that simpler would better for the rules, too (obviously when there would be no performance improvement) and the cars are old enough now that there are going to be mixed powertrains. There's a guy on Rennlist asking about GT5S or SP3 for his S2 that has had a 968 engine installed, which is what prompted me to ask about this. There's another guy in Atlanta (John H. if anyone here knows him) who does a lot of DE's with an S2 that is the same way (no idea if he wants to move to Club Racing, though).

Anyway, just some thoughts. I'm good, now, though I'd like to be able to drop in an NA engine for the sake of reliabilty.

While not currently the way you are suggesting, it could change. Much has with Super Cup/SP3. We just clarified the rules to say you could swap 5 speed trannies in the class. This is heading in the direction you say. Remember these broad sweeping changes to Super Cup have just happened. And no one knew if these changes would be good or bad for the class. They were really made out of an attempt to save the class. And they look to be working.

Yep, was astounded to see 15 SP3 cars sign up for Road Atlanta! That bodes very well. Last year, we couldn't field enough cars to qualify for hte tire contingency, and this year, we better than doubled the class. Of course it would help if I could get through the first practice session without either wadding up my car, or having it break on me.

Again, really like the format, I think you and John are doing a great job, along with Walt, in making it work. Sure I'd love to see some changes, but overall, it is working very much to my liking.

It's a great class, and a great value with fantastic racing.
Up here in the North, we seem to get more entries in PCA events, as all the SP3s come out.
I suspect there's more of you in the South, which has me just a little worried come Nat's!

Giving serious consideration to your idea. To further the discussion from the SP3 side, you may want to give some consideration to sending the idea on through Walt over on the PCA side.

Thanks. I've gotten some feedback from a couple of different sources on my thoughts, too. I need to learn the process for suggesting a change - I had for too long misinterpreted the rules, but now that I'm clear on them, it'll help me out, as well.

After more thought on this subject, we plan to make this change for 2014 provided we can work out something with PCA to make it easy for their scruts to quickly identify the engine number so the proper weight for a car can be quickly determined for weighing cars.