BluemaxxRacing

Ok guys, so I need some of your help getting these new PCA rules understood and where I can put my car. As many of you know, I have a '99 996 that I have been running in C-stock for the last 2 years. Now, I can't keep it in stock because it is completely stripped out and I want to keep it that way, which means that I can put it in the new GTB class or I can go into one of the higher GT classes, right?

Here is what is confusing to me. I don't really get the whole chart for the 14 different engine types, especially since my 3.4 liter water cooled engine is not listed there. I understand the new Performance index and I think it looks super interesting. But how does the 14 different engine types figure into the Performance Index? Assuming I completely forget the different engine types, here is what I have come up with.

Right now, my car is weighing in at around 2700 lbs without me in it. With me and my gear lets say it will be back up to around 2900 lbs. When computing my numbers into the Performance Index = (Weight/[Displacement x Horsepower/Liter for engine type]) x 100 this is what I get;

2900 / 300 x 100 = 966.66

This puts me in GT6. Is this right??

Van

I think it should be 2900 lbs/(3.4 L X 100) = 8.53

Gasser

Not sure if the engine 986 is a typo but I think your conversion factor will be around 135/L So

135*3.4=459

So your final number would be 632 and would put you in GT3. You could add weight and then run in GT4.

Good luck...

I will say on EDIT, I could not find your engine type and hp figure but my 6cl air cooled is 110 and I can't imagine a water cooled would be less per liter than an air cooled. I think the 135hp/L will be right but will wait for clarificaton.

Geoffrey

Your car has a 986 type engine which has a performance factor of 135. You need to use the cc of the engine represented in liter (I'm not sure off hand what the bore and stroke of that engine is) so if you have a 3400cc engine it is represented by 3.400l. If you have a 3745cc engine it would be 3.745l. Using your weight of 2900lbs, the factor would be

2900 / (3.400 x 135) x 100 = 632 which fall into GT3. Your car would compete aginst a 993RSR with 400hp, a 2.5l 944 Turbo, lightweight 3.4l early cars. I think you would have difficutly being competitive in that car at that weight. If you could lower the weight to 2700lbs with driver I think you'd be far more competitive. I would consider looking into the GTB class for your car.

karlooz

the 986 and 996 share the same type of technology, blocks and 4 valve water cooled heads so using the same 135hp/L is not a stretch.

BluemaxxRacing

Thanks Van but based on the Index, my full equation would be as follows;

2900/[ 3.4 ltr displacement X 87.06 Horsepower/Liter for engine type]) x 100

I get 87.06 for my hp/ltr by dividing 296 by 3.4 = 87.06

I now wondering if I should be plugging in the 6 cyl 986-based number of 135 instead of my 87.06 like Glasser did??

Geoffrey

No, the performance index for an engine type is the theoretical maximum HP/L that engine type can possibly make. In the case of your 986 type engine the performance index is 135hp/l. Your value of 87.06 has no bearing on the calculation.

BluemaxxRacing

Glasser, Karlooz and Geoffrey - thanks so much for the help! Really clears things up for me. Looks like GT3 is the class for my car for all weights between 2700 and 3100 lbs.

No thanks!!

PedroNole

At 3,105lbs you would be at the very top of GT4. That would be a whole lot better than being at the top of GT3 especially if you have a semi-stock motor. Your biggest downfall is the HP/L calculation (135) they assign to you for the water pumper. Even so, I would think you would be lot better off adding weight and running in GT4 than trying to lose weight for GT3. Maybe GTB is the way to go in the end although it doesn't look like they have much info on it yet from what I could see.

Jump into GT4, the water's warm

Ed Newman

water cooled 911's can only run in GTA and GTB. GTA is for factory based race cars and GTB is for street based race cars.

38D

You can only add ballast to move up one class, not 2 or more.

karlooz

really? that bites. so a boxster with a water cooled 3.4L can run in gt3 but a 996 3.4L can't. something wrong with this picture.

PedroNole

He did the wrong math/calculation in his original post. He would really be running in GT3 so I suggested adding balast to go to GT4. Is that wrong?

Larry Herman

Where did you get this from? If they are he same weight, with the same water-cooled motor at 3.4L, then they will run in the same GT class.

I think that we need a primer on the new GT rules.

BluemaxxRacing

I agree, Larry. This is why I was partially confused to start with.