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PostPosted: Fri Dec 01, 2017 9:12 am 
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kjbrew01 wrote:
Based on what I am reading the maximum tire size is 245? I am curious why there wasn't another weight break for more tire above the 2750lb mark, maybe like 3200+lbs. My competition weight was previously 3340lbs (TTC) and I have never ran a tire as small as a 245. I hope the durability will be there in the smaller sizes, given they will not be autocross tires anymore. Maybe I read the rules wrong

It seems to me that this nominal 245 mm / actual 266 mm limit is going to penalize heavier cars, while continuing to give an advantage to lighter cars.

Let's just say that you have 2 cars in TT5, with one weighing 2850 lbs and the other weighing 3300 lbs (a 450 lb difference). Both hit the weight:power ratio limit of 14.0, and there are no weight adjustment factors for either car.

2850 lbs @ 266 mm = 10.71 lbs/mm
3300 lbs @ 266 mm = 12.41 lbs/mm

Using the lighter car's 10.71 lbs/mm, a 3300 lb car would need to use a measured 308 mm section width tire. But, with nothing greater than 266 mm measured allowed, that isn't legal.

Using the heavier car's 12.41 lbs/mm, a 2850 lb car would need to use a measured 230 mm section width tire.

Does anybody else have concerns about heavier cars being at a disadvantage to lighter cars, given the maximum 266 mm width?

It's my own theory that assigning weight:width ratio limits or correction factors could help out here, if the goal is truly to make an even playing field for all cars. Not necessarily for 2018, but definitely for the next rule set.

Mark

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PostPosted: Fri Dec 01, 2017 10:18 am 
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Mark, in my opinion it is a trade off. The lighter car might exit the corner faster, but the heavier car will be faster at the end of the straight for two reasons:
1. Better unmodified weight to power ratio (due to weight modification rules)
2. Similar drag but more power
So, like before, on twisty tracks the light cars will have an advantage. On tracks with long straights the heavier cars will have an advantage. This seems like what we saw in the TTA-TTG history of NASA. Cars in the same base class had the same base tire size irrespective of weight. I know that one could take points by increasing tire size in the past (and present TTD-TTG), but having a limit makes for easy comparison when inventing a new rule set.

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PostPosted: Fri Dec 01, 2017 10:57 am 
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I think the 265hp (oem) rule pretty much sums it up, the class is designed for cars in the 200hp sub-3000lb range, other cars (like mine) are forced to go to ST4 or faster. I had hoped to run ST5 next year, but can't due to the 265hp limit.

Just like ST4 has a 275mm limit, ST5 has a 245 limit regardless of weight.

My opinion.........I personally feel any car that can meet the power/weight rules should be allowed in any class.

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PostPosted: Fri Dec 01, 2017 11:58 am 
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I wasn't even really concerned about the performance penalty, just mainly whether the 245 R7s can hold up. on 2nd thought I bet they can, I was running 255 A6/7 without any issues so I bet the 245/40/17 (seems wider than the 245/45/17) would be plenty up to the challenge of the heavier car. My cars base weight was 3552 and 232 oem HP so it does fit into ST5, just going to be a bit of an odd ball being so heavy. More motivation for me to focus on weight reduction over any power increases.

Unrelated but I noticed the rules allow for essentially replacing the front bumper cross beam, but nothing is stated about the rear. Based on that we can convert our front bumper cross beams over to tubular ones but have to keep the OEM rear ones?


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PostPosted: Fri Dec 01, 2017 4:20 pm 
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davidfarmer wrote:
I think the 265hp (oem) rule pretty much sums it up, the class is designed for cars in the 200hp sub-3000lb range, other cars (like mine) are forced to go to ST4 or faster. I had hoped to run ST5 next year, but can't due to the 265hp limit.

Just like ST4 has a 275mm limit, ST5 has a 245 limit regardless of weight.

My opinion.........I personally feel any car that can meet the power/weight rules should be allowed in any class.


I know of a TT car that without "restricting" the engine it would have 25-30% more peak power. As it stands, this car is screaming fast out of the corners.. I haven't seen the dyno but I would imagine it doesn't have much of a "curve" and more just flat power band at just under the HP limit from 3000-7000rpms.

So, I think that excluding cars that have stock HP higher than 265 prevents them from being "restricted" to just running a crazy flat power band.


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PostPosted: Fri Dec 01, 2017 6:01 pm 
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MemphisRob wrote:
So, I think that excluding cars that have stock HP higher than 265 prevents them from being "restricted" to just running a crazy flat power band.



If you think this is an advantage then you don't understand how the average horsepower calculation works.


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PostPosted: Fri Dec 01, 2017 10:41 pm 
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Here is how we know when we have something right...........................everyone on both sides complains that the other guy has an advantage :lol:

So, we are now hearing from the light car drivers that the heavy cars (mostly without the A-Arm suspensions) are at an advantage because of the A-arm Mod Factor, larger engines with better "torque", and better weight table Mod Factors, and now the heavy car drivers stating that the lighter cars have an advantage because of tire size and the need for them to do control arms and sphericals, etc.

One region states how the M3 sets track records, and another region has S2000's destroying everyone, and yet another has Miatas and FR-S's leading every event. NASA has been fairly vigilant over the years to try to ensure that no single model becomes the only possible winning model in ST/PT/TT classes. I don't expect that to just stop.

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PostPosted: Fri Dec 01, 2017 10:56 pm 
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NASA Section Width templates were posted early today.
https://www.nasaproracing.com/rules

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PostPosted: Fri Dec 01, 2017 11:16 pm 
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944buzz wrote:
So if I am reading this correctly a full fiberglass fender as long as it maintains the original shape is legal?

Does this pertain to doors as well? Does the door have to open and close or can it be a skin?

Thanks!

Since technically fenders and doors are not part of the "unibody", they can be changed out as long as they have identical body lines to the OEM vehicle.
Although there is no current requirement for the door to remain functional, I personally would keep it functional, because this is exactly the kind of thing that NASA executives see during the season, and then say, "What, they don't have to keep their doors functional? They should....fix that in the rules....." Or, it gets added to the CCR, etc. Then, you are stuck trying to make them functional again.

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PostPosted: Fri Dec 01, 2017 11:20 pm 
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kjbrew01 wrote:
Unrelated but I noticed the rules allow for essentially replacing the front bumper cross beam, but nothing is stated about the rear. Based on that we can convert our front bumper cross beams over to tubular ones but have to keep the OEM rear ones?

Yes, provided that you have a vehicle that is not being held together by the front bumper cross beam (changing to a tube for such a possibly imaginary vehicle would then be a partial tube frame conversion).

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