Tire points

[ttweed]

Tom, I don't think that's quite right. Under the new rules, a 72 hp gain is 160 points. A 352 hp increase would be 774 points...

Yes, you're right, Russell--that higher figure was generated by fat fingers on the calculator keyboard....

My bad. Still, 72 HP is the equivalent of the point penalty for dropping a 3.6 into an early 911S chassis, which is quite a potent improvement.
TT

[Mmagus]

**** Small Hi-Jack****

that higher figure was generated by fat fingers on the calculator keyboard....
TT

http://www.youtube.com/watch?v=8DtbPOXFk00&NR=1

****Back to the regularly scheduled debate****

[Cajundaddy]

Tom, I don't think that's quite right. Under the new rules, a 72 hp gain is 160 points. A 352 hp increase would be 774 points...

Yes, you're right, Russell--that higher figure was generated by fat fingers on the calculator keyboard....

My bad. Still, 72 HP is the equivalent of the point penalty for dropping a 3.6 into an early 911S chassis, which is quite a potent improvement.
TT

Yes it is quite potent. Now a thought experiment to give a little perspective:

What do you estimate would be the lap time improvement at say Buttonwillow #1 with this 3.6L transplant, 2-4 seconds? Dan? Russell? Erik? Now what would be the lap time improvement by removing street tires and adding fresh racing slicks instead of the motor, 4-8 seconds? Erik? Jad? Paul? Otto? While we might debate exact numbers, I think everyone would agree that for the same 160 pts, tires would give a far greater performance advantage. This is why we should be gathering data and comparing lap times to bring points for tires, motor transplants, turbo boost, and weight reduction into similar points for similar performance benefits. Of course it will vary somewhat from track to track and model to model but we can get numbers fairly close (within the 50lb-50hp-50tw have-fun-and-play target). Right now the motor transplant guys pay dearly in penalty points while the soft tire compound guys get big performance gains for relatively small penalty points.

Neutrality note: I run spec so none of this affects me directly one way or the other. Having a fixed motor and tire choice makes it purely a drivers sport for me. That may change at some point though so finding ways to improve modification rules and move towards a more level playing field benefits all drivers. And on that note...

[Gary Burch]

Tom, I don't think that's quite right. Under the new rules, a 72 hp gain is 160 points. A 352 hp increase would be 774 points...

Yes, you're right, Russell--that higher figure was generated by fat fingers on the calculator keyboard....

My bad. Still, 72 HP is the equivalent of the point penalty for dropping a 3.6 into an early 911S chassis, which is quite a potent improvement.
TT

That would be a nice upgrade, but, you would need a substantial tire upgrade(penalty) to make the swap even close to being an advantage. It is apples to oranges. The tires give the advantage without the engine upgrade, the engine upgrade is useless without the same tire upgrade, or even bigger tire upgrade.

[944Greg]

Yes, getting the rules a little closer to reality before next year would be great.

My Street Stock (PS/S class) 996 bumps into CC09 from CC10 as I take 20 points for having treadwear 180 street tires. At the Time Trial at SOW, Tawfik was in my class with his race car. He was 5 seconds faster.

My question is, I can max out my points in CC09 if I put on Hoosier R6's. Will that gain me 5 seconds at SOW? I would have to run times almost as fast as Mike Avitt in his GT3 on R-compound rubber to get to Tawfik's time. I think Tawfik has the CC09 title already.

I do have at set of narrower 17" wheels/tires that would put me in CC11. Maybe I'll check and see who is in that class.

[rshon]

What do you estimate would be the lap time improvement at say Buttonwillow #1 with this 3.6L transplant, 2-4 seconds?

Well, it's a little more complicate than that. There is the track layout (high-speed/long straights vs. slow-speed/twisty), gearing (whether you can keep the engine in the power band, and how wide or narrow the power band is), and whether or not the car is grip limited (which is a function of tire stickiness and suspension setup), but I'll fall into Greg's trap and admit that the biggest mitigating factor for horsepower is how much the car weighs. 72 hp in a 2200 lb car would make a much bigger difference than 72 hp in a 3000 lb car. (See Jad's input and Greg's thoughts in the "other" thread).

I can tell you that at Streets I would have rather had 30 or 40TW tires than my "extra" 45 hp in an allegedly 2850 lb car...

[Mike Cornelius]

I think Tawfik has the CC09 title already.

hey, not so fast! Tawfik is a good driver in a well prepped car, but I finished about a second behind him on corded NT01's...I will challenge him for the championship!

[Carl Vanders]

In Autox with SCCA, there is a ton of proven data available on the same car running street tire vs dot r tires . Basically, there are several stock classes (that runs a6/v710) and the same stock classes but running street tires. (Morgan T has done very well running the stock street tire class) They have developed a Bri index and on a 60 course, I believe its apx 1.5-1.75 sec difference, but its slightly bias towards the race tire. So about 2 seconds is a good average. That said, the new breed of street tires have Greatly improved!, ie , Dunlop z1, kumho xs, brig r11, Ventus s2, YOks 08 and the Toyo r1. There is also a fair amount of data on Slicks vs A6 and most would say for autox there is not a huge difference and conditions and course dependant.(although there is new breed of slicks hitting market) Currently its about a .5 difference if you run slicks but that class also includes being able to drop weight. Scca autox courses which are typically more technical and more turning elements could favor the race tire more than our course?
I think that data could be mined and used to help set up tire pts fairly. For TT thats a whole different game.

In a perfect world, it would be interesting to see a data sheet based off mod points system that correlate to actual time off a 60-70 sec course, Example 10 pts equals .25 sec.

[AGill]

I think Carl is on to something...data should be a our friend. At the very least...we will be making a change that is based on something we can later go back and consult.

FWIW, I ran at SOW last month and was running r6's for part of the time and street tires the other part. I had to go to street tires because the r6's weren't going to make it to timed runs. I'll put my flame suit on as I know this goes against what many beleive is a cardinal rule, but I ran different tires with different treadwear ratings front to rear. 280 in the front and 200 in the rear. I say this only so we have accurate data. Call it a weighted (for tire width) average of 235tw. I was exaclty 2.5 seconds slower with street tires; however the street tire setup actually felt better as the car rotated better...if the car was handling the same with the r6's I bet it could have been closer to a 3 second gap.

[Cajundaddy]

I think Carl is on to something...data should be a our friend. At the very least...we will be making a change that is based on something we can later go back and consult.

FWIW, I ran at SOW last month and was running r6's for part of the time and street tires the other part. I had to go to street tires because the r6's weren't going to make it to timed runs. I'll put my flame suit on as I know this goes against what many beleive is a cardinal rule, but I ran different tires with different treadwear ratings front to rear. 280 in the front and 200 in the rear. I say this only so we have accurate data. Call it a weighted (for tire width) average of 235tw. I was exaclty 2.5 seconds slower with street tires; however the street tire setup actually felt better as the car rotated better...if the car was handling the same with the r6's I bet it could have been closer to a 3 second gap.

A good test! Adam is the poster boy for this topic because he recently discovered race rubber and now is running very quick times in that C4.

I know, lets put PS2 tires on Jad's car for the timed runs at at Cal Speedway in April. I am guessing 5 seconds off his best lap there. Whadayasay Jad??

[Cajundaddy]

What do you estimate would be the lap time improvement at say Buttonwillow #1 with this 3.6L transplant, 2-4 seconds?

Well, it's a little more complicate than that. There is the track layout (high-speed/long straights vs. slow-speed/twisty), gearing (whether you can keep the engine in the power band, and how wide or narrow the power band is), and whether or not the car is grip limited (which is a function of tire stickiness and suspension setup), but I'll fall into Greg's trap and admit that the biggest mitigating factor for horsepower is how much the car weighs. 72 hp in a 2200 lb car would make a much bigger difference than 72 hp in a 3000 lb car. (See Jad's input and Greg's thoughts in the "other" thread).

I can tell you that at Streets I would have rather had 30 or 40TW tires than my "extra" 45 hp in an allegedly 2850 lb car...

Yes of course results will vary based on the track. I chose BW because it is a good mix of technical corners and fast straights. SOW was interesting this year. Your car and mine are pretty close in weight and tires but you have 100hp advantage. As expected our cornering speeds were pretty close but you left me by 5 car lengths on the straights and climbing uphill. Net difference in timed runs ~ 2 seconds.

[Jad]

I think Carl is on to something...data should be a our friend. At the very least...we will be making a change that is based on something we can later go back and consult.

FWIW, I ran at SOW last month and was running r6's for part of the time and street tires the other part. I had to go to street tires because the r6's weren't going to make it to timed runs. I'll put my flame suit on as I know this goes against what many beleive is a cardinal rule, but I ran different tires with different treadwear ratings front to rear. 280 in the front and 200 in the rear. I say this only so we have accurate data. Call it a weighted (for tire width) average of 235tw. I was exaclty 2.5 seconds slower with street tires; however the street tire setup actually felt better as the car rotated better...if the car was handling the same with the r6's I bet it could have been closer to a 3 second gap.

A good test! Adam is the poster boy for this topic because he recently discovered race rubber and now is running very quick times in that C4.

I know, lets put PS2 tires on Jad's car for the timed runs at at Cal Speedway in April. I am guessing 5 seconds off his best lap there. Whadayasay Jad??

Ugh, NO. Sorry, but I don't play games at 150+ mph next to the wall , and I won't be there . I would be happy to bolt someones street tires on for a session at Chuckwalla to compare . However, just like the engine needing better tires to really shine, race tires need a better suspension, or at the very least a far different alignment. Street tires are far easier to drive, thus more comfortable and balanced than race tires, as Adam found. This isn't simple and there isn't a correct answer as there are a LOT of variables. Fontana in a 944 spec car could produce nearly the same time on Sears Roadhandlers and full slicks as most of the course is simply power limited (when driven flat out!), whereas Pahrump would significantly favor the race tire.

[rshon]

SOW was interesting this year. Your car and mine are pretty close in weight and tires but you have 100hp advantage. As expected our cornering speeds were pretty close but you left me by 5 car lengths on the straights and climbing uphill. Net difference in timed runs ~ 2 seconds.

Yes, but last year I had almost 3 seconds on you with the original engine and narrower tires. Maybe too much rear sway bar this time, as my car was definitely grip-limited and I could not put all the power down in some of the tighter corners. There are days I feel like firing my mechanic, but I've known him almost my whole life. Of course, the biggest variable is still the "mutated ill-tempered sea bass" behind the steering wheel...

[Jad]

Oh great, now we need a point scale for drivers too!

[rshon]

Oh great, now we need a point scale for drivers too!

Well, no. That's why we need to keep the focus on measurable and/or documented data pertaining to the cars (HP, Weight, Tires) and NOT use anecdotal comparisons between different drivers in different cars to fix the system (this is one of the sources of variability in the old BRI system; some classes had a lot of good drivers, other classes sometimes had more inexperienced ones). I couldn't categorically say if Dave is a faster/slower/same driver than me or not. Or if he's more or less consistent than I am (I probably mess with my setup and tires more, and that's definitely the source of some variability on my part). Only if people are driving the same car on the same day with the same setup can you comment on the relative prowess of the driver.