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cars and classes

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Dan Thompson
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cars and classes

Post by Dan Thompson » Wed Aug 15, 2007 6:02 pm

was looking at my cars classification today and noticed some new cars listed in TT11
New CaymanS and new BoxsterS among other high HP cars.
Gee, lets see a 295 HP car with modern suspension and computer aids, with way wide modern wheel/tire combinations up against my 30+ year old 110HP 2.0L 914 with ancient suspension and no computer aids, on 205s on 5.5" wheels.

Lets see, take both cars to TH, BW, LS or SP and run them back to back...

I wonder which car I would be faster in? :? :? :?

This is what drives me crazy....

there is no way these cars should ever, ever, ever end up in the same class....period. :shock: :(
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Post by Zone7Rep(Larry Sharp) » Thu Aug 16, 2007 7:33 am

but you still win ?

The rules wont get closer unless someone makes them so .. they are always open to change Dan .. but you forget one little point .. lighter is way faster...:) you got them by about 800 pounds which is huge
1993 RS America
Grand Prix White
Car #6

1974 911 Carrera (resides in Australia)
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1974 914-6 GT (resides in San Luis obispo)

1987 944 turbo (location unknown)

1979 911SC(Hummers have it)

1972 911T (location unknown)

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Post by Dan Thompson » Thu Aug 16, 2007 4:47 pm

yes, I still win so far, until the newbie drivers get their acts together and they show up at a TT event.
a 2:14 (new class record by a prepped 944) at TH is going to be a real uphill battle for my car. Since the BP and BR records are both 2:15s at TH.
My weight advantage is only good for so much in the corners, then the HP takes over and I get whooped. :)
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Post by Zone7Rep(Larry Sharp) » Fri Aug 17, 2007 7:05 am

I think you and I should sit down and review the TT base numbers for 4 cylinder cars .. that is the issue ...
1993 RS America
Grand Prix White
Car #6

1974 911 Carrera (resides in Australia)
Light Yellow

1974 914-6 GT (resides in San Luis obispo)

1987 944 turbo (location unknown)

1979 911SC(Hummers have it)

1972 911T (location unknown)

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Post by dtfastbear » Fri Aug 17, 2007 8:04 am

Dan Thompson wrote: My weight advantage is only good for so much in the corners, then the HP takes over and I get whooped. :)
Weight doesn't make a difference in acceleration?
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Post by Dan Thompson » Fri Aug 17, 2007 10:28 am

sure I have an 800# advantage and they have 3x the HP....so my car would need to weigh ~1/3 of theirs....so 1000# total weight for my car :?

and yes Larry that is why I proposed changing the starting points for 4 cylinder 914s this year as well as Bill Dally's similar proposal from last year.
I would love to talk to you about the starting values for 914s. :D
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Post by dtfastbear » Fri Aug 17, 2007 10:56 am

Unfortunately, I don't think it's that simple... I'll offer as an example John Tavernetti's time of 2:10.0 in his Cayman S. I have a TREMENDOUS amount of respect for John as a driver, so I think we can use his time as a pretty good baseline of what that car is capable of in the hands of a good amateur driver. I think I'm also a decent driver, and I've been able to drive my 110 HP, 2300 lbs, 205 tire-shod miata to a 2:09.0 at Thunderhill. Better drivers than me are down in the low 8's. Sure, my suspension is only 17 years old, not 30, but my point is that weight makes a GIANT difference in practice on the track.

Not an apples to apples comparison by any means, but I think many folks underestimate the value of lower weight on the track. In fact, I remember many folks arguing that the rules didn't do enough to penalize weight advantages...

I have absolutely no basis for arguing the 914 4-cyl base points, Dan, so I won't. I'm just trying say that the match up of those two cars you mention isn't as ridiculous as you're insinuating in my opinion.

I'll go back in my hole, now... :)

Dean

Edited - Upon further reflection, I think John ran perhaps significantly faster during practice at that last TT - 2:08? 2:07? But I still believe the gap isn't a canyon - it's just a gap that a small base points adjustment could close.
Last edited by dtfastbear on Fri Aug 17, 2007 11:29 am, edited 1 time in total.
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Post by Zone7Rep(Larry Sharp) » Fri Aug 17, 2007 11:07 am

Dan lets not limit the adjustment to just 914's // I say go for 356 912 914 924 and 944
1993 RS America
Grand Prix White
Car #6

1974 911 Carrera (resides in Australia)
Light Yellow

1974 914-6 GT (resides in San Luis obispo)

1987 944 turbo (location unknown)

1979 911SC(Hummers have it)

1972 911T (location unknown)

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Post by Dan Thompson » Fri Aug 17, 2007 11:44 am

Zone7Rep(Larry Sharp) wrote:Dan lets not limit the adjustment to just 914's // I say go for 356 912 914 924 and 944
agreed

and Dean, I think your Miata might have a wee bit more than 110hp :lol:
Also the full out mentality of the Spec series vs the TT series has some basis in all this. :?

but this is all apples and oranges since we are specifically talking about a CaymanS and a 2.0L 914.
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Post by dtfastbear » Fri Aug 17, 2007 12:05 pm

Dan,

I don't have your email address - I'd be happy to send you the dyno sheet for my orange/apple. But you're right about it having a wee-bit-more than 110. It actually had 113HP. Although I did run a 2:09.0 before dyno'ing and adjusting the timing and AFM when it actually had only 110HP (exactly) and a sub-optimal torque curve (you can see the baseline in the dyno sheet).

Since that time I've put in a better engine (up to 121HP now!) The fact that I've improved the engine significantly but have never gone faster than I did with 110HP is interesting in its own right... perhaps driving is the bigger variable.

Cheers,

Dean
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Bill Pickering
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Post by Bill Pickering » Sat Aug 18, 2007 5:19 pm

I think this is a good discussion. I am a believer in the lighter is faster philosophy and that the driver makes a huge difference. But I also believe that the power to weight ratios in the cars are more of a tell-tale and that the groupings of cars by power to weight would help with classifications. John T.'s Cayman S is a good example. He's a great driver and as he gets acclimated to the new car he's going to go faster and faster. He's currently in my class, TT8. He ran a 2:10 at the last TT, I ran a 2:12. The faster Thill time in my 2.5 Boxster is 2:10.5 on V710's. At the last TT, I chose to run on Boxster Spec series rubber, which is 225/255 Victoracers. I would have been in 2:11's or 2:10's if I ran the V710's, so in principle the cars are close.

But I also believe that on a power to weight basis, the Cayman S or 996/993's in my class with superior power to weight will be at a significant advantage over my Boxster. But my Spec Boxster is significantly faster than the TT9 group, so there is no clear cut answer.

If I look at the cars on power to weight alone I get the following:

Cayman S 3150lbs with driver / 295 HP = 10.67 lbs per HP
(2:10 lap time TT8 class)

Spec Boxster = 2885lbs with driver / 201HP = 14.35 lbs per HP
(2:10.5 lap time TT8 class)

Dean's Spec Miata = 2300lbs with driver? / 110 HP = 20.9 lbs per HP
(2:09 lap time Spec Miata)

For kicks, I throw in my Thill lap times with my 911 last year with a 3.6:

911 = 2400lbs with driver / 300 HP = 8lbs per HP
(2:02.8 lap time GT2 class)

Personal correlation is that I am significantly faster in a car with a superior power to weight ratio. If I'm looking at Dean's awesome Spec Miata times, I believe he would be significantly faster in a a Cayman S versus my Boxster based on a power to weight advantage of 40%. That is a huge advantage in my opinion. Once John gets accustomed to tracking the new car, he should be significantly below 2:10's, probably below 2:05's since we've seen these times turned by 996's with identical power to weight ratios that have full interiors and are street driven.

I believe my Spec Boxster will get into the 9's and 8's. I also believe if I was driving a Cayman S I eventually would post quicker times in it than my 2.5L Boxster. It is my opinion that the base points need to be adjusted on some of the cars for better equality. But we don't have many people running for time anymore, so it really doesn't seem to matter anyway.

The driver does make a huge difference, but in my case I have data points showing the same driver (me) going faster with a superior power to weight. It appears I will be purchasing a street 993 or 996 in the near future, so I'll try driving one of those next year at Thunderhill and see what times I turn. I believe I can go faster than the Boxster in a TT8 prepared 993/996 since they have superior power to weight.

Bill P.

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Post by Dan Thompson » Sun Aug 19, 2007 6:45 pm

" perhaps driving is the bigger variable. "

I agree with that. :D

to a degree, but I still feel the newer cars with newer suspensions and 3X hp belong in a different class, or possibly the 914s belong in a different class.
Don't Spec Miatas have "their" own class? :?
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Post by dtfastbear » Wed Aug 22, 2007 7:57 am

Yes, spec miata's do have their own class for sprint racing, but we race them against other types of cars, some with significantly more HP (and weight) in endurance racing and mixed car classes like Improved Touring.

I don't disagree with your assertion that the newer cars belong in a different class, Dan. Bill makes a good point that the true limits of the Cayman S probably haven't been "shown" at a GGR event, yet. So, the gulf in lap times between the 914 and that car is likely to grow.

I just wanted to weigh-in and say that cars with even only 100HP CAN be very fast if they are light enough and are set up correctly. It sounds like we all acknowledge that.

I hope some adjustments in base points to the 914 will get those cars into a place where folks are satisfied that they can be competitive.

Cheers,

Dean
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Post by Grant K » Mon Aug 27, 2007 4:43 pm

Anyone want to wager some money on the fact that a good driver in a Cayman S could easily put a few seconds on Dan in his "lightweight" 914 on any track in Nor Cal? Bet a well piloted Cayman S could smoke a well piloted 110 HP Miata too. :lol:

I have followed well driven Cayman S's in my 200+ HP 1750 lb 914-6 which is classed about 6 classes higher than Dan's current car. I have a hard time hanging with Cayman S's and my car is signficantly lighter and more powerful than Dans little street legal 2.0. On Laguna Seca I was clicking off 1:44's and a Cayman S was right there for several laps with me. I dont know too many 2.0 liter 914's that can get much below 1:47 on Laguna Seca. Whats the record for old BP class 914's at Laguna?

I think its funny that anyone could reasonably consider putting a trendously well enginered modern Porsche with 300 HP in same TT class with a 40 year old 110 HP 914 on 5.5" rims. Modern cars do have signficant advantage in suspensions that actually hold tires in correct aliignment. Lets not even start on braking effecincy between a Cayman and a stock 914! Power to weight ratio is still terribly skewed to Caymans favor. Especially given that T Hill is typical venue for PCA events.

Hey Dan are you worried about my potential purchase plans? I didnt even think about the fact that we would be in similar class if I get a Cayman S. LOL!
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Post by Dan Thompson » Mon Aug 27, 2007 5:15 pm

for me the driver is of minimal importance in this discussion....as it should be.

the point of contention is and will remain the potential of the car irregardless of the driver.

that is the problem with a lot of our current rules like PAX which is almost entirely predicated on the driver as much or more than the cars potential...
that is the data that was used for the PAX....GGR Zone 7 AX results...
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Post by dtfastbear » Tue Aug 28, 2007 7:22 am

Dan,

That is the data that WAS used for PAX up until about 5 years ago when I was asked to do the PAX index. Using that data lead to conclusions like Lp having a more favorable index than Li... clearly not right!

I've made it pretty publick knowledge that the current index was created with my thumb in the wind, educated guesses and a lot of experimentation running scenarios across the data set you mention.

I'm actually pretty happy with the way the PAX results turn out each year. I feel like very deserving drivers are up there at the top of the PAX results. That being said, take the results with a healthy dose of salt. They weren't engineered using reams and reams of data with national-level drivers like the SCCA PAX indexes are.

Grant - not sure who your post was directed at - I think every single person on the thread agreed that the Cayman S should be in a different class...

Cheers,

Dean
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Post by Grant K » Tue Aug 28, 2007 2:51 pm

dtfastbear wrote:Dan,

Grant - not sure who your post was directed at - I think every single person on the thread agreed that the Cayman S should be in a different class...

Cheers,

Dean
Comments arent really directed at anyone in paticular - I'm just a trouble maker in general. But the fact is that somone setup classing that allows a Cayman S in same class as Dan's poor little wimpy weazy wobbley oil weeping street prepared 914-4.

Funnier yet is the classification system will allow a 600+ HP Le Mans bred C GT to run against a mildy prepared 914 in same TT class. I know, I know, the 914 won its class in Le Mans back in the 70's, but that doesnt mean it should be put in same class as a C GT.

If I made a few changes to my car I'd be running a 200 HP 914 in similar class as a new 415 HP 997 GT3 RS. Now for me thats fun and a challenge however I know others find that type of match up discouraging.

There just needs to be a sanity check for power to weight ratios in TT.

...I have absolutely no complaints about AX classifications. Actually I dont think I have any complaints in general as I havent even run a TT with PCA yet.
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Post by David Leong » Tue Aug 28, 2007 3:06 pm

I havent even run a TT with PCA yet.
Glad we established that. Most of the chatter has always been about hypothetical.
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Post by Grant K » Tue Aug 28, 2007 3:25 pm

David Leong wrote:
I havent even run a TT with PCA yet.
Glad we established that. Most of the chatter has always been about hypothetical.
There isnt much conjecture related to the differnce in HP. :wink: Think thats the primary issue of concern. I dont need to drive GGR TT events to know I would get my butt kicked by a well driven C GT. LOL!

I have been on track with GT3 RS's they are much more capable cars than a 914 too. Thats cool I like being outclassed it makes me work harder.

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Post by johntavernetti » Thu Aug 30, 2007 3:55 pm

Hey guys,

I think Dan’s original complaint was about TT11. I run in TT8, so there is a 3-class gap between him and me. The only way a Cayman S (with its 500 base points) could run in TT11 would be on street tires & without the factory sport suspension (PASM) and completely, completely stock. Even then, it would only be 1 point away from TT10, so if the driver so much as changed the air filter he would be in TT10, and still on street tires. In fact, if it weren’t for the Boxster-exemption from the 5-point “factory rear spoiler” then the stock Cayman S would already start out in TT10 (with 505 points). If it has PASM, it starts at 515 points anyway.

The 914/4 starts with only 150 TT base points, so it’s got 350 or 365 modification points to work with. Maybe that’s still not enough... I don’t know.

Having said that, I think my car is capable of running faster…maybe in the high 2:08s??? But that's with Toyo RA1s. Time will tell. One of the main limitations is the lack of camber in the stock suspension. Don’t get me wrong, it’s a fantastic car and easy to drive.... But I still have 0.8 seconds to trim off before I get the TT8 lap-record set by a 993S, so it’s not exactly a ringer with it’s 500 base points.

To my knowledge, the fastest ever “claimed” laptime at T-Hill for a Cayman S is 2:05.8, and that was in a car that had a full Moton coil-over suspension, GT3 seats, GT3 control arms, aftermarket wheels and racing brake pads (and maybe other mods that I don’t know about). So that wouldn't be a TT8 car anyway, so it's irrelevant.

The discussion above has ignored these varying degrees of preperation for a Cayman S. Bone-stock on street tires, there is no way it would do 2:10s. And just like any other car, it won't do 2:05s at TH or 1:44s at Laguna without mods that take it up several classes to at least TT7.

As for the larger question of weight vs. lightness, I personally believe that even with equivalent power-to-weight ratios, a lighter car still has big advantages. Mainly, turn-in speed and mid-corner speed. The lighter car has the advantage there, because the heavier car (even with bigger tires) simply cannot overcome the inertia of the extra mass (especially in long, fast corners which count most against the clock). Brakes are better on the new cars, but they have much more mass to slow down too, so it is a difficult advantage to exploit.

Below is a graphic comparison between Dave Stomp’s Toyo-cup car and mine at T-Hill. The power/weight ratios are somewhat similar:

Measured weights with driver:
Me: 3,200 lbs / 295 hp = 10.85
Stomp: 2,400 lbs / 230 hp = 10.43

This is a velocity vs. distance comparison (reading left-to-right, the first braking zone you see is for T1):

Image


The difference in lap-time is significant! His 2:05.4 vs. my 2:10.0.

As you can see from the traces...those extra 800 pounds require me to slow down more before the corners, and because the P/W ratios are roughly the same, I can’t make it back up on the straights. The only advantage I have is a superior shift linkage, which keeps my acceleration-curve steep while his levels off noticeably between shifts because he has to be patient with the old 915 tranny. Otherwise, he beats me by braking less, carrying more speed through most corners and maintaining that lead on the straights.

By the way, I have no opinion about how 914’s should be classed. Just thought I would add some data to your debate. Enjoy!

JT

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