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Thread: What is a "touring car?"

  1. #281
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    Quote Originally Posted by Andy Bettencourt View Post
    Which compounds this problem if you allow 'sports cars' better aero. So what is Prod doing to compensate? I think the baseline knowledge is there already.
    EP has the perfect example in three cars that share the same displacement motors, the e36 sedan/Z3/and Z4

    e36 325 sedan - 2525lbs
    e36 Z3 2.5l - 2450lbs -> 75lbs lighter
    Z4 2.5l - 2550lbs -> 25lbs heavier

    then there's the:

    e36 328 sedan - 2725lbs
    Z3 2.8l - 2650lbs -> 75lbs lighter

    There's two thing going on, first the Z3 has semi trialing arm rear suspension instead of the multi-link that the sedan and Z4 have, so roadster aero with the removed windshield net 25lbs, with the hard top you still get the 25lbs but aren't competitive. but the semi-trailing arm rear suspension gets a 100lb weight break for the net 75lbs removed. I'd argue that in the case of a ST Z3 it should have the full 100lbs removed because I can't take advantage of removing the windshield and using a roadster cage.
    Net the reason that Miatae/Rx8 are taking names in STL has more to do with the power plant and suspension than roadster/sportcar aero.
    STU BMW Z3 2.5liter

  2. #282
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    Anyone who thinks 25 pounds - or even 75 pounds - is enough to make a repeatable difference, let alone serve as a purposeful "competition adjustment," is demented.

    K

  3. #283
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    Quote Originally Posted by Knestis View Post
    Anyone who thinks 25 pounds - or even 75 pounds - is enough to make a repeatable difference, let alone serve as a purposeful "competition adjustment," is demented.K
    Truth.
    Last edited by Ron Earp; 09-15-2014 at 06:41 AM.

  4. #284
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    Then you have STU's 50lb weight break for solid rear axle cars, and 50lb weight penalty for alternate rear suspension for solid axle/semi-trailing arms. Seems it's already in writing. It seems Greg's observation on the final order is based more on motor output than on what it's wrapped in.
    STU BMW Z3 2.5liter

  5. #285
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    I didn't say it wasn't common practice; I said it's an act of the demented.

    Greg's picks are dominated by sports cars with the most powerful engine eligible. Why? Because people willing to spend coin to try to run up front understand that's the formula for success. Why would anyone do otherwise given the physics of the situation?

    My proposition was that, particularly with the human beings we have at the levers of policy, a sports car is going to have an inherent advantage over a touring with the SAME engine.

    K

  6. #286
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    Quote Originally Posted by Knestis View Post
    I didn't say it wasn't common practice; I said it's an act of the demented.

    Greg's picks are dominated by sports cars with the most powerful engine eligible. Why? Because people willing to spend coin to try to run up front understand that's the formula for success. Why would anyone do otherwise given the physics of the situation?

    My proposition was that, particularly with the human beings we have at the levers of policy, a sports car is going to have an inherent advantage over a touring with the SAME engine.

    K
    But with all due respect, that's due to assumptions that CG is lower, that CD is lower, and that frontal area is smaller. That MAY be the case, or it may not. My gut non-scientific observation is that Miatas don't draft as well as Integras, and over 120 mphish (again, total observation bias here) the Integra has the advantage. But without numbers it is all guess work.

    Which is the problem with trying to quantify difficult "effects" like aero, or torque, or "bad rear suspension" (as the owner of a live rear axle car, I frankly couldn't justify giving it a break against most stuff out there given what we can do with the rules in IT) -- it's just WAY above our skill level to do so in my opinion.

    I would, however, really like to see numbers on aero, real CD x Frontal area numbers, of sedans/coupes v. sports cars. I'm sure some sports cars do quite well. I'm also pretty sure some coupes/sedans do as well.

    Was at Homestead this weekend, was down there for work Friday and stayed and rented Mike VS's ITS Miata. Ran with the STL cars -- I think there were 5 dedicated STL cars. Two twin Celica GTSes, an Integra (Peter Keane?) and two Miatas. The Celicas were pretty. Peter's car is black and looks bad ass.
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  7. #287
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    Quote Originally Posted by Knestis View Post
    ...a sports car is going to have an inherent advantage over a touring with the SAME engine.
    All discussions in regard to Super Touring must always, always, always divorce engine and chassis discussions. Because we can so freely swap family engines in family chassis, they may be coincidental but they are not directly related.

    So for example, "the RWD Miata is not dominant because it has a lower-powered engine" or "the Honda Civic is a great car because it has a powerful engine" is an invalid discussion point. On the other hand, "the Honda Civic is a great strut chassis" and "the Miata is a great sports car option" are valid discussion points.

    Engines should be adjusted by engine-related inputs/factors; chassis should be adjusted by chassis-related inputs/factors. There are crossovers, such as power-to-weight considerations and/or effects of weight on chassis, but they are otherwise parallel lines that should not meet.

    Quote Originally Posted by JeffYoung View Post
    I would, however, really like to see numbers on aero, real CD x Frontal area numbers, of sedans/coupes v. sports cars.
    Because we have some flexibility with aero in Super Touring, I'm not that stuck on aero considerations. We add air dams, undertrays, splitters, and wings, and we lower the car to reduce the amount of underbody airflow. All go a long way toward improving - and in some case, hurting - aero, but in a generally-equitable way*.

    There are other non-quantifiable; the Miata, for example, gets its factory cD numbers off the base car, which is a convertible. Yet, we allow the factory hard top, which no doubt goes a helluva long way toward improving that cD. And, related to above, the STL-compliant airdam goes a long way toward cleaning up the jelly bean nose that forces a lot of air under the car.

    The one manufacturer-published aero factor that seems significant to me is frontal area. I see that as a general characteristic of the size of the hole that the car has to punch through the air.

    GA

    * "Hurting" meaning rear wings. Which, of course, benefit RWD cars a shat-ton better than they do FWD cars... Airdams increase drag as well but their benefits far outweigh that, and generally equitably among most cars, regardless of drive layout.
    Last edited by Greg Amy; 09-15-2014 at 10:17 AM.

  8. #288
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    Yeah, I agree -- I think frontal area is a more significant factor at this level of racing than CD. It seems to play out in the real world as well. My car has crappy CD, but is tiny. Seems to do ok at 120+ as a result.

    Note also that I think "downforce" aero at these speeds and with these implements is a mistake. Just my opinion but whatever downforce you generate is going to be far offset by drag, which is the key thing to me from observation. For IT, and I would think STL, you want the slipperiest car possible with the smallest frontal area.

    For the NSX fanbois (I've been toying with the idea), CD looks good but frontal area? That car is WIDE and not all that short.....
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  9. #289
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    Some data I had handy in a spreadsheet:

    Car Cd Area (sq ft) CdA
    RX7 0.31 19.19 5.95
    Integra 0.33 19.50 6.44
    Camaro 0.34 22.00 7.44
    Mustang 0.36 22.50 8.10
    280zx 0.39 21.00 8.09
    TR8 0.42 20.70 8.69
    240Z 0.44 21.00 9.24

  10. #290
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    That's nifty info. Do you have the years those numbers apply as well? i.e. RX7 had 3 body styles and various bumpers and whatnot across its life. Same with Integra, Camaro, Mustang...
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    EProd RX7

  11. #291
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    Those are for ITS bodies. Second gen RX7 etc.

  12. #292
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    OK, thx. just curious. I'm sure the Camaro bodies over the years have had quite the change in cd...
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    EProd RX7

  13. #293
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    Quote Originally Posted by Ron Earp View Post
    What does a 2L RWD car have to weigh in STL?

    Looks like 2800 lbs?
    I think more like 2950?

  14. #294
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    Quote Originally Posted by Chip42 View Post
    for Ron:
    2.0L STL weights
    RWD w/ SLA: 2849
    RWD w/ F Struts: 2795
    RWD w/ SLA and non USDM 2% penalty (i.e. BMW S14B20): 2905
    RWD w/ F Strut and non USDM 2% penalty: 2850

    FWD w/ SLA:2700
    FWD w/ F Struts: 2633
    FWD w/ SLA and non USDM 2% penalty: 2754
    FWD w/ F Strut and non USDM 2% penalty: 2685

    Honda K20 vs BMW S14B20: Honda wins on any track : 20+ more hp and almost 300# lighter.

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    Quote Originally Posted by Greg Amy View Post


    We actually increased the weights across-the-board in STL (Dec 2011?) to attract/accommodate 1.5L cars...with B-Spec'rs as the targets.
    I thought that was becuase of the expected increased base weight of all cars due to increased chassis rollover protection requirements, and the inability of cars to get down to current base weight.

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    Quote Originally Posted by Andy Bettencourt View Post
    WRT the 'what do you think', I also need to be more educated on what the SCCA has done in the past. STL has the same 'issue' as other classes. I bet EP and FP also have the same 'issue'. Getting some success stories from the Prod ranks on how they have attempted to balance Miata's, Preludes, 240Z's, Integra's, 2002's, S2000's, RX8's, Caterham's, 914's, 944's etc.

    Seems like the concepts may already live inside the CRB.
    Prod allows relocation of suspension pickup points, increased compression, head porting and non factory gearboxes. I other words, STU, but with lower power and different bodywork allowances.

    Do sedans or "sports cars" win more frequently in the prod classes? Hmm...

  17. #297
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    Quote Originally Posted by JS154 View Post
    Honda K20 vs BMW S14B20: Honda wins on any track : 20+ more hp and almost 300# lighter.
    Logic fale: my cohort has fallen into the trap!

    Quote Originally Posted by JS154 View Post
    I thought that was becuase of the expected increased base weight of all cars due to increased chassis rollover protection requirements, and the inability of cars to get down to current base weight.
    Nope. As I recall the conversation, it was to give the 1.5L cars a chance to make minimum weight, with the idea that B-Spec cars may gradually migrate to STL once their usefulness is past.

    I remember it vividly, as I had just finished spending a winter cutting out sh*t and replacing panels with plastic to lose 90# to get down exactly to the pound to my minimum 2340# weight with an empty fuel tank with me in it...and then we added 90# to my car...I now carry 100# of ballast in the back of the car to make 2430#...damn you Nemesis!!!

  18. #298
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    Eric, the BMW 2.0L is saddled with a 2% weight penalty because Americans wouldn't buy it so BMW didn't sell it here. That k20 in an s2000 or nsx would be a lot closer to a bmw in weight, too.

    And read up on prod. The VAST majority of cars allowed in both P and ST are prep 2, with stock pickup points and the same head prep, and usually 11 or 12:1 cr and 0.400ish cam. So... Not that different.

  19. #299
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    Is this the appropriate time to disclose I've actually considered and starting pricing stuff for a mid 1990s Lotus Esprit with the European DM 2.0 motor for STL?

    Take that, FWD shitboxes!
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  20. #300
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    Quote Originally Posted by JeffYoung View Post
    Is this the appropriate time to disclose I've actually considered and starting pricing stuff for a mid 1990s Lotus Esprit with the European DM 2.0 motor for STL?
    LOL! What in the hell is a European DM 2.0 motor...?

    I think that would be fun.

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