[flash]

jim - actually the 248 is one of the less accurate dynos out there - it has a high error tolerance compared to some others - it's less expensive though, so very popular



i get that what you are saying, and without getting into a big long discussion of dynos, depending on how they conduct the test, and knowing how the dynojet works, and its inability to accurately measure drivetrain loss, it could be off by 10hp without much effort - that equates to a 120lb difference in weight - even 2hp is 24lbs - that's a lot of ballast



back to the point of the thread - how cool is it that a 968 beat out everything else? what other cars are in that class?

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[Charles Geer]

[quote name='flash' post='32985' date='Mar 21 2007, 07:43 PM']jim - actually the 248 is one of the less accurate dynos out there - it has a high error tolerance compared to some others - it's less expensive though, so very popular



i get that what you are saying, and without getting into a big long discussion of dynos, depending on how they conduct the test, and knowing how the dynojet works, and its inability to accurately measure drivetrain loss, it could be off by 10hp without much effort - that equates to a 120lb difference in weight - even 2hp is 24lbs - that's a lot of ballast



back to the point of the thread - how cool is it that a 968 beat out everything else? what other cars are in that class?[/quote]



Actually after reading about Jims Dyno numbers, 214 hp to 216 it appears that these Dynos may indeed be if nothing else, consistent. We Dynoed my car last year and it showed 221 rwhp. We Dynoed it again 2 weeks ago and it showed 222 hp (With the exact same curve).



Any German cars can run in GTS. For GTS 3 it is typical to see alot of E 36 M3s. They are a perfect fit because you don't have to do alot to them to make that 11 power to weight ratio. Here is a basic breakdown of cars that you may find in GTS 3.



1) E 36 M3 with Chip = 250 RWHP. Calculation: 250 * 11 = 2750 (weight of car with driver)

or 2550 (Car weight without 200 lb driver)



2) E 36 M3 with Chip & Cams = 270 Rwhp. Calculation 250*11= 2970 (weight of car with driver)

or 2750 (Car weight without 200 lb driver)



3) 964 RS America with Chip= 250 RWHP. 2750 (Weight of car with driver) or 2550 withthout driver



4) 997 (911) = 305 Rwhp. Calculation 3355 lbs (weight of car with driver) or 3155 (showroom stock weight of

car, leave everything in it add roll cage and cool race seat and she's a GTS 3 car).



5) 968 = 222 Rwhp. 2442 (weight of car with driver) or 2242 (without driver) (Get your carbon fiber ready).



***The white and Blue BMW that blows by me on the straight was a GTS 5 car making 380 RWHP.

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[flash]

thanks - interesting match - very different philopsophy of design across those cars



all i can say about the dyno's consistency is that the operator is doing a great job and being consistent with the conditions of the test - a lot of it is really up to the operator anyway - if he takes care to measure the transaxle temp, drivetrain loss, and all of that, gets the intake sensor in the same place every time, uses the same probe, yada yada, then you can get reasonable and consistent results - if he doesn't, and just does something as simple as let the car sit for 20 minutes before doing a test, it can easily vary as much as 10 hp from a test done right off the track - 5lbs of tire pressure can be 1-2, 4 clicks on the rachet strap can be another 1-2, 6" of movement on the intake sensor can be 5 - it's not hard to make things change, and if the guy did it wrong, you could be penalized for something that doesn't exist



i wonder how they manage that kind of control track to track? seems like it would start a lot of arguments over how much power somebody really has



that whole thing is one of the reasons i don't enjoy production class racing as much as more open class stuff that allows the tuner to be as much a part of the equation as the driver - i get the idea behind "leveling the playing field" but i enjoy both driving and setting up the car



by the way, 222 at the wheels gives you a good 255 flywheel, and we know that is way more than stock - what mods did they let you do to get there?

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[Jim Child]

I can tell you nobody's measuring transaxle temp, and drivetrain loss doesn't matter for our purposes as the class rules are based on pounds per wheel horsepower. I can also tell you that cars do sit at impound anywhere from 5 to 30 minutes after coming off track waiting their turn on the dyno. Even with all of that people are only seeing variations of 1 or 2 hp. I've seen a lot of cars dynoed trackside and never seen a variation of 10 or more horsepower. NASA does allow a 4hp forgivness to compensate for dyno variability as long as the car is running at its declared minimum weight.

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[flash]

very interesting - even dynojet will tell you their dyno has a variance of 1%, which is 2 plus hp in this range



nearly every other dynojet set we see varies 3-4 within even the same set of runs



since they are using rwhp numbers, drivetrain loss is mitigated, but the transaxle temp is a huge issue - tossing out the anomolous readings, cold to hot i've seen repeatedly 6kw differences in drivetrain loss, on this car, which means approximately 8 hp difference in what gets to the wheels



none of that even begins to take into account the effect that a light flywheel might have (and there is one that PCA has approved, along with the S2 setup)



i have no idea how he is doing it - there must be some set of tricks to accommodate all of those variances



that guy must be getting paid good money - if he isn't, he really needs to get to a tuning shop because he has found some magic



lol - i think i would be working on something to play with the transaxle temp and the intake pickup point temp to lower the numbers and make sure i didn't get dinged

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[ether_joe]

congratulations Charles on the new lap record! woohoo!

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[333pg333]

[quote name='Charles Geer' post='32926' date='Mar 21 2007, 06:22 AM']The exhaust on my car is very deceptive. I let a friend drive my car (who races BMW's) and he had a hard time shifting by sound. The exhaust was built to take advantage of the 3 liters great torque. What's deceptive is that the engine rpms are running much higher than the car sounds. Throughout that race

the car never dropped below 5100 RPM...not even in the braking. She has a rare factory Firehawk chip that cuts the fuel off at 7100 RPM. A couple times you will hear me hit the Rev limiter. I Shift at the limit every shift and try to down shift at that same limit as well.[/quote]

Your right it is very deceptive! I would swear blind that you were shifting well before redline occasionally. Just shows to go you. <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" />

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[Jason Judd]

I just saw the clip of your race and it looks like a hoot! I hope to keep my cool amongst those close quarters.



But, I have a question...



Charles, are you pulling a Dale Earnhardt...is that an open face helmet?



Must be my eyes...I must be wrong!



Jason

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[Charles Geer]

[quote name='Jason Judd' post='33113' date='Mar 23 2007, 04:52 PM']I just saw the clip of your race and it looks like a hoot! I hope to keep my cool amongst those close quarters.



But, I have a question...



Charles, are you pulling a Dale Earnhardt...is that an open face helmet?



Must be my eyes...I must be wrong!



Jason[/quote]



The face mask flew off when I stuck my head out the window <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" />

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[flash]

he was going so fast it ripped his face off



cool



so, what mods do you have that got you to 255 AND past the stewards?

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[S_Cal968]

Well done Charles! Thanks for sharing... As mentioned, including the rear view was great.

So what does your deceptive exhaust system consist of? Did you give up any low end torque?

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[cooz]

hey charles...nice goin & congrats...



why did you stick your head out the window? was there a pay-toll i missed? you should get e-z pass!



norm mandell <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

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[Charles Geer]

[quote name='S_Cal968' post='33129' date='Mar 23 2007, 09:29 PM']Well done Charles! Thanks for sharing... As mentioned, including the rear view was great.

So what does your deceptive exhaust system consist of? Did you give up any low end torque?[/quote]





We gave up high end speed for low in grunt. We tried to build a car that can be tossed into turns at high rates of speed, but yet exit the corners at high rates of speed as well (Fast in, Fast out). The MO 30 stock brakes were more than plenty to late brake most makes of cars. The option code 220 limited slip diff provides plenty of stability over rough curbing under acceleration. The top end speed isn't stellar but it's sufficient. We are generally about 5 miles per hour slower on Road Atlanta's back straight than other GTS3 cars. 90% of the time we can make this gap up at the next braking zone or at the entry to the next turn.







[quote name='flash' post='33123' date='Mar 23 2007, 07:14 PM']he was going so fast it ripped his face off



cool



so, what mods do you have that got you to 255 AND past the stewards?[/quote]



Engine has never been opened. Has about 54000 miles on it. 944 S2 Harmonic Balancer really doing the trick to keep the engine vibrations to a minimum.

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[Jim Child]

[quote name='flash' post='33123' date='Mar 24 2007, 02:14 AM']so, what mods do you have that got you to 255 AND past the stewards?[/quote]



For GTS, the only rule is to stay in the lbs/hp range for your class. Beyond that you can do anything you want to the car.

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[flash]

ah - not like production class limits then - got it - interesting - thanks

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[Charles Geer]

[quote name='flash' post='33154' date='Mar 24 2007, 12:40 PM']ah - not like production class limits then - got it - interesting - thanks[/quote]



It's the best rules I've seen so far to endure fairness. Literally anyone can race any car from VW Golf to a cup car.

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[Renalicious]

I'm curious, are any of these events televised?

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[Jim Child]

[quote name='Renalicious' post='33203' date='Mar 25 2007, 05:57 PM']I'm curious, are any of these events televised?[/quote]



Unfortunately not. One of these days there may be some kind of coverage for NASA Nationals. I know they're working on that.

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[rhudeboye]

Watched your video 4 times now. Your very consistant in and out of the corners and I agree w/ a comment made earlier, you "keep your cool" in the tight quarters. How long have you been at this?



That Ferrari seems to only get a good run when the RPMs are high or it could've just been the skills of the driver.

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[Charles Geer]

[quote name='rhudeboye' post='33207' date='Mar 25 2007, 12:08 PM']Watched your video 4 times now. Your very consistant in and out of the corners and I agree w/ a comment made earlier, you "keep your cool" in the tight quarters. How long have you been at this?



That Ferrari seems to only get a good run when the RPMs are high or it could've just been the skills of the driver.[/quote]



First race April 2005.

5 Race weekends with PCA F stock

2 Race weekends with Nasa.



Got my start with Autocross 7 years ago in a 1991 911 Turbo (Autocrossed for 2 years)



Bought a 993 supercup 2 years later. First car that was close to neutral handling. Used the car in the drivers ed program where I had earned my way to instructor level. Race instructor tought me to be more agressive exiting turns ("Unwind the wheel and slam the throttle to the floor"). He also tought me to use all of the track, plus gators, and in rare occasions, dirt.



Bought 968 2005 and sold cup car. Read alot of European Race articles where the 968 clubsport is revered as the essential race car. 968 is not looked at as a fun car but rather the fastest handling car to drive (in Europe).



I find that the 968 is indeed faster through the turns than the 993 Supercup.



I'm working on learning to drive an extremely agressive line (which the 968 loves) similar to that used by BMW factory driver Bill Auberlen. Ths line appears to be faster than a normal race line and provides an excellent view in front of the car you want to pass.



Currently working on "Maximixing Angles, Space and Time" approach to racing.

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