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ST4 SUGGESTED RULE CHANGES FOR 2018

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esr

daytona,

 

I drive a 350z de, they are also thinking of moving the minimum weight to 3100 for 275 tires, so at that weight with 6 points my car is out of st4. I hope they make the correction to the base ration and make it a true 12:1 class

Many of us have brought up this concern, you can see it in previous post.

 

 

 

Going to 6 data points will have a significant impact on avg hp, so if that’s the direction please consider a comparable adjustment to the base ratio. Many of the cars that have been racing in ST4 (e36’s/350z’s/S2000’s etc) are already at or beyond what they can reach for power to weight. Without an adjustment expect this to become more of an E46/E92 M class which I don’t think is the intention.

 

GTS chose to not use a 3k rpm band in the averaging bc it allowed too much room for tuners to make adjustments to exploit it. If someone has a sequential which can stay primarily around a 2k rpm range it’ll make a mockery of this revision. But I guess since sequentials aren’t a concern in ST4 it doesn’t matter as much.

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JonB
Going to 6 data points will have a significant impact on avg hp, so if that’s the direction please consider a comparable adjustment to the base ratio. Many of the cars that have been racing in ST4 (e36’s/350z’s/S2000’s etc) are already at or beyond what they can reach for power to weight. Without an adjustment expect this to become more of an E46/E92 M class which I don’t think is the intention.

 

GTS chose to not use a 3k rpm band in the averaging bc it allowed too much room for tuners to make adjustments to exploit it. If someone has a sequential which can stay primarily around a 2k rpm range it’ll make a mockery of this revision. But I guess since sequentials aren’t a concern in ST4 it doesn’t matter as much.

 

Daytonars4 - when you say that 'many of the cars that have been racing in ST4...are already at or beyond what they can reach for power to weight...' do you mean that by now using 6 points at 500 RPM increments it will be difficult to make the car competitive as the avg hp will now be much lower? In my case (running a e36 m3 with @234 avg hp) I am already coming in about 100lbs over on weight. 2 more data points would bring my avg down to around 220, which would make it really tough to be close to an ideal weight. Is that why you would also be suggesting to make an adjustment to the base ratio? Just trying to understand the implications of 6 vs 4 data points for the avg.

 

Jon B

NorCal ST4

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Alan_Wolfe
Just to be clear and accurate about this:

4 data points covers 1500 rpm range

6 data points covers 2500 rpm range

 

While that is probably the intention, that is not how the math was set up.

 

The Interval of the evaluation = the partition size * number of points. So 4 points x 500rpm evaluates a 2000rpm interval, and 6 a 3000rpm interval. You can't arbitrarily make the evaluation exclusive of the lower partition.

 

The ST rules describe a Riemann Sum(https://en.wikipedia.org/wiki/Riemann_sum) when they add up the points as a means of evaluating different curves against one another(dividing by the constant 4 does nothing). One problem is that a LEFT sum (as opposed to RIGHT, or MID) is codified in the rules by 8.2 "If any of the above data points at higher RPM than Max HP RPM do not exist due to redline, then those potential data points will not be used in the calculation of Avg HP". LEFT sum is an OVERESTIMATION of area under the curve PROPORTIONAL TO THE SLOPE OF THE CURVE. A flatter curve means less of an overestimation.

 

This will not go away by adding more points.

 

Without even getting into the "race-ability" advantages of a flat curve(which we should not, because it too difficult to quantify), you can now see why so many people have chosen to tune their cars as flat as possible: because the ST rules math will give engines with a steep power curve a weight ratio disadvantage right off the bat.

 

As I suggested, the best way we can deal with this is to decrease the partition size, which increases accuracy. Simply increasing the interval does nothing.

 

Poor 4 cylinder NA. I feel your pain... And wait until the Rotary shows up. Poor poor rotary.

 

If the calculation is in fact using a Riemann Sum Approximation, then we should go to using 100 rpm intervals instead of 500 rpm intervals. This would increase the accuracy of the Approximation, especially for motors that do not have a flat HP curve. It would also reduce the difference between left rule, right rule, or midpoint rule approximations.

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Dover
Just to be clear and accurate about this:

4 data points covers 1500 rpm range

6 data points covers 2500 rpm range

 

While that is probably the intention, that is not how the math was set up.

 

The Interval of the evaluation = the partition size * number of points. So 4 points x 500rpm evaluates a 2000rpm interval, and 6 a 3000rpm interval. You can't arbitrarily make the evaluation exclusive of the lower partition.

 

The ST rules describe a Riemann Sum(https://en.wikipedia.org/wiki/Riemann_sum) when they add up the points as a means of evaluating different curves against one another(dividing by the constant 4 does nothing). One problem is that a LEFT sum (as opposed to RIGHT, or MID) is codified in the rules by 8.2 "If any of the above data points at higher RPM than Max HP RPM do not exist due to redline, then those potential data points will not be used in the calculation of Avg HP". LEFT sum is an OVERESTIMATION of area under the curve PROPORTIONAL TO THE SLOPE OF THE CURVE. A flatter curve means less of an overestimation.

 

This will not go away by adding more points.

 

Without even getting into the "race-ability" advantages of a flat curve(which we should not, because it too difficult to quantify), you can now see why so many people have chosen to tune their cars as flat as possible: because the ST rules math will give engines with a steep power curve a weight ratio disadvantage right off the bat.

 

As I suggested, the best way we can deal with this is to decrease the partition size, which increases accuracy. Simply increasing the interval does nothing.

 

Poor 4 cylinder NA. I feel your pain... And wait until the Rotary shows up. Poor poor rotary.

 

If the calculation is in fact using a Riemann Sum Approximation, then we should go to using 100 rpm intervals instead of 500 rpm intervals. This would increase the accuracy of the Approximation, especially for motors that do not have a flat HP curve. It would also reduce the difference between left rule, right rule, or midpoint rule approximations.

 

 

I don't think it needs to be this complicated. I plugged the four numbers from my peaky power curve into the Trapezoid Rule (average of the right sum and left sum / very little error) and came with 0.1% of the arithmetic mean of the 4 points. Try the same with your actual numbers and see what you get. I think you'll find that the "add 'em up and divide by 4" approach is close enough for government work.

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mtag408

Rafael.

You have a lot to say for someone who only race one race weekend, this whole year. You talk a lot about car disparity, tires ect. But not sure what you are trying to gain? If you put Andrew Kidd on stock tires, he will still be faster then you are. I ran the same times you did back in April, on used NT01 tires, on basically stock street car, in my first ever race. You keep going on about car disparity, which i believe should be left for those, whom actually are racing in the series, consistently, with competitive times. I wouldnt think to start asking to change the rules because i got beat every race, but also know my skills are not on par with the leaders in this ST4. Unless you start coming out, and racing every weekend, i do not see how you plan on getting faster. You can look in the race from April where i followed you half of a race, and perhaps you can take some notes.

 

On another note, congrats on everyone that came out and race NWC, it was fun, clean racing. Glad i got a chance to get to know, and race with so many of you, looking forward to next season, and hope you all can come out and race more.

 

Martin

S2000 #58

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DarkGift
only reason I am considering it is for lack of a good fast spec series

 

Fair enough given "fast" is very subjective.

 

I drive a 350z

 

Wait...what?!? Um NASA SpecZ. Please direct your energies at building up your region's SpecZ field if you want a "fast" spec series. Our local guys did that and now we have upwards of 20 entries at events and very tight racing (and we're a relatively small region). You come off as the guy who doesn't want to do any (serious) work, wants the rules written to match his personal needs and to hell with whatever is best for the growth of the class/sport, and thinks if he just shouts whatever nonsense the loudest (and most frequently), he'll get his way. Then bitches when he still gets beat at the one event he actually shows up to because clearly everyone else must be cheating.

 

Also could you please learn how to quote when you reply. Your posts are a PITA to read.

 

Edit: Fixed link to go to class view.

Edited by Guest

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daytonars4
Going to 6 data points will have a significant impact on avg hp, so if that’s the direction please consider a comparable adjustment to the base ratio. Many of the cars that have been racing in ST4 (e36’s/350z’s/S2000’s etc) are already at or beyond what they can reach for power to weight. Without an adjustment expect this to become more of an E46/E92 M class which I don’t think is the intention.

 

GTS chose to not use a 3k rpm band in the averaging bc it allowed too much room for tuners to make adjustments to exploit it. If someone has a sequential which can stay primarily around a 2k rpm range it’ll make a mockery of this revision. But I guess since sequentials aren’t a concern in ST4 it doesn’t matter as much.

 

Daytonars4 - when you say that 'many of the cars that have been racing in ST4...are already at or beyond what they can reach for power to weight...' do you mean that by now using 6 points at 500 RPM increments it will be difficult to make the car competitive as the avg hp will now be much lower? In my case (running a e36 m3 with @234 avg hp) I am already coming in about 100lbs over on weight. 2 more data points would bring my avg down to around 220, which would make it really tough to be close to an ideal weight. Is that why you would also be suggesting to make an adjustment to the base ratio? Just trying to understand the implications of 6 vs 4 data points for the avg.

 

Jon B

NorCal ST4

 

Yes John B, you are explaining exactly the issue I’m describing. You don’t want to turn ST4 into a class where people have to run built motors or carbon panels etc. So the ratio needs to be within reasonable reach of the target cars for the class.

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mtag408

Rafael,

You have a lot to say, for someone who only raced one weekend this whole season. Basically, you come out, raced once in April and have not shut up ever since about car disparity, but not sure what you are trying to gain. if you put Andrew kidd on stock tires, he is still going to be faster then you are. Actually pretty sure the spec miata guys are faster also.

I ran the same time as you did on used NT01 on basically a street car, and in my first ever race. You talk a lot about car disparity but no driver disparity. Unless you start coming out, and racing i dont see how you plan on getting faster, regardless of what car you are in. You can look at the race from April where i followed you for half of the race, perhaps you can take some notes.

If you do not want to put the work in on your car, then just come out and have fun. Which this is what we have all been doing all season long.

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tomtang

ESR, are you coming to Sonoma? Come to the last nor-cal race of the year.

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Calif_Kid
Chris, I posted my incar of the start...

Dave, I'd love to see your video, but I don't see a link. Where is it posted?

 

-Ian

Ian,

 

I saw that Dave Schotz posted two videos:

 

Time Trials

Sunday ST4 race start

 

and Nasa Speed News ST4 race is at

 

- Jim

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clock

 

 

I don't think it needs to be this complicated. I plugged the four numbers from my peaky power curve into the Trapezoid Rule (average of the right sum and left sum / very little error) and came with 0.1% of the arithmetic mean of the 4 points. Try the same with your actual numbers and see what you get. I think you'll find that the "add 'em up and divide by 4" approach is close enough for government work.

 

So by playing with my redline, I can make the 4 points describe a midpoint or right rule. What this allows me is the ability to create different average horsepowers I could report with the exact same dyno graph. The 500rpm leeway lets me create an average curve 10hp lower than my current one, and all I had to do was drop my revs 100. Cars with torque like mine can play these games but a honda could not. They are stuck with Left rule. I don't think people want me to show up with 10 more horsepower and the same sticker.

 

For a honda the difference between the theoretical "flat" curve and their average sloped curve is more like 5 hp. So I just described a potential mathematical slop of 15hp(171lbs) for a honda vs a larger displacement or FI car that has the freedom to choose and build the best power curve. 171lbs. No, I don't agree the system is accurate enough.

 

6 points is not going to do what people thinks it will. It will just open it up to more power games. I don't think that is the intention of class. I will reiterate that we should decrease the partition size. I mean its ST, we are already pretty used to complicated forms and calculators .

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esr

don't take it personal man.

I am happy for you that, you have a place to race that fulfills your racing needs.

Let others try to find theirs.

 

not sure why you even comment, maybe you could ask some questions. I am pretty sure you would learn a few things

 

 

 

only reason I am considering it is for lack of a good fast spec series

 

Fair enough given "fast" is very subjective.

 

I drive a 350z

 

Wait...what?!? Um NASA SpecZ. Please direct your energies at building up your region's SpecZ field if you want a "fast" spec series. Our local guys did that and now we have upwards of 20 entries at events and very tight racing (and we're a relatively small region). You come off as the guy who doesn't want to do any (serious) work, wants the rules written to match his personal needs and to hell with whatever is best for the growth of the class/sport, and thinks if he just shouts whatever nonsense the loudest (and most frequently), he'll get his way. Then bitches when he still gets beat at the one event he actually shows up to because clearly everyone else must be cheating.

 

Also could you please learn how to quote when you reply. Your posts are a PITA to read.

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GrahamDowney

Come out & race a few events, see how you and your car stack up against the field before lobbying for rules changes. My dad is driving an over weight under powered Civic running mid to rear of the pack. He's a decent driver & is having lots of fun running where he is. Remember, were all "racing" for dollar store trophies and rights to talk shot & brag. Let's remember to enjoy ourselves and not take too seriously, it's a hobby after all.

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Savington

6 points is not going to do what people thinks it will. It will just open it up to more power games. I don't think that is the intention of class. I will reiterate that we should decrease the partition size. I mean its ST, we are already pretty used to complicated forms and calculators .

 

As someone who has played the flat power game, I agree with this. Opening to 6 points opens up a world of possibilities for those who can easily tune their powerbands (any DBW car, any turbo car, any car with a standalone and variable valve timing). If you expand the measured power area beyond the RPM range actually used on track, the potential for powerband tweaking goes up dramatically. If I never use the 4400-490rpm range on track, but it's counted in the rules, that opens up a huge opportunity for me to artificially draw down my average power and increase my actual power.

 

I'll race next year no matter what, my car can easily be tweaked to fit whatever rules are decided on, but I think smaller partitions and a focus on the RPM range actually being used is a good idea. 1500rpm is too small, but 2500rpm is definitely too big - something like a 2000rpm band measured at 9 points (peak + every 250rpm on either side) might be a good middle ground.

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GrahamDowney

I like that idea Andrew.

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daytonars4

6 points is not going to do what people thinks it will. It will just open it up to more power games. I don't think that is the intention of class. I will reiterate that we should decrease the partition size. I mean its ST, we are already pretty used to complicated forms and calculators .

 

As someone who has played the flat power game, I agree with this. Opening to 6 points opens up a world of possibilities for those who can easily tune their powerbands (any DBW car, any turbo car, any car with a standalone and variable valve timing). If you expand the measured power area beyond the RPM range actually used on track, the potential for powerband tweaking goes up dramatically. If I never use the 4400-490rpm range on track, but it's counted in the rules, that opens up a huge opportunity for me to artificially draw down my average power and increase my actual power.

 

I'll race next year no matter what, my car can easily be tweaked to fit whatever rules are decided on, but I think smaller partitions and a focus on the RPM range actually being used is a good idea. 1500rpm is too small, but 2500rpm is definitely too big - something like a 2000rpm band measured at 9 points (peak + every 250rpm on either side) might be a good middle ground.

 

This to me sounds like the best approach to this power issue. More points within the 2k rpm range will properly adjust the avg for those with very peaky curves. It will also help avoid the issue of having everyone have a large reduction in their avg whp for 2018. As someone with a turbo car and who had a DBW car, I promise you. You don't want to make 3k rpm the range for the avg.

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esr

sounds like a plan!

 

nevertheless lets see what these sharp guys like block and daytona and a few others out there can come up with!

just brain wear, is renewable energy.

in the end Nasa will decide an we will conform

now is the time, i am sure they are listening

 

Come out & race a few events, see how you and your car stack up against the field before lobbying for rules changes. My dad is driving an over weight under powered Civic running mid to rear of the pack. He's a decent driver & is having lots of fun running where he is. Remember, were all "racing" for dollar store trophies and rights to talk shot & brag. Let's remember to enjoy ourselves and not take too seriously, it's a hobby after all.

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