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Sorry for the naive question if the answer is obvious, it could be just that I am getting old and can't recall, (and too lazy to search old posts)  What is the rule of thumb for the weight typically used in the swap calculator?  I thought it was some X% less than found in literature to account for some pulling of weight out of the car, but not necessarily race weight....

Edited by tneker

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The problem with having to ask tech for every combination is tech will get bombarded. 

 

My first question When i dream up a swap combo is what’s the final vpi?

 

the last thing I’d do is build it and then ask for a points answer.

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22 minutes ago, tneker said:

Sorry for the naive question if the answer is obvious, it could be just that I am getting old and can't recall, (and too lazy to search old posts)  What is the rule of thumb for the weight typically used in the swap calculator?  I thought it was some X% less than found in literature to account for some pulling of weight out of the car, but not necessarily race weight....

90% of the heaviest model in that generation of car. 

 

Race weight for a fair number of the cars in question is known but not considered reasonable to use. Over 20% difference between the weight that is used in the swap calculator and a typical race weight on some of the more popular swaps. 

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3 hours ago, mhr650 said:

... or the V6 MR2 comes out at whatever points they need them to be in order to keep the suspension and aero those cars already had.

It would sure be interesting to see one of their log books to see why almost 200 points on top of all the free stuff isn't enough to build a competitive car.

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8 minutes ago, mender said:

90% of the heaviest model in that generation of car. 

 

Race weight for a fair number of the cars in question is known but not considered reasonable to use. Over 20% difference between the weight that is used in the swap calculator and a typical race weight on some of the more popular swaps. 

 

OK, honest question: if you have empirical data upon which to base the math, why is it considered unreasonable to use? That seems like a recipe for badness. 

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13 minutes ago, atxe30 said:

 

OK, honest question: if you have empirical data upon which to base the math, why is it considered unreasonable to use? That seems like a recipe for badness. 

The claim is that lightness is universally available to every team in equal quantity, so actual race weight shouldn't be used as a metric. The excuse is that it would penalize the teams that work harder to reduce weight.

 

This is based on the idea that the percentage of weight that can be removed from every car is exactly the same for the amount of work put into removing said weight. In reality, the actual amount of weight that can be removed varies widely for the same amount of work. For instance, a team that is able to take out 400 lbs to get an E30 down to 2300 lbs from its starting point of about 26-2700 lbs with a weekend's worth of work would struggle to get half that weight out of a Civic or Miata.

 

It's a convenient way of saying that they worked for it but you didn't so they should be allowed to keep their weight advantage.

Edited by mender
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3 minutes ago, atxe30 said:

OK, honest question: if you have empirical data upon which to base the math, why is it considered unreasonable to use? That seems like a recipe for badness. 

Because the formula wasn't designed with that data in mind. They decided to use 0.9 * curb weight when setting up the other variables in the formula, so if they went back after the fact and changed the weight to something other than 0.9 * curb, it wouldn't spit out the values that they were aiming for in the first place. 

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5 minutes ago, enginerd said:

Because the formula wasn't designed with that data in mind. They decided to use 0.9 * curb weight when setting up the other variables in the formula, so if they went back after the fact and changed the weight to something other than 0.9 * curb, it wouldn't spit out the values that they were aiming for in the first place. 

I'm pretty sure the 90% was to "appease" people like me who pointed out that luxury sports cars can lose more weight than an econo car. It didn't do anything to fix that inequity, just shifted everyone the same amount.

 

Then things got messed up even more when somehow the heaviest model and year was allowed, and the split between the swap calculator weights and reality increased noticably.

Edited by mender
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7 hours ago, Jer said:

Please re-post the list, I was looking for that!  Thank you.  As far as I know we are not using power to weight but I'm sure some semblance of that is inherent in the calculator.  

 

Power to weight is absolutely used to set the point at which the points exceed 50 for an engine swap. Doesn't matter what your starting power is, if you increase it and cross that threshold then you pay an exponential point penalty. 

 

Critical to the swap calculator is picking the right power to weight target. Assuming the weights are right, some 500 point stock non swapped cars meet a higher value than the calc would allow for 50 points. Some get around this with really low weights to "get around" the target power to weight. Other of us just stack engine mods on a low vpi car till we get there. If you can't cook the books with either of these methods you are kind of screwed (under current rules).

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1 hour ago, Huggy said:

The problem with having to ask tech for every combination is tech will get bombarded. 

 

My first question When i dream up a swap combo is what’s the final vpi?

 

the last thing I’d do is build it and then ask for a points answer.

 

I totally follow you.....but i also wonder if in the absence of online calculated vpi data to most accurately and quickly game the system with the optimal car....people might go back to racing cars they know, that are affordable, and easy for them to find parts for. 

 

With the golden standard car already set to a model with only 5000 examples ever brought to this country, do we need more help making unicorns easily found? 

 

Shoe on the other foot, when you email tech it should be to ask what engines are allowed in x model car, not "here is a list of 10 car and engine combos, help me find your loopholes" 

 

In some way the citrus guys handle this better by not giving a quick and easy way to probe the perimeter of their rules. Doesn't seem to hurt their field size. 

Edited by Black Magic

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Drew, you need to add the '87-92 Supra at the top of your list. The Edmunds curb weight for the '92 is 3463 lbs for the non-turbo and Champcar has it listed at 3600 lbs instead of 3117 lbs.

 

Somehow it gained 4% instead of losing 10%.

Edited by mender
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10 minutes ago, mender said:

Drew, you need to add the '87-92 Supra at the top of your list. The Edmunds curb weight for the '92 is 3463 lbs for the non-turbo and Champcar has it listed at 3600 lbs instead of 3117 lbs.

 

Somehow it gained 4% instead of losing 10%.

 

Agree, that list was just a few spot check car i looked at, just to clarify it isn't a list of all cars. 

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10 hours ago, Jer said:

...Please help us identify weights that are off, also. 

Just helping out. :)

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Well I asked a question and got some answers and it spurred some discussion.  That's generally good.  

 

Things I've learned

1) Weights that are not correct, are on a path to be corrected.

2) Some folks would like to see all the numbers developed behind closed doors and we all just live with it.  Maybe that's best

3) Some folks want the transparency that is offered with the current tool (swap calculator)
 

How do I feel about it?   

We need a way to do this(value swaps), and we need to do it right and stick to it.    I think between adjusting VPI and putting in the proper weights the current tool works very well.  

I think changing the system to add a list of "common" swaps has several pitfalls that will arise in the process and it will be a ton of work and confusion to end up where we are already.  Some people like it and some don't.     Which swaps are "common" ?  If the common swaps are close to the swap math,  but are a little lower it seems like I would ask why doesn't my not so common swap get that benefit?  If its a little higher, I would want to know why I can't just use the numbers that the swap math gives me.  It seems problematic to me to use both systems.  

If there is a list of common swaps, maybe that list should be the only ones that are allowed, and if you want to do something different you have to petition to have it added.

 

I personally, think its better to just keep working on the inputs to the current formula and make it better.   To me that is the most transparent way, and the simplest way. 

 

My thoughts, as I look out the window and think "man, hell must have frozen over by now"

 

 

 

 

 

 

 

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16 minutes ago, JDChristianson said:

 

If there is a list of common swaps, maybe that list should be the only ones that are allowed, and if you want to do something different you have to petition to have it added.

 

 

 

I don’t understand anyone’s objection to this, we already use this exact procedure when someone wants to race a car that is not on the VPI list. If you want to race a swap that is not on the list you are just petitioning to have a new car added to the list.

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15 minutes ago, mhr650 said:

 

I don’t understand anyone’s objection to this, we already use this exact procedure when someone wants to race a car that is not on the VPI list. If you want to race a swap that is not on the list you are just petitioning to have a new car added to the list.

 

As long as the list and the calculator spit out the same # it will be ok.   IF they contradict each other it will lead to confusion.     If the calculator says it should be a given VPI that's what the fixed list should say as well.    Otherwise, the fixed list becomes a way of circumventing the calculator.   There is no point in adjusting weights and hp in the calculator if you can just circumvent it with a list.   Then everyone with a swap just petitions their car to be on the list at a lower VPI. 

Edited by Snake
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35 minutes ago, JDChristianson said:

 Which swaps are "common" ?  If the common swaps are close to the swap math,  but are a little lower it seems like I would ask why doesn't my not so common swap get that benefit?  If its a little higher, I would want to know why I can't just use the numbers that the swap math gives me.  It seems problematic to me to use both systems.  

My vision of a common swap is just that, common, a "new" car has been invented, simply add a line reflecting the desired value rather then tinker with starting values as doing such will mess with allowable mods to the non swapped.

 

Any "new" cars on the list take place of the swap calculator and are a fixed, non re-sawpable value.

 

Example:

m50 swapped e30 = 495pts

Edited by Team Infiniti

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9 minutes ago, Team Infiniti said:

My vision of a common swap is just that, common, a "new" car has been invented, simply add a line reflecting the desired value rather then tinker with starting values as doing such will mess with allowable mods to the non swapped.

 

Any "new" cars on the list take place of the swap calculator and are a fixed, non re-sawpable value.

 

Example:

m50 swapped e30 = 495pts

What problem is being solved by taking cars out of the swap formula and giving them special values? Why add yet another layer of manipulation to the process?

 

Remove the layers that have already been built in, allow the swap formula to actually regulate power to weight of swapped cars and then see if more manipulation is justified.

Edited by mender
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17 minutes ago, mender said:

What problem is being solved by taking cars out of the swap formula and giving them special values? Why add yet another layer of manipulation to the process?

 

Remove the layers that have already been built in, allow the swap formula to actually regulate power to weight of swapped cars and then see if more manipulation is justified.

Not all cars respond the same to similar power to weight, at some point we can simply look at the results of multiple teams effort with a certain swap and accurately extrapolate its desired value, in reality this is method is most accurate.

 

What does it matter how the desired pts. value output is achieved?

Edited by Team Infiniti

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14 hours ago, enginerd said:

Because the formula wasn't designed with that data in mind. They decided to use 0.9 * curb weight when setting up the other variables in the formula, so if they went back after the fact and changed the weight to something other than 0.9 * curb, it wouldn't spit out the values that they were aiming for in the first place. 

That's my take on this- The weight is just one of the variables used to produce the expected results (ie m50 swapped e30 = 500)

I still don't understand why some people have their panties all in a wad regarding the weight variable in the formula.  Who cares other than a select few, and does it really matter in the end?  The weight variable is just one of the numbers used and it doesn't matter if it matches anybodies real race weight for a specific car.  As the real race weights for any given car are completely different from team to team, car to car.

If the m50 swapped e30 is to remain at 500 (or less), then modifying the weight multiplier in the formula would require tweaking some of the other variables.

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3 minutes ago, chip said:

That's my take on this- The weight is just one of the variables used to produce the expected results (ie m50 swapped e30 = 500)

I still don't understand why some people have their panties all in a wad regarding the weight variable in the formula.  Who cares other than a select few, and does it really matter in the end?  The weight variable is just one of the numbers used and it doesn't matter if it matches anybodies real race weight for a specific car.  As the real race weights for any given car are completely different from team to team, car to car.

If the m50 swapped e30 is to remain at 500 (or less), then modifying the weight multiplier in the formula would require tweaking some of the other variables.

Quoted because I want to thank you twice.

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Because some people know what the effect of equalizing actual power to weight will be.

 

That will eliminate pure power in a straight line as a deciding factor in going faster than another team. A simple means of equalizing not only the competition but also the amount of work and money that can be spent to gain an advantage and stabilizing a racing series to ensure that people can race year after year without taking out a mortgage to keep up. It also allows new people to get into the sport by keeping older cars that may just need some moderate repairs to get back on track a viable option to building the latest and greatest just to get to mid-pack, let alone on the podium.

 

I can build lots of reliable power and dominate with my right foot. I've done exactly that on the oval and on the road course. A few seasons of that usually sees the size of that class decline unless I start building engines for other racers in that class (yes, a win for me and as a business plan, one that works well for a while). Everyone ends up spending more money, and the guys who can't afford to keep up with the rich guys fade back and eventually quit or go to another class, leaving an ever-escalating cost to finish on the podium. A situation that has been repeated many times across the continent: rich guys ruling the local racing and the other guys starting another series that they can afford. Sound familiar to anyone?

 

What works better is to control costs by establishing limits to the high cost means of going faster than the other guy: engines, tires, and, lately, shocks. Most long-lived series establish a means to control final power to weight within a fairly narrow range, either by actual power to weight or by weight per unit of engine displacement. Easiest is actual power to weight, which is a direct measurement rather than one that can be manipulated by backdoor rule changes.

 

Making a series about the drivers instead of the cars is a good business plan. Tossing out a means of doing that because some people want to game the system is the wrong way to go about that. 

 

 

Edited by mender
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14 minutes ago, chip said:

That's my take on this- The weight is just one of the variables used to produce the expected results (ie m50 swapped e30 = 500)

I still don't understand why some people have their panties all in a wad regarding the weight variable in the formula.  Who cares other than a select few, and does it really matter in the end?  The weight variable is just one of the numbers used and it doesn't matter if it matches anybodies real race weight for a specific car.  As the real race weights for any given car are completely different from team to team, car to car.

If the m50 swapped e30 is to remain at 500 (or less), then modifying the weight multiplier in the formula would require tweaking some of the other variables.

 

I think the panties are wadded because two of the cars with the most erroneous weights are

1) the car with the most wins in champcar history (e30),

2) the car that might have the most FTDs of any car make in champcar history (swapped MR2)

 

Cars that have had success. Not sure a pinto with an erroneous weight would have set the world on fire.

 

Their erroneous weights allowed motor swaps that on a power to weight basis would not be allowed in most other cars at 50 points. They got to break the power to weight intention of the swap calculator in a pretty big way, maybe it was offset in starting vpi, maybe it wasn't (hard to justify that for the mr2). 

 

In the end we just need to know what motors are allowed in what cars. I would think some element of the swap calc math would be used by tech\tac to set allowed engines, and a egregious motor allowance for a highly successful car would still be possible, but hopefully as a conscious value set by a person or group after thought, rather than a clever math manipulation of an online calculator by a car owner in his underwear at 3 am.....  

 

The goal (I hope) would be to reduce the amount of doctoring we have to do with starting vpi, weights, which vpi to use when swapping, etc to make sure people can't break the parity with an excel function, and instead have pre determined values for a "combo" that seem appropriate with similar types of cars getting similar values\capabilities. The more silly things we (Tac\tech) have to account for, like possible swap combos vs speed of unswapped car (how to set base vpi), radiator size, coolers yes\no, how much discount for disproportionate fuel capacity, available spare material to make free parts from....the less accurate the total VPI to performance correlation is gonna be. 

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Messing with the rules changes this on a stationary wall:

Related image

 

 

To this being carried around by special interest groups :

Image result for distorted target

 

For the sake of stability in the series, let the swap formula do what it was designed for and stop trying twist and move the target.

 

 

Edited by mender
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26 minutes ago, chip said:

That's my take on this- The weight is just one of the variables used to produce the expected results (ie m50 swapped e30 = 500)

I still don't understand why some people have their panties all in a wad regarding the weight variable in the formula.  Who cares other than a select few, and does it really matter in the end?  The weight variable is just one of the numbers used and it doesn't matter if it matches anybodies real race weight for a specific car.  As the real race weights for any given car are completely different from team to team, car to car.

If the m50 swapped e30 is to remain at 500 (or less), then modifying the weight multiplier in the formula would require tweaking some of the other variables.

 

Not letting the desired result drive the experiment is WRONG??? Sounds like scientist gibberish to me. We speak american 

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