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On 6/30/2021 at 5:04 PM, turbogrill said:

Boxster also have 15 gallons of fuel?

It's rated at 17 gallons. And it's a convertible so it's easier to chop-top it.

 

On second thought, yeah this looks under-valued. Which is a great reason not to seriously campaign one. Seems like it's just begging for a VPI increase.

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1 hour ago, Grant said:

 

On second thought, yeah this looks under-valued. Which is a great reason not to seriously campaign one. Seems like it's just begging for a VPI increase.

If you get twenty boxsters to enter each race it will get treated kindly 😄

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3 hours ago, TimS said:

If you get twenty boxsters to enter each race it will get treated kindly 😄

I just added mine and put on an infinitely average performance... All this magic must have something to do with level of prep and those useless driver things behind the wheel. But man is it fun, and a pretty easy platform to operate.

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So,

 

Boxster: ((2400lbs / 200whp) * 19 gallons) / 475 pts= 0.48 pwr gal per vpi
NC:  ((2100 lbs / 160whp) * 15 gallons) / 400pts=  0.49 pwr gal per vpi

E30: ((2200 lbs / 170whp) * 19 gallons) / 450pts = 0.52 pwr gal per vpi

 

(Higher is better)

 

My E30 numbers are probably not accurate at all, just something internet told me.

 

probably a terrible metric.

Edited by turbogrill
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8 hours ago, turbogrill said:

So,

 

Boxster: ((2400lbs / 200whp) * 19 gallons) / 475 pts= 0.48 pwr gal per vpi
NC:  ((2100 lbs / 160whp) * 15 gallons) / 400pts=  0.49 pwr gal per vpi

E30: ((2200 lbs / 170whp) * 19 gallons) / 450pts = 0.52 pwr gal per vpi

 

(Higher is better)

 

My E30 numbers are probably not accurate at all, just something internet told me.

 

probably a terrible metric.

Spec B min weight is 2600 and a little change. Getting the boxster to 2400 i think is challenging, there's just not a lot to remove. it doesn't have the crazy heavy sound deadening stuff the e30 has, etc. would be interesting to see if the boxster folks out east that win would share their run weight....

Edited by atxe30
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43 minutes ago, atxe30 said:

Spec B min weight is 2600 and a little change. Getting the boxster to 2400 i think is challenging, there's just not a lot to remove. it doesn't have the crazy heavy sound deadening stuff the e30 has, etc. would be interesting to see if the boxster folks out east that win would share their run weight....

 

Got it! Spec MX-5 has a race weight of 2500 lbs. 

 

It's very difficult to get any sense in weights. For instance our NC is 200-300lbs heavier than the top runner NC, it's gutted but not extreme and we some stuff that can be removed (chillout, AGM battery, surgetank, stock rotors, 50% stripped harness, various sheet metal, etc).

 

I don't think champcar could use the lightest possible car as a metric, since most members wont take it to that extreme (drill holes in frames, lightweight rotors, lightweight fasteners,etc). That just becomes ridiculous for what we are doing.

 

 

 

 

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10 hours ago, turbogrill said:

So,

 

Boxster: ((2400lbs / 200whp) * 19 gallons) / 475 pts= 0.48 pwr gal per vpi
NC:  ((2100 lbs / 160whp) * 15 gallons) / 400pts=  0.49 pwr gal per vpi

E30: ((2200 lbs / 170whp) * 19 gallons) / 450pts = 0.52 pwr gal per vpi

 

(Higher is better)

 

if you want higher is better, shouldn't you go whp/lbs ?

then they all come out 0.003

 

 

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thinking about this a little more, i could prob get to 2400 building for CC. i was thinking of spec b weight re spec b rules.

 

spec b requires keeping oem dash, wiring harness, using heavy porsche oem wheels, etc.

 

plus, it's a lot cheaper building for CC. the Spec B suspension package is close to 9k at this point and wheels are unobtainium, so you have to way over pay to get what you need.

Edited by atxe30
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10 minutes ago, tommytipover said:

 

if you want higher is better, shouldn't you go whp/lbs ?

then they all come out 0.003

 

 

 

True! My formula is faulty.

 

Having a PWR goal is a little strange in this series since weight is unmandated. Do you take a crazy light car as the standard or the average car?

 

In the extreme you would have to trade reliability/safety/driver comfort with performance.

 

But I guess that is only applicable for top teams needing the last few tenths. The majority should focus on driver skill, car setup and pit strategy. 

 

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7 minutes ago, atxe30 said:

and with PCA bailing on COTA for next year, the wheels in my head are turning.....

 

haha...why are the bailing?

Is it because they run Nascar at COTA? COTA has now been forever molested with cutoffs and freedom beer. PCA could never go there, would be like a vampire eating garlic in daylight.

 

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10 hours ago, turbogrill said:

Boxster: ((2400lbs / 200whp) * 19 gallons) / 475 pts= 0.48 pwr gal per vpi

I'm not one to kiss and tell, but i've spent the past 18 months researching, talking to folks and buying into a formula that works. Just between us girls...

  1. That's a really, really light assumption there.
  2. 200 at the wheels? No sir. (not just my car, but even in full SPB trim some of the most competitive cars in the country don't get at that or are even being set up to)
  3. Fuel: maybe with a jug in the passenger side... but that's again, pretty optimistic.

The teams at the top running Boxsters are squeezing that top % and driving hard to get the job done, but the same applies to all the platforms. All this talk is really aimed at the pointy end...

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my understanding is they have lost money the last 2 years. think its like ~50k a day to rent the track and PCA event fees are light (like 800 bucks for club racing at COTA), as opposed to the ~2300 WRL charges...

 

it's always just about the money :)

 

 

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2 minutes ago, ManhattanMcC said:

I'm not one to kiss and tell, but i've spent the past 18 months researching, talking to folks and buying into a formula that works. Just between us girls...

  1. That's a really, really light assumption there.
  2. 200 at the wheels? No sir. (not just my car, but even in full SPB trim some of the most competitive cars in the country don't get at that or are even being set up to)
  3. Fuel: maybe with a jug in the passenger side... but that's again, pretty optimistic.

The teams at the top running Boxsters are squeezing that top % and driving hard to get the job done, but the same applies to all the platforms. All this talk is really aimed at the pointy end...

i'd be curious to hear about the way you've eval'd this. I'm going to be done stripping the car this weekend and then it will be decision time.

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12 minutes ago, ManhattanMcC said:

I'm not one to kiss and tell, but i've spent the past 18 months researching, talking to folks and buying into a formula that works. Just between us girls...

  1. That's a really, really light assumption there.
  2. 200 at the wheels? No sir. (not just my car, but even in full SPB trim some of the most competitive cars in the country don't get at that or are even being set up to)
  3. Fuel: maybe with a jug in the passenger side... but that's again, pretty optimistic.

The teams at the top running Boxsters are squeezing that top % and driving hard to get the job done, but the same applies to all the platforms. All this talk is really aimed at the pointy end...

 

I just picked numbers from forums! Maybe they where the 2.7? But it's rated 201hp, so getting close to 200whp shouldn't be a impossible with all the free stuff you can do (port head, port intake, port header, etc etc etc). 

Also the fuel would be with a cell or large filler tube, you are allowed to go +2 gallons over rated. 

Weight is so difficult to assess, SPB still has windshields, A pillars, stock rotors?, stock harness?,etc etc...

 

(My post was mostly to push for a forumla, but I realized that all those parameters are so fudgy and using a very expensive extreme build might not be the spirit of the rules)

 

 

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1 hour ago, ManhattanMcC said:
  1. That's a really, really light assumption there.

His weights are without driver. Given the B-Spec minimum weight is 2650, I'd imagine 2400 is pretty easy within ChampCar. Those cars look like they run the stock dash, wiring, etc.

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E30s and Boxsters should look better on paper vs. the NC, because they have many handling disadvantages: worse weight bias (E30s are very front heavy) and poorer suspension geometry. The Boxster uses struts on all four corners (yuck), while the E30 is some prehistoric design.

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6 minutes ago, Grant said:

E30s and Boxsters should look better on paper vs. the NC, because they have many handling disadvantages: worse weight bias (E30s are very front heavy) and poorer suspension geometry. The Boxster uses struts on all four corners (yuck), while the E30 is some prehistoric design.

as an e30 *and* boxster owner: damn dude, that's hurtful!!!

Edited by atxe30
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5 minutes ago, atxe30 said:

as an e30 *and* boxster owner: damn dude, that's hurtful!!!

Hah sorry. I have a deep seated hatred of struts. They've cost me a lot of money in the form of poor tire wear.

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2 hours ago, Grant said:

Hah sorry. I have a deep seated hatred of struts. They've cost me a lot of money in the form of poor tire wear.

 

I guess it all come down to dynamic camber during roll?

 

Surprised that no one has built a double wishbone from a strut using materials? It's "just" adding a second control arm and moving the strut location?

 

Seems like something a true champcar person would love to do.

 

McPherson Single Strut vs Double Wishbone

 

 

 

 

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37 minutes ago, turbogrill said:

 

I guess it all come down to dynamic camber during roll?

 

Surprised that no one has built a double wishbone from a strut using materials? It's "just" adding a second control arm and moving the strut location?

 

Seems like something a true champcar person would love to do.

 

McPherson Single Strut vs Double Wishbone

The strut housing on the E30 is integral to the entire corner and any changes would be extremely complicated. Besides, there is an easier way to deal with dynamic camber during roll:

Eliminate roll

Edited by enginerd
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2 hours ago, turbogrill said:

I guess it all come down to dynamic camber during roll?

That's part of it, but I prefer to think in terms of instant center migration. On a dual wishbone car, when a corner compresses the instant center tends to move towards the hub (increasing camber gain) and usually either stays at its starting level or drops a bit.

 

The instant center of struts under compression moves very far down and away from the wheel, decreasing camber gain and increasing the roll couple (moment arm between the center of gravity and instant center). The result is you need more spring rate to control roll, and even more to control camber. As enginerd says these cars just tend to have extremely stiff springs.

Of course this also applies when the car is lowered. Strut geometry tends to go to crap unless some roll center correction is done, while dual wishbone can actually improve slightly.


BMW seems to do struts better than other manufacturers. I think because the inline engines give them more room to tilt the strut top inward. Unsurprisingly I think Subaru's are the worst.

Edited by Grant
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well crap, bad afternoon at the garage. new injectors installed and a re-tune on the dyno.

 

good news: topped out at 254whp/257tq.

 

bad news: either the clutch or the pressure plate appears to have failed at a lower power run and it grenaded the bell housing (i got a text with a nice photo of cast aluminum fragments scattered around the dyno)....

 

sheesh.....

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