Can somebody explain this pop up valve stuff?

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Philippe Bellefleur
this is where I was going but the trolls are going ape shit...

Despite my instincts saying this is a bad move... I'll try, again, to have a reasonable conversation about this.

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Rolling Blunder
An engineering drawing and spec sheet would be interesting to see, might upgrade such a mandate from "entirely dubious" to "98% dubious", though it wouldn't do much to convince anyone that the supplier isn't a blowhard and/or middleman (edit for clarity: Angle, not MattP).

I am certain a drawing and spec sheet exists, expecting it to show up on this forum by simply asking for it is fairly futile. The contact information for the (elected, volunteer) CARS Technical director, (elected, volunteer) CARS Region directors, and (elected, volunteer) CARS President are all on the
CARS website, and would be the better places to ask the questions.

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Rolling Blunder
...I do think ARA made a smart decision to split the onus for boost monitoring with competitors. The sanctioning body shoulders the vast majority of the cost (sensors and hardware), while the competitor is forced to spend ~$20 (maybe less) and 15 minutes of time to get equipped with off-the-shelf, mass-produced (read: CHEAPER) adapters and wiring to meet the mandate.

Where do you think the sanctioning bodies (CARS Specifically) get their funding from? If CARS took on the Majority of costs, it would be funded through license increases so that every license holder would pay something towards the program that is intended to stop the top 30% from spending stupidly on engine builds. I've said before that I think a SF of 70 is too low for the break as it will quickly start capturing some cars that are running fundamentally stock drivelines.

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Rolling Blunder
I also fail to see how this "solution" would be a more effective way to normalize competition vs. using a $25 ASME-coded pop-off valve from someplace like McMaster.

I'm quick to admit that I don't have the depth in this area to know one way or another about 'budget' options to this solution, but... I know everyone on the committee and I have trust and faith in the technical committee to be making the right choices and having good reasoning behind their decisions.

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Rolling Blunder
(Using hard seals would mean a tolerance of 4%, equating to ~1 psi on a 25 psi valve, soft seals 2 psi... minimal, and about as well as can be had without totally unnecessarily complex and expensive hardware.

It won't necessarily equate, but the difference between first and second place at Tall Pines this year was 1m32s over 2h16m of racing, or 1.1%. The difference between second and third was 36s, or 0.37%. Then 1.5%, 2% and 0.11%
1% is 6 seconds on a 10 minute stage, or depending on the stage somewhere around a half a second a k... which is a big deal.
Now, obviously the impact of the variance will only be when the valve is at max pressure, so not a constant issue for sure, my only point was that I don't think 1% is as trivial as it sounds.

(If someone can do the math on %change of boost pressure vs. %change on HP/TQ That would be interesting.)

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Rolling Blunder
...it would be helpful to know what the specs on the proposed valve are to make an honest comparison... only so much air can flow through a given area. In that vein, there would still be the old tricks of placement and intentional overboosting to force more performance past any valve (assuming the restricted engine isn't already at the absolute limit of choked flow).

Again, not my wheelhouse and I'm not here to defend, but properly placed questions should get you the answers you're looking for. That said, this first came out a year ago, and was released as a rule change in mid-April, over a year before the new implementation date. (I'm not here to represent the decision makers as I had zero involvement in the process.)
My understanding from being involved in the competitor round-table last year was that the part is the same as is being provided to the WRC for R5 cars, which means CARS wasn't paying to repeat design work... but ask the question to the right people if you want a 'good' answer.

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First Rally attended (2000), First Rally competed in (2001)
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Last Updated, May30, 2022

So, with a bit of asking the right people some questions...
I gather CARS is using the FIA pop-off Valve as described in this document.

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FIA Documentation
Objectives:
The so called “Pop-off valve” must:
- limit the boost pressure on a turbocharged engine without electronic control.
- offer no disparity between all valves produced and sold to competitors.
- be sold to the competitor at a price lower than 350 euros.

Conditions:
The so called “Pop-off valve” must:
- work with turbocharged engines from 1.4l to 2l capacity with an air restrictor from 28mm to 35mm diameter.
- be capable of an airflow through it of at least 150 g/s.
- be able to be mounted on the FIA tube placed in the air admission after the throttle (See Appendix 1) and be sealed.
- be suitable for an FIA sticker to be glued and be visible for control.
- open at a fixed pressure. This pressure, depending on the application, could go from 1bar to 2 bar (relative).
- open at a fixed and repeatable pressure (+/- 20 mbar around the targeted relative pressure).
- lock to the open position in case of overboost, it can be rearmed by decreasing the pressure in the intake system below threshold of more than 0.8 bar.
- have multiple exit ports to avoid exit to be easily closed.
- operate correctly with no maintenance for a one year use.
- be sealed to be sure that no one can open it without destroying it.
- be transparent to allow easy check of cheating attempt.

Validation:
- A minimum of 10 hours of bench test with 3 different engine manufacturers must be completed. Full report of the tests validated by the engine manufacturers must be supplied in order for FIA to be able to assess level of operation of the valve.
- A minimum of 2 tests sessions of 1 complete day with 2 different car manufacturers must be completed. Full report of the tests validated by the car manufacturers must be supplied in order for FIA to be able to assess level of operation of the valve.

Post Homologation Checks:
FIA reserves the right to pick valves randomly, either on the field or at the valve manufacturer factory and to conduct tests on the valves to verify whether they are compliant with the these Specifications.
If tested valves do not comply with the conditions listed above the FIA may remove the homologation of the product without prejudice to FIA’s other rights.

The document lists a maximum price, not a fixed price, of 350 Euro, approx $530cad today.
The implied reasoning behind going to the FIA item is that it's already been designed and build with the specific use in mind, with compliance testing and checking being part of the design requirements. In other words, why start from scratch when the final product will be counted in 'tens.'

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First Rally attended (2000), First Rally competed in (2001)
Cars Built (1), Engines Built (0) Cages Built (0)
Driver (8), Co-Driver (47), Drivers (19)
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Rallies attended (120) Countries attended rallies in (11)
Last Updated, May30, 2022



Edited 1 time(s). Last edit at 01/11/2019 03:41PM by Not Trolling.

Something interesting that I found out at the competitor round table during the CARS AGM in Calgary last weekend. (Which was open to anyone with an opinion they wanted to discuss)

The Popoff valve for CARS was ordered without the plastic tamper-proof cage that it is normally shipped with, because not having it cut the cost by 100gbp per unit. Instead, the units will be sealed with security tape that will show as being voided if removed.

On pricing...
A single unit ordered direct from the supplier would be $636cad including shipping, taxes, and any import duties (I haven't bothered checking if they are exempt of tariffs or not)
Through the group buy, they are $450cad, to the end user's door - $186cad cheaper.

There was a clarification on speed factors as well... they are set on 'mean' pace, so the loss of the faster cars (L'Estage) doesn't mean there is a drastic up-swing in speed factors.

Teams are given 3 months to fit the device after getting a 70sf.

Importantly, American teams who don't want to be bothered can still run in a CARS national event, they just won't be scored in the championship. (but would be eligible for NARC and Cascadia points)

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First Rally attended (2000), First Rally competed in (2001)
Cars Built (1), Engines Built (0) Cages Built (0)
Driver (8), Co-Driver (47), Drivers (19)
Clerk (29), Steward (1), Official (17), Volunteer (5)
WRC Spectator (1), WRC Photographer (6), WRC Observer (4)
Rallies attended (120) Countries attended rallies in (11)
Last Updated, May30, 2022

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Not Trolling
Importantly, American teams who don't want to be bothered can still run in a CARS national event, they just won't be scored in the championship. (but would be eligible for NARC and Cascadia points)

Apparently I was wrong about this... NARC points would be based on CARS legal finishing positions so you'd want to have a blow-off valve for that.

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First Rally attended (2000), First Rally competed in (2001)
Cars Built (1), Engines Built (0) Cages Built (0)
Driver (8), Co-Driver (47), Drivers (19)
Clerk (29), Steward (1), Official (17), Volunteer (5)
WRC Spectator (1), WRC Photographer (6), WRC Observer (4)
Rallies attended (120) Countries attended rallies in (11)
Last Updated, May30, 2022