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Al F.

2019 RCR #8

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Al F.

Rule reference 6.21.5


Recommended Revised Wording

6.21.5 Any air filter or air filter assembly may be fitted and OE assemblies may be modified. Air boxes and filters must reside inside the engine compartment or in the OEM stock location. Air filter installations that appear to create a ram air effect may be subject to verification per rule 7.7. For the purposes of the rules, ram air shall be defined as manifold air pressure that, at speeds of 80+ MPH, exceeds that of an open throttle body for speed density cars or open MAF for MAF cars when compared to the intake assembly in question. Factory ram air assemblies are expressly prohibited regardless of rule 7.7.


Reasoning for change:

Will provide more clarity because it clarifies the intent of the rule as it is now. The problem with the rule as it's written, the way I see it, is that it reads to me like 6.21.5 trumps 7.7 for a questionable intake assembly. This change more clearly allows a questionable intake assembly that does not provide ram air to stand. It also defines what ram air is for the series so all directors can now judge on the same criteria. Ram air doesn't always boost air pressure above atmospheric. Even if it staves off a pressure drop when compared to an open intake, it's still offering a performance advantage. Factory ram air intake assemblies remain prohibited.

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ls168camaro

Good idea. Might be easier to change 6.21.5 to "Air filter installations intentionally designed to create, or appear to create a cold air or ram air effect are not allowed, even if they were OEM stock"


Or change 6.9.2 to remove the mesh covered cooling duct opening.


6.9.2 All cars must have a minimum of two properly functioning OEM rear brake light assemblies. All

other OEM light assemblies may be replaced with facsimiles, plates, covers, or mesh covered cooling

duct openings as long as these maintain the stock external appearance. Replacements for recessed

lights must also be recessed. Front turn signals and fog lights may be removed.


Suggested change

6.9.2 All cars must have a minimum of two properly functioning OEM rear brake light assemblies. All

other OEM light assemblies may be replaced with facsimiles, plates, and covers as long as these maintain the stock external appearance. Replacements for recessed

lights must also be recessed. Front turn signals and fog lights may be removed.

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Dustin M.

My intent with this RCR is to allow a competitor who has a 3" hose blowing air in the direction of a cone air filter to prove he's legal, not for someone reinventing a Vararam with force fed sealed box to defend themselves. If anyone can better capture this it would be really helpful.

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ls168camaro

I understand your intent but why bother and just close the loophole since nobody agrees on what constitutes ram air (even the directors disagree)? Clearly some think it's an advantage to remove their headlight and run a duct to the filter. That seems to go against the original intent of stock appearing and not allowing something to create an advantage over another competitor.


What does it take to allow a competitor to prove he is legal? An added cost to get some sort of data system with recording capabilities? And then you have to come up with what the baseline manifold air pressure is for each car and intake setup?


How do you account for the wind direction and wind speed?


Why only at speeds over 80 and not at any speed? What if someone tunes their setup so that it catches air below 80 but because of how the air goes around the car it doesn't catch it below 80?


Do you know for sure that manifold air pressure is the way to determine if it's legal? What if I put a diode somewhere in line with the map sensor that provides a specific reading so as it appears legal?


I always thought the intent of our rules was to try and limit people from being able to create an advantage and limit the amount of money they can spend as that is what hurts most racing series and limits their growth.

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Dustin M.

We will agree on what RAM air is if it is clearly defined in the rules. We can define it as we see fit, and I have defined it as I believe it to be. If anyone thinks I'm wrong, then this is the perfect place to challenge that notion. It's widely known on the Corvette forum, and by my own ass cheeks, that by the top of 2nd (around 65mph in my Z06) and all the way through 3rd (about 95) gear a Vararam or Hurricane (like I have) ram air intake really starts to make a difference. It's proven on the drag strip as well, an easy 2-3 tenths. We can call the threshold 100mph if you like, the point is at 80 mph if it is a ram air intake, you'll see it beyond a shadow of a doubt.


If the competitor wishes to push the envelope and run an intake that runs an eyebrow, the onus is on him to prove it's legal. It's not up to the director to haul around datalogging bits for every generation of electronics for all platforms or, god forbid, a carb'd car. If the owner wants to run on the edge, they must prove that their intake is legal.


I'm not worried about wind direction or speed. The data would be pulled from full speed laps and not just a quick blat down and back so unless you have in excess of a 40mph tailwind, the data will be solid.


We're not allowed to modify aero so I really don't see a speed sensitive location for an intake being a significant factor. Air pressures should all globally shift with vehicle speed.


If you put a diode in the MAP sensor circuitry, it's not going to allow you to alter the curve of the MAP. A diode is a 1 way valve for trons. The MAP curve is what reveals whether or not it's a ram air intake. I get where you're going here, but getting the MAP sensor to lie about the curve would be a massive nerd undertaking and I really don't see the juice being worth the squeeze here. That said, you bringing this up reminded me of something: MAF Ford cars don't still have a MAP sensor like MAF GM cars (right?). I'll see if I can cook up some better verbiage to cover this. MAF can be used too, just a matter of a director being able to look at the 1s and 0s and make sense of it.


One can go to OReilly's and Lowe's and build a dirt cheap cold air intake. When you attempt to shield an intake from hot underhood air and simultaneously feed it cold air things can get a little sticky. As long as sufficient leaks are built in to prevent pressurization (and data proves you're legal), then I believe the intent is met. Look at the LT1s: factory airboxes are damn near impossible to find. Then look at the Fox Mustangs: you can get a legit cold air intake, bolt in and go, that shoves the filter down in front of the tire behind the bumper. Per the rules, you can remove material from the bumper. That hole can now provide fresh, cool (relative term for the Texans) air for the intake without being a ram air and all while staying within the intent of the rules. My only question in this instance is how do we define the engine bay? Was the intent here to keep air filters out of the interior of the car or what?

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Dustin M.

Here's another hack:


6.21.5 Any air filter or air filter assembly may be fitted and OE assemblies may be modified. Air boxes and filters must reside inside the engine compartment or in the OEM stock location. Air filter installations that appear to create a ram air effect shall be subject to verification per rule 7.7. For the purposes of the rules, ram air shall be defined as manifold air pressure or mass airflow that, at speeds of 80+ MPH, exceeds that of an open throttle body for speed density cars or open MAF for MAF cars when compared to the intake assembly in question. Factory ram air assemblies and sealed force fed custom fabricated airbox assemblies are expressly prohibited regardless of rule 7.7.

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Al F.

what if we just allow ram air? Make 6.21.5 simply state that any air filter or air filter assembly and ducting upstream of the TB/Carb may be used. Isnt that the easiest to police?

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Dustin M.
what if we just allow ram air? Make 6.21.5 simply state that any air filter or air filter assembly and ducting upstream of the TB/Carb may be used. Isnt that the easiest to police?

 

The fatal flaw here is the delta on the Dyno vs at speed. Say you lay down a stationary 260whp, but at the top of 3rd gear you're making 265 or better. You could intentionally create an intake that is restrictive at rest but comes alive at speed. This is super easy to fake vs faking a curve on a questionable intake.

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PeteL

I think we are making this too complicated. We can argue over what is or what looks like a ram air system forever, but if the ducting isn’t sealed all the way from an inlet, duct, scoop, etc. in a high pressure area on the exterior of the car to the intake manifold, it isn’t ram air no matter what it looks like or is named. A simple visual check to make sure that the inlet ducting is clearly not sealed from some point on the outside of the car all the way to the throttle body or throttle plate is the only thing that is required to rule out a ram air system. Measuring manifold pressure may be simple for an injected car but not so simple for a carb car. Allowing ram air will start a ram air war that we don't need in CMC.

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Al F.

Thanks for the perspective Pete. So would this do what you're saying:


Air inlet ducting upstream of the TB/Carb must have a cross sectional flow area that allows air to not enter the TB/Carb that is at least as large as the cross sectional flow area of the TB/Carb at the butterflies.

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Dustin M.

The inlet can be smaller than the cross sectional area of the butterfly/butterflies and still provide ram air if properly sealed. Thank you Pete for echoing my claims. As I've indicated before, blowing air on a cone filter is not ram air regardless of one's perception. The only reason I complicated this was to squash peoples' perceptions of what ram air is.

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MHISSTC

I think I get Dustins point here of trying to ensure a level playing field with some defined accountability, but all this just seems way too complex to try and police and try and determine if it's ram vs. non-ram air fed and if it actually makes a difference, and if anyone is cheating the system.


If you really wanted to make it simple, even with sealed airbox systems that have no other way for excess air to spill out anywhere so as not to create a higher volume of air flow into the engine, why not simply state the air being fed to the intake must be from a non-high air pressure location from somewhere around the car? Or even make a list of acceptable locations from which air could be drawn into the intake/airbox/ducting/etc.That would eliminate any sort of forward facing box or ducting that could trap air and provide any sort of increase in air pressure and volume in addition to other high pressure locations such as at the cowl along the base of the windshield.


Using the Fox Mustangs as an example, the OEM carb air cleaner housing is a dual snorkel affair that draws air from outside of the hot engine bay by placing the snorkels inside the inner fender well in front of the front tire, but far enough back from the front end openings that there is no air being trapped and force fed into the intake. The same goes for the OEM EFI setup that has a filter box inside the engine bay, but draws air in from the same front inner fender location.


By the way Dustin, the engine I built for my CMC car has a carburetor.


I'm not as familiar with the GM setups, but what's wrong with keeping all GM OEM air boxes or air cleaner housings in place as long as they aren't ram air system like the SLP SS and Firehawks? Factory unmodified airboxes and filter housings in their factory locations seem to be a lot easier to police than anything else that is either aftermarket or modified.

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Dustin M.

Simpler is better, let's see how this sounds?


6.21.5 Any air filter or air filter assembly may be fitted and OE assemblies may be modified. Air boxes and filters must reside inside the engine compartment or in the OEM stock location. Air filter installations that appear to create a ram air effect shall be subject to verification per rule 7.7. For the purposes of the rules, a ram air intake shall be defined as one that sources its air from a high pressure location, is ducted and sealed all the way to the engine.


So even if someone builds a legit ram air intake and then installs a minuscule leak, the director still reserves the right to make the racer prove themselves per 7.7.

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PeteL

To avoid arguments about what parts of a given car are high pressure areas and clarify duct sealing, I would suggest this wording:


7.7. For the purposes of the rules, a ram air intake shall be defined as one that sources its air from a location on the exterior of the car and is ducted and sealed from that source all the way to the engine. Ducting that appears to be sealed when the hood is closed or has small leaks or bleeds will be considered sealed.


The last sentence will prevent someone from putting a pinhole in their ducting and claiming it isn’t sealed or rigging something up that is unsealed with the hood up but is sealed when the hood is down . Still leaves it up to judgment but determining if something looks sealed is easier to agree on than if something looks like ram air.


I think it also eliminates the need to disprove through manifold pressure measurements if something is ram air. In my experience, it’s a lot harder to get good, reliable, repeatable and incontrovertible data than it might seem.

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BADVENM

Not sure how to word my question but basically we're required to dyno with the hood up and usually there is a fan or two in front of the car blowing air toward the front of the car. Is this RCR going to take that into consideration (or does it even need to), mainly because the car is stationary on the dyno and traveling at xx mph on the track?

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Dustin M.

If you don't have a ram air intake then this shouln't be a concern. The 2 places I've ever been have the fans low and point them at the radiator, not the air intake. If IAT is different between the dyno and the track it could have an effect, but we've already been living with that all this time so I'm not particularly concerned about capturing that. You'd basically need a dyno-specific cheater intake for that, but if your intake is anything but stock that's already captured on the dyno sheet so you'd be stuck racing with it.


So here's the latest and greatest taking Pete's wording into account. I think we may have something here.


6.21.5 Any air filter or air filter assembly may be fitted and OE assemblies may be modified. Air boxes and filters must reside inside the engine compartment or in the OEM stock location. Air filter installations that appear to create a ram air effect shall be subject to verification per rule 7.7. For the purposes of the rules, a ram air intake shall be defined as one that sources its air from a location on the exterior of the car and is ducted and sealed from that source all the way to the engine. Ducting that appears to be sealed when the hood is closed or has small leaks or bleeds will be considered sealed.

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Al F.

So what is a small leak or bleed? What is unsealed? A pinhole? A 1/16” día hole? 1/4” día hole? A 1/16” gap around the comical air filter circumference?

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MHISSTC

Why would a person want to modify an OE assembly?


Are we talking about one particular assembly with a very specific modification, or is the intent to just allow any and all do what they want as long as it all resides inside the engine bay and doesn't look like it provides any ram air effect?


Very early on in building our car we had a huge aftermarket cone air filter assembly installed inside the engine bay. We assumed with it's large size and wide open design compared to the stock airbox it would make more power. Just for fun we did a dyno run with the stock box to see just how much better the aftermarket one was. We were humbled to find out the OEM airbox and cheap paper air filter actually produced more power than the supposedly better cone filter. I guess Ford knew what they were doing and we kept the OEM airbox in place after that.


Anybody else have any similar stories about OE vs. aftermarket assemblies they want to share?

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Dustin M.
So what is a small leak or bleed? What is unsealed? A pinhole? A 1/16” día hole? 1/4” día hole? A 1/16” gap around the comical air filter circumference?

 

To me those are all bleeds/leaks. How about we define a square inch measurement that suffices as a legal bleed? Call it 3 square inches or a 2" diameter hole? Bigger? The exact number would require data, but a WAG of a 2" hole seems like more than enough in my mind. Super easy to police too.


Scott my car didn't some with a stock airbox and I suspect others may be in my shoes. The LT boxes aren't falling off of trees, though I'm sure I could find one if I really wanted to. The point of all of this is to simply clarify the rule as it is now so there's less grey area especially when it comes to a cold air intake vs ram air because of peoples' varying perceptions.


Still pretty concise.


6.21.5 Any air filter or air filter assembly may be fitted and OE assemblies may be modified. Air boxes and filters must reside inside the engine compartment or in the OEM stock location. Air filter installations that appear to create a ram air effect shall be subject to verification per rule 7.7. For the purposes of the rules, a ram air intake shall be defined as one that sources its air from a location on the exterior of the car and is ducted and sealed from that source all the way to the engine. Ducting that appears to be sealed when the hood is closed or has leaks or bleeds smaller than 3 square inches total will be considered sealed.

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ls168camaro
what if we just allow ram air? Make 6.21.5 simply state that any air filter or air filter assembly and ducting upstream of the TB/Carb may be used. Isnt that the easiest to police?

 

Is this reverse psychology? Why would we even consider allowing people to spend $250-500 on an aftermarket ram air kit or more for a custom built setup?

I thought most of our rules were designed to close loopholes instead of allowing more things to be exploited?


I still say add that it's illegal to have a ram air or cold air intake. I also suggest that we not be able to remove the headlights for a duct (period) and especially for one that allow you to duct air towards the air filter.

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MHISSTC
I also suggest that we not be able to remove the headlights for a duct (period) and especially for one that allow you to duct air towards the air filter.

 

Would I be allowed to removed a headlight and cover it with hardware cloth for the purpose of providing an inlet for brake cooling ducting?

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blk96gt
I also suggest that we not be able to remove the headlights for a duct (period) and especially for one that allow you to duct air towards the air filter.

 

Would I be allowed to removed a headlight and cover it with hardware cloth for the purpose of providing an inlet for brake cooling ducting?

I have a duct going from my headlight cover to my oil cooler which is on the opposite side of my intake. Would you want this against the rules?

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ls168camaro
I also suggest that we not be able to remove the headlights for a duct (period) and especially for one that allow you to duct air towards the air filter.

 

Would I be allowed to removed a headlight and cover it with hardware cloth for the purpose of providing an inlet for brake cooling ducting?

I have a duct going from my headlight cover to my oil cooler which is on the opposite side of my intake. Would you want this against the rules?

 

That's what the (period) meant. Yes, our class was designed to be stock appearing and removing the headlight covers goes against this. There are other areas available for brake ducts I believe but again that isn't required. With stoptechs I don't think brake ducts are needed and I also believe that most brake duct setups on our cars don't do that much.


Yes, I would want your headlight duct for your oil cooler to be against the rules. Again you have other areas for air or you can put a fan on the cooler like others have done. Of course you don't have to run an oil cooler like plenty of others. My understanding for your platform is there aren't any issues with overheating even with a cheap factory replacement radiator.

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blk96gt

That's what the (period) meant. Yes, our class was designed to be stock appearing and removing the headlight covers goes against this. There are other areas available for brake ducts I believe but again that isn't required. With stoptechs I don't think brake ducts are needed and I also believe that most brake duct setups on our cars don't do that much.


Yes, I would want your headlight duct for your oil cooler to be against the rules. Again you have other areas for air or you can put a fan on the cooler like others have done. Of course you don't have to run an oil cooler like plenty of others. My understanding for your platform is there aren't any issues with overheating even with a cheap factory replacement radiator.

Headlight covers weren't stock. Headlights were stock. I'm not removing a headlight cover, I'm adding a hole to the cover to duct air to the oil cooler.

You want brake ducts even with StopTechs.


Of course I don't have to run an oil cooler, but I have one because I don't want 300+degF oil temps.

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ls168camaro

That's what the (period) meant. Yes, our class was designed to be stock appearing and removing the headlight covers goes against this. There are other areas available for brake ducts I believe but again that isn't required. With stoptechs I don't think brake ducts are needed and I also believe that most brake duct setups on our cars don't do that much.


Yes, I would want your headlight duct for your oil cooler to be against the rules. Again you have other areas for air or you can put a fan on the cooler like others have done. Of course you don't have to run an oil cooler like plenty of others. My understanding for your platform is there aren't any issues with overheating even with a cheap factory replacement radiator.

Headlight covers weren't stock. Headlights were stock. I'm not removing a headlight cover, I'm adding a hole to the cover to duct air to the oil cooler.

You want brake ducts even with StopTechs.


Of course I don't have to run an oil cooler, but I have one because I don't want 300+degF oil temps.

 

Huh? The headlight cover is the factory headlight with the guts behind it removed. Then the rules say to run a facsimile and maintain a stock external appearance. A mesh covered cooling duct doesn't meet the stock appearing criteria in my world. I also don't consider chicken wire to either be mesh or stock appearing. What kind of mesh cover are you running? Do you think it's stock appearing?


Your legal and I wouldn't worry about it. But you seem to be wanting the hole in the cover so you can duct air to an oil cooler which isn't required. It's like complaining about not being able to run a custom differential cover on my Ford 9". As others have done in the past you can come up with a different solution and maybe it would be better. What does your data show when running with and without the cooler? How does the data look if you moved the cooler in front of your radiator. Whats the size and quality of the cooler. What are the oil temps on the other cars like yours and what do they do? (No need to answer as I don't care)


I wish brake ducts were the reason I'm never on the podium. But since acquiring this car with stoptechs and weighing over 3,350 I have never experienced an issue without brake ducts. Just don't ask for a blower to be allowed to cool your brake ducts but your welcome to use the same blower on the windshield.

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