"The Confines of the Engine Compartment"

[Greg Amy]

GCR 9.1.3.D.1.a.4 says, in part, "Air intake source shall be within the confines of the engine compartment or stock location." Define "the confines of the engine compartment".

GCR Technical Glossary (Appendix F) defines "engine compartment" as:


Engine Compartment – The loosely defined volume, nominally enclosed
by panels on top and sides, which is the normal location of the engine in
a car.


"Loosely defined", indeed. Question is, how loosely?

"So where's he going with this?" you may ask. I had an email exchange with someone, asking about the compliance to the ITCS of the Jackson Racing intake system for the Miata (http://www.mossmiata.com/Shop/ViewProducts.aspx?PlateIndexID=73251). He had seen it in other Miatae for sale and wanted to know if he could install it on his own car. Photo, installed:

http://www.miataturbo.net/attachments/miata-parts-sale-trade-5/88820d1379172121-sale-jackson-racing-cold-air-intake-90-93-1-6-miatas-2u5q0ox-jpg

This appears to pull intake air from above the radiator support. At first glance, I'd call it non-compliant, however nowhere is there a clear delineation of "engine compartment" for the front or bottom, and in this particular case the "top" is the hood, and this parts sits under that.

We briefly touched on the subject in the 2008 discussion of the ARRC CRX fender well intake protest (http://www.improvedtouring.com/forums/showthread.php?25258-Cold-Air-Intakes-(CAI)-for-88-91-CRX-Illegal). Within that, we recognized that there was some ambiguity, but never truly delved upon it.

Stock 1.8L engine compartment:
http://carphotos.cardomain.com/ride_images/2/4031/4321/22577160004_large.jpg?v=0http://home.roadrunner.com/~chrisaj/archive/miata/miata_engine.jpg

Stock 1.6L engine compartment:
http://www.practicaltech.ca/jpg/auto/miata/miata_engine-bay.jpg

Since the top of the "engine compartment" is inferentially defined by the Technical Glossary as the bottom of the hood, and this part fits within that without modification, isn't anything under the hood part of the "engine compartment"? If so, where does that allowance end in the forward direction?

And what about "prohibited function"? The regs clearly indicate that pulling air from outside the "engine compartment" is clearly prohibited, and the regs further clarify that you cannot run a minimal radiator to make open space to route air to the engine intake. But what if you are not modifying anything to grab air from that area?

About the only thing I can suggest is that it's non-compliant because the "engine compartment" definition in the Glossary states "the normal location of the engine in a car", and there's no way that the area above and in front of the radiator is a normal location for the engine. But it's not clear where that "normal location" definition ends, nor is it clear if that definition changes based on make/model (and if it does, then any space that the engine does not "normally" occupy - basically all the clear space around the engine - would not be allowable places from which to source air.)

Is it the aft edge of the radiator? Does that change with the allowed radiator design change? Is it the aft edge of the radiator support? Of the forward edge of the rad support? And if that part were trimmed back an inch to that plane, but still pulled air from above the radiator and radiator support, would it then be compliant?

I'm torn. Without using much intorturation, I see how this could be allowed, as-is.

I'm sure no one else on this board will have a strong opinion on it, but figured I'd ask anyway...

GA

[dickita15]

I must admit i am uncomfortable with the intake breaking the plane of radiator.

[Greg Amy]

I must admit i am uncomfortable with the intake breaking the plane of radiator.

Fair enough. So look at that photo of the item installed (http://www.miataturbo.net/attachments/miata-parts-sale-trade-5/88820d1379172121-sale-jackson-racing-cold-air-intake-90-93-1-6-miatas-2u5q0ox-jpg) again. Note that the piece that extends well past forward of the radiator is the mounting system, and there's no limits to the mounting system for the air intake, only limits to where the air is sourced. If he were to trim back the top of that item, where the initial opening of the air source is, to a point right at the vertical plane of the aft edge of the radiator, would that not satisfy the letter (and potentially the intent) of the reg?

GA

[Knestis]

<johnbishop> It's illegal. Period. </johnbishop>

Kirk (who freely admits that combining obtuse references to both html and '70s-era IMSA is probably leaving pretty much everyone out of the joke)

[Greg Amy]

<johnbishop> It's illegal. Period. </johnbishop>
Wish we could....but then there'd be all kinda arguments over how come *I* got to be John Bishop...:shrug:

[joeg]

I have no problem with it. Unless you are going to mandate bone stock air filters and housings, it works.

[Greg Amy]

I think I may have accidentally discovered where the item is moot, regardless of compliance.

Look again at that photo of the stock 1.8L Miata (http://carphotos.cardomain.com/ride_images/2/4031/4321/22577160004_large.jpg?v=0http://home.roadrunner.com/~chrisaj/archive/miata/miata_engine.jpg). Note that there's a plastic cover over the area on top of the nose, in front of the radiator. This Jackson Racing part pulls air from that area when that cover is removed, and I cannot think of any way where removing that panel is compliant to the regs. Therefore, even if that intake is compliant, I don't think it's nearly as effective unless another non-compliant mod is also done, negating the whole point.

The 1.6L Miata seems to be open there, so may be useful for that car.

Agree/disagree?

GA

[Ralf]

Wouldn't that air intake be considered ram air and therefore not be allowed? "Velocity stacks, ram air or cowl induction are not permitted unless fitted as original equipment."

[Greg Amy]

Wouldn't that air intake be considered ram air and therefore not be allowed? "Velocity stacks, ram air or cowl induction are not permitted unless fitted as original equipment."
I don't think so. In my mind it's clearly not velocity stacks; doesn't meet the definition of cowl induction (nowhere near the cowl); and ram air IMO requires facing the perpendicular flow of oncoming air.

One can argue that there is increased air pressure being created in front of the radiator due to forward motion, and this intake system takes advantage of that. I disagree; I suggest that since that area in front of the rad is way wide open with numerous holes all around, any pressure increase is minimal, if at all (and would be tough to prove regardless). Lack of significant increased air pressure negates the idea that it's ram air.

Good thought, though.

GA

[chuck baader]

I have always considered the engine compartment as a place where the engine resides. Clearly, the engine does not reside in front of the radiator, therefore, the engine compartment ends with the rear of the radiator. Non compliant.

[Andy Bettencourt]

I have never considered that intake to be legal for an ITA Miata. I believe, like RP, that anything flush or encroaching on the plane of the radiator sources from 'outside' the bay. That's oversimplified for sure.

[lawtonglenn]

I have never considered that intake to be legal for an ITA Miata. I believe, like RP, that anything flush or encroaching on the plane of the radiator sources from 'outside' the bay. That's oversimplified for sure.


I have always considered the engine compartment as a place where the engine resides. Clearly, the engine does not reside in front of the radiator, therefore, the engine compartment ends with the rear of the radiator. Non compliant.

+1

[Greg Amy]

I tend to agree with the above. However, re-read my post from above and tell me what you think...we're talking only an inch difference here...


Fair enough. So look at that photo of the item installed (http://www.miataturbo.net/attachments/miata-parts-sale-trade-5/88820d1379172121-sale-jackson-racing-cold-air-intake-90-93-1-6-miatas-2u5q0ox-jpg) again. Note that the piece that extends well past forward of the radiator is the mounting system, and there's no limits to the mounting system for the air intake, only limits to where the air is sourced. If he were to trim back the top of that item, where the initial opening of the air source is, to a point right at the vertical plane of the aft edge of the radiator, would that not satisfy the letter (and potentially the intent) of the reg?

[gran racing]

The advice I'd give to that person is that it's quite debatable whether that intake is legal or not. They should also further look into whether there are truly any gains to be made. Then based upon those pieces of information, decide whether or not the hassle is going to be worth it. I looked into it after seeing that intake at Summit Point on the way back from picking up my Miata. I then spoke with ISC and a few other companies. I don't think that is a better option. I do know that every time I raised my hood in impound (do often regardless of whether or not required to), it would cause questions. Then questions about what else might I be doing too. It's also an easy protest that I have to imagine would come with a small protest bond fee. Curious, what do you think that would be?

After this simple protest is filed, it's then going to be a debate amount the powers that be just as being done here. Maybe found illegal then move on up to National.

Back to the real question, it sure looks debatable and right on the edge of the rules if it's not illegal.

That plastic cover near the rad. All year 1.8s have them? I don't recall ever seeing one on a Miata. I'll admit you made me go outside and take a look at mine. It's not there. For cooling purposes, I'd almost think it would be better to have it. My intake is not in that area and don't think there's any impact.

[Greg Amy]

>>> It's also an easy protest that I have to imagine would come with a small protest bond fee. Curious, what do you think that would be?

Nothing, just the $25 protest fee. Bonds are collected to cover the expense of any destructive inspections (e.g. engine tear-down) to reimburse the protestee if found compliant. In this case, there are no such costs.

>>> After this simple protest is filed, it's then going to be a debate amount the powers that be just as being done here. Maybe found illegal then move on up to National.

After the protest is filed, the Chief Steward will form an SOM to discuss the issue. They may ask for feedback from ITAC/CRB members. At that point they will present their decision. The protestee at that point can file an appeal to Topeka, at which point an Appeals Court will be formed to review the issue.

>>> Back to the real question, it sure looks debatable and right on the edge of the rules if it's not illegal.

Concur. Which is why I brought it here (with the permission of the original questioner.)

>>> That plastic cover near the rad. All year 1.8s have them? I don't recall ever seeing one on a Miata.

Yup, but it's a commonly-lost item. I think it's held in by a couple of plastic clips that are easily broken/brittle from time. Since we can replace the radiator with a sufficiently-large one, it's quite possible an advantage to 1.8L Miata drivers to "leave it lost" and allow cooler air to come into the engine compartment...probably a "weenie protest" item, unless coupled to something like this intake...but technically non-compliant.

GA

[JLawton]

I think you have to also look at the intent of the rule(s). From that perspective I dont think it's legal.

[lawtonglenn]

I don't mean to complicate the issue, but it reminds me of the stock airbox/ramair setup of the S5 RX7.
It seems to me that if none of the fast RX7 guys utilize these stock parts, it probably isn't worthwhile.
What I do know is that we toyed with it, and we determined that its volume flow restriction would likely
outweigh any possible (and doubtful) pressurized advantage

3731

[gran racing]

In this case, this intake was included on a Miata driven by an extremely talented driver (I'm almost certain - Price). I never would have protested him because he could drive circles around me and I would have known it sure as heck wasn't the intake.

Andy - what's your take on the performance of that intake versus say an ISC?

[Greg Amy]

I think you have to also look at the intent of the rule(s). From that perspective I dont think it's legal.
I concur. In my opinion the intent of the reg is to allow opening up of the restrictive stock air filter systems while avoiding allowances of things like ram air, cowl induction, and cold air intakes. We subsequently opened that further by allowing anything upstream of the throttle body/MAF/etc.

On the other hand, all air comes from outside the engine compartment, and it has to get in there somehow. We're seeing cold air boxes and radiant and convective heat shields around air filters and intake tubes to minimize the heating effects of the engine compartment.

With that in mind, how does this fit into that mindset? Is it incremental, and if so, within the boundaries of the intent? Or is it revolutionary to the point of being extra-compliant?

I dunno, that's why I'm asking. But at this point, ignoring the value of it, I'm thinking if you trim back the upper edge of the rectangular section such that it is at or behind the vertical plane of the aft edge of the radiator then you're compliant.

GA

P.S., Mr Original Asker, please note that nothing decided on this board even begins to imply what answers you'd get during a protest and/or appeal. This is the Internet and these opinions are worth exactly what that implies...

[gran racing]

Mr. Original Asker: It this were to be protested, I'd honestly flip a coin on what the results were. Would most likely just depend upon who happens to be making the decisions, whether they are having a good day or not, among other risky variables.

Nothing wrong with bringing it up for discussion, that's for sure.

[Andy Bettencourt]

We tried one to baseline from a HP and an air-intake temp perspective. We built a better one by V.3 and V.4. (by my definition - torque curve)

As to the plastic over in front of the radiator, I kept mine. It actually keeps better air into the radiator. Back in the day, the 1.6 SM guys were adding the 1.8 piece IIRC to improve cooling. It might be specifically allowed in SM.

[seckerich]

I don't mean to complicate the issue, but it reminds me of the stock airbox/ramair setup of the S5 RX7.
It seems to me that if none of the fast RX7 guys utilize these stock parts, it probably isn't worthwhile.
What I do know is that we toyed with it, and we determined that its volume flow restriction would likely
outweigh any possible (and doubtful) pressurized advantage

3731


Go back and look again, you missed something.

[MMiskoe]

The rules are pretty clear about no 'ram-air' and this would put the air intake into an area of higher pressure than it would normally have in it's stock location. You have to remove the plastic trim for it to work.

Two strikes, you're out.

[gran racing]

Agreed. No plastic piece and no air intake there? Cool (IMO). No plastic piece AND intake there? Too far.

Now I need to go find one of those plastic pieces. Agree with Andy on using it to keep temps down.

[lawtonglenn]

Go back and look again, you missed something.

ok Steve ... we still have the parts ... six pack of lager for some hints? :)

[seckerich]

PM me and I will send you a picture.

[Wreckerboy]

As to the plastic over in front of the radiator, I kept mine. It actually keeps better air into the radiator. Back in the day, the 1.6 SM guys were adding the 1.8 piece IIRC to improve cooling. It might be specifically allowed in SM.

It is allowed for the 1.6 in both SM and SSM, and makes a big difference in cooling. I've run my car back to back with and without and the differences on an 80 degree day were immediate.

[Rabbit05]

I have never considered that intake to be legal for an ITA Miata. I believe, like RP, that anything flush or encroaching on the plane of the radiator sources from 'outside' the bay. That's oversimplified for sure.


I have always considered the engine compartment as a place where the engine resides. Clearly, the engine does not reside in front of the radiator, therefore, the engine compartment ends with the rear of the radiator. Non compliant.

+1


Just to debate the definition of the Engine Bay/Compartment .

Where would the radiator be located, or described as being located, if it's not the considered the engine compartment ? I would think anywhere under the hood, and aft of the grill , would be considered as engine bay . Plus, I believe in the definition that Greg supplied, makes no reference to for or aft of the radiator being a boundary for the engine compartment.

-John

[Chip42]

Just to debate the definition of the Engine Bay/Compartment .

Where would the radiator be located, or described as being located, if it's not the considered the engine compartment ? I would think anywhere under the hood, and aft of the grill , would be considered as engine bay . Plus, I believe in the definition that Greg supplied, makes no reference to for or aft of the radiator being a boundary for the engine compartment.

-John

cool, so my whole car is engine compartment?
<--- drives an MR2

[Rabbit05]

yes ...yes it is...:D HA I totally forgot about the mid/rear engine cars...!

You must now drive backwards....

[Marcus Miller]

It is allowed for the 1.6 in both SM and SSM, and makes a big difference in cooling. I've run my car back to back with and without and the differences on an 80 degree day were immediate.

Agreed, these do matter for cooling. Dave, look around online, some of the Miata aftermarket places have the factory pieces availabe (gomiata I think?). I just put an NRG aluminum panel on my SU car becauase bling matters... (and it was the same price as the factory piece, and I don't have rules to live by)

[Gary L]

...definition that Greg supplied, makes no reference to for or aft of the radiator being a boundary for the engine compartment.

-John

Damned good thing, particularly if you're talking about cars like the Fiero or the soon-to-be-classified-I'm-sure Austin America. :)

[billf]

Hi guys,

Just responding to the question of "Ram Air", as it was discussed in the forum. Back in the day, I was protested for this item in ITB. I then referred to the GCR Technical Glossary, where "Ram Air" is defined (fancy that). In 2011, the definition was: "A type of induction system in which the incoming air is obtained from an extension into the airstream outside the bodywork." Bold is mine.

No one has mentioned a reference to the glossary, so I thought I'd bring it up. If this definition still exists, then the discussion could take another turn?

Good racing,

Bill:024:

Good racing.

[JeffYoung]

No real impact I think Bill.

THe issue here is what is "inside the engine compartment" since our rules allow the pickup of air there, or in the stock location.

To me, the radiator has to be the forward definition of the engine compartment. Otherwise, you could use the void between the grill and the radiator on pretty much any car to make an effective and never intended cold air intake.

Based on that, he Jackson intake is not legal as it extends past the rear of the radiator. Cut it off there and probably legal.

[Greg Amy]

I agree with you, with the following:


...radiator has to be the forward definition of the engine compartment. Otherwise, you could use the void between the grill and the radiator on pretty much any car to make an effective and never intended cold air intake.
This is supported philosophically, in that the regs do not allow you to make a shorty radiator and leave a hole next to it for air intake. It would be nice, howver, for that to be explicitly clarified in the regs (easy to supplement the "engine compartment" definition within the ITCS.)


Based on that, he Jackson intake is not legal as it extends past the rear of the radiator. Cut it off there and probably legal.

I agree that the intake portion of it should be behind the plane of the radiator. However, there is no restriction to the mounting portion of it needing to be behind that, as long as air is not taken in from there.

GA

[Knestis]

3735

Audi 4000 5+5, just for giggles...

I miss that car.

K

EDIT - Whoops. Thats a 4000Q but the radiator layout is the same; ditto for the ITB Coupe.

[JeffYoung]

Agree.


I agree with you, with the following:


This is supported philosophically, in that the regs do not allow you to make a shorty radiator and leave a hole next to it for air intake. It would be nice, howver, for that to be explicitly clarified in the regs (easy to supplement the "engine compartment" definition within the ITCS.)



I agree that the intake portion of it should be behind the plane of the radiator. However, there is no restriction to the mounting portion of it needing to be behind that, as long as air is not taken in from there.

GA

[Chip42]

I dislike the radiator being considered a standard part of the outline of the engine compartments due to mid engined cars and oddballs like the 5cyl audis, not to mention 1/2 width radiators found on many hondas and a few other cars.

in the case of the miata - yeah, a fine, common sensical boundary, but I think we should be clear with ourselves that it is not a valid definition in MANY cases.

[JeffYoung]

I dislike the radiator being considered a standard part of the outline of the engine compartments due to mid engined cars and oddballs like the 5cyl audis, not to mention 1/2 width radiators found on many hondas and a few other cars.

in the case of the miata - yeah, a fine, common sensical boundary, but I think we should be clear with ourselves that it is not a valid definition in MANY cases.

This is a pretty easy "know it when you see it" thing though. Something like "within the confines of the engine compartment, which is typically bounded by the radiator (front), hood (top), inner fenders (sides) and subframe or other engine mounting points (lower)" -- something like that.

[Chip42]

definition comes from the technical glossary in the GCR and we just use the term and the allowances for intake ducting in the ITCS. I doubt they will rewrite the definition to suit tin tops because wings and things. better just to, as you say, know it when you see it.

[Racerlinn]

3735

Audi 4000 5+5, just for giggles...

I miss that car.

K

EDIT - Whoops. Thats a 4000Q but the radiator layout is the same; ditto for the ITB Coupe.

Turd, meet punch bowl.

[Knestis]

Sploosh!

[Rabbit05]

Ha !! Those 5+5s are rare ! Nothing like having the radiator off to the side. The top cover of the radiator makes for a nice tool tray and beverage holder . :)

[vtluu]

To further muddy the waters...

I've read this thread closely as I had a friendly discussion this past weekend with one of our scrutineers about the legality of the intake I've run for years:

3767 3768

It's a modified Racing Beat intake; the latter came with a hole in the back of the "box" for a more stock-like intake routing, which I fiberglassed closed and ran a straight pipe over from the throttle body, through the MAF and into the side of the box.

Inarguably, the intake & intake box are located within the confines of the engine compartment, and aren't a ram air system nor cowl induction. In my case the point of contention is what "source" means. The induction box (mostly) seals the intake filter off from the engine compartment so it draws air from the wheel well. So you could say it's drawing air from outside the engine compartment... but as someone here pointed out earlier, all air comes from outside the engine compartment one way or another.

It would be nice to get some kind of "official" (such as it is) word on this; I haven't contacted the ITAC in so long that I don't even remember how...

[Greg Amy]

It's a gray area that, like splitters, we've all chosen to ignore. IMO, as long as all the bits are physically located within the "confines of the engine compartment", and you're not doing cowl induction or ram air, then it's compliant to the current letter of the regs, despite having been sealed off from the rest of the engine compartment. Its compliance to the spirit of the regs in current context IMO is also OK. But it would be extremely hard to interpret it to the original context of the regs because, as with splitters, they didn't exist back then at our level of competition.

There's no longer any "official" method of getting rules interpretation. You can send a request to the ITAC for clarification (http://crbscca.com) but that clarification is really non-official and will only last through the current year and/or ITAC; all it does is indicate to you how the CRB/ITAC would rule should they be asked during a protest/appeal. The other way is to have someone protest you ($25 and you'll probably get that back) and run it through protest/appeals.

GA

[JeffYoung]

And we really don't offer clarifications anymore (we've been asked not to).

My personal opinion is that this intake is legal as it is within the confines of the engine bay BUT the IT Miatas and RX7s I've seen have a habit of having the hood bend up slightly in that area to effectively pressurize the area around the filter, which is even more effective here due to the well designed and essentially sealed box. If the hood is bent up, I could see this conceivably being called "ram air."

[Andy Bettencourt]

It's a gray area that, like splitters, we've all chosen to ignore. IMO, as long as all the bits are physically located within the "confines of the engine compartment", and you're not doing cowl induction or ram air, then it's compliant to the current letter of the regs, despite having been sealed off from the rest of the engine compartment. Its compliance to the spirit of the regs in current context IMO is also OK. But it would be extremely hard to interpret it to the original context of the regs because, as with splitters, they didn't exist back then at our level of competition.


GA

I would only add one thing...like exhaust heat shields and custom intake shrouding, in order to be compliant under the 'intake is free' or 'exhaust is free', these designs must be attached to said free item.

So that Miata intake shroud above looks legal provided it's actually attached to the intake tubing in some way.

[Andy Bettencourt]

And we really don't offer clarifications anymore (we've been asked not to).

My personal opinion is that this intake is legal as it is within the confines of the engine bay BUT the IT Miatas and RX7s I've seen have a habit of having the hood bend up slightly in that area to effectively pressurize the area around the filter, which is even more effective here due to the well designed and essentially sealed box. If the hood is bent up, I could see this conceivably being called "ram air."

Which would put doing that illegal from two angles. 'Modifying' your body work is illegal in this context and even if it was legal it wouldn't be allowed here since it facilitates a specifically disallowed modification.

[vtluu]

Thanks Greg, Jeff, Andy.


So that Miata intake shroud above looks legal provided it's actually attached to the intake tubing in some way.

Is duct tape considered a legal method of attachment? :D

[Greg Amy]

Is duct tape considered a legal method of attachment? :D
Yup. In fact...when I did a heat shroud on my ITA NX2000 many moons ago, Andy was looking under the hood. He made a comment regarding the shield being a separate part from my intake. I reached over, grabbed a roll of duct tape, and connected them together.

The look on his face was priceless... ;)

[chuck baader]

Fasteners are free!!

[Andy Bettencourt]

Yup. In fact...when I did a heat shroud on my ITA NX2000 many moons ago, Andy was looking under the hood. He made a comment regarding the shield being a separate part from my intake. I reached over, grabbed a roll of duct tape, and connected them together.

The look on his face was priceless... ;)

And in one move, it was legal!

[JS154]

cool, so my whole car is engine compartment?
<--- drives an MR2

I would consider the engine compartment to be forward of the firewall, aft of the radiator core support, and surrounded by the inner fender wells and hood.

[Chip42]

Out of context that quote makes me look like I was being serious...

[Greg Amy]

Out of context that quote makes me look like I was being serious...

No worries, Chip; we rarely take you serious anyway...

;)