Cold-Air Intakes (CAI) for 88-91 CRX Illegal

[Xian]

Now Christian, us V8 RWD guys read the rules too......

You've seen my car. There is a space behind the plenum (where the carbs are now) that sits under a slotted grate on the hood. The grate is where the car used to taked in air to the vents into the cabin. Entirely legal to put a box under that and draw air there.

David, I truly don't think the Air Snake is legal given the INTENT of the rule, but I agree with you I see the "do what you want" if stock is outside the engine bay as well.

Gary, you are legal. I consider that o-ring to be part of the "pipes/tubes/resonators" ahead of the carb/AFM that you can modify/replace, etc. It's free. Take it out, replace with bigger tube.

Andy, I'll take some pictures of my car this weekend and send them to you for your thoughts.

I think you read 'em with too tight of an interpretation Carbs? Huh? You mean those things you can use as paperweights now that you've gone EFI?

Looking at the pic above, I'd consider the donut to be part of the intake... seems like you could ditch it and go from there.

[GKR_17]

Jeff,

Take your fender source logic to the extreme and apply it to the standard engine compartment... all the air in the engine compartment must come from somewhere so the actual source is outside the engine compartment. Clearly not legal though.

[JeffYoung]

That's a good point.

So how do you define a "stock" air pickup location that is outside the confines of the engine bay? Would limit to to simply drawing air from teh same spot (which I think is the intent of the rule and an intent which I will follow)? Or do you believe that it means you basically can run pipes and tubing anywhere along the "air intake stream" within the confines of the bodywork?

I think most of us believe the correct interpretation is a hybrid -- you can put a filter or air box in the general location, outside the engine bay, of the stock air pick up.

I'm just not sure that is logically consistent with the "strict" interpretation of the rule which would require stock pickup hardware or the "liberal" one that allows the Air Snake.

Jeff,

Take your fender source logic to the extreme and apply it to the standard engine compartment... all the air in the engine compartment must come from somewhere so the actual source is outside the engine compartment. Clearly not legal though.

[StephenB]

The MkIII Golf takes its air from inside of the engine compartment. Remember that "in the engine compartment" means "anywhere in the engine compartment."

Now, the fact that you could see it through the grill raises another potential issue. I can't foresee a combination of legal allowances under which I could, say, use a narrower radiator and put the air intake inside the engine compartment, but right in a blast of air coming through the grill...

K

So my question in regards to the above scenario...
If there is space to allow a tube to run up to the grill without modifying anything I would think it would be legal as long as it wasn't mounted flush up to the grill. If it was mounted say 1" behind the grill it is essentially getting air that is from inside the engine compartment. Now if it was mounted directly to the grill then the air is from outside the engine compartment as it never really entered the engine compartment. What are your thoughts on this?

In Gary's scenario with the Volvo I would think that you would not be allowed to add a filter outside the engine compartment because in reality is is getting it's air from the edge of the body where the gromet is. by extending this you are modifying the location of the air intake. In my car I have a stock plastic peice that takes air from behind the bumper. The piece of plastice goes through a hole in the fender about 1/4 of an inch. to stay legal I continued the use of this exact same piece of plastic however I used a larger diameter tube going in between the intake box and this plastic that protrudes the fender.

On a completly different conversation but still on this topic... by using a large opening then reducing to a smaller tube you would theoretically increase the velocity of the air entering you airbox. Does anyone know if this helps performance?

[JeffYoung]

Andy and I had a long debate about this a while back. I think with the way the GCR defines velocity stacks, you are allowed to do this -- a narrowing, tuned tube that speeds up air flow -- on FI cars but not carbed cars because air intakes, tubes, pipes etc. are free but velocity stacks (defined as a device speedign the flow of air into a carburetor) are specificaly prohibited.

I think it is a flaw in the rules, but I also think it is the correct interpretation of them.

On a completly different conversation but still on this topic... by using a large opening then reducing to a smaller tube you would theoretically increase the velocity of the air entering you airbox. Does anyone know if this helps performance?

[dspillrat]

-- on FI cars but not carbed cars because air intakes, tubes, pipes etc. are free but velocity stacks (defined as a device speedign the flow of air into a carburetor) are specificaly prohibited.

My understanding is, air horns, velocity stacks..etc... are allowed if they came as original equipment......

david

[dspillrat]

That's a good point.

So how do you define a "stock" air pickup location that is outside the confines of the engine bay? Would limit to to simply drawing air from teh same spot (which I think is the intent of the rule and an intent which I will follow)? Or do you believe that it means you basically can run pipes and tubing anywhere along the "air intake stream" within the confines of the bodywork?

I think most of us believe the correct interpretation is a hybrid -- you can put a filter or air box in the general location, outside the engine bay, of the stock air pick up.

I'm just not sure that is logically consistent with the "strict" interpretation of the rule which would require stock pickup hardware or the "liberal" one that allows the Air Snake.

Agreed Jeff,
The volvo intake air source clearly is completely outside the engine compartment if I decipher the diagrams correctly? If so, no combustion air from inside the engine compartment is allowed within the stock air intake.....air filters are free....placement should be allowed outside either of "Volvo" or "MG" engine compartments ...... Why shouldn't the air filter be allowed within in the allowed air supply source?

David

[dspillrat]

Hell Fire.......:eek:

Fuel Injection, 50 degree cooler air....... Looks like we may need to add a few pounds to this rocket ship!!!!!

David

[JeffYoung]

Correct...and I know why you are stating that...lol....

Reward weight??!! Don't I have to actually win something first? I suspect the FI and 50 degrees cooler air isn't going to overcome the existing brakes and handling.....I can't run with you as is!

I do have a few improvements on handling though. Figured out that 275/35/15s fit the rears...........if you can get camber, then just add tire......

My understanding is, air horns, velocity stacks..etc... are allowed if they came as original equipment......

david

[Ron Earp]

Here are a couple of pictures that might help with the discussion. The first picture is a stock TR8 which shows the fender well air intakes.

The second picture is an stock FI TR8 that shows some type of piece that seals against the hood. Not sure what that is for, is it for air or a water drain?

[JeffYoung]

Internet Master Earp comes through for me.

In that first picture, yes, what he is circled is exactly what I am talking about. Stock, a hose leads to a plastic piece which is screwed to a oblong hole about 3" by 5". Inside the hole is a void in front of the inner fender liner/well, that "picks up" air from (a) under the car and (b) from the radiator scoop.

Air Snake!

The second picture, so you understand why that plenum is different from the one in the negine build thread, appears to be a UK TR7V8 (they only sold a handful of actual TR8s in the UK) with a Land Rover 3.9 transplant. Different (and better plenum) on those motors.

and to think, I cold have run that better plenum and no one would have been teh wiser....lol......

Seriously, let me know what you guys think on the fender well holes. My interpretation of the intent of the rule is I can take air from them, but have to "stop" the air snake at the plastic piece in the hole, but I think a strict legal interpretation would allow me to run tubes and pipes anywhere in the upstream air intake path within the confines of the bodywork (although, again Grafton makes a good logical point as to why that strict legal interpretation is wrong).

Here are a couple of pictures that might help with the discussion. The first picture is a stock TR8 which shows the fender well air intakes.

The second picture is an stock FI TR8 that shows some type of piece that seals against the hood. Not sure what that is for, is it for air or a water drain?

[Ron Earp]

How do the FI engines and the carb engines differ? I know the carb engine brought air in through the fender well holes. How about the FI engine?

[JeffYoung]

Same, essentially. A flexible tube ran from the AFM to a large square air box with the filter that was attached to the fender hole on the passenger side of the car. The driver's side, unlike the carb car, was not used.

The air box was very restrictive and apparently putting a cone filter simply in the area of the hole (engine side) was worth 5-10 hp.

I still think best place to take in air is under the grate at the base of the hood.

How do the FI engines and the carb engines differ? I know the carb engine brought air in through the fender well holes. How about the FI engine?

[R2 Racing]

My Honda's are displeased that there's VW, Triumph, & Volvo talk in their forum. They're kind of elitist.

[Ron Earp]

I still think best place to take in air is under the grate at the base of the hood.

Without real pressure readings I don't think I could make that call. Too much lore in TR8 land, just like the Jensen. I have a pressure sensor and datalogging meter if you wish to explore that.

[JeffYoung]

Aw, Ruck, go roll your car and then win the ARRC or something!

Seriously, generically speaking, which side of the Air Snake debate are you on?

My Honda's are displeased that there's VW, Triumph, & Volvo talk in their forum. They're kind of elitist.

[Knestis]

>> If there is space to allow a tube to run up to the grill without modifying anything I would think it would be legal as long as it wasn't mounted flush up to the grill. If it was mounted say 1" behind the grill it is essentially getting air that is from inside the engine compartment. Now if it was mounted directly to the grill then the air is from outside the engine compartment as it never really entered the engine compartment. What are your thoughts on this?

I personally don't think that's intorturtation. We do a conceptually similar thing on my Golf, having cut up the bottom (pre-filtered) side of the air box to allow it to pull air from the vicinity of the space behind/below the front bumper, on the outside toward the fender well.

One data point: We punched out (well, Greg A punched out) a right side headlight at the Summit 12 hours. I seem to recall that Cameron came away from that convinced, based on data on the DL1, that the ECU got smarter as it figured out that cool air was being packed into that space, and adapted to make more power.



K

KK

[shwah]

That's weird. Any idea why they made the change? Doesn't matter - just curious.

I have no idea. I think both are good source points, but use the headlight because it collects less rubber in the airbox that way.

[Xian]

Seriously, let me know what you guys think on the fender well holes. My interpretation of the intent of the rule is I can take air from them, but have to "stop" the air snake at the plastic piece in the hole, but I think a strict legal interpretation would allow me to run tubes and pipes anywhere in the upstream air intake path within the confines of the bodywork (although, again Grafton makes a good logical point as to why that strict legal interpretation is wrong).

Maybe I was misunderstanding your prior explanation (I thought you were saying the stock tubing went thru the fender all the way to a location in front of the radiator)... my stance is that your Air Snake can go to exactly the same spot as the stock intake tubing. If the stock tubing ends at the fender holes then the Air Snake must end there too. Just b/c the stock setup gets you to the fender air doesn't mean you can follow that air up stream to wherever you want within the stock bodywork. All My $0.02.

Christian

[shwah]

My understanding is, air horns, velocity stacks..etc... are allowed if they came as original equipment......

david

I have seen a Volvo running with velocity stack on the throttle body as well. I questioned it, we disagreed on legality. Have not had a 2nd opportunity to race with the car, so have not re-read the rule to clarify my own interpretation.