Suggestions for a cold air intake

After my recent cabin heat problem, I've been doubting my plans to have a cold air intake taking air from the cowl area.

As some of you know, I run stacks (crossram, with the stacks right above the valve cover. I intend on making an airbox that has an intake pointing to the front. What are possibilities in getting a filter and pipe somewhere that both banks can get cold air and enough filter in there ? I've been breaking my head over this ever since this popped up.

PS : I also run a Canton accusump that sits right between the headlights under the frame extension horns. So this place is out of the question (if I ever could get a hose of suitable size over there.

Fancy a new hood?



Not a great picture - but you could use a higher (taller) hood with that airbox. Most of the "requirement" for tall cowl induction hoods is at lower speeds. There is a guy on eBay that sells just the cowl section. I ordered one - good quality product. Don't know what shipping would do to costs though.
Gets you past the stuff up front.
Link FWIW: https://www.up22.com/scoopw1.htm


Cheers - Jim

Some years ago, one of my lamented projects involved up/over air intake for the basic TPI induction, split out to two massive air cleaners in front of the a/c condenser.....but having been caught in a couple of FLORIDA rain storms, the car started to run ragged.....next day it was fine, pulled the accordian rubber off the induction and found it had WATER in it....and dripping down the aluminum induction tubes too, did not notice anything the other day in a rainstorm.....but did not pull it down to look either.....

one of my projects is to give up on that and put the old K&N oval filter on front of the engine TB again, blocking off the cold air, BUT I would have to do some welding to the radiator support, so I set here in a quandary.....:surrender:

1% increase in HP for every 11degree F drop in inlet air temp (approx)

over about 35 mph a area of slightly higher high pressure will begin to form at the base of the windshield...

alternatively you could use NACA ducts facing forward on the hood

to separate the rain a plenum is useful and the air filtration mounted inside with baffles and drain holes that are not dominant terms in the airflow

Yes, the rain...have to keep an eye on it.

Is it even possible that water would enter via de cai of an L88 hood ?

Air Box Tribute

For your consideration. My Rochester EFI project couldn't use the standard fuelie air cleaner assy because of other mods. My solution is sort of a tribute to the '57 airbox cars. The difference is I built my airbox inside the wheel well using the body as the upper part of the air tube. With my set-up there is enought room above the front tire at full travel to build a second inner fender. The cross-sectinal area of the space between the outer body and new inner fender is at least twice the area if my throttle body. I cut a hole in the front of the factory inner fendor behind the grill opening for a bell mouth and a second hole on the back of the factory inner fendor to match a modified Hemi Challenger air cleaner assembly. A short 4.5 inch diameter aluminum tube runs from the air cleaner to the Rochester's throttle body. For your cross ram you would probably want to have two air boxes one in each fender. It only takes up the space to run the internal tubes to the IR plenums. The IR plenums might need to have the inlet point to the side. Works in my C2. I don't have a picture of the assembly but you can see the opening of the air cleaner on the rear fender just behind the remote power steering reservoir. Other pics are air cleaner mod.

Grampy, your work is on a whole different level. :thumbs:

Grampy said:

For your consideration. My Rochester EFI project couldn't use the standard fuelie air cleaner assy because of other mods. My solution is sort of a tribute to the '57 airbox cars. The difference is I built my airbox inside the wheel well using the body as the upper part of the air tube. With my set-up there is enought room above the front tire at full travel to build a second inner fender. The cross-sectinal area of the space between the outer body and new inner fender is at least twice the area if my throttle body. I cut a hole in the front of the factory inner fendor behind the grill opening for a bell mouth and a second hole on the back of the factory inner fendor to match a modified Hemi Challenger air cleaner assembly. A short 4.5 inch diameter aluminum tube runs from the air cleaner to the Rochester's throttle body. For your cross ram you would probably want to have two air boxes one in each fender. It only takes up the space to run the internal tubes to the IR plenums. The IR plenums might need to have the inlet point to the side. Works in my C2. I don't have a picture of the assembly but you can see the opening of the air cleaner on the rear fender just behind the remote power steering reservoir. Other pics are air cleaner mod.

Click to expand...

Sounds like a neat solution and very interesting. I have been checking out the old Rochester FI setup of the C1/C2 era as well, but I couldn't find enough pictures to get a good look at it.

However, I assume this is a C1 or C2. Those have a lot more room in the inner finder. The C3 doesn't have enough room above the tire to even fit a cone filter. Only possibility would be in front of the tire, but even that space is not big. (How big is that box btw/of which car is that filter box). Even then, the space behind the rear tires/behind the inner fender well, which is probably the only underhood space left; on the left is taken by a vacuum reservoir and vacuum pump, on the right it's occupied by the FI fuel surge tank and low pressure pump (even then I do not have AC, so I have more space than other cars). Placing a hole in the inner fender of a C3 is problematic as well. The left had the brake booster and main cyl sitting in the way, between that and the alternator I managed to squeeze in the air/oil seperator for the PCV. On the right the coolant reservoir sits in the way and more to the front you have the suspension and then the space is too small to even get a 3.5-4" tube through the fender...

I have been thinking something like this :


Where the airbox would sit on top of the engine in the higher bulge of the L88 hood and draw it's cool air from the cowl. However that last one, seemed not to work after I was getting in hot air from the hood.

I would appreciate some more pictures of your setup grampy, there could be details i'm overlooking here. Congrats on that splendid job btw.

Couple of photo's to give you an idea :




Never mind the alu foiling on the right. I found out that my surge tank was heating up quite a bit because of the headers, so this was a test to see if shielding would help. I have some plyable heat shielding coming in, that will replace it.

BTW : I hate those mesh filters, but it's the only thing close to a filter I could find after the foam socks almost caught on fire due to a backfire in the intake (which still happens enough during tuning). I don't trust their filtering ability so I'm not getting enough time to tune it correctly. Well, the season's almost over and I have only driven about 200 kms during and in between the work on the car. At least I have it running somewhat. oh well...

Would a hood like DeeVee8's avatar work?

Looks more like a heat extractor hood than a cold air hood to me. Besides I don't like that style too much (no offense DeeVee8)

I know the problems. For as big as these cars are for a 2 seater you'd think you could put anything you want into them; but you can't.

Yves, I think you would be supprised at the cross sectional area available above the tire. A 4 inch diameter tube has a cross sectional area of about 12.5 sq. in. Your tire will be about 10 inches wide so even a 4 cm clearance above the tire would net about 15 sq. in. I have no problem getting a 25 sq.in cross section and the car is lowered so I only have about 9cm of ground clearance. Getting the air flow thru fender well back to the stacks should not be a problem.

The air filter could be the biggest packaging issue. A flat panel filter can be mounted where the air goes into or as in my case where it comes out of the fender tube. I'm more familiar with the C2 but I would think the a flat panel filter would fit in front of the inner fender inside the grill opening - I'll admit that some of my solutions are not always maintenance friendly. Is there filter that fits on the stacks that you could wrap and airbox around?

As usual I'm on the road so I can't measure anything. The air filter panel I used is about 30cm X 20cm X 3cm. Suggested air filter area in sq. in. can be can be calculated using the dispacement in cu. in. X max RPM / 25500. In your case with two air tracks you would divide the result by 2. My air filer assembly is from a 2009 Hemi Challenger via ebay.

Grampy

Grampy I'm not seeing the relationship between free space above the tire and cross sectional area of the tire or the pipe. A 4" pipe is 4" high so I would think you loose 4" in clearance when the tire or A-arm moves up...I think, the only way to put a tube in there would be very close to the inner wall of the inner fender and in the corner it makes with the surround. The inner fender on the C3 has a cutout where the A-arm sits. I'm not with the car at the moment, but that area is very small and I think you need the clearance for the movement of the A-arm.

The only place to put some sort of airbox would be in the fender well right in front of the tire, within the fenderlip.

Isn't prone to sucking water when you drive through rain ?

Hi,

Let me try again. This solution might be something you could use.

I did not use a round tube in the wheel well. I formed a continuous fiberglass L shaped ledge along the inside of the wheel well from front to back that arches over the max travel of the front wheel. The ledge extends all around the inside of the wheel well - front, inner fender, back, outer fender . I then used flat sheet alumuinum that arches over the tire and is sealed to the ledge all around to form a cavity above the tire from the front of the wheel well to the back. The ledge is roughly 5cm or more back from the fender lip. The aluminum plate is shaped to fit but is about 30cm wide. The body shell and inner fender is the upper part of the cavity which is odd shaped in cross section. The cross sectional area of this cavity is much bigger than the area of a 4 inch circle everywhere along it's length, it just not circular in form. For an inlet, I cut a 5 inch hole behind the grill that connects into the formed cavity. At the back of the inner fender where the windshield wiper washer reservoir was mounted I cut the outlet hole in the same size and shape as the air cleaner base (see earlier picture). This gives me a large area funny shaped tube with air pick up in a high pressure, low temperature area next to the radiator support and outlet near the the Rochester inlet. From air cleaner to FI unit I used 4.5 inch round aluminum tube.

While this solution might not package well for you it would solve your problems of finding cold high pressure air source and channneling that air to a place close to where you need the air without intruding into the engine compartment.

It's worth having a look at the space available and let your imagination do the rest. Since you are feeding about 3 liters per bank you should be able to use tubing smaller than 4 inch in the engine compartment and still maintain very reasonable air flow velocities if that would help.

Just thinking outloud. From the pictures it looks like the C3 wheel well might be like the C2 where there is a lot of space behind and above the wheel because the inner fender is kind of cubic. Would a conical air filter fit sideways above and behind the front wheel so the outlet was facing your stacks? Pipe the air thru a 4in hole in the inner fender straight to the stacks. Put the filter in a cavity.

For the rain I have two solutions. The best one is I live in Southern California so I don't see much of the stuff. The other is a drain on the back side of the wheelwell before the air filter. The big benefit of this project is the cool air not a few mm Hg of dynamic pressure so put in a good drain. If you want the dymanic pressure plug the drain.

Grampy

I think (kinda) what you have there, but it might be better if you could take a picture of what you did.

In the rear of the fender well there is no room. The tire (255/60) already scrubs the fender well in that area. Maybe above the zone of the tire, but I would need to check.

Anyway this is not a bad idea, so I'm going to take off the tire today or tomorrow when I can. I'll post it here. (if I do not get that pesky starter problem again)

Grampy, do you have info on how big a tube is necessary to feed a 5.7 liter at a maximum of 7800 rpm ? Best I could come up with was a minimum of 90 mm or 3.5". I was counting on giving each bank a 3.5" tube, but tubing parts are not readily available in alu here. Mostly 76 mm (or 3")

if you have an L88 hood...I liked the way this was done.

http://www.corvetteonline.com/news/unique-modern-l88-corvette-has-shining-moment-at-russo-steele/

Interesting, but I doubt the filter is big enough to feed the engine. I bet he is seeing a pressure drop across the filter at some point. recommendations for my filter setup from K&N was a minimum of 133 sq. in for a SBC. They advise to go 50% over the minimum to be sure.

An C4 ZR1 used a 188 sq. in filter for a 400 something hp. Go figure.

I went to take a good look at the available space in the wheel well. With the tire pointing straight ahead, about 15 cm in front of the tire, maybe 10 cm above it and less in the rear. That is not taking into account that the edge of the tire goes closer to the fender lip when turning in.

I found a few pictures taken during the layout stage for you to look at. To see if what I had in mind would package I chalked some lines that clear the tire at max deflection in the inner wheelwell. The chalk lines also pick up existing feature lines in the fiberglass so i could more easily locate a mounting flange. I then taped 5cm wide strips of posterboard across the space. That made a more 3 dimensional picture and let me make some rough measurements to calc a flow area. I placed the posterboard about every 15cm along the length. I was trying to stay above 25 sq in flow area. Maybe I have a lot more space to work with in the C2. You'll note the 12 scale in one picture. The wheelwell is about 15 inches wide so even a 1 inch deep cavity will have more flow area than a 4 inch tube.

By the looks of it, the C2 has a lot more space in those areas, neat idea nonetheless. Thanks for sharing them.

this may not be fancy enough but why not use the front part of the 79+ dual air tubing that goes over the radiator and by the front pass side of the car......this will give you the 2 factory engineered feed points and route them into a custom made box around the stacks.

it made my car run tremendously better.