The Ultimate Airbox

[Jack B]

It is almost like the perfect women, the quest for the perfect air box never seems to end. The following applies to both NA and nitrous cars, but, physically won't work on the SC or turbo cars.

If you want to install a clean two stage nitrous system you basically shouldn't use the factory air box. The plumbing and required space is at odds with the stock air box. I settled for the cones and a block off plate, but, after I started logging the IAT, it was obvious there was a drawback.

The perfect airbox should do the following:

1. Seal to the naca duct. The naca duct forces air into the engine all the way to about 100 mph. At higher speeds the efficency starts to fall off. The Gen 2 cars use the naca duct, but, the oem airbox is neither sealed nor direct.

2. Seal to the space in front of the radiator. This is THE high pressure area in the front of the car. This is the area that the Roe under-fascia kit takes advantage of. The Gen 1 cars had this feature, but, the route was not direct and it did not seal.

3. Seal out the high air temp under the hood.

4. Provide a straight direct route into the throttle with minimal turbulence.

5. Provide a radiused/stack into the throttle bodies.

Well here it is, the pictures are below. I won't be able to try it out for about three weeks. It seals both the naca duct and the front high peressure area into the airbox and it is straight into the throttle bodies.

 

[2001 GTS]

Interesting...definately would like to know the results.

How did you seal to the space in front of the radiator to get rid of the high pressure?

-Steve

 

[Chuck 98 RT/10]

I like the tapered funnel leading to the hoses. Where did you get that piece?

 

[Jack B]

Chuck:
A company called Vararam is about ready to release a new airbox for the viper. Their version seals to the naca duct and doesn't pick up the grill air. They have some great claims. They are the product of choice in the vette market. This is the tail-piece to their unit.

2001GTS:
The front merely uses the vipair to direct the air into the air box. If you look at the vipair and the front plate off of a Gen 1, they look identical. This method improves on both by feeding into a sealed box.

 

[Chuck 98 RT/10]

The tapered funnels seem like they would be a big improvement. The carbon fiber box was tapered like that and I remember Dean saying he believed it gave him a couple more mph at high speeds.

 

[V10SpeedLuvr]

That looks awesome. I've always wondered why noone made an airbox directly connected (sealed) to the NACA duct. But, you're a little too late, the "ultimate airbix" is already out! Its called the Vipair

 

[Knight Viper]

Keep us posted. I love the ingenuity of our owners, the desire to squeeze ever drop of performance we can get out of these cars and still look for more. Keep up the good work

 

[ViperRay]

It looks good and makes a lot of sense.
How are you planning to "try it out" Jack? At the dragstrip, comparing it to the stock airbox?

A dyno test would be good if you used fans or forced air somehow into the duct with hood closed that would simulate driving.

 

[jp]

Have any one actually measured the pressure in the NACA duct...?

 

[Paul Hawker]

I experimented on my 96 by taping tell tales on my NACA duct, and was amazed to see that they actually blew "out" during high speed runs.

That area of the hood is a high pressure area, and not well suited to provide any sort of "Ram Air" effect.

Best area for a low pressure intake would be at the windshield cowling. The heater air intake is already located there to enhance airflow at speeds.

Believe the Carbon concept explored this to enhance airflow to the 10
separate induction stacks on the GTSR intake.

 

[Saint_Spinner]

As mentioned, Vararam seems to be the first mod most C5 owners make. alot of corvette customers are very, very satisfied with that company. I can't wait to see what they achieve with this one. Keep us updated.

 

[Jack B]

Paul:

The naca duct pushes in sufficient air up to about 100 mph, at that point it becomes less efficient. That is why I vented the front of the grill up into the box also, everything comes together at the box and is sealed.

When I talked with Vararam they mentioned they had logged manifold pressure on a viper at high speeds and wot. I could be wrong but I thought they said they saw 1.2 to 1.4 atmospheres.

 

[FE 065]

I tried sealing the OEM airbox to the NACA duct, and the car ran out of breath at about 5000rpm. Felt like more torque, but just didn't want to wind as high easily.

Also tried telltale string in NACA duct, and it also blew OUT before 50mph.

While the NACA duct's opening area should be enough on paper, it just isn't.

 

[Jack B]

In addition to the NACA you also have to bring in the high pressure air from front of the radiator. Look at the Gen1, all it uses is the air from the front of the radiator.

 

[SUN RA KAT]

Keep us informed, Jack - I'm very interested in getting one if it works as well as we all hope and the price isn't too obscene.

 

[Chuck 98 RT/10]

Any progress on these?

 

[Jack B]

Chuck/Ken:

It has worked very well, the IAT is always the same as the outside air. Last year it was always substancially higher. This is substanciated by dozens of logs. The car seems to accelerate faster at higher speeds. There is no doubt this set-up makes more hp at speed and always brings in cooler air. For what it is worth I had to add fuel (when compared to last year) across the board to keep the a/f at 12.8 while road testing. The a/f is also more consistent since the IAT is kept in a tighter range, which keeps the PCM from doing its reverse magic.

As far as duplicating the unit that would have to be a winter project. The initial unit was time consuming, however, it should be very repeatable. There are several pieces, but, they all blend together to look very oem.

 

[2001 GTS]

Going in that direction...got a vipair on the way

 

[Chuck 98 RT/10]

I'm not interested in the Vipair part. I want the funnels leading to the hoses.

 

[FE 065]

Option 2, maybe try removing the NACA duct altogether and modify the exit on the Vipair for more flow

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[GTS-R 001]

We have Vipairs that do not have the contour for the Naca, we developed them for people that bought our carbon airboxes for their Gen1's

 

[Jack B]

Chuck:

That is the tail piece from the yet to be released Vararam kit for the viper. You have to call and be lucky enough to catch them, then, be persistent and they will sell you that piece.

You will have to adapt it to the the throttle bodies as is noted in the pictures. That consists of the hose/tube adapters and the 3" smooth tubes which are a a 3"OD X 45 deg exhaust pipe trimmed and chromed. The pipe length will vary by by your design.

You are right, when the smooth tubes make a transition into a flat opening like the oem airbox, turbulence restricts the air flow, the venturi tube transition on the Vararam solves that issue.

 

[FE 065]

Dang, how about a pic from the front of the Vararam piece showing them venturi tubes?

Can you give us a for instance on the price of the Vararam piece you bought ?

Soon to be released? I did a quick forum search and there are posts on the Viper Vararam almost 2 years old. Any word on what's been holding this up for so long

 

[Vic]

Chuck, back when I was making my own air box for my Vette, I used some vacuum cleaner parts, you know, from the big wet/dry shop vacs. There are various attachments that have funnel shapes. It seems laughable, I know, to use vacuum parts, but hey, it was just experiemental stuff, and if I found a design I liked, the prototype could always be copied, laid up in carbon fiber, to look classy. (I gave up on it and bought a Viper!)

 

[BadVenm]

Have any one actually measured the pressure in the NACA duct...?

That would be my question. Someone had once said that the NACA duct actually is in a very poor position for air flow and poor size to feed enough air to the engine if it did bring air in, more there for looks than function.

Is that remotely close to right?

 

[Chuck 98 RT/10]

Have any one actually measured the pressure in the NACA duct...?

That would be my question. Someone had once said that the NACA duct actually is in a very poor position for air flow and poor size to feed enough air to the engine if it did bring air in, more there for looks than function.

Is that remotely close to right?

The goal of the duct is to draw from cooler air outside of the engine bay, not for any ram air effect.

 

[Jack B]

Here is the front side, the vipar is the black material in the front and the cut-out is where the the NACA duct sits with he hood closed. The vararam part wasn't very expensive, under $100. They did me a favor and had no way to price it, so the cost may go up or down the next time one is purchased. What is not shown is the air filter that goes in from of the venturi area.