Cold Air for Paxton S/C
- Thread starter OVERBOOST
- Start date
I just measured the bottom side of my NACA duct and it's 10.5" wide. Which is the real indication of how much space the NACA duct is taking up in the inlet of your airbox when the hood's shut, not just the opening.
The picture of the b&w GTS and of your car shows the new airbox using the same fastener locations over the radiator as OE, and the new airbox inlet isn't even as wide as the distance between the fasteners. The new airbox inlet width is narrower than OE; the OE the airbox inlet is wider than its' front hold down knobs.
I also just measured the distance from the tallest part of the front of the OE airbox (in between the front hold down knobs) to the underside of the hood by laying some Play-doh on the airbox and shutting the hood. It's only 1/2" right at the front. The hood clearance does increase as you move to the rear, but the air's still restricted to pretty much the same height as OE as it goes over the radiator.
As far as I can see, your airbox inlet is no wider than that area I measured the hood clearance at, and at best could only be 1/2" taller.
If there is somehow an actual increase in height, it's small and below the NACA duct. You're not getting much high pressure air under the NACA duct through that narrow slit underneath.
The picture of the b&w GTS and of your car shows the new airbox using the same fastener locations over the radiator as OE, and the new airbox inlet isn't even as wide as the distance between the fasteners. The new airbox inlet width is narrower than OE; the OE the airbox inlet is wider than its' front hold down knobs.
I also just measured the distance from the tallest part of the front of the OE airbox (in between the front hold down knobs) to the underside of the hood by laying some Play-doh on the airbox and shutting the hood. It's only 1/2" right at the front. The hood clearance does increase as you move to the rear, but the air's still restricted to pretty much the same height as OE as it goes over the radiator.
As far as I can see, your airbox inlet is no wider than that area I measured the hood clearance at, and at best could only be 1/2" taller.
If there is somehow an actual increase in height, it's small and below the NACA duct. You're not getting much high pressure air under the NACA duct through that narrow slit underneath.
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The Macedo airbox is much wider than the naca duct. It also measures 3" from the floor to the hood and is sealed to the hood. The airbox is much wider than the duct. Although the stock airbox inlet is wider (I sold mine) than the Macedo airbox, it also sits above the rad while the Macedo box is flush. The opening is more than the 30sq. in. required by Direct Connection research as adequate to be classed as ramair and benefit from extra hp.
I also installed the Roe Racing front facia scoop to increase the postive pressure in front of the radiator, where much of the intake air comes from. The Roe facia scoop also comes with a sheet metal plate that blocks the rear of the nose to the middle of the engine so that any undercar air goes past the air space behnd the radiator creating less positive pressure behind the radiator. This creates a much lower pressure area behind the radiator thereby increasing the airflow from inside the nose through the radiator (and into the airbox).
The increase in air pressure probably creates the greater amount of airflow over stock, not the opening size. That's where the Vipair also gets it's extra power.
This is the smilified version as there is more benfits from the size of the opening changing to the larger volume behind the opening, but that's too complicated for me to explain.
Ted
I also installed the Roe Racing front facia scoop to increase the postive pressure in front of the radiator, where much of the intake air comes from. The Roe facia scoop also comes with a sheet metal plate that blocks the rear of the nose to the middle of the engine so that any undercar air goes past the air space behnd the radiator creating less positive pressure behind the radiator. This creates a much lower pressure area behind the radiator thereby increasing the airflow from inside the nose through the radiator (and into the airbox).
The increase in air pressure probably creates the greater amount of airflow over stock, not the opening size. That's where the Vipair also gets it's extra power.
This is the smilified version as there is more benfits from the size of the opening changing to the larger volume behind the opening, but that's too complicated for me to explain.
Ted
Simms
Enthusiast
Ted, that car has always been a strong car. Back when Tony owned it and Dave afterwords, it was always a good runner and driven HARD! I see you are enjoying it and putting the miles on as well. Good for you.
Larry did an awesome job for me as well. It's been over 3 years since he built my engine, and I have enjoyed drags, track days, and hard street miles.
Enjoy it, and be safe.
Joseph Dell
Enthusiast
The box looks great! Here's an idea to try: While the air filter isn't _that_ restrictive, it does pose a restriction. And that elbow on the paxton kit... that's a killer. If you remove that and run what was a 7psi kit, i wouldn't be surprised if you hit 10 or 11psi! So try this (if you have the time and/or patients):
- Buld another airbox, but make it fully rectangular.
- Remove the current paxton elbow and air-filter. replace with a rectangle K&N filter (bigger, more surface area) and put it over the opening of your new box. You will see huge power increases with this.
On my when-it-was-stock-except-for-a-paxton set-up, i picked up over 50rwhp just by pulling the filter b/c the elbow was so darn restrictive.
Good luck and great work!
- Buld another airbox, but make it fully rectangular.
- Remove the current paxton elbow and air-filter. replace with a rectangle K&N filter (bigger, more surface area) and put it over the opening of your new box. You will see huge power increases with this.
On my when-it-was-stock-except-for-a-paxton set-up, i picked up over 50rwhp just by pulling the filter b/c the elbow was so darn restrictive.
Good luck and great work!
Ted, that car has always been a strong car. Back when Tony owned it and Dave afterwords, it was always a good runner and driven HARD! I see you are enjoying it and putting the miles on as well. Good for you.
Larry did an awesome job for me as well. It's been over 3 years since he built my engine, and I have enjoyed drags, track days, and hard street miles.
Enjoy it, and be safe.
Thanks Simms, I wish for you to be safe also. I'm lovin' the hell out of my car.
Ted
MacManInfi
Enthusiast
Certainly not the first time I've heard that the filter/elbow is restrictive. It's a good suggestion. The elbow in particular seems weird because it tapers down so small to tuck into the air filter. Starts as a pretty decent diameter, and tapers down. I've wondered if I got an elbow that didn't taper down, and another air filter to fit the larger pipe if that would be better as well. Certainly on my Cobra Mustang, when I swapped the Vortech inlet pipe and filter with an Anderson power pipe (larger diameter), I saw a big jump in power on the dyno. Did cause my car to lean out though, and had to re-tune.
Anyhow, thanks for the tip. Gives me some motivation to keep working towards a better solution.
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