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Old 07-15-2014, 11:36 PM   #1
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Ram air intake on SVTF

Hi all, I've come to the conclusion that superchargers and turbochargers cost more than I want to spend and are probably more power than I could use as well. So I've begun looking into doing a ram air intake. I've been told that, done correctly, a ram air intake can act almost like its forced induction, since at higher speeds the air is compressed as it enters the piping/tubing. I've only seen one post on the forum related to a ram air system and it was a DIY mod that seemed to work similarly to a cold air intake, but did not compress the air much. Of the few I have seen, all were basically tubing attached to the stock air box to pull the air from the grille. I've considered buying a CF hood and I have seen some with hood scoops, so I am also looking into utilizing a hood scoop to make a ram air intake.

First off, are there any ready made kits out there for svt foci? I'm prepared to make an attempt at fabricating my own, though it would probably go from "fabricating" to "ghetto-rigging" pretty quickly.

Secondly, has anyone done a true ram air system on their svtf? Either with a hood scoop or in the front grille. What sort of power and compression gains could I be looking at, if any? And how would I go about getting a tune for it? I doubt many people have done ram air systems and I'm not sure a dyno tune would work perfectly because air has to forced into it by driving to do what it is supposed to.

Thanks!


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Old 07-15-2014, 11:55 PM   #2
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Kind of an after thought, but I always assumed all CAIs went into the wheel well. Do some go to the front grill? I imagine one that goes to the grill would achieve a similar result if I added plastic/metal to direct the air and force it into the air filter on the CAI.
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Old 07-16-2014, 12:57 AM   #3
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I hate to burst your bubble on this one, but while Ram-Air works in theory, it will have absolutely zero effect on your car's performance. If anything, the added weight will slow you down.

Some rough maths for you:

At 100mph, air is at approx .176psi

At 200mph, air is at approx .7psi


Your car at full throttle will still be in a vacuum. Meaning that even at 200+mph, you will not be experiencing any effective "boost".


Yes, you might see some performance gain, but nothing that could be measured, and it would only occur at a speed where it wouldnt be noticible.


Google a "ScramJet" It uses a very similar theory where a high-speed intake of air's kinetic energy is converted into highly compressed air, which is then combusted.

ScramJets usually wont fire until they reach mach5+



When it comes to making power, there is no cheap or easy solution. Your best bet is a decent drop-in filter, a better cat/exhaust, and tune. Otherwise, the SVT is prettymuch tap-city without going into proper boost.
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Old 07-16-2014, 07:42 AM   #4
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who ever told you that a ram air was like forced induction has been on the crack pipe
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Old 07-16-2014, 07:51 AM   #5
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Quote:
Originally Posted by foreverford View Post
who ever told you that a ram air was like forced induction has been on the crack pipe
Or in marketing for an auto manufacture
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Old 07-16-2014, 11:50 AM   #6
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Quote:
Originally Posted by ViperThreat View Post
Some rough maths for you:

At 100mph, air is at approx .176psi

At 200mph, air is at approx .7psi
What are those measurements based on? Is it the pressure of air being blown into a straight tube that's capped on one end? Cuz if your air scoop is larger than your intake tube, you should get better results.

True, it won't be like forced induction. Yeah, you probably won't see positive air pressure at WOT. But it will reduce pumping losses from the engine trying to "suck" in air. And it will be better than having a cold air intake in the bumper/fender where there is usually low (negative) air pressure.

Make the ram air and do some sort of before and after testing, and tell us what actually happens.
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Old 07-16-2014, 03:53 PM   #7
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Quote:
Originally Posted by Levi05 View Post
What are those measurements based on?
3 years of studying aerospace engineering. (mathematics dawg)


Quote:
Is it the pressure of air being blown into a straight tube that's capped on one end? Cuz if your air scoop is larger than your intake tube, you should get better results.
Air will take the path of least resistance. Even if you had a large funnel opening, the compacted air that is created in that area will force other oncoming air to go around, thus losing the compression effect.

Quote:
True, it won't be like forced induction. Yeah, you probably won't see positive air pressure at WOT. But it will reduce pumping losses from the engine trying to "suck" in air. And it will be better than having a cold air intake in the bumper/fender where there is usually low (negative) air pressure.
The performance increase would be so nominal it wouldn't even register on a dyno. (compared to a comparable CAI)
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Old 07-16-2014, 05:46 PM   #8
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Quote:
Originally Posted by ViperThreat View Post
3 years of studying aerospace engineering. (mathematics dawg)




Air will take the path of least resistance. Even if you had a large funnel opening, the compacted air that is created in that area will force other oncoming air to go around, thus losing the compression effect.



The performance increase would be so nominal it wouldn't even register on a dyno. (compared to a comparable CAI)
Maybe I asked that wrong. How do you measure the air pressure at those speeds? Moving air wouldnt have any pressure unless there is some resistance to that flow.

I agree with the path of least resistance thing. But you still said that there would be pressure in that funnel. it would be a constant pressure too, as long as there is that air "running into it". The front of your car and the base of the windshield are considered high pressure areas. Thats how you get airflow through your radiator and airvents.

...and just being a butthead here, but gains from a ram air intake wont show up on a dyno cuz the car isnt moving...

has anyone actually done any real world testing on ram air intakes? Time to google...
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Old 07-16-2014, 08:33 PM   #9
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Quote:
Originally Posted by Levi05 View Post
Maybe I asked that wrong. How do you measure the air pressure at those speeds?
Save myself the typing : http://www.ehow.com/how_6003776_conv...speed-psi.html


Quote:

...and just being a butthead here, but gains from a ram air intake wont show up on a dyno cuz the car isnt moving...
Windtunnels :-D
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Old 07-17-2014, 01:33 AM   #10
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Pressures are even lower than I realized when broken down to PSI, had to do my own BOTE (back of the envelope) calculations to confirm ViperThreat's numbers without looking anything up. (terminal velocity vs. body weight/surface area)

Significant enough that factory ram air when used on carbureted motorcycles had to include piping the carb vent to the intake area, but that's a very sensitive measure (more delicate than a barometer). Very low gains from that BTW, more for the bling factor.

Cold air ducted from the front (as done on my stock '04 PZEV 2.3) has more effect than any pressure from the ram air.
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