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basslover911 06-11-2009 11:39 PM

WAI vs Ram Air Intake --- at speed...
I think that a Ram air intake would be BETTER (even though obviously at outside air temps) than a WAI at speed.

Why? Because the extra pressure would decrease losses in the intake manifold.

Kind of like this,
and pointing STRAIGHT into the air intake through one of these air filters <-pretend its an air filter I couldnt find pictures of closed inline air filters

and STRAIGHT into the throttle valve...

I know, very theoretical to have everything STRAIGHT... but such is the case in my 350z...


Frank Lee 06-11-2009 11:52 PM

There are formulas online for figuring the efficacy of ram air.

And this:

And google "autospeed ram air" cuz they've done lots of piddling around with it.

basjoos 06-12-2009 08:24 AM

In general, anything that increases the amount of oxygen going through the engine also increases the amount of gas burned since the engine controller adds gas in proportion to the amount of oxygen it detects in the system. WAI reduces the amount of fuel burn by reducing the density of the air entering the engine and reduced air density contains a reduced amount of oxygen in it, producing a FE improving effect identical to that of driving at an higher altitude. A ram air intake increases the air pressure and density of the intake air, acting as a sort of mild super/turbocharger (without the engine load of the latter), and so would increase the fuel burn.

When hypermiling you spend most of your time at low throttle settings where the throttle plate is mostly closed and is by far the biggest intake restriction.
Compared to the throttle plate, other parts of the intake air path contribute little to the intake manifold losses when running at low throttle settings.

tjts1 06-12-2009 12:32 PM

Ram air is definitely the way to go for FE. The more air you can stuff into the intake without consuming extra energy, the less work your engine will have to do breath in. Its pretty simple. Also the colder the air the better. Check out all the autospeed articles on the subject. This has been proven over and over again.

I'll cut and paste the articles here from the dead thread for easy access.

Eliminating Negative Boost - Part 1
Eliminating Negative Boost - Part 2
Eliminating Negative Boost - Part 3
Eliminating Negative Boost - Part 4
Eliminating Negative Boost - Part 5

Negative Boost Revisited, Part 1
Negative Boost Revisited, Part 2
Negative Boost Revisited, Part 3
Negative Boost Revisited, Part 4
Negative Boost Revisited, Part 5

Doing the Impossible

Modifying the VL Turbo Intake

Into the Intake - Part 1

We Have a Record![/QUOTE]

Ram Air Project

doviatt 06-12-2009 12:35 PM

I sense a contradiction. ???
FE not power.

basslover911 06-12-2009 12:42 PM

^I know, because the air is less warm it would be lower FE.

BUT because it lowers the pumping losses it would raise FE (and more than the cold air takes away) yielding a net increase in FE.


i_am_socket 06-12-2009 12:46 PM

Now, here's a question:

What if you warmed up a ram air intake? Could you warm up a ram air intake? You get warm dense air with more pressure?

Or is it simpler to just modify the throttle plate?

doviatt 06-12-2009 12:47 PM

There are some good points here. I've got some reading to do on autospeed.

basslover911 06-12-2009 12:53 PM


Originally Posted by i_am_socket (Post 109499)
Now, here's a question:

What if you warmed up a ram air intake? Could you warm up a ram air intake? You get warm dense air with more pressure?

Or is it simpler to just modify the throttle plate?

That is where I was going with this. IF ram air helps, and WAI helps, then why not both?

Maybe construct a ram air of metal pipe and run the coolant hoses around it to heat it.

Now my question is, how much positive PSI acts on a car's front bumper at 60-65mph? Anybody know?

tjts1 06-12-2009 01:01 PM

Ram air is not matter of PSI. The goal is to reduce the pressure loss that happens inside in the intake ahead of the throttle plate due to its geometry to zero. If you wanted warm RAM air you can just setup a very large intake behind the radiator. But you would be wasting your time.

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