Nadrealista

Also need to replace air filter, should I stay with stock filter element or is there something to be gained by going with K&N filter instead. Or do you only gain more sand/dirt in you engine with K&N?

wannawankel

Paper filter replaced on an acceptable interval, is superior. The air pump (engine) can only handle so much air at atmospheric conditions (that changes when you turbo something).

My opinion based upon the cleanliness of the post-filter air intake tube is that the K&N lets too much environmental debris/dirt/dust/salt vs a paper filter. I've seen this on my motorcycles (I've converted POS previous owners changes back to OEM paper filters) and on one car (my old Integra that I did the K&N conversion myself). The K&N is also tricky in oil loading - a few times I had oil wicking into the post filter air inlet.

Nadrealista

that is kind of what I was worried about. yes you do get more air/power though K&N but at the cost of also letting more dirt in which is abrasive and causes engine wear..so no free lunch :-(

wannawankel

I don't believe that any atmospherically operating engine will get more power by the filter choice (or no filter installed) - the volume of air entering the engine at standard temperature and pressure (STP) is the same and is based upon the rotational volume or (for dem pistons) stroke volume. All things change when you change temperature (cold air is more dense per the same volume hence more air) or you increase pressure with one of those fancy Turboz.

You'd probably better spend you $$$ getting more cold air in with a cold air duct (or for fun create a ice chest heat exchanger that sits on top of your hood) to deliver colder air.

UnknownJinX

Wasn't the power gain pretty minimal with the K&N anyway? And yeah you have to worry about oiling and filtering capabilities.

The stock intake is pretty good and I suppose that ram air could help with decreasing the intake air temperature. I recall someone doing an experiment with that and mentioned that the car maintained power better at higher temperature, which is what you see at a track, so it is useful. But yeah, it's more for maintaining the power than for making extra power.

Nadrealista

I was looking at my air filter, this is what it looks like after 10,000 miles of mainly driving to from and on the track. Can you notice the circular shape where the dirt is mostly caught. That corresponds nicely to where that intake tube is in the airbox.

This shows that most air really goes through the center of the filter and not much goes through the corners or sides.




You can also see that there is a some misalignment between the where the air comes into the airbox and where the intake scoop is.

Nadrealista

I would agree this is true at part throttle operation where you have engine created vaccum pulling air through the filter into airbox/intake/engine, however once you go wide open throttle I would expect to see some benefit from cold air ram intake set up forcing increased amount of air into engine especially at higher speeds. For example my average lap speed @ summit point main track is over 80 mph so I would expect to see more g/s @ MAF for a given engine/car speed over stock set up?

Also I curious how reliable MAF g/s is with respect to HP produced by renesis engine with given AFR. Lets say healthy engine with stock airbox/filter will pull max of 220 g/s @ 9000 rpm makes 180WHP. Will 242 g/s produce 198HP - 10% more power all other things being equal? Can we translate that easily in HP produced @ given temperature, humidity and AFR?

Loki

iTrader: (1)

Yes, but perhaps not in the way you're suggesting. Most of the air goes through the center over time because most of the time you're not at wide open throttle. By itself this isn't descriptive of the flow at wide open throttle where it matters.

Nadrealista

Decided that I wanted to scoop more cold air so I went to racing depot again and got this fancy air scoop :-)

Loki

iTrader: (1)

There's a bit more to it. Air is tricky, if your ducting is not optimized for ram effects, you could easily find that its converts air pressure at the front into heat in the middle and no substantial gain at the end. Air loves to compress and heat up, instead of flowing how you want it to. Ideally your ram duct needs to be straight, so the 2 90 degree turns in corrugated dryer hose may not be ideal.

I would set up a test bench with a leafblower and some pressure or flow meters and experiment with the duct shape out of the car before you try to fit it into the available space.

Nadrealista

given the low cost and simplicity of this mod I think I'll just test it on the car and run some MAF logs just to see how it flows on the street and on the track (in couple weeks). I can also compare my lap times and speeds at certain points of the track to see what is delta with HD CAI :-) vs stock intake.

I am essentially replicating RB ram air duct just using hardware from home depot.

RB ram scoop also has 2 90 turns

Nadrealista

Racing depot cold air intake project finished. I think it turned out pretty good. We’ll see what the data shows on the track.

kevink0000

You run without the front license plate at the track, right?

Nadrealista

Take a look at my avatar

UnknownJinX

The thing is that, even if the ram effect works, it doesn't really do that much in terms of increasing pressure. You can actually calculate it with the venturi effect equation.

I would focus on intake air temp over intake air pressure. That's probably where most of the "gains" (more like better-maintained power) comes from.

TeamRX8

iTrader: (25)

it’s pretty obvious that the person who built that neither has natural nor trained engineering skills

Nadrealista

These guys say otherwise, but then again they sell ram air intakes for living. They did do extensive testing and have data so who knows. It is a long read but based on what they saw NA engines operate under atmospheric pressure (measured in intake manifold I think) in the higher rpm ranges and ram air intake helps keep them operating at atmospheric pressures throughout the entire rev range and if designed properly they can get you a bit above atmospheric pressure at higher speeds.

I have track day in 2 weeks so we will see what the data from lap times shows and if my home depot ram intake makes a difference :-) with respect to intake temps and MAF g/s.

Vararam Industries - About

The reality of ram air is that it does work, and is an effective tool for any engine builder or tuner to use to achieve their performance goals. We will cover many areas of ram air system design and function in this discussion but first let's hear what Harold Battes, President of SuperFlow Corporation (this is the company that makes flow benches and dynamometers) and one of the foremost fluid dynamics engineers in the US has to say about it.


Ram air is an attempt to put the induction losses back into the manifold during the cylinder firing process by pre-packing the manifold with air. This will lead to much higher air flow rates in your cylinder heads at lower lift values and will maintain proper manifold pressures and port velocities at higher Rpm during WOT operation under actual road loads above 50 Mph. This allows you 100%, or in the case of the VR-1B, over 100% intake efficiency at only 70-75 Mph depending on the car in question. The VR unit will build and maintain 100% efficiency at only 50-55 Mph. This makes for a much quicker, faster car at speeds that are more usable. Other intakes are struggling to make pressure at this level and require much greater road speed to build pressure if at all.

A properly designed ram air system will increase an intake's CFM, make pressure or even create positive boost. That is boost above 1 atmosphere or 14.696 PSI (this is considered the maximum pressure that most factory atmospheric engines can generate in the manifold without some form of forced induction or unless the motor has been modified; head work, performance cam etc. But as you will find rarely does any motor do this under actual road or track loads. That is a dyno vs. the actual road itself. Most factory intakes are about 80-85% efficient on average. Some, such as the LS1, are closer to 93-95% (depending on the cars year model) from the factory.

Here is where the problem lies. Most people at this point, in order to try and test a system themselves, will simply hook up a boost gauge, drive down the road at WOT and watch as the gauge moves from a negative Psi (usually -14.50) to 0. Then they say that it doesn't work, not taking into account any increases in CFM of the intake system. Let's say they do measure it properly and measure an increase in manifold pressure or boost over stock or even achieve "positive boost" at which point they may see (using the example from Harold Battes) +.176 Psi and say, oh well that's only worth a small amount of Hp, nothing could be further from the truth.

All motors under actual road or track loads will lose pressure in their manifold. This can be anywhere from -.001 Psi to the most that we have seen, -2.0 PSI on a 427 that made over 2 Hp per cubic inch. No matter what type of motor or who built it this will occur. We will expand on this later.

When this occurs, there is a loss of Psi and Cfm as the two are related in that depending on the intake manifold design and the firing of the motor itself you cannot have a Psi increase without a flow or density increase unless you decrease the plenum volume in the intake manifold itself or alter the firing condition of the motor. Some motors fire two cylinders at once, therefore two cylinders must receive a given volume of air at the same time. This makes it harder to make manifold pressure because most manufacturers or engine builders will increase the volume in the manifold or alter the camshaft accordingly to bring in more air but we won't get into that in this discussion.


Psi, Air Density, Flow Rate and Horsepower
All of these effect one another, however, all do not have to be present to make Hp (Psi is not required). First, let's go over what you will need to use to measure manifold pressure. You will need a boost gauge that reads below 1 Psi. Some use a millibar gauge. Others use a laboratory grade electronic manometer that reads as low as .001 Psi. Some of these devices can be configured to read in both values. The reason is simple. You need to be able to measure as low as .001 Psi accurately because you are looking for .10+ changes in manifold pressure and a typical boost gauge will not indicate this for you. A typical boost gauge won't even move unless there are changes of up to 1 Psi, positive or negative.

In any engine as you go to wide open throttle (WOT) pressure is created in your intake manifold. The general assumption is that the motor is breathing or developing 1 atmosphere or 14.696 Psi. The motor, if efficient, will build to 1 atmosphere however this rarely occurs in any motor. What normally occurs is that the motor builds to a given pressure, somewhere below or equal to 1 atmosphere, and then begins to loose pressure under increased load. This loss of pressure is somewhere below 14.696 Psi. These losses of intake PSI are dependent on intake manifold design, camshaft profile, cylinder head design, compression ratio, the Rpm you are turning and the overall heat and frictional losses that occur. Usually on a stock motored 2001 LS1 the pressure loss is about -.75 Psi and it's costing you Hp. A totally stock C5 can be below 1.1 Psi at WOT depending on the year. A Ram Air system is designed to draw or pack that pressure back in to the manifold. Well you say, what's -.75-1.10 Psi really worth? In order to give you this explanation, we will keep it simple but we will have to set up some control parameters. This is for Psi only; we will cover CFM and Air density later.

To factor your gain if using a ram air system, test your car with whatever intake system; stock or modified. Monitor the intake pressure on the dyno to give you your Hp/Psi formula. You may then proceed to road test monitoring the pressure increases if any to determine the true power and overall efficiency of your system.

The day: a textbook 14.696 Psi or 1 atmosphere.
The car: a showroom stock car, no modifications at all.

I will give you an example: a totally stock 2001 6-speed Corvette and a textbook 14.696 PSI day. These are rare but will suffice for this explanation. There will also be some variation from car to car as there are casting irregularities, deviation in cam lobes and overall build differences. This is why some guys get the ringer car and others well...fall a little short. This deviation will show up in the manifold pressures at WOT. So basically use this as a reference. The best way to see how well your intake system works is to dyno your own car whether stock or modified and measure the manifold pressure at peak and then the drop at higher Rpm. This will give you a good base to use these formulas. You must remember that the on-road losses will be greater than the losses on the dyno. Automatic cars will lose more than 6-speed cars due to increased loading in each gear.

WOT=13.946 Psi, that's -.75 Psi, car dynos at 310 Hp at the rear wheels. In other words, your car is losing this pressure under load and it will lose more under actual road and track loads. (For our explanation this will suffice)

The equation is simple. 310 Hp divided by 13.946 = 22.23 Hp/Psi. Remember that the car is -.75 Psi at WOT. So the equation is: 22.23 Hp x .75 = +16.67 Hp increase. Now at this point you are not into positive boost yet. You are only at 1 atmosphere (14.696 Psi). If you have an aftermarket intake system you would simply add the gains that you saw on the dyno to this figure for your total power at that speed and Rpm.

Now let's try a 99 6-speed C5 with its more restrictive factory intake system using the same control for the test.
WOT=13.45 Psi, that is -1.25 Psi, car dynos at 301 rear wheel Hp.
301 Hp divided by 13.45 Psi equals 22.38 Hp/Psi.
22.38 Hp x 1.25 Psi equals 27.98 Hp increase at 1 atmosphere.

A VR achieves this at 50-55 Mph. (Rarely will "any" car lose intake pressure in 1st gear or 0-45 Mph. If so it has very poor intake efficiency.

In both of these tests the cars ram air intake systems returned the motor to 1 atmosphere only, NO positive boost. Positive boost would be any figure above 1 atmosphere or +.176 Psi. This would be 14.696 Psi +.176 Psi = 14.872 Psi (absolute pressure or total pressure). To figure this you can simply use the same Hp/Psi formula:

99 6-speed C5: 22.89 Hp x 1.426 Psi = 32.503 Hp increase @ 14.872 Psi.
At a 12% correction factor from rear wheel Hp to flywheel Hp that would be a 36.403 Hp increase. Cars will vary some what from year to year and weather will affect barometric pressures as well.

The best factory stock manifold reading that we have ever seen on a C5 was on a 02 Z-06 which was -.50psi at WOT in 3rd gear. 4th gear it fell even further. This is why we test on the road only for pressures as it will very from a dyno. The Dyno showed a .50 loss of manifold pressure. This same car pulled 359.7 rear wheel Hp at .50psi below 1 atmosphere. On the road in the same 4th gear as the dyno pull this car's intake pressure fell to 14.01 Psi at WOT. That's .686 Psi below 1 atmosphere with the factory intake system.

An off-the-shelf VR equipped with an Hp filter installed on these cars is worth about 12-14 rear wheel Hp static. This same car pulled 372.1 at the same -.50 Psi static. This gives a Hp/Psi of 26.26.

1st gear = 1 atmosphere (the car will do this stock)
2nd gear = .04 above 1 atmosphere (stock car drops .25psi here) = + 7.62 Hp
3rd gear = .12 above 1 atmosphere (stock car drops .50 psi here) = + 13.13 Hp
4th gear = .10 above 1 atmosphere (stock car drops .69 psi here) = + 18.12 Hp

Now add your dyno improvement of +12-14 Hp to any of these figures for your total power gain at speed. Multiply by a 12% correction factor for flywheel Hp which equates to a best of 34.18 Hp gain on this run. VR-1Bs make torque gains that are equal or greater than their power gains. VRs develop tremendous power under the curve as well. Check out Ram Air and the dyno in this discussion for more information.

This is the car that everyone looks at because it is the fastest factory stock Corvette. But it also gains the least of any of the C5s from this system. Yet all of our customers who have tested the systems on these cars are getting 3.5-4 tenths and 3.5-4.0 Mph through a ¼ mile. Now you see why.

These are the same formulas used for turbocharger design and application under road loads. A turbocharger is rated by its CFM at a given boost level. In our case we need to determine the Hp per Psi ourselves as there is no way to accurately flow an internal combustion engine during actual operation other than one of two ways.

1. Dyno and monitor Hp/Psi levels at each Rpm under load.
2. Dyno and monitor Rpm levels vs. CFM/Hp under load.

The most accurate is #1 and is most widely used in the racing industry. You see CFM must first overcome these same losses to make 1 atmosphere then move on to +1psi. In other words a turbo, when making +1 Psi, is really making +2 or more depending on a certain motor's losses that had to be overcome. This is part of turbo lag. Basically, your engine becomes the turbo or air pump delivering CFM at each given pound per square inch or Psi. CFM increases as does Hp. If the CFM is increased in the intake system it can be caused by an air density change, a flow rate change or both acting together. The second here is usually the case in most systems. A cooler denser air charge will mean that each molecule of air is packed that much tighter allowing for more air in a given area or volume. This air density change will affect flow rate. However, you can also increase the flow rate by the design of the air box itself or by forcing air into it. We will expand on this later.

Now at what type of speeds do you need to be traveling to start to achieve this ram effect or boost back to 1 atmosphere and above? For this you have to look at each given ram air system and intake or vehicle package as a whole. Here is some of what you must consider in any such system.

Scoop Style: A forward facing, NACA, deflecting and cowl.

Forward Facing Location: This is regarded as the most efficient and allows for maximum pressurization with minimal head loss.

Deflection: This would be a scoop located behind a given area that is fed by a deflecting object or winglet. These are very inefficient due to the loss of energy from the deflecting process and the air turbulence that is generated.

NACA: An efficient design but placement is critical. If placed incorrectly, no pressurization will occur. This is why Katech moved the C5-R's inlet to the front screens in the fog light area.

Cowl: These are useless for ram air unless fed by some form of deflecting object. However, they are very good for cold air boxes if designed correctly.

Aerodynamics Leading to the Scoop: A direct shot is best becasue if the air is curved or deflected in any way it will destroy the dynamic pressure that you will need to achieve any boost at all. Head losses in the scoop area or the velocity lost due to scoop design placement or friction, etc.

The System's Overall Design Package: Is it a proper air box? Does it feature properly sized divergents or venturis for the speed and application you have intended it for?

Manifolding: Is the system large enough to support your car static?

Filtration: How much pressure drop is there across the filter? Air must pass through the filter at speed. When this occurs there is a loss of pressure (most cotton-based filters lose from -.75-1.25 Psi). If multipliers are not used leading to the filter; EX: ram tubes, decreasing radius scoops; then all that you will have is a filter hanging in the wind. This may yield some increases in CFM but to build manifold pressure will require a substantial amount of road speed. This is more important than the overall flow rate of the filter being used. What style of filter is it? A panel, a cone or a round filter.
Aerodynamics leading to the filter are very important here, in general you never want to use a cone type of filter in a ram air system (the air must turn into the filter then return back to the intake, this is because of the cotton construction it will simply not flow air at angles). This is why race cars, where possible, use a panel or flat filter. This gives a direct shot with minimal losses to changes in direction, something that air does not like to do. IF a cone must be used a competition foam filter is recommended (you will not find these at the local speed shop but from specialty manufacturers only) as foam can flow air in all directions. Round is good if sealed in a round air box. Example: a carbureted car.
Does the vehicle use an individual intake system per cylinder or does the motor share a common plenum area? This has a great effect on system design.

TeamRX8

iTrader: (25)

yet you still don’t understand what makes the one you dismissed better than your own

Nadrealista

Finally had a time to do a quick run with the car and see how the intake feels. Car really felt alive and it was pulling strong and linear all the way to the rev limiter especially in higher gears (3-4). very happy.

Outdoor temperature was 44F and on part throttle I was getting 10C (50F) air intake temperature so 6F delta however once I would go WOT intake temperature would quickly drop to 8C (46.4F) which is only 2.6F delta

Then I did quick 2nd gear run to redline then partial 3rd gear run on the off ramp to see what the MAF was reading - looks little over 200 g/s according to the data below.

not bad for a CAI using <$20 in material from home depot (dryer hose, scoop and 2 x 4" hose clamps)

motodenta

You can get around with one 90 turn by using this:
indeed there are tones of them with various sizes.

TeamRX8

iTrader: (25)

another guy who thinks he’s a better engineer than he is

you still have a 90, just a large one without a radius

and you think that’s a better design than the other, but it’s really not. I’ll give you credit for using a larger diameter hose than that other attempt. Try to consider both area and smoothness of the turn. The one above is not any better for sure, just different. I’m not particularly a fan of RB products, but they did a better job on this part than either of you two guys are giving them credit

fwiw, the highest NA MAF numbers I’ve ever personally recorded are up in the upper 270 - lower 280 g/s range.
.

motodenta

Are you talking to me?
It was one of you guys who had an issue with RB on high speed and it gone after back to OEM.
In my opinion, both would work the same as the flow is mostly laminar. If the RB used 2 45 degrees instead of 90 it would way better.

Nadrealista

RB one is definitely superior design, but if I can get 80% of its performance for the fraction of the cost then I prefer to go that route. After all the air from the scoop has to go trough stock filter element and airbox then it gets smoothed out by two mesh screens before it hits the MAF. So I am not so sure how much benefit there is from having super smooth ducting before stock airbox. While dryer hose does not have as smooth surface it does lets you make very smooth turns.

I do wonder if there is any benefit to removing those 2 baffle plates in the stock airbox?

Loki

iTrader: (1)

How does that compare to before, though? As I recall, with the stock or with the RB duct there WOT air temp is similar. There arent really any heat sources before the MAF if you are getting your air from the bumper either way.

Nadrealista

Before I pulled VFAD off it was clear form the plastic trim underneath( that keeps most of the air flowing trough the radiator) it that stock air intake gets air trough the gap left in the plastic trim making it essentially CAI indirectly as that air comes up after bouncing of the radiator. I was more going for ram air effect and scoping cold-er air up front was additional benefit of the scoop placement. data from the track will be more telling looking at my apex/exit and top speed at the end of the straights.

from some other forum members : "I am running a factor intake and the temp at the MAF is 7 to 10 degrees higher than the outside temp gauge while driving."
"RB Revi + duct here, and the usual difference between ambient and intake temperature is 5 degrees Celsius which is about 9 degrees Fahrenheit. This is while driving on the freeway."

here what HKS found with stock intake vs theirs, again I think gains are from higher volume of air rather than colder air getting into engine as logs show below:



stock intake vs odula ram:


stock

odula ram cai