[thunderjet302]

I've searched, and searched, and searched multiple forums on the March Ram Air system trying to find any hard data as to whether or not it actually works in a 1/4 mile environment. What I mean by "work" is add E.T. or MPH to a 1/4 mile run. Everything I find is just people complaining that the scoop picks up dirt/pebbles/leaves/water and no one actually testing the system to see if it actually makes the car faster in the 1/4 mile. I really want to know the March system doesn't add any performance vs. drawing air from the inner fender or putting the air filter in the inner fender.

Here's why I'm curious if the system actually works. I've been running just the box portion with a 9" conical K&N for a couple of years.



I tested the March box with a 9" conical K&N vs. the stock airbox with a panel K&N at the track, on the same day, and on back to back to back to back runs. The March box and conical K&N are consistently worth .1-.2 seconds and 1-2 mph through the 1/4 mile on my setup. I attribute that to the larger surface area of the conical filter more than anything else. Both setups are drawing air from the same location through the same size opening. The car also ran exactly the same times with the March box covering the conical filter as it did with the conical filter open in the engine bay.

So from testing I know the K&N conical filter in the March box benefits my setup. Now I have the scoop and hose from the kit sitting in my garage. I'm wondering if I would see any gain in the 1/4 mile from hooking the scoop and hose to the box? The only way I can see the scoop and hose providing any gain is if it somehow adds a tiny amount of pressure to the air box. With the number of bends air has to navigate through the scoop and hose to get to the air box any "ram" effect is probably negligible. Does anyone have any hard evidence that the scoop and hose actually improve 1/4 mile performance vs just the box sucking air from the inner fender? If not I guess I'll have to be the guinea pig next time I go to the track.

 

[indy2000]

the factory air box was a 'cold air intake'.......... a "ram" air maybe not.

I am sure the changes in air quality will have a greater affect on performance than that "ram" air intake.

 

[thunderjet302]

the factory air box was a 'cold air intake'.......... a "ram" air maybe not.

I am sure the changes in air quality will have a greater affect on performance than that "ram" air intake.

The factory air box and the march air box pull "cold air" from the same opening. My theory as to why the car picked up (I did testing on the same day so as not to skew results) with the March box over the stock air box is the March box allows for a filter with a larger surface area than the stock panel filter. I'm mostly curious if the tubing and scoop in front of the filter is helpful or a hindrance in delivering air to the filter.

Temperature, barometric pressure, and humidity often have more of an effect on 1/4 mile times than anything else. A 20* temperature swing with a different level of barometric pressure and humidity can often decrease E.T. by .1-.2 seconds and increase MPH by 1-2. This is why it's so important to check the impact of small changes (like using the scoop and with the March Ram Air box) on the same day so as to eliminate the weather conditions as variables.

 

[indy2000]

Well, first there is NO pulling of air........air enters the airbox cause the atmosphere has MORE pressure than the airbox.

the argument regarding surface area, is sound, but if both airboxes have the same pressure differential, and the stock air filter is not a restriction, than having a larger air filter, will make no difference.

There is way more to it than volume, "ram" affect can only happen at the inlet of the intake valve

If the stock air box is a restriction, then an air box that isn't, will flow more air.

With electronic engine management, one must careful with back to back comparisons.......ideally, multiple samples are needed to generate a baseline.

 

[thunderjet302]

I was attempting to eliminate any variables in the stock air box with K&N panel filter vs the March box with conical K&N filter so I could get a sound result. I drove to the track and disconnected the battery to clear any adaptive strategy the computer had. I let the car cool for 30 minutes and made a run with the stock air box and K&N panel filter. I then pulled into the pits, disconnected the battery, let the car cool for 30 minutes, and swapped to the conical filter and March box. I made another run. The car picked up .1 E.T. and 1.3 MPH. I then repeated the procedure back and forth 4 times. Each time the car would pick up between .1-.2 seconds and between 1-2 mph when I ran it with the March box and conical K&N filter. I also made sure the MAF was setup correctly for the type of filter arrangement used to take the MAF out of the equation as causing an improvement. I've kept the March box and conical K&N filter on the car as in my combination's case it shows an improvement.

I should note that yes I understand that on a naturally aspirated engine no air is being pulled into the engine per say. Air outside of the air box is at higher pressure than the air in the air box as a running engine creates a vacuum so air at atmospheric pressure moves in to the air box. The only real way to "ram" air into the engine is through forced induction. I seems to me that the March arrangement (see attached image) would only be effective if it somehow created a pressure differential in the air box higher than atmospheric pressure. With the system only having one entrance point for air it may be possible, at speed, to pressurize the air box slightly. Unless the scoop and tubing is capable of proving a slight increase in air pressure over atmospheric in a 1/4 mile run it would seem to be more of a restriction to incoming air than a help.

 

[indy2000]

In your effort to eliminate variables, by erasing the kAM, you have introduced more.

are you able to log fuel trims, maf flow, fuel mass, and exhaust 02 content?

As I can appreciate your efforts, I think you first must find all sources of error, and quantify them, and see if your results actually fall outside the range of error to be significant.

Otherwise, your results really would not be reproducible.

I think a simple measure of manifold pressure during the entire run, would be easier to use as a measure, of airflow.

 

[thunderjet302]

Lacking the ability to data log all of those parameters you suggested is why I erased the KAM before each run. It was my attempt to reduce variables. I did not realize that by erasing the KAM I introduced more variables, in effect rendering my testing invalid. Damn. There has to be something to results given the car responded to the March box and conical filter although it could be related to MAF signal more than anything else.

I may attempt to hook up a vacuum gauge to the inlet track and see what it is reading at WOT. It would make it quite easy to measure whether or not the scoop and hose assembly would have any effect on intake efficiency. Air pulled from the inner fender should be the same temperature as ambient air outside of the car, especially at speed. Any tubes/scoops/snorkels letting air into the air box from outside or below the car would not be letting any ambient air in that is cooler than air drawn from the inner fender.

 

[Michael Yount]

You might get a bit of "ram" over the last few hundred feet, but even then, not much. More velocity is required to get enough extra delta-P to make a significant difference. Not directly relevant, but enlightening. RAM AIR: What's It Worth? | Sport Rider

 

[thunderjet302]

Hmm so in a car that traps right around 100mph in the 1/4 mile "ram air" may be worth about 2hp. I'm pretty sure the tubing to plumb that ever so slightly pressurized air to the airbox provides more of a restriction than just pulling air from the inner fender.

I think it would be very hard to measure any performance gain from adding the scoop and hose to the airbox. Even if the car picks up or looses a tenth or two of mph that can easily be explained by run to run variances.

 

[Nitrous SSC]

Marketing.........

 

[thunderjet302]

Marketing.........

Well "Ram Air" does sound cool......

 

[5.8 TurboCoupe]

Think that youre already getting any benefit of that setup with just the cone filter and March box, I doubt the scoop would change the numbers on your timeslip one bit.

For a few hundred bucks and an afternoon installation though, a mild nitrous system would move the numbers around nicely though.

 

[thunderjet302]

Think that youre already getting any benefit of that setup with just the cone filter and March box, I doubt the scoop would change the numbers on your timeslip one bit.

For a few hundred bucks and an afternoon installation though, a mild nitrous system would move the numbers around nicely though.

I agree that the box and filter do more than the scoop and hose.

Nitrous or boost would help but I'm trying to keep everything N/A.

 

[5.8 TurboCoupe]

Understood, clean looking Bird btw, engine bay looks great.

 

[TomR]

Wind pressure in pounds per square foot is approximately velocity squared times .0026

100 MPH is 26 psf, which is 144 sq in. So the psi is 26/144 = 0.18 psi at 100 MPH air speed.

Another problem is the actual pressure from forward velocity would be related to the delta between intake air speed and the vehicle's speed. If you are trying to force air in at 100 MPH and the velocity of normal airflow into the inlet plenum was 40 MPH you have a velocity delta of 60 MPH which is 60^2 * .0026 = 9.36 psf or 9.36/144 = 0.065 psi boost.

There might be some dynamic I am missing or misinterpreting in the velocity delta, but it locally seems to me you can't add boost if the air from the boost source is lower velocity than air velocity into the load. Even if we ignore this issue, 100 MPH is less than 0.2 psi boost in perfect conditions.

 

[5.8 TurboCoupe]

We can always count on Tom to give us the sobering math on stuff. Way to kill the ram air theory Tom! The guy would need to trap 1300 or 1400 mph to get much benefit lol. Even if the scoop could endure those velocities, I think he'd run out of shutdown at the track fairly quick.

 

[Sledger46]

I had that ram air setup on my Mustang back in the early days, but I don't remember the car picking up any performance. Now, back to your results between the stock air box and the aftermarket air box. In the first post you said "The March box and conical K&N are consistently worth .1 second and .25 mph through the 1/4 mile", but later you said the results were "Each time the car would pick up between .1-.2 seconds and between 1-2 mph". There is a big difference between .25 and 1-2 MPH. Can you verify that MPH result? What MAF are you using and how is it calibrated?

 

[AL P]

Try taking the conical out of the box again and taking the passenger side headlight out of the car. On my Foxbody that was always worth a tiny little bit of ET and around 1 mph. If you want to go a little further, cut the hole behind the headlight in the fiberglass panel a little bigger to let more air in.

It is tough to gauge these little changes but if you apply them systematically over the entire car, you will be significantly faster than other people. Little things like a 3" race crank pulley and a shortbelt that bypasses everything but the alternator and water pump make a difference when applied as part of a program of changes.

I used to have a 4 rib 45.5" short belt on my fox body that only touched the water pump pulley between the 6 o'clock and 9 o'clock positions, it then went over the top of the tensioner, to the alternator, before going back down to the crank. It would slip at high RPM, squeal a little and not turn the water pump as much. Of course that is exactly how I wanted it to work.

 

[thunderjet302]

I had that ram air setup on my Mustang back in the early days, but I don't remember the car picking up any performance. Now, back to your results between the stock air box and the aftermarket air box. In the first post you said "The March box and conical K&N are consistently worth .1 second and .25 mph through the 1/4 mile", but later you said the results were "Each time the car would pick up between .1-.2 seconds and between 1-2 mph". There is a big difference between .25 and 1-2 MPH. Can you verify that MPH result? What MAF are you using and how is it calibrated?

It was a typing error on my part. I went back and corrected it. It should have read the car picked up .1-.2 seconds and 1-2mph with the March box on a consistent basis.

The MAF I was using at the time was a C&L 76mm unit calibrated for 24lb injectors. There are two different "calibration" tubes for that meter and 24lb injectors. One for a stock airbox and one for a conical filter on the end of the MAF. I ran the black tube with the conical filter on the end of the MAF mounted in the March Box and the blue tube when using a stock airbox with a K&N panel filter (see attached chart). It is possible that the MAF sample tubes could account for the changes even though they should be "calibrated" the same. I was trying to eliminate variables by clearing the KAM before each run. I did test the conical filter open in the engine bay against it being mounted in the March box. That made no difference in 1/4 time or trap speed. The box keeps the engine from ingesting hot underhood air on the street so I run it.

In any event I no longer have a C&L MAF on my car but instead a PMAS 80mm slot MAF.

 

[PMAS]

Any cold air system that does not place a 90 degree bend on the inlet of the MAF is better than one that does. I like systems that use the air box to make the turn into the fender. This is less restrictive than making the turn with a small pipe. This isn't even mentioning the havoc a bend on the inlet of of a MAF causes to the signal.

Remember that having longer pipe with more bends is VERY restrictive.
You lose more than you gain from the "cold air" or the "ram air" by having a complicated tube that is long and turns and bends into the fender well.