Frankly I'm not buying that resonance back to the cone filter is giving any power gain. (Geez, this is like another thread. Does it come up every few months?) From the plenum on the intake and back, the four intake pulses are overlayed. The result would be pulses with a frequency of 2X the RPMs.

A bigger and longer tube gives a lower frequency response. I believe that configuration, with a good filter, would give more power as higher pressure and less turbulent air is available at the entry to the AFM. Laminar flow will be higher then turbulent flow. (It is written!)

Has anyone demonstrated that it is resonance in the intake or is that conjecture? Saying that theories don't support a conjecture is suspect in itself.

 

First, you don't have to buy it. But it's true. It's not conjecture. Now, you can model it, or you can to a dyno and test it. The fact is, you can go to the dyno and test it and determine the best length faster than you can collect all the appropriate data (if that's even possible) and model it properly (and then you still have to test your theory on the dyno). Sometimes it's just quicker and easier to test than it is to model.

Nobody is debating that the runner length between the valve and the plenum has generally greater effect on resonance tuning and power. But changing this is expensive and to do it right really requires some modeling to the lengths close, some flow bench testing for reshaping the ports, and a bit of fooling around with plenum size and intake manifold runner length. The CAI tubing is really really simple to test.

Speaking of testing, Campeck, until your car is runing 100% don't even bother to go to the dyno. Testing on a car with problems or one that isn't 100% will really skew the results.

To summarize all of this....

1. Campeck is on exactly the right tack

2. I personally believe the AFM adapter is critical to making gains. In this regard, Campeck has the best one I've seen, if still not quite 100%. Without a good tapered adapter that tapers from round to square, you introduce a lot of turbulence exactly where you don't want it - at the metering device.

3. The barn door is the wild card here. It's an impediment to flow, but resonance tuning should still show gains because there will be a chamber from the opening of the CAI tube to the AFM if nothing else and this should improve the flow. The problem, as Danno mentioned is you basically have a dual resonsance chamber. Actually, all intakes (except those with MAP sensors) will have this to a greater or lesser degree. This one will be a little more complicated because the barn door will alter the equation more than most IMHO.

4. It's important to monitor the AF ratio while dyno testing. With the engine management system on the 944, changes in VE will generally cause changes in AF ratios. If they go too far off it can affect performance. For instance, if the air flow is increased too much, some fuel may need to be added (an adjustable FPR is expedient) to get the gains that are possible. This is something the Honduh boys know only too well.

Something else that hasn't been discussed is that if you replace the boot between the TB and the AMF, you can change where the AFM is located in the air stream and moving it around could produce some additional gains. I watched a friend move his MAF on his Sentra SE-R by 6" and gain 2hp (using a CAI). This was a controlled test too with care taken to strap the car down the same amount (which can affect results), the water temp was stabilized at the same temp, etc. There is a bit of alchemy involved, but playing around can sometimes find more gains.

 

OK, so this has been brought up in a million threads as well, but let's consider ditching the AFM for a generic MAF, like one off a junkyard car, or even a Granatelli. Won't work with the stock computer? We convince/pay Danno to mess around with a MegaSquirt or something (thinking low budget) and ditch the stock computer outright. Then we can ditch batch fire as well and go with sequential firing of the injectors. We're looking at what, like $600.00 in parts and Danno's time, which we can spread out across the lot of whomever is interested in ganging up on this issue. By doing this we eliminate the AFM issue altogether. And Danno seems kind of interested in this already based on some of his posts so far.

Interest?

 

First, you need to learn more on what you're trying to talk about. That's what's true.

Picture the individual throttle bodies on many old race cars. Very short to give a resonant boost effect at high engine RPMs. Then picture what you are describing. Realize that the resonant frequency at the AFM needs to be 4x faster then in the runners to feed all four pistons.

The configuration you are describing has a primary resonance in the hundreds of Hertz. To provide a pulsating boost it needs to resonate, at least the second or third harmonic, at 10000Hz.

Here's a quick tool to find the harmonic resonances of a tube.
http://hyperphysics.phy-astr.gsu.edu...es/opecol.html

Can a few horsepower be gotten by improving on the stock air box and filter? Certainly. Is it because of resonance in the tube is getting more air into the cylinders? No.

 

This might help you prevent sucking in water. I have installed them on many friends cars and they work great

AEM’s patented air bypass valve virtually eliminates the chance of hydro-lock in the event the filter of your AEM Cold Air induction system becomes submerged in water. The valve installs along the upper portion of the inlet pipe and shuts down induction at the filter when it becomes submerged, rerouting air through its external diaphragm to keep water out and air flowing in. Patent # 6,394,128

 

Dude, you are the one who needs to know more about what you are talking about. I'm not making this up. Do I kow the formulas involved? No. But I have several friends who are automotive engineers working for OEMs or Tier 1 suppliers, one of whom is also an aftermarket performance parts industry consultant (and at one time worked in the TRD GTP engine program). First of all, I'll take their word over yours any day of the week and twice on Sundays. Second, regardless of whatever you think you may know, the real world has show it works. So keep saying it doesn't work. The real world says it does.

 

Not to turn this into an mr2 discussion but a stock ct26 on a healthy well maintained engine will boost to around 6500rpm, redline is 7200.

 

I think it would be great. I couldn't take advantage of it because by the rules I'm stuck with the stock injectors and AFM. Also, any changes I make to the ECU must occure strictly inside the stock box and the stock box must retain the stock plug which must plug into a stock wiring harness.

But for a road car, a MAF and sequential injection should be the basis for a big improvement.

 

What is wrong with the stock injector fire and how would sequetial make it better. Id like to know because i have no clue what the pros or cons of either are.

 

Sequential pulses the injectors in the same order as the firing in the engine. This way, each injector only pulses every other revolution of the engine.

Non sequential injectors all pulse at the same time and on every revolution of the engine. The pulse is also half as long as sequential. BTW, pulse is the duration the injector is open.

Sequential injectors allow you to adjust when the pulse occurs, relative to the opening of the intake valve.

 

ok.
I geuss the next step for my car is a completely new ECU system and an MAF.
for the tests, (when the car is running right) I will put the stock cat back on, and unplug the WILK chip to see the difference in a complety stock car.
then I will but my setup back on and test it then. If I havent cut the pipes all to hell by then.
lol.

Im ALMOST!!! dont with the fiberglass underpeice. it actually doesnt look to bad. no holes need to drilled or anything. we just bought a new camera so I will get pics in a couple of days.

 

the next mod for my car should be a seat that bolts down. it sure is fun to have a 944 in the twisties when your *** is flying around everywhere

 

Sequential injection provides better mixture control. If the injector fires when there is no flow, it will wet down the intake port. Now, the engines spin fast enough that it's not like the injector is just spraying the port and nothing is getting mixed into the airflow. Sequential injection just provides for better mixture control and better dispersion into the air flow.

 

Hey G,

I understand your circumstances under IT rules. Still wouldn't mind your input on this if we could actually get something going with a budget MAF setup. I don't know if MegaSquirt would be the best bet, but if somebody like Dan could figure a way to set it up, maybe using the stock speed/position sensors to avoid having to come up with a trigger wheel then we would be on the way to doing this on the cheap. That would (1) eliminate all the folks saying the AFM is the issue and (2) eliminate all the people who say it isn't a good dollar to power investment.

 

I'd love to help in any way I can. I truly believe there are gains just waiting to be had with these cars, but it will take someone to understake a decent development program. I've been tempted to look for a 944 road car to do just that, but damn, I have to get my race car done first (moving into our new shop next week so I can finish it).