Just got back from SAC picked up the rest of my intake setup goodies. How does it look? the golfball takes the place of the stock A/F Meter.



Check out the cone it sucks air from the front also. And you can see the Adapter plate for the A/F meter.



I figured this thing is going to be sucking alot of air, so I picked up a digital A/F gauge to be safe.



As soon as I get my turbo back I will post installed pics.

 

nice

 

That TID is beautiful and will flow really well (I'm jealous!), but that air filter adaptor for the AFM is crap. Sorry. A 90deg angle at an air entry point is absolutely the worst shape, causing a lot of turbulence from air trying to rapidly change direction. The HSK cast aluminium adaptor is a gradual square-to-round transition that would flow much better.

 

Where do I pick up the HKS one? I'm not attched to that adpater it came with the filter.

Thx

 

I see the foot now comes shoed...

interesting. Is it still not for sale?

 

That shoe is a high end body kit from Taiwan, it would cost you big bucks for the toe with that mod.

But in all seriousness does anyone know where I can see a PIC of the HSK adapter. I would like to try to fabricate somthing similar with what I have... if not I will just buy it.

Thx

 

Okay I found this picture on rx7store.net. Is this the adapter your talking about? its listed as "HKS Airflow Meter Adaptor" I am assuming thats what you meant.



I don't see how that is a gradual flow? Either it has a smaller end for the air filter pipe... or they just ground off the excess metal from the square. Now, if its a smaller inlet that completely defeats the purpose. It will be less airflow with a smaller pipe on it. If all I need to do is grind out the excess metal that should be no problem.

Fill me in!

 

So I went out to my garage just now and grabbed my AFM. This just does not add up. Look at these pics, either way your air flow is limited by the square opening on the AFM .. this we all agree on right? Now look at the above PIC of the HKS there is no way it can be tapered that much in that short of a distance without a whole nother size cone adapter. Am I making any sence? Am I looking at the totally wrong "HKS HSK" adapter?

 

oh, nice, where did you pick all of that stuff up from?

 

OK, first of all, the Evil opinion is that the stock S4 AFM is garbage, and you are forever cursed by airflow restriction as long as it is on your car.

Now that I have that out of the way, you will notice that the HKS adapter is cast so that it transitions from a circle to a square. Yours does not transition, and has a drag-inducing lip where the pipe meets the plate. If you ground out the plate to match the pipe, then you would still have a square air barrier around the edges because of the AFM. If you have trouble visualizing this, then place a pipe on the end of the AFM and look into it - see the square restriction? That's the problem. I'm not sure if the HKS is a 100% fit, either, but it looks very close. You could just go with what you have, or you could maybe mold some fillets inside of your adapter, or simply spring for the ghastly $20 price of the HKS adapter.

BTW, maybe it's just the pics, but it looks like the inside diameter of your filter is too large for that pipe.

 

Its certainly not the $20, I's the fact that i think it will make NO difference. The final result still is that you are resticted by the square on the AFM. If I buy the HKS adapter and put a pipe on it, and look down the pipe I am still going to see a square on the AFM at the end. I notice there is no drag lip on the HKS, but if you compare pics there is no way tou can taper that thing that much in what 1 inch or less? So I am of the opinion that the whole adpater is smaller requiring yet another reducer. "reduction" in air intake is a bad thing .. thus a reducer is not going to help my air flow at all. I would rather have a little drag than a reduction in air flow.

Ya, its the pics .. all the piping lines up perfectly.

Edit: Node, I got all of these item done at Midnight Performance in Rancho Cordova CA. Its mostly a homda shop, but they are good guys. Also, Evil I didnt mean to come off sounding rude.. when I reread my reply it kinda seemed that way. I just think that whole adapter is a over reaction & I am trying to understand this all, thx for the help

 

Yep, that's the one. No, this piece is cast. It's ~73mm OD, ~65mm ID and and transitions reasonably smoothly to 63x50mm (inside) at the AFM end. That picture doesn't show it very clearly, but once you see it you'll understand why it's much better than the other one, and will cause virtually zero turbulence. An entry with 90deg edges cause significant turbulence. Personally I'd have made the casting longer for an even smoother transition, and made the walls a little thinner, but that's a casting limitation.

BTW, I made one of these from sheetmetal for my 12AT. It was 3" for the filter and 50x50mm for the AFM, all Stainless steel. The square-to-round transistion was ~60mm long, bent into many small sections like A/C ducting to make the transistion. So if you have access to sheetmetal working equipment and a TIG welder, you could knock one up.

 

OK, maybe I can help you see why the sudden round to square is bad for airflow.

The air will become very turbulent around the "lip" and the incomming high velocity air will be restricted to an even smaller flow area than the square area as it has to go past these areas of slow turbulent air extending from the lip!

-edit- too slow to respond...

 

Okay damnit. Since I am a perfectionist and you have now caused me to start thinking, I am going to order that adapter tomorrow. If I don't; I will be driving around in my car thinking .. "is my intake more turbulent than it should be" Then I am liable to run into a tree or somthing cause I am thinking about my intake instead of the road. So, you may have saved another 10AE from ultimate distruction .. or you may have saved a tree. Thx to all your guys help there is going to be one more tree to keep the air clean.

Adapter it is.. anyone want to buy the one I have for $20 HAHA the cost of the proper one ... that was a joke all.

 

It will; not a huge difference, but a definite, measurable difference. Of course you are, you always will be with the AFM, but you might as well make it flow as best you can. Oh yes you can. The free area of the HKS adaptor is exactly the same as your one, but will cause much less turbulence. The end result is more flow, not a reduction. We're not talking an extra 20hp here, just minimising the restriction of that cursed AFM!

 

Grasshopper, when you can ****** the aeronautical science degree from my hand, then it will be time for you to leave.

Like I said, though, the AFM is a restriction in itself, so I'm not sure how much a little more restriction is going to hurt the airflow. Yes, it's an overreaction, but it's a restriction nonetheless. I was just trying to answer your question and explain why it was a restriction, and did not mean to imply that it was a big deal for a street car. Geez, if you really want to get down to it, the screw heads on your throttle plates are an airflow restriction, LOL. Your reply wasn't at all rude. Besides, anyone who has been on this forum for more than a few weeks should know to put on their thick skin when they log on.

The HKS adapter accepts 2.75" ID filters, so it is large enough for quite a bit of airflow. The pipe diameter only affects drag indirectly as a product of velocity. A small pipe isn't going to present a problem until the airflow reaches 0.4-0.7 mach. A larger diameter pipe does not necessarily mean better airflow, and will sometimes actually reduce the air velocity to a point where airfow momentum is hindered. Granted, there are a lot more aerodynamics involved, but that's the basics. I think that both your pipe size and the HKS pipe size are just fine.

 

 

I did it, I placed the order with my flywheel. Put in a extra $20 for the HKS adapter. I will post good close up pics soon .. to show how gradual the angle is.

 

Okay since you all busted my apple cart about my AFM adapter I went and purchased the right one... it came in today. I am happy I did though .. you can see in this Pic the improvement & nice taper it has.

Thanks for the advice fellas

 

evil-

what is the other option to not having the afm? what do you do? i'm not completely familiar with the rx7 options. On most cars you run a stand alone with a MAP sensor but what about on the rx7? i want to get rid of that sucker

 

Are you guys referring to some way of eliminating the AFM with some kind of plug to fool the computer sorta like an FCD?

 

uhh no i dont think that has come up yet but i was just about to ask the same thing! Why botehr with all this square entry turbulence crap when what we really should be doing is figuring out a way to get rid of this piece of **** afm and making the intake system a whole hell of a lot more flowing
well i have no clue how to do it but id love to see some ideas

 

Yes, most standalone engine management systems will eliminate the need for the AFM. You could also convert to a carb setup, but that would cost just about as much with new components, so the EMS is a much better choice in my opinion. Sorry, there is no cheap and easy way to do this, but a well-tuned EMS will make a huge difference in the power and driveability of the car. For example, I drove a Wolf3D-equiped NA FC around a parking lot in all 5 gears and never once put my foot on the gas - just try that with the factory EMS! BTW, that same NA FC also raced my TII evenly (if not a little faster), even though it only had stock porting and internals.

Excellent! With the HKS adapter on your AFM, do you now see how there are no longer 4 lips which disrupt the airflow as it flows from the round adapter to the square AFM hole like there was with the old one?

 

Ya, I understood what you were saying a month ago .. when this thread started. I just did not think it was that big of a deal... but it was bugging me.. and always would have bugged me had I not changed it. So I did

 

The clue is in the name; airflow meter. The AFM is the ECU's main load sensor. It measures how much air is entering the engine so it can calculate how much fuel to inject. Without it the ECU has no idea what's happening, so there's no way the engine can run.
Aftermarket ECU's (and some factory ones) eliminate the AFM by using a MAP (manifold absolute pressure) sensor to get an indirect airflow reading.