91VertT2

So I started looking for an MAF adapter to get rid of this crappy intake tube. And I ran into a problem. No adapter looks like it'll fit my application.

misterstyx69

iTrader: (142)

so,what are you trying to do?..put a Cone filter on it?

91VertT2

I can't. I don't have anywhere to plug my maf to that while thing is one piece. Inside it has a cone that depending on the vacuum goes further in. I wanted to eliminate all that crap with a single pipe but there doesn't appear to be aftermarket adapters for my application. I've always seen the maf box never this cone thing.

misterstyx69

iTrader: (142)

I deal with S4 and they need a adapter just to make the front round.
the S5 is already round.
It looks like it would collapse with trying to put a cone filter on it..
So,From looking at it,if you put a piece of tube(like IC pipe) slightly inside it,then you can support the rubber,then toss a cone filter on the end of it and clamp it.

Evil Aviator

That "crappy intake tube" is the Airflow Meter (aka MAF sensor) for 1989-1992 models of the RX-7, and your engine will not work without it. In stock form, you would not normally see it because it is hidden by the air filter box. If you want to attach a cone filter, just measure the diameter of the tube (I believe it is 2.5"), and buy a universal cone filter to fit it. The cone filter attaches with a hose clamp or zip-tie. See this link for filter sizes: K&N Universal Clamp-on Air Filters for a Variety of Universal Air Filter Applications

Here are some pictures showing a cone filter attached to a 1989-1992 Airflow Meter (AFM).







If you want to get rid of the AFM, then you will need to take your car to a professional auto shop and have them install a standalone engine management system that will replace your stock system. Installation and tuning will usually cost between $2,000 and $10,000.

I am saying this to help you out rather than to bash you, but an engine swap is well above your level of knowledge at this time. If you can't afford to pay a professional, then you will need to get some help from a friend who has an appropriate level of mechanical knowledge and skills.

If I understand the question correctly, he is trying to figure out how to attach the S4 AFM but the S5 AFM is in the way.

91VertT2

Thanks for all the advice guys, I'm going to take this on as a weekend project when I get a chance and post pictures of what I did for others with the same issue.

Edit: I already have the swap and I wasn't looking to eliminate the MAF I'm familiar with pistons not rotaries lol. I want to let it go because it looks likes it's constricting airflow maybe I'm wrong. Anyway I'll see what I can fabricate thanks.

Evil Aviator

Wut?

Thank God for that, lol.

I would recommend posting your ideas in the 2nd Gen section prior to doing the work. These cars have been around for over 20 years, so what works and what does not work is pretty well determined at this point.

Actually, you are not familiar with airflow sensors or engine management systems at all because it works the same for both piston and rotary engines. No problem though, here is a brief description...

The 2nd generation RX-7s have a mass airflow engine management system that relies on a mass airflow sensor to accurately control the fuel flow and ignition timing of the engine. Being a mass airflow type of engine management system, the engine control unit can't run the engine without the mass airflow sensor. The mass airflow sensor is called an airflow meter (AFM), and specifically it is a vane type airflow meter, which consists of a mechanical measuring plate and an air temperature sensor. The 86-88 models use a flapper-type vane, while the 89-92 models use a cone-type vane. The cone-type vane is what you are seeing inside your AFM. No, it does not restrict flow by any significant amount until you get to about the 400hp level.

If you want to eliminate the AFM then you will need to convert to a speed-density engine management system. This type of system controls engine fuel and ignition based primarily on inputs from a manifold absolute pressure (MAP) sensor and tachometer, so there is no use for an AFM. Most aftermarket standalone engine management systems (AEM, Electromotive, Haltech, Microtech, Motec, Wolf, and other brands) are designed to work in speed-density mode, and these aftermarket systems are the choice for high-performance race cars. If you see an 87-92 RX-7 with an air filter directly mounted to the turbo, or with a pipe and no AFM, then it is using an aftermarket speed-density engine management system. The car can also be converted to an alpha-N system that primarily uses a throttle position sensor (TPS) and tachometer, but this is not advisable for a turbocharged engine.

More about airflow meters:
Air Flow and Mass Sensing Devices
http://www.autoshop101.com/forms/h34.pdf

More about aftermarket speed-density systems, commonly called a "standalone EMS" on this forum:
http://www.aemelectronics.com/files/...asics_V1.3.pdf
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