New Guy...Intake questions
 

Hey all:

I just joined this forum. I also just bought a 88 Convertible a few weeks ago. I have two questions.

1. Can I make the intake less restrictive simply by slipping a K&N cone over the TB?

2. What is the airpump for? Some sort of emissions? Does it do the same thing as the EGR? Can I take it off?

Thanks for any info you can send my way.

You can get an HKS adapter plate that will allow you to mount a K&N cone filter to the AFM. Another option is to simply use the K&N drop-in filter. I think that K2RD still has a sale on the HKS adapters, and their site has an excellent mod explanation section for RX-7 newbies. I don't think that HKS has the adapter on their web site, but I'll list a link to them also.
http://www.k2rd.com/Online_Catalog/FC3S/FC3S-index.htm
http://www.hksusa.com/

Yes, you can remove the air pump, but it will only save you about 1 HP, you will probably not pass emissions, and your car will make a backfiring noise when downshifting. The air pump supplies air to the main cat and to the anti-afterburn system, while the EGR valve recirculates exhaust gas back into the intake manifold. I don't think that it's worth removing the air pump unless it's broken, you don't want to pay a ridiculous amount of money for a new one, and you don't need to pass emissions.

Air Pump
 

The air pump is necessary if you are running the cats. It does not matter if you have to pass an emission inspection or not.

Removing the air pump and leaving the cats on the car will quickly result in the cats becoming clogged and restrictive.

The air pump also helps with the exhaust back pressure that is necessary to activate the 5th. and 6th. ports.

The EGR valve is for the reduction of detonation at any throttle position besides wide open. It works by inducing oxygen poor exhaust gasses into the intake, thereby reducing the effeciency of the combustion. This has the effect of reducing the combustion temps and pressures to prevent "pinging". Removing it will have no ill effect on your engine, but you will need to make a blocking plate to take its place. You will also need to cap off the vacuum line from the EGR control solenoid to the EGR valve. Do not remove the vacuum solenoid or disconnect it. Doing so will confuse the ECU.

The EGR valve is prone to get fouled with carbon or stick open and constantly leak exhaust gasses into your intake, or get a leak at the diaphragm which will cause it to not work anyway. Other than that there is really no need to get rid of it. The air pump is as the other post stated, a very small drain on the available horsepower.

As for the air filter, you can certainly benefit from a less restrictive system, but you need to install the filter in front of the air flow sensor. The car will not run with this sensor removed. It is the electronic device that is attached to the bottom of your stock air cleaner box. The tube going to the throttle body attaches to the rear end of it.

Thanks for the help guys. I just saw an extra accessory on the engine, and I wasn't sure how much power it was sucking. Not to sound like an ignorant red-neck, but this car is way more complicated than what I am used to like my Neon, other Neons, a blown Dakota R/T, T/A, even a Mitsubishi Mirage (not for performance, just an engie swap ;)).

My car came with the K&N drop in, but from previous experiance, These don't seem to give much performance increase. Thanks a lot for the info.

Brent

They have a lot of little systems, but the 86-92 RX-7 FC3Ss are not as complicated compared to other sports cars.

Now the 93-95 RX-7 FD3Ss are way complicated.

They use a bazillion little air hoses that help make the turbo setup feel more like a big NA engine.

There was a thread that showed how to put a cone filter up under the fender above the passengerside brake duct. I wish i had saved it at the time but it seems like the best cold air intake set up so far. Granted he had a scoop out in front of the radiator and I think PVC pipe to get the fresh air right to the filter. I know his piping from the throttle body down into the fender was PVC. :blue: