Greetings,

This has been a great source of valuable info as I have been working on rehabbing a 1979 RX7. It has 72,000 original miles, and is overall in great shape. Until I started the project, it sat in my brother's garage for 5 years, unstarted and unused. I have completed a complete replacement of sagging front and rear suspension, replaced all fluids, spark plugs, etc., and it fires up and runs.

It has an aftermarket header and no thermal reactor or air pump. I assume it is a racing beat header. It appears to have a catalytic converter installed, but I am assuming it is the OE heat exchanger. It also has the OE muffler at the back end. It has a very metallic sound to it, so I have ordered the Racing Beat Power Pulse muffler.

Question: should I leave the heat exchanger in place, or should I look to install a catalytic converter? Will a catalytic converter provide any emissions benefits if it is simply swapped out with the heat exchanger?

 

If you don't have emissions laws for older cars in Minnesota, you should definetly replace the heat exchanger with racingbeat's mini presilencer. It will provide that deep/ non- tinny sound you are looking for. I have their header, presilencer, and muffler, and I must say, it sounds absolutly awesome.


~b.k.

 

Are you sure its a heat exchanger ? I didn't think headers hooked up to the exchanger but maybe I'm wrong.

Anyway, you want at least one presilencer and a free flowing exhaust to take advantage of the headers. That should give you a decent sound and some ponies as well. Next you want to address the stock crab either get different 4 barrel (holley?) or have sterling doctor the existing one or go to a progressive two barrel (weber?). Doing one of these will boost your hp from stock by about 40%.

 

It should just be the old factory heat exchanger. The Racing Beat one will bolt right up to it. If you have to pass a visual inspection, I guess you should keep the heat exchanger or get the mini presilencer and put a dummy heat shield over it. But then again, I doubt the header would pass a visual inspection anyways. You probably won't pass an emissions test b/c the thermal reactor that used to be where the header is was part of the emissons system (I'm pretty sure). If you installed a cat, I think you would also have to provide some sort of air supply (factory air pump) to it to keep it from burning up.

 

Thanks for the info. That last point is one I was wondering about. Without an air pump, will a catalytic convertor simply burn up? I am hoping that the racing beat muffler will give me a decent sound for now, and when I get the extra $, it sounds like the presilencer will help quite nicely. Right now, HP is not a top priority, but rather, getting a really great looking car on the road to enjoy some weekend cruising. More in the "grand touring" mode than the burning rubber between stoplights mode.

 

The air pump is only needed with the thermal reactor - it keeps THAT cool, but not the cat-
Stu Aull
80GS
Alaska

 

As 7aull states, the SA's do have an airpump installed in stock form, and this uses the diaphragm valve on the intake manifold to control airflow into the Thermal Reactor (TR). The TR is simply a huge and heavy cast iron bulb that allows the exhaust pulses from each rotor to mix before they're exited out the downpipe to the presilencer. This setup in stock form works well enough, as the TR gets really freaking hot and that's what burns off the unburned hydrocarbons and cleans up the exhaust. Without it and the airpump working, you will not pass inspection if required in your area.

The RB header will totally replace the TR, downpipe, and presilencer in stock form, but you'll want to get the right presilencer for your header installation to get enough suppression of sound. Without it, the car will sound like a lawnmower at the end of a 14 foot sewer pipe.

That said, if you wanted to convert to a standard cat system, you could replumb the air pump outlet to the cat and probably get by. It won't be properly metered air, but it will get excess O2 into the cat to react with the platinum core and burn off the bad stuff. This would probably pass visual inspection for the catalytic converter and airpump, and you'd probably also get it to pass the performance test as long as you weren't running too rich due to an improperly tuned carb.