Kim

I have decided to go with a side exit exhaust in my racecar.

Reason is that the exhaust system, in its current configuration, heats up the fuelcell.

In this outdated picture, you can see how it sits, the fuelcell is now half recessed in the floor, inbetween the two mufflers.

http://www.wankelkim.net/rx7/fb/exh.JPG



What I would like to do is make it come out in front of the passengerside rear wheel.

It should be easy enough, cut the floor to clear the "framerails", have it come in the cabin and exit out the bodywork. Ofcourse there will be some covering up inside the car.

One of my concerns is noise, the class allows me to run 110db. Any ideas?

Second is the manifold length, is there a baseline of where to collect the two pipes? Im thinking Versus Length and diameter.

I'm sorry but i'm totally lost when it comes to exhaust tuning.

I will make some repackable mufflers to fit the system, any advice on packaging material?



Thanks in advance



-Kim

Lynn E. Hanover

It depends on what engine modifications you are running. Get a Racing Beat catalog

(www.racingbeat.com) as it has a selection of headers and header kits that work well. The book has every tip there is about modifying and racing rotories.



Generally, it is most important that both primary tube lengths be exactly the same length. I cut a length of vacuum cleaner hose and use that with a tape stripe to get the distance to the collector right. Running the hose through the header pipes as I build it. After that a 24" long megaphone to a 3" or 4" exhaust tube.

The tubing should run straight out from the port for as long as room will allow before the first turn. And total primary lengths based on multipals of 10-12 inches. Primary ID is 1 7/8" or 2" with 2 being easier to find. Use 1/8" wall as the minimum as thinner will melt through.



Turn the tip down at the ground to help with noise. Use Lava rocks as muffler filler. Used in fake gas fire places and outdoor cookers. Or, machine shop swarf from lathes, stainless if you can get it. Or stainless scrubbing pads from a resturant supply house. Even well muffled, the noise with a side exhaust will be so bad as to make radio communication impossible.



Lynn E. Hanover

Kim

Thanks once again, Dr. Hanover.

Guess I will stick with rear exit exhaust then, but in some different configuration.

Ha ha I never thought about lava rocks, sounds to me like it would rattle like a snake though. , but atleast its one thing that will withstand the rotary heat.

Maybe pack them in lathe swarfs, I have plenty of those in my(workplace) shop.



Would anything other than freeflow(straight trhough) mufflers work?

Lynn E. Hanover

The big Flowmaster with the diamond shaped baffles works well for a while. Then you have to cut it open and weld everything back together. I added 8 lengths of ready rod through to support the baffles and hold the top and bottm halves together. Ran that mess for several years. I now have a Giant Borla that is no longer made. 4" straight through with 5 little stainless tubes in the center also perferated as is the main tube.

Stainles swarf packing. 4" system out in front of the passenger side rear wheel. Turned down on te end and it makes about 100 Db at 50 feet.



You could build the Flowmaster in a night.



Lynn E. Hanover