In the October issue of sport compact car there is an article on how to builod your owen exhaust system. and i was wondering if it would be cheaper to buy all the tubing, muffelers, and paying someone to weld it all togather. or to just a prefabed exhaust system like an Apexi N1.

thanx
pinfield

 

well if u build it urself u can make it exactly how u want it. and u won't have to worry about maybe an angle being a little off on a prefab

 

It all depends on what you want. I just happen to own RX-7s with the full spectrum of exhaust systems...

84 GS: $700 USD - Racing Beat "Street Port" System, installed by my friends for free.
88 TII: $100 USD - Custom el-cheapo catback straight-through exhaust (TII's don't need mufflers if the stock DP is retained), made and installed by the local generic muffler shop.
88 20B: $2,600 USD - Custom 3" 321 SS exhaust with two Apexi N1 mufflers, high-fow cat with quick-change replacement pipe, and Porsche-style wastegate bellows, all installed by a record-holding race team.

If you have a professional shop install a custom exhaust, you can bring them your own mufflers and cats, but let them supply the pipe.

 

has neone heard of a company called powertone they clame to have created a negative back preasure muffler. has neone used on of these or know some one who has? i personally have never even heard of such a thing. sounds like it would be a great thing to have it it really works.

 

evil avitar,
so your saying that my 87 TII doesnt need mufflers at all? and by DP you mean downpipe right? and y would keeping that make it so that i dont need mufflers

 

even though i don't know the price of building one urself..i think buying a good name brand aftermarket one is a better idea..

if u build it urself, there are lots of things to consider in a exhuast system like diameter, and that will affect the flow rate, and also the durabiltiy, properties of metals,material selection, bent angle of exhuast... and etc etc...
i believe those engineers out there don't just get paid for sitting around, they probably have done some good work and research and design some good exhuast.

 

Right. I guess that I should have added that you also need to retain the main cat. The turbine wheel absorbs a whole lot of noise when on-throttle, and the main cat quiets down the idle noise pretty well. To be honest, I haven't tried it with a high-flow downpipe, but everyone else that I have talked to who has tried this says it's too loud without mufflers. I guess that you could try it and see how it works with a DP, but you may also run into a lean problem with all these backpressure-reducing mods.

On my particular car, the pre-cat was gutted because it was clogged, so now it acts as an expansion pipe. The main cat is stock, and acts as a muffler. A local muffler shop made and installed a cheap steel Y-pipe with dual exhaust, much like the stock unit, but without the mufflers. The car is only slightly louder than stock, and the only other noise I have noticed is an amplified effect of the good old Mazda afterburn "popping noise" when decelerating while in gear. Yes, this is a major ghetto setup, but it does work, and I really don't want to put any money into this car because I have my hands full with the other two.

 

Per my advice, BigRed is the first guy to try www.powertone.com on his FD.

it's the lightest CB shy of buying a Titanium CB out there.

Also, It's less likely to scrap on incline or declines due to it's low profile design.

he did notice some HP and MPG increases, but we weren't able to dyno that difference yet.

The car still is running stock boost iwth Main cat. I suspect if this patent were to work, it will need to be under higher boost and free flowing exhaust.

One thing is for sure.... it's the best sounding exhaust I have heard.

Don't sound rice at all.

As a matter of fact it makes it sound like it's a power boat with that exhuast under water tone.

really something else.

Also, the price is cheap.

 

we are working on recording an MPG or wav file to share.

more on this later......

 

I would go with the actual system that is made. They have the a better bend cause it's mandrel bent. Or buy the actual one, then have someone bend the pipes to fit your car like the one that is made for it....then return the one.

 

What muffler did he put on his FD? Also, what other universal mufflers can stand up to the heat of a rotary engine?

 

A quality custom exhaust is made with mandrel bends and straight sections welded together.
Press bends have no place in a custom performance exhaust.

 

Does anyone else have any experience with Powertone mufflers? I think it's a great concept that seems like it could work pretty well.

 

I didn't I'm only running the tips.

 

For clarification it is only the tips that have this negative back pressure design. their mufflers are stainless steel and free flowing in design but have nothing to do with the negative back pressure. I really didn't want to leak out this info until I got some sound and video clips, but ah.. oh well. I think this would be a great application for FC's also

 

nope.. the negative back pressure is a design of flowing EXTERNAL air.. more HP or freer flowing exaust wouldn't have an effect on how the system works. exaust is pulled out, rather than pushed at anything above 40mph.

 

as long as it's full stainless steel (powertone, borla) you should be okay. a company like flowmaster doesn't use stainless steel in their muffler design.

 

It is a stainless steel construction and should be OK.

The nice thing is that the muffler, not the tips looks like a cat.

 

the diagram for that muffler shows fiberglass padding. Wouldn't it melt after about a week?

 

BigRead has had it for well over that.

However, it's not straight piped yet and he drives it in moderation.

I might order it from them without the fiberglass packing and replace the Cat with their powertone muffler.

 

I haven't looked at the glasspack recently.. but i'm guessing it's gone. No noticeable change in tone though... also removing that will just allow for more air to flow easier.

 

I was just thinking that since I already have the Racing Beat CB, I should check with Powertone to see if they have a Dual witha 3" pipe that can be welded to the existing 3" pipe that is currently mated to the muffler.

This should make the job easier and cheaper.

I had a few offers of people interested in buying my racing beat CB, but this might serve me better in the long run.