We all know that headers on an NA rotary are loud, but they don't have to be! I recently tried an experiment and bought a Car Chemistry "sound suppression insert". Click here to see the product info:

http://www.carchemistry.com/ccinserts.html

I picked up the 2-1/2 inch insert from Summit Racing.com for a total of about $60 bucks shipped. I bought the one with the 3 disks.

The install is strait forward. I'm running a Racing Beat header and pre-silencer. I installed the insert into the header collector just before the pre-silencer and tack welded it in place. (I had to grind the insert a bit to get it to fit into the header) I bolted it back together and fired the engine.

HOLY FREAKING CRAP! This thing works!!! The car is now quieter than it was before I replaced the catalytic converter with the RB Silencer! There is no drowning inside the car and the tone is deeper. I'm astounded at how well this product works. There was zero noticeable effect on power.

Check out the website for Car-Chemistry. They have dyno results showing there is no power loss on a V-8 engine with open headers. They also claim that you can run open headers with their inserts and still be street legal. Using the 3 disk insert will reduce sound volume approximatly 20 db!!!

 

Let us know how long they work.

The hot, sharp exhaust pulses from a rotary engine header are able to crack the welds out of most baffels put in their way.

 

Interesting. I would like to see a NA dyno test with those.

 

SureShot: Will do. You and I both are very curious to see how long this product lasts. Construction of the Car Chemistry insert is a thin gauge mild steel. If they do break apart, I'll be building my own insert from stainless.

Banzai: I'll have dyno numbers, but probably not until next spring. I have my baseline number of 167 RWHP, but that was with a catalytic converter installed. I'm running a silencer now, so it wil be hard to judge true before and after performance. I can say that by the seat of my pants, the performance is the same.

 

Yo,

Dude, how the heck did you do that?! I was running no cats and only got 140RWHP. Are you running a streetport or S-AFC or something?!

Enquiring GTUs minds wanna know!

Kevin
1989 GTUs "I want 167!"

 

I'd rather have a loud exhaust...there's no way that thing doesn't effect performance.

 

big street port most likly, my friend did a small street port with RB full exhaust an got 160whp. with tuned afc.

does the afc make a good amount of power more than if u didnt have it on an NA?(tuned)

 

This is great info. I have seen these header collector inserts in the Summit catalog but thought that the resistance they would cause would defeat the purpose of having a header in the first place. I guess I was wrong.

Do keep us informed on how they hold up, Wozzoom. I want to use my header for the sake of my street port and TII exhaust sleeves, but not if it makes the car audibly fearsome. I'm older than a lot of you guys; I like a quiet FC with a *nice* exhaust note that won't break my (or anyone else's) ears.

 

I'm running: a streetported S5 engine, S-AFC, 550 secondaries, T2 fuel pump, PR 6-port sleeves, RB Header, RB Silencer, and RB catback.

when I hit the 167 RWHP, I was running a Bonez high-flow cat with air-pump.

 

I was under the same assumption, but I guess I'm getting old too because the noise was just to much for me to handle. (I turn 30 on Saturday *gulp*) This insert lets me have the best of both worlds...

Makenzie71: You're probably right. There is no way that I didn't loose a couple HP on the top end. But being able to drive the car on the street and not have everyone giving me the evil eye more than makes up for it!

rx7raca: The S-AFC is essential to get every HP out of an NA. I went to the dyno with my AFC and did a base run with all the settings at 0. I then made a couple runs and adjusted the AFC. I found 12 RWHP.

 

THAT'S how you do an NA!

I went to the "car talk" section of cars.com & asked what car they would recommend for me.
They said the average age of an RX-7 owner is 23, and at 59 I'm too old for an RX-7!
They suggested a Buick Roadmaster!

So I went & bought a TII.

 

Hey! Bill bought a TII. I thought we might have been losing you when you told me the N/A was for sale. We have to have more cheese dip at the next BBQ, right?

As far as on topic discussion, wozzoom made a great find. I've often worried about how my car will sound after I add the header. I was probably gonig to run a converter to muffle it somewhat. Now, who knows what I might do.

 

I have drove some cars with the RB header & presilencer anad even though I am.... well older...the big 4-0! I found it to be VERY quiet...Almost stock like quiet...

I would imagine this prtoduct would have to restrict some power?
I also wonder how it would hold up vs, the amount of heat in our engines...
I am considering a header...but then again, I am also feeling like getting another Turbo too...

 

Yo,

Woo! I just ordered my S-AFC II on Saturday...these are great words to hear!

Why did you go with the 550 Secondaries? I thought the NA 440's were good up to 250HP or something. Easier to "lean down" with the S-AFC?

Keep up the good work on the GTUs! I'm trying to catch up...

*grin*

Kevin
1989 GTUs "Mods in last 2 weeks: TB Mod, Ported UIM, MIM, LIM, silicone lines, fuel injectors cleaned."

 

You also have to consider that NA engines do like a little back pressure on the bottom end. Back pressure keeps the exhaust pulse in the chamber longer, thus pushing on the rotor longer before being forced out the exhuast port.

So yes, putting any type of restriction in the exhaust will steal some power from the top end. But you also gain a little usefull *grunt* down low.

Of course this is all theory because the only emperical evidence I have is the seat of my pants. We'll have to wait till spring to see my dyno results.

 

I say the louder the better!!

 

I went with the 550s in my secondaries because I was running out of fuel at 7000 RPM on the dyno. I went to +20 on the S-AFC and there was no difference. I latter found out that I had a bad secondary injector.

So was my bad injector causing my lean condition or was it my ported engine gulping too much air? Not sure.

With a stock engine, you should be fine with the 460's.

1986 "Mutt" - Mods in the last 2 weeks? Header silencer
1989 GTUs - Mods in the last 2 weeks? New clutch and a thick layer of garage dust...Waiting for tranny rebuild.

 

I guess there comes a time in everyones life where you realize that you don't want to draw attention to yourself anymore.

I have 5 points on my license the way it is! (To many speeding tickets) The less attention I get, the better!

 

hey what can I say I like to feel and "hear" the power, oh don't worry I've had my number of tickets as well, but I know what you mean about drawing attention, that's why I went with a mindtain exhaust, sound pretty close to normal up until about 4k, now my friends apexi n1 is alittle over the top

 

I'm not going to try and argue about "Hearing the power"... Everyone has their own opinion.

The real point of this thread is to show that you can have the power and STILL be relativly quiet. It's good to have options!

 

Speak softly and carry a big eccentric stick, baby.

 

Jerry,
Check out the picture & sound links in my sig.
Mazdatrix header kit $90
Cheap "turbo pac" silencers $40 x 2
Cheap bomb mufflers $20 x 2
Using the origonal Y pipe (cut), flanges & tips
All welded up by a local shop <$300 total.