Gotta build my exhaust tomorrow but i need hint before.. help!
01-29-10, 11:34 PM
#1
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Gotta build my exhaust tomorrow but i need hint before.. help!
Either tomorrow or sunday i'm going to change my exhaust. To make things easy and quick.. i will get header later.. right now i will stick with thermal reactor. Two options are open for me.
1. leaving stock piping and heat exchanger..after heat exchanger a 22" louvered glasspack (used) and on place of stock muffler a round can ( 12" by 4"..also used)
2. from thermal reactor 2.25 straight pipe to stock muffler (removing heat exchanger and those 2 pipes) --> A. the small pipe from reactor all the way back next to the muffler which i think is for backfires and --> B. the pipe coming from the bottom of the carb going right after the heat exchanger)
I want to know how they will sound and gains on both.. and if number 1 will last.. cuz i know i will burn those mufflers fast.
If i go for number 2.. the pipe from carb to heat exchanger i just take it off and cover it with??? and the pipe coming from thermal reactor to next to my muffler cut it and make it all one exhaust pipe?? then i would have no backfire no more??
Hopefully i'm clear.. let me know guys.. and thx again!!
P.S i know that stock muffler won't burn or nothing.. the other ones will..i still have that in mind
1. leaving stock piping and heat exchanger..after heat exchanger a 22" louvered glasspack (used) and on place of stock muffler a round can ( 12" by 4"..also used)
2. from thermal reactor 2.25 straight pipe to stock muffler (removing heat exchanger and those 2 pipes) --> A. the small pipe from reactor all the way back next to the muffler which i think is for backfires and --> B. the pipe coming from the bottom of the carb going right after the heat exchanger)
I want to know how they will sound and gains on both.. and if number 1 will last.. cuz i know i will burn those mufflers fast.
If i go for number 2.. the pipe from carb to heat exchanger i just take it off and cover it with??? and the pipe coming from thermal reactor to next to my muffler cut it and make it all one exhaust pipe?? then i would have no backfire no more??
Hopefully i'm clear.. let me know guys.. and thx again!!
P.S i know that stock muffler won't burn or nothing.. the other ones will..i still have that in mind
01-30-10, 11:41 AM
#2
No sense in doing an exhaust to your thermal reactor, when you are planning to get a header
later. Like taking 2 steps forward but 1 back. The header is designed to bolt up to a presilencer,
then to our stock exhaust (if you go the RB route).It will cost the same either way,
and the header will net you more HP gains than the thermal back.
Do some research on what mufflers will work on a rotary, the glasspacks will crap on you
ASAP. I can bet that from your first install, and a 20 minute drive home, your exhaust will
NOT sound the same. Viva la Borla!
later. Like taking 2 steps forward but 1 back. The header is designed to bolt up to a presilencer,
then to our stock exhaust (if you go the RB route).It will cost the same either way,
and the header will net you more HP gains than the thermal back.
Do some research on what mufflers will work on a rotary, the glasspacks will crap on you
ASAP. I can bet that from your first install, and a 20 minute drive home, your exhaust will
NOT sound the same. Viva la Borla!
01-30-10, 12:02 PM
#3
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#2 is better, but you won't gain much hp, restriction is likely to be the reactor
01-30-10, 01:14 PM
#4
If you must replace your exhaust in sections, you're better off starting at the front instead of the rear.
Mount headers and pitch the TR and air pump, and seal the two ports. You may have to add a flange and short pipe to connect the headers to the existing exhaust but you'll have better horsepower and performance. Plus that change will give you a slightly better sound through your stock muffler.
Later, when you decide which muffler you want, you'll have to add the center section to connect everything.
Of course, doing it all at the same time is the prefered route, but sometimes you don't have the choice.
Mount headers and pitch the TR and air pump, and seal the two ports. You may have to add a flange and short pipe to connect the headers to the existing exhaust but you'll have better horsepower and performance. Plus that change will give you a slightly better sound through your stock muffler.
Later, when you decide which muffler you want, you'll have to add the center section to connect everything.
Of course, doing it all at the same time is the prefered route, but sometimes you don't have the choice.
01-30-10, 06:15 PM
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If you must replace your exhaust in sections, you're better off starting at the front instead of the rear.
Mount headers and pitch the TR and air pump, and seal the two ports. You may have to add a flange and short pipe to connect the headers to the existing exhaust but you'll have better horsepower and performance. Plus that change will give you a slightly better sound through your stock muffler.
Later, when you decide which muffler you want, you'll have to add the center section to connect everything.
Of course, doing it all at the same time is the prefered route, but sometimes you don't have the choice.
Mount headers and pitch the TR and air pump, and seal the two ports. You may have to add a flange and short pipe to connect the headers to the existing exhaust but you'll have better horsepower and performance. Plus that change will give you a slightly better sound through your stock muffler.
Later, when you decide which muffler you want, you'll have to add the center section to connect everything.
Of course, doing it all at the same time is the prefered route, but sometimes you don't have the choice.
i think the only muffler that would resist a lilttle bit more the heat and pulses from a rotary are magnaflows..and cherrybomb vortex muffler (not the glasspack) any other ideas for low budget??.. but i want to know if that vortex muffler has the same glass inside as the glasspack..if it does then it might get burned....my future setup if i wait would be headers to a single 2 1/4 pipe..2 18" resonators and an oval dual tip muffler.. wonder how would it sound.
Last edited by 79blue_killer; 01-30-10 at 06:30 PM.
02-02-10, 02:22 PM
#6
I have a 1980 RX7 and basically rebuilt the exhaust in sections too, because it was rotting away. Finished the last modifications this weekend. Here's what I have:
RB road race headers, connected to custom made dual pipe mid-section, connected to RB Power Pulse street port dual inlet muffler. No presilencers. Car is quick and runs good.
First remove the air pump completely. Mine had it's own belt so nothing else was affected and I didn't have to modify any pully or belts.
Disconnect the exhaust pipe from the thermal reactor (TR).
Remove the heat shield and remove the thermal reactor.
4 bolts hold the thermal reactor and the top rear is a PITA. Mazda has a special tool to remove it, or else you can use an articulated elbow and shortened socket. Expect to use a lot of cussing to make the job go easier.
After removing the thermal reactor, there are two openings that you must cover with brass plates. I forget what they're called, but you just close them off. It has something to do with the air mixture that the pump is circulating through the thermal reactor. Since you won't have a thermal reactor and won't be pumping any air the passages are unnecessary. Ask for them from RB when you order your headers.
Block off any vacume hoses that went to the thermal reactor because you won't need them either. Leave the exhaust ports open because they'll feed into the header.
The following link will take you to a thread that I started when I had to re-do my exhaust and remove the thermal reactor.
https://www.rx7club.com/showthread.p...hermal+reactor
As far as the original center section is concerned, disregard that small pipe. It'll be worthless without the TR so you can cut it off if you want.
I don't think headers will mate with the original exhaust flange because of the bend that went up to the TR. So you'll probably have to cut the exhaust pipe and weld on a section with the proper flange to mate with the headers.
Something you should know about the stock exhaust pipe. It's double walled and getting something to weld onto it may be tricky. Mine was coming apart and welding patches didn't work too well. So you may be better off replacing the whole mid-section when you add the headers.
Another thing...the exhaust is real hot so RB recommends the heavier 1/8th inch walled pipe they sell versus the standard exhaust pipe. When I replaced my center section, I didn't install any presilencers, so I was short pipe when I ordered from RB. Therefore, I had to use two foot long regular pipes (dual exhaust remember) at the rear where it bolts to the muffler intake.
I could really hear the difference when I got on the throttle. When the exhaust passed through that section it changed pitch and sounded like bumble bees. This weekend's projection was completely replacing the center section with the proper pipe all the way. Sounds good and runs good.
You'll notice a big difference without your exhaust going through the TR. Plus you'll lose the weight of the TR and air pump, and you won't have the air pump pully syphoning power from the engine.
When you get done, you may or may not have to tweak your idle mixture and idle speed slightly. Not hard to do and just takes a screwdriver.
Good luck.
RB road race headers, connected to custom made dual pipe mid-section, connected to RB Power Pulse street port dual inlet muffler. No presilencers. Car is quick and runs good.
First remove the air pump completely. Mine had it's own belt so nothing else was affected and I didn't have to modify any pully or belts.
Disconnect the exhaust pipe from the thermal reactor (TR).
Remove the heat shield and remove the thermal reactor.
4 bolts hold the thermal reactor and the top rear is a PITA. Mazda has a special tool to remove it, or else you can use an articulated elbow and shortened socket. Expect to use a lot of cussing to make the job go easier.
After removing the thermal reactor, there are two openings that you must cover with brass plates. I forget what they're called, but you just close them off. It has something to do with the air mixture that the pump is circulating through the thermal reactor. Since you won't have a thermal reactor and won't be pumping any air the passages are unnecessary. Ask for them from RB when you order your headers.
Block off any vacume hoses that went to the thermal reactor because you won't need them either. Leave the exhaust ports open because they'll feed into the header.
The following link will take you to a thread that I started when I had to re-do my exhaust and remove the thermal reactor.
https://www.rx7club.com/showthread.p...hermal+reactor
As far as the original center section is concerned, disregard that small pipe. It'll be worthless without the TR so you can cut it off if you want.
I don't think headers will mate with the original exhaust flange because of the bend that went up to the TR. So you'll probably have to cut the exhaust pipe and weld on a section with the proper flange to mate with the headers.
Something you should know about the stock exhaust pipe. It's double walled and getting something to weld onto it may be tricky. Mine was coming apart and welding patches didn't work too well. So you may be better off replacing the whole mid-section when you add the headers.
Another thing...the exhaust is real hot so RB recommends the heavier 1/8th inch walled pipe they sell versus the standard exhaust pipe. When I replaced my center section, I didn't install any presilencers, so I was short pipe when I ordered from RB. Therefore, I had to use two foot long regular pipes (dual exhaust remember) at the rear where it bolts to the muffler intake.
I could really hear the difference when I got on the throttle. When the exhaust passed through that section it changed pitch and sounded like bumble bees. This weekend's projection was completely replacing the center section with the proper pipe all the way. Sounds good and runs good.
You'll notice a big difference without your exhaust going through the TR. Plus you'll lose the weight of the TR and air pump, and you won't have the air pump pully syphoning power from the engine.
When you get done, you may or may not have to tweak your idle mixture and idle speed slightly. Not hard to do and just takes a screwdriver.
Good luck.
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