Should I take my cats off?
09-03-11, 09:06 PM
#1
Full Member
Thread Starter
Should I take my cats off?
Just bought a 27,000 mile 93 RX7 with some mods.....K+N cold air induction, Blitz intercooler (not a lower front mount), Blow off valve, and Dragger Muffler. Had the compression checked and it's great, came in at above 115. The car is not loud enough and would like more power. I was going to put a down pipe and get rid off all the Cats and leave the Dragger muffler on. I was told that if I did that I would need to get the car tuned and add an aftermarket computer to piggy back the factory Ecm. I was also told NOT to run over 10 psi of boost because the motor won't last. So I would like some input on that. Also I went on youtube and listened to some cars with upgraded exhuast and they actually sounded kind of crappy. Any suggestions on removing the Cats and straight piping it (which my local muffler shop can make the pipes for me) or should I buy some type of name brand? Also will removing the Cats cause the boost to be too high?? Thanks in advance! Bill
09-03-11, 09:16 PM
#2
The point about not running over 10psi is good safe advice. Remove the upper cat and install a downpipe. Leave the main cat. Install a boost gauge. Make sure it's still at 10psi. If it's not, install a boost controller and set it to 10psi.
Straight piping is the kind of modification that can lead to excessive boost and make your compression go from 115 to 15. That's why it's best to leave the main cat.
After you get the car running well and you know your boost level, you can consider your next mod.
David
Straight piping is the kind of modification that can lead to excessive boost and make your compression go from 115 to 15. That's why it's best to leave the main cat.
After you get the car running well and you know your boost level, you can consider your next mod.
David
09-03-11, 09:17 PM
#3
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you mean you have the little stock mount blitz intercooler?
I personally run an air pump and I have an aftermarket cat from rx7.com and a downpipe
you defiintely need a downpipe, because that precat can damage the vacuum lines
but there is no reason for you to contribute to smog if you don't have to
you are not pushing enough power to warrant removing the emissions, that's just my opinion
so what I would do, is get a greddy profec B boost controller and a downpipe
if you can afford it, get the rx7.com cat as well
and if you still have money to blow, get a power FC and a larger intercooler
a Vmount you can buy here in the groupbuy section for 1250$ supposed to be very reasonable
but, before you get a new intercooler, you must get a boost controller or PFC
edit:
btw, some guy on the WTB forum was paying money for used stock cats, so you might be able to get some money back as well
I personally run an air pump and I have an aftermarket cat from rx7.com and a downpipe
you defiintely need a downpipe, because that precat can damage the vacuum lines
but there is no reason for you to contribute to smog if you don't have to
you are not pushing enough power to warrant removing the emissions, that's just my opinion
so what I would do, is get a greddy profec B boost controller and a downpipe
if you can afford it, get the rx7.com cat as well
and if you still have money to blow, get a power FC and a larger intercooler
a Vmount you can buy here in the groupbuy section for 1250$ supposed to be very reasonable
but, before you get a new intercooler, you must get a boost controller or PFC
edit:
btw, some guy on the WTB forum was paying money for used stock cats, so you might be able to get some money back as well
09-03-11, 09:17 PM
#4
Welcome to the world of rotaries and congrats on scoring such a low mileage fd!
There's a couple of things to know about this,
The very first thing you should do before anything is buy an Apexi Power FC
You need this because you are running on the factory ecu which runs the car lean
Once you have the apexi in, then go ahead and get a down pipe...if you want to replace the secondary cat, you'll have to get either a high flow cat mid pipe, or a mid pipe with a muffler in it. your waste gate isn't ported so you can't install a straight through mid pipe
As for the sounds of a rotary, you gota understand that the high pitched scream of a rotary is an amazing sound that has been tarnished because of all the rice rocket hondas that put on fart cans for mufflers
The sound of a rotary is backed up by alot, so let her scream man, cus she's going to whether you like it or not lolol
There's a couple of things to know about this,
The very first thing you should do before anything is buy an Apexi Power FC
You need this because you are running on the factory ecu which runs the car lean
Once you have the apexi in, then go ahead and get a down pipe...if you want to replace the secondary cat, you'll have to get either a high flow cat mid pipe, or a mid pipe with a muffler in it. your waste gate isn't ported so you can't install a straight through mid pipe
As for the sounds of a rotary, you gota understand that the high pitched scream of a rotary is an amazing sound that has been tarnished because of all the rice rocket hondas that put on fart cans for mufflers
The sound of a rotary is backed up by alot, so let her scream man, cus she's going to whether you like it or not lolol
09-03-11, 10:13 PM
#5
Full Member
Thread Starter
The point about not running over 10psi is good safe advice. Remove the upper cat and install a downpipe. Leave the main cat. Install a boost gauge. Make sure it's still at 10psi. If it's not, install a boost controller and set it to 10psi.
Straight piping is the kind of modification that can lead to excessive boost and make your compression go from 115 to 15. That's why it's best to leave the main cat.
After you get the car running well and you know your boost level, you can consider your next mod.
David
Straight piping is the kind of modification that can lead to excessive boost and make your compression go from 115 to 15. That's why it's best to leave the main cat.
After you get the car running well and you know your boost level, you can consider your next mod.
David
09-03-11, 10:16 PM
#6
Full Member
Thread Starter
you mean you have the little stock mount blitz intercooler?
I personally run an air pump and I have an aftermarket cat from rx7.com and a downpipe
you defiintely need a downpipe, because that precat can damage the vacuum lines
but there is no reason for you to contribute to smog if you don't have to
you are not pushing enough power to warrant removing the emissions, that's just my opinion
so what I would do, is get a greddy profec B boost controller and a downpipe
if you can afford it, get the rx7.com cat as well
and if you still have money to blow, get a power FC and a larger intercooler
a Vmount you can buy here in the groupbuy section for 1250$ supposed to be very reasonable
but, before you get a new intercooler, you must get a boost controller or PFC
edit:
btw, some guy on the WTB forum was paying money for used stock cats, so you might be able to get some money back as well
I personally run an air pump and I have an aftermarket cat from rx7.com and a downpipe
you defiintely need a downpipe, because that precat can damage the vacuum lines
but there is no reason for you to contribute to smog if you don't have to
you are not pushing enough power to warrant removing the emissions, that's just my opinion
so what I would do, is get a greddy profec B boost controller and a downpipe
if you can afford it, get the rx7.com cat as well
and if you still have money to blow, get a power FC and a larger intercooler
a Vmount you can buy here in the groupbuy section for 1250$ supposed to be very reasonable
but, before you get a new intercooler, you must get a boost controller or PFC
edit:
btw, some guy on the WTB forum was paying money for used stock cats, so you might be able to get some money back as well
09-03-11, 10:20 PM
#7
Full Member
Thread Starter
Welcome to the world of rotaries and congrats on scoring such a low mileage fd!
There's a couple of things to know about this,
The very first thing you should do before anything is buy an Apexi Power FC
You need this because you are running on the factory ecu which runs the car lean
Once you have the apexi in, then go ahead and get a down pipe...if you want to replace the secondary cat, you'll have to get either a high flow cat mid pipe, or a mid pipe with a muffler in it. your waste gate isn't ported so you can't install a straight through mid pipe
As for the sounds of a rotary, you gota understand that the high pitched scream of a rotary is an amazing sound that has been tarnished because of all the rice rocket hondas that put on fart cans for mufflers
The sound of a rotary is backed up by alot, so let her scream man, cus she's going to whether you like it or not lolol
There's a couple of things to know about this,
The very first thing you should do before anything is buy an Apexi Power FC
You need this because you are running on the factory ecu which runs the car lean
Once you have the apexi in, then go ahead and get a down pipe...if you want to replace the secondary cat, you'll have to get either a high flow cat mid pipe, or a mid pipe with a muffler in it. your waste gate isn't ported so you can't install a straight through mid pipe
As for the sounds of a rotary, you gota understand that the high pitched scream of a rotary is an amazing sound that has been tarnished because of all the rice rocket hondas that put on fart cans for mufflers
The sound of a rotary is backed up by alot, so let her scream man, cus she's going to whether you like it or not lolol
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09-04-11, 01:07 AM
#8
no special knowledge to install the Apex'i at all, plug and play installation, it simple replaces the stock ECU behind the passenger side kick panel
also do a search according to your region at the bottom of the forum home page for Apex'i tuners near to you...it is definitely worth it to take a trip and get the car properly tuned
poor tuning is the #1 reason why rotaries have gotten such a bad rap over the years
a well tuned rotary will give you less headaches than a piston engine, and a wholeeee lot more fun too
and it makes your life a hell of a lot easier if you buy an Apex'i with a commander
i would recommend buying one from rx7store.net...and then go to Autozone and buy exhaust header wrap (about $20) and wrap the downpipe
oh and one thing you also need to make sure you do is change your Air Separator Tank to an aluminum unit
and thanks a lot for complement man
they are Volk GT-U
sizes:
front- 18x9 (+34 offset)
rear- 18x10 (+44 offset)
also do a search according to your region at the bottom of the forum home page for Apex'i tuners near to you...it is definitely worth it to take a trip and get the car properly tuned
poor tuning is the #1 reason why rotaries have gotten such a bad rap over the years
a well tuned rotary will give you less headaches than a piston engine, and a wholeeee lot more fun too
and it makes your life a hell of a lot easier if you buy an Apex'i with a commander
i would recommend buying one from rx7store.net...and then go to Autozone and buy exhaust header wrap (about $20) and wrap the downpipe
oh and one thing you also need to make sure you do is change your Air Separator Tank to an aluminum unit
and thanks a lot for complement man
they are Volk GT-U
sizes:
front- 18x9 (+34 offset)
rear- 18x10 (+44 offset)
Does it take any special knowledge to install the Apexi Power FC, because there is nobody in my area that has a clue about these cars. What is involved with that install? Any input on those ebay downpipes that sell way less than $100.00?? Also you have to tell me what name brand and size wheels and tires are on your Silver RX7, they look amazing!! Thanks Bill
09-04-11, 09:08 AM
#10
Full Member
Thread Starter
09-04-11, 09:55 AM
#11
You don't need an Apexi PowerFC if your boost stays at 10 psi. If boost goes up you can dial it back down to 10psi with manual boost controllers, which are cheap. I went fancy with my manual boost controller (JoeP inlines) and spent only $80.
One thing to watch for is boost at 4500rpm. If it spikes higher at 4500, install the manual boost controllers.
With the muffler and intercooler I'd guess you're on the border if you install just the downpipe. If you take out the cat too you'll certainly have major changes in boost to deal with.
One thing to watch for is boost at 4500rpm. If it spikes higher at 4500, install the manual boost controllers.
With the muffler and intercooler I'd guess you're on the border if you install just the downpipe. If you take out the cat too you'll certainly have major changes in boost to deal with.
09-04-11, 10:57 AM
#12
Full Member
Thread Starter
You don't need an Apexi PowerFC if your boost stays at 10 psi. If boost goes up you can dial it back down to 10psi with manual boost controllers, which are cheap. I went fancy with my manual boost controller (JoeP inlines) and spent only $80.
One thing to watch for is boost at 4500rpm. If it spikes higher at 4500, install the manual boost controllers.
With the muffler and intercooler I'd guess you're on the border if you install just the downpipe. If you take out the cat too you'll certainly have major changes in boost to deal with.
One thing to watch for is boost at 4500rpm. If it spikes higher at 4500, install the manual boost controllers.
With the muffler and intercooler I'd guess you're on the border if you install just the downpipe. If you take out the cat too you'll certainly have major changes in boost to deal with.
09-04-11, 11:43 AM
#13
The injectors and stock ECU do have mapping to support right up to 12psi, but that leaves no margin at all. The extra 2psi is padding to support minor boost control issues, so if you choose to use this you're taking more risk. This extra risk (less margin for error) is ok for some and not for others.
If you want to run more boost it is far more sensible IMHO to install mods that maintain or improve this cushion before going above 10psi.
If you want to run more boost it is far more sensible IMHO to install mods that maintain or improve this cushion before going above 10psi.
09-04-11, 12:21 PM
#14
Full Member
Thread Starter
The injectors and stock ECU do have mapping to support right up to 12psi, but that leaves no margin at all. The extra 2psi is padding to support minor boost control issues, so if you choose to use this you're taking more risk. This extra risk (less margin for error) is ok for some and not for others.
If you want to run more boost it is far more sensible IMHO to install mods that maintain or improve this cushion before going above 10psi.
If you want to run more boost it is far more sensible IMHO to install mods that maintain or improve this cushion before going above 10psi.
09-04-11, 12:50 PM
#15
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/
Pretty much everything you have asked is covered there. As for IMHO:
http://www.internetslang.com/IMHO-me...definition.asp
09-04-11, 01:02 PM
#16
Full Member
Thread Starter
Take a step back and read through the FAQ thread:
https://www.rx7club.com/showthread.php?t=68640
Pretty much everything you have asked is covered there. As for IMHO:
http://www.internetslang.com/IMHO-me...definition.asp
https://www.rx7club.com/showthread.php?t=68640
Pretty much everything you have asked is covered there. As for IMHO:
http://www.internetslang.com/IMHO-me...definition.asp
09-04-11, 02:19 PM
#17
At this point, information is your best modification. Search, read, learn... As mentioned, the FAQ thread is a great start.
You will learn quickly that fuel, ecu, cooling and instrumentation systems are very important on these cars.
Buy quality parts!.... You will save time, money and headache by staying away from knock-offs. Racingbeat makes quality exhaust parts.
You will learn quickly that fuel, ecu, cooling and instrumentation systems are very important on these cars.
Buy quality parts!.... You will save time, money and headache by staying away from knock-offs. Racingbeat makes quality exhaust parts.
09-04-11, 03:13 PM
#18
You can run 14 PSi (the reliable limit of the twins, engine can do more with the right stuff) and a full catless exhaust. However, in order to do this you have to do some things first.
You need to pull the twins off and port the internal wastegate. You need get an electronic boost controller like the Greddy Profec B Spec 2. If your still running the stock intercooler, that needs to be upgraded. You need to get a PowerFC and when the car is ready get it tuned by a professional ROTARY tuner like Steve Kan. You will be able to run catless and safe this way. You do not need an injector upgrade on a stock motor with stock twins but might need a fuel pump upgrade and fuel filter should be changed if it wasn't recently.
I might be forgetting something so just use that as a baseline minimum. And yes all that costs money but that is the name of the game if you want to keep your motor happy.
Edit - If you want to get rid of your air pump, just get the Greddy pullies for that or ebay knockoff of it (no harm in this). However, don't eliminate the air pump unless you have removed your cat or your cat won't last very long. Also, you won't feel a difference with this power wise.
thewird
You need to pull the twins off and port the internal wastegate. You need get an electronic boost controller like the Greddy Profec B Spec 2. If your still running the stock intercooler, that needs to be upgraded. You need to get a PowerFC and when the car is ready get it tuned by a professional ROTARY tuner like Steve Kan. You will be able to run catless and safe this way. You do not need an injector upgrade on a stock motor with stock twins but might need a fuel pump upgrade and fuel filter should be changed if it wasn't recently.
I might be forgetting something so just use that as a baseline minimum. And yes all that costs money but that is the name of the game if you want to keep your motor happy.
Edit - If you want to get rid of your air pump, just get the Greddy pullies for that or ebay knockoff of it (no harm in this). However, don't eliminate the air pump unless you have removed your cat or your cat won't last very long. Also, you won't feel a difference with this power wise.
thewird
09-04-11, 03:41 PM
#19
Full Member
Thread Starter
At this point, information is your best modification. Search, read, learn... As mentioned, the FAQ thread is a great start.
You will learn quickly that fuel, ecu, cooling and instrumentation systems are very important on these cars.
Buy quality parts!.... You will save time, money and headache by staying away from knock-offs. Racingbeat makes quality exhaust parts.
You will learn quickly that fuel, ecu, cooling and instrumentation systems are very important on these cars.
Buy quality parts!.... You will save time, money and headache by staying away from knock-offs. Racingbeat makes quality exhaust parts.
09-04-11, 03:45 PM
#20
Full Member
Thread Starter
You can run 14 PSi (the reliable limit of the twins, engine can do more with the right stuff) and a full catless exhaust. However, in order to do this you have to do some things first.
You need to pull the twins off and port the internal wastegate. You need get an electronic boost controller like the Greddy Profec B Spec 2. If your still running the stock intercooler, that needs to be upgraded. You need to get a PowerFC and when the car is ready get it tuned by a professional ROTARY tuner like Steve Kan. You will be able to run catless and safe this way. You do not need an injector upgrade on a stock motor with stock twins but might need a fuel pump upgrade and fuel filter should be changed if it wasn't recently.
I might be forgetting something so just use that as a baseline minimum. And yes all that costs money but that is the name of the game if you want to keep your motor happy.
Edit - If you want to get rid of your air pump, just get the Greddy pullies for that or ebay knockoff of it (no harm in this). However, don't eliminate the air pump unless you have removed your cat or your cat won't last very long. Also, you won't feel a difference with this power wise.
thewird
You need to pull the twins off and port the internal wastegate. You need get an electronic boost controller like the Greddy Profec B Spec 2. If your still running the stock intercooler, that needs to be upgraded. You need to get a PowerFC and when the car is ready get it tuned by a professional ROTARY tuner like Steve Kan. You will be able to run catless and safe this way. You do not need an injector upgrade on a stock motor with stock twins but might need a fuel pump upgrade and fuel filter should be changed if it wasn't recently.
I might be forgetting something so just use that as a baseline minimum. And yes all that costs money but that is the name of the game if you want to keep your motor happy.
Edit - If you want to get rid of your air pump, just get the Greddy pullies for that or ebay knockoff of it (no harm in this). However, don't eliminate the air pump unless you have removed your cat or your cat won't last very long. Also, you won't feel a difference with this power wise.
thewird
09-04-11, 03:53 PM
#22
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Thread Starter
Alright, then that is what I will do! Thanks again!
09-04-11, 03:54 PM
#23
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I am not sure where you live, but rx7world.net is in south carolina
anyway, I dont know what a dragger muffler is, but if you just want to change the sound there are different mufflers to choose from
anyway, I dont know what a dragger muffler is, but if you just want to change the sound there are different mufflers to choose from
09-04-11, 04:04 PM
#24
Full Member
Thread Starter
I am in Myrtle Beach, does rx7 world tune and work on these cars or are they just an internet source for parts??
