3rd Generation Specific (1993-2002) 1993-2002 Discussion including performance modifications and Technical Support Sections.
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Old 12-13-02, 02:09 AM
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ttb
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by no means am i an expert...just from reading numerous threads it seems that the "10psi rule" is the most consistent one i've seen. there was a guy that did all this fancy testing and it was posted on his site somewhere. obviously if you start getting an intake, cb, dp, mp then you're boost is not going to be 10psi anymore. i would say that's the danger. i don't think ecu is a "reliability" mod bc probably more often than not it's people thinking "oh i got a new ecu, now i can do all kinda stuff to it" and then kaboom.
Old 12-13-02, 02:17 AM
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http://www.newwave.net/~flanham/wlan.../3modrule.html


"I've tested a few cars and I would like to test even more with a variety of modifications. My conclusion is as long as a the car has nothing wrong with it, there should be plenty of fuel with the stock ECU to support *several* modifications while still keeping a relatively conservative a:f ratio, as long as boost is kept within the fuel cut (or about 10psi). Those who want to run slightly more boost (such as 12-14 psi) could probably get away with using only a Fuel Cut Defender"
Old 12-13-02, 09:33 AM
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I posted this on one of the other "im lookin' for a 7' posts". Here is my take on it. Grab some popcorn, it could be a while...

It depends on what you want to do with the car. Regardless of any of the **** you are going to hear on this forum, most of it is just that ****. There are some very knowledgeable people on this forum, but very few have ANY evidence to back up any claim they made. We hear every day that you need to get a new ECU of you do any air mods ...or if you do 3 mods. Just for reference the 3 mod rule is crap. I have seen RX7's on the dyno that hadcatback's, dp, etc, they run rich, very rich without a new ECU..

This is a very special car that requires somewhat special attention, but its not the bitch that everyone says it is. let me make life simple for you. Read as much as you can on this forum. This forum is INVALUABLE and you can learn alot. Unfortunately the forum has alot of mis-information too. The bottom line is that nobody wants to spend the time or the money to test these theory's so it ends up being speculation. Nobody on this forum can ever give 1 shred of proof that an ECU is required when begin to mod the car. Lets take a look at why you need an ECU. the only reason is for fuel reasons. Well guess what? You can get a boost controller relatively cheap and keep it at 10 PSI and you mod the hell out of your car. Actually you can do ANYTHING to you car (except additional injectors or single turbo) without the need of an aftermarket ecu, nobody can prove me wrong.

next, lets look at the fuel issue. On one hand you have a group that says the stock injectors are good for 360 rwhp, others say 12 lbs boost max. You have one group that says the injectors will max out and fail BEFORE the fuel pump ever will. Others say you need to upgrade the fuel pump to get the max benefit of the injectors (even stock). I say thats a bunch of crap too. Unless you are putting greater than 310 HP to the wheels ( and some say 360, like I said NOBODY really knows for sure) you don't need new injectors/fuel pump. Basically, if you get a new fuel pump/injectors you need an ecu, if you get a power FC you can see your duty cycle, if it stays below 85 pct, you should be fine.

Now lets take alook at the mid pipe issue...everyone told me that fuel smell will be unbearable and so will the noise. They said I will spike and EVERYONE says you WILL get boost creep without a boost controller unless you get a ported waste-gate. Guess what? My midpipe spikes (so did my highflow cat) none of the other issues came to bear. Sure its loud, but from inside the car its not that noticeable (outside the car is). The fuel smell is hardly and issue, sometimes idling you smell it, most of the time you don't. Boost creep? What a joke. My after my transition spike it holds to the redline with what I set my power FC too.

now lets tackle the idea of "Reliablilty Mods". I replaced my stock radiator with a KOYO. My stock radiator had 140K miles at the time, while it had not problems I wanted the largest radiator I can get. I have had so many problems with things not fitting, radiator fans dying, intercoolers not fitting corretly, etc cause of the size of the radiator. To do it over again, I may have left it stock. I guess I don't have to worry about the plastic endtanks breaking on the koyo though. Ok, so now we are at the downpipe. I think this is a great and inexpensive mod. After you get alot of miles on your car, your precat may get clogged, the downpipe never will. For what its worth, my precat had 133K when I replaced it and was not clogged.

So back to the orignal point of my post, it depends what you want to do with the car. If you want to race it and get max HP, yes you need to replace all the things you mentioned, Injectors, fuelpump, ecu, downpipe, cat, catback, intake, etc. But if you are just looking for reliability, you need only do a few. The plastic AST does tend to break and in my opinion is the most important. But again, half the people on this forum say to eliminate it. Yet the rest of us wonder why it is that mazda put the damn thing on the 787B AND on the RX7 when they tried to keep the weight and cost down on the car. Of the ones that want to replace it with a metal one, someone brain surgeon theorizes that the shape is like a coke can and not square like the stock one, so there is no practicle purpose for the metal one other than it will not break like the plastic one. This is a vicious circle with no end in site. What you are left with is nothing but speculation and very little facts to back any of this up. If you want the car for a daily driver its easy, I use mine every day, its my only car. Just do the few reliablilty mods I mentioned and you will be fine. If you want to use it as a daily driver or goto the track like I do, then do the other upgrades too, its costly but you get a great fun car.

Last edited by ZeroBanger; 12-13-02 at 09:35 AM.
Old 12-13-02, 11:01 AM
  #29  
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Originally posted by Mazderati


You are by all means entitled to whatever conclusion you come to. I, however, disagree with your statement regarding the boost pressure and lean run condition.

By your statement, that would mean that the 3rd generation RX-7, or many other cars, could have attatched anything as long as the boost pressure did not exceed 10 psi. If this were so, that would mean that a full open exhaust, huge intercooler, air intake, ported throttle bodies and intake and everything else that will lean out the stock computer could be used with no problems as long as 10 psi of boost was not exceeded? If boost pressure is the only concern, could the statement be taken to the extreme and a single turbo put onto the motor and ran successfully via the stock comptuer? Obviously not. I don't think you will find many people who have delt with rotary motors, or any motor really, that will agree with the above.

Some persons might even suggest that a computer is the best modification that can be done to the car whether stock or modified.

It's your car, your time, your money and your choice. I would, however, guard against a "10 psi is safe no matter what" method of doing things.

Good luck.

Kyle
Well, you are entitled to your opinion, even if it's wrong. Check out the link that TTB gave you. Wade has done extensive testing with a wideband and different mod levels. Even with all the bolt-ons and a streetport, the A/F ratio was still safe at 10 psi. My own tests on my car have borne this out as well. With a downpipe and cat-back, I'm still below 10:1 A/F ratio from transition to 7500 rpm at which point it goes up to 10.2:1.

All that said, I wouldn't run a midpipe or streetport on the stock ecu because those mods require timing changes and the midpipe has a tendency to create boost spikes and creep. But yes, you could run an intake, downpipe, cat-back, intercooler, and probably a hi-flow cat on the stock ecu if you limited boost to 10 psi and eliminated large spikes at the transition.

You really shouldn't contradict other people's real world evidence without providing some legitimate evidence to back your statements up.....
Old 12-13-02, 11:04 AM
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Originally posted by rynberg


Well, you are entitled to your opinion, even if it's wrong. Check out the link that TTB gave you. Wade has done extensive testing with a wideband and different mod levels. Even with all the bolt-ons and a streetport, the A/F ratio was still safe at 10 psi. My own tests on my car have borne this out as well. With a downpipe and cat-back, I'm still below 10:1 A/F ratio from transition to 7500 rpm at which point it goes up to 10.2:1.

All that said, I wouldn't run a midpipe or streetport on the stock ecu because those mods require timing changes and the midpipe has a tendency to create boost spikes and creep. But yes, you could run an intake, downpipe, cat-back, intercooler, and probably a hi-flow cat on the stock ecu if you limited boost to 10 psi and eliminated large spikes at the transition.

You really shouldn't contradict other people's real world evidence without providing some legitimate evidence to back your statements up.....
I was there when rynberg dynoed his car so I can vouch for this.
Old 12-13-02, 02:01 PM
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Originally posted by rynberg


Well, you are entitled to your opinion, even if it's wrong. Check out the link that TTB gave you. Wade has done extensive testing with a wideband and different mod levels. Even with all the bolt-ons and a streetport, the A/F ratio was still safe at 10 psi. My own tests on my car have borne this out as well. With a downpipe and cat-back, I'm still below 10:1 A/F ratio from transition to 7500 rpm at which point it goes up to 10.2:1.

All that said, I wouldn't run a midpipe or streetport on the stock ecu because those mods require timing changes and the midpipe has a tendency to create boost spikes and creep. But yes, you could run an intake, downpipe, cat-back, intercooler, and probably a hi-flow cat on the stock ecu if you limited boost to 10 psi and eliminated large spikes at the transition.

You really shouldn't contradict other people's real world evidence without providing some legitimate evidence to back your statements up.....
You're right about the fact that I'm not going to take a $5,000 chance at leaning my car out. I tend to think safe is better then sorry.

I suppose not only am I wrong for looking out for running lean but Pettit, M2, Rotary Performance and the vast majority of other RX-7 tuners out there are also wrong. These companies, and many others, wouldn't sell and promote computers like they do if the stock computer was up to the task.

If things such as boost spiking, lean run conditions and the stock computer not being able to handle listed breathing modifications, how in the world did they come about? Someone with too much time on their hands?

Kyle
Old 12-13-02, 03:16 PM
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Those chips were invented for one purpose -- running higher levels of boost than stock. I can scan my dyno plot again and you can see my A/F numbers for yourself. Also, Wade's results are all on his website.

I'm not saying that getting an aftermarket ecu is a bad thing, just that it's not absolutely necessary if you restrict boost to 10 psi. Personally, if everyone had access to a good tuner, I think that getting a PFC right away and tuning it to the car would be a great first mod. However, few of us live near a good tuner (there's only a couple) and tune-by-mail does NOT work. Also, just because you have an aftermarket ecu, doesn't mean that you are safe. Many people have popped motors on Pettit ecus or PFCs.

You seem to be very concerned about running lean in your posts. Again, look at the data. The stock ecu runs PIG rich. There is plenty of room to add more breathing, as long as you stay at 10 psi.
Old 12-13-02, 04:42 PM
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Well, I own a 94 and I would have to say that they have just as much issues as 93s do...and I am sure you could buy a 95 and it be as bad off as a 95...what it boils down to is that these cars are used and it's hard to find one that has been taken care of and in good shape..

If I had to do it over again I would have bought that 95 I found with no engine and no transmission for 9k, then spend about 5-6k on an engine on mods...this way you know exactly where they car is coming from...I bought my 94 Silver R2 for 17k and have spent 7k on it already in reliability and a few mods and still I don't have that proted motor that I want...after that goes in it will be another 4k...so at the end of it all I would have spent 28k on the car listed in my sig below with a ported motor...If I had done it the other way I would have saved myslef a bunch of cash...it gets expensive fast
Old 12-13-02, 04:43 PM
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this sig below
Old 12-13-02, 10:39 PM
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Note: M2 recommends reprogramming of the ECU when 2 or more modifications have been performed on either the intake or exhaust paths (i.e., aftermarket airbox & catback necessitates ECU reprogramming to adjust fuel & timiming curves to accommodate the increase in horsepower).

The above was taken from Mostly Mazda's site regarding their ECU modification. But what would they know...

Kyle
Old 12-13-02, 10:43 PM
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Originally posted by Mazderati
Note: M2 recommends reprogramming of the ECU when 2 or more modifications have been performed on either the intake or exhaust paths (i.e., aftermarket airbox & catback necessitates ECU reprogramming to adjust fuel & timiming curves to accommodate the increase in horsepower).

The above was taken from Mostly Mazda's site regarding their ECU modification. But what would they know...

Kyle
yea they don't have any vested interest in selling an ECU. Good point!
Old 12-13-02, 11:58 PM
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Arrow Dude, good advice

If nothing else, you just want a base car that is in good mechanical shape. The modifications make it a million times more difficult to tell if there is something wrong with the car. As for year, the differencs are very mild for 93, 94, 95 if all the recalls are done. 93 does have the most issues but if you get a good one for cheap, there is no reason to say no just because of the year.

I picked up a 93 TT FD, been an econimcal nightmare for 6 months dealing with all the crap going wrong.

These cars are very expensive so a little up front to get a car that has been well maintained and is mechanically sound will go a long way later on.

Best advice is to read the newby sticky link on purchasing an FD and take to heart that part about having someone check the engine mechanical out. If nothing else you can deal with the rest so long as the engine mechanical is OK.

With respect to the type of car to buy, just don't get an automatic, that will lock you out of a number of great upgrades. That and not having the turbos will require a very heafty initial investment to get the mechanical infrastrucutre in there to support it.

Sure that this is nothing more then everyone else has already said so good luck and hope you pick a winner!!


As for upgrades, I do strongly recommend the DP from the stock system, get that pre-cat out before a fire starts. Intake is good but tool around with it to make sure all the critical stuff is working right first before modifying your stuff up. The AST plastic tank, if its new it won't be an issue, if its more the a few years old, replace it. Recommend the Billit one rather then the aluminum one. Cost is a fraction higher but the payoff will be the filler neck not leaking after a few years.

Last edited by shred; 12-14-02 at 12:03 AM.
Old 12-14-02, 02:30 AM
  #38  
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Originally posted by Mazderati
Note: M2 recommends reprogramming of the ECU when 2 or more modifications have been performed on either the intake or exhaust paths (i.e., aftermarket airbox & catback necessitates ECU reprogramming to adjust fuel & timiming curves to accommodate the increase in horsepower).

The above was taken from Mostly Mazda's site regarding their ECU modification. But what would they know...

Kyle
and they never tell you how much boost they're running huh?
Old 12-14-02, 02:59 AM
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The main problem is having more than 2 mods causes you to overboost, which WILL blow the motor, thats why vendors recommend to upgrade the ECU (and to make money ). However, another option is to get a boost controller and keep it at 10psi or under. Now, if you upgraded the turbos and have a street ported engine, thats really pushing it, but repeatable, overwhelming evidence has shown that minor bolt-ons (NOT turbos), such as IC, dp, cb, intake, run at 10psi (this requires some form of boost control, pills, needle valve, profec, etc) and you are fine with the stock ecu. Now, back to the original question, another great reliability mod is the CWR dua oil coolers. In general, cool=reliability. Cool oil, cool intake charge, cool water temps. Heat kills the car, bottom line. Cermaic coat the dp, get dual oil coolers, run low boost, thats the key to longevity. An ideal setup would also include a nice IC, cold-air intake, y-pipe, basically free up the breathing, then run low boost on top of that, say 8psi, which is lower than stock. The flow mods will compensate for the lower boost so you'll still end up ahead power-wise, and the engine will last longer. Also a vented hood won't hurt either.
Old 12-14-02, 03:02 AM
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There isn't any point in arguing over which is or isn't better regarding the computer issue. Some of you all have formed an opinion as have I. I'll stand by my statements and will continue to regard an engine managment upgrade as one of, if not the, most important modifications that can be applied to the 3rd generation RX-7.

Kyle
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