m0t03

I live in MN, so my car is stored right now. I bought my FD in late summer and I am planning on putting on mods over the winter. I only have a turbo timer installed. Sitting in my room I have a Blitz catback exhaust Pettit downpipe a Blitz blowoff valve and I should be getting some Greddy pulleys. My question is I've been wanting to get a midpipe. I was just wondering what other mods you should have before installing one. I know a new ECU, I was thinking about the Pettit ECU. Any recomondations? The PFC is a little spendy. Do you need to port your wastegate, with a mispipe? How much does that cost? Everyone running midpipes what mods do you have on your 7.

Mike

rx7eaven

I would go with a PFC, although they are more expensive they are much better imo. I have the pettit and I am only so so happy with it. Midpipes run anywhere from $145 and up. I don't have a midpipe b/c of emissions and I don't want to have to worry too much about boost creep and spike.

Magnificent 7

Mods are listed in the sig. Cat-back is so new that I haven't had the opportunity check it our thoroughly for boost creep. I had what seemed like a little bit of boost creep (about a 1 psi rise to about 13) one time in 4th or 5th under load, but haven't been able to duplicate that. So I'm not sure. I would recommend porting the wastegate. It was easy for me in that I had it done to the new turbos during the engine swap. Good luck.

KZ1

PFC is cheaper than pettit, especially if you buy the commander. You don;t need any more gauges, no fan mod, you can get 200$ for the old ECU, Trust me the hacked up stock ECUs are crap, and not tunables. however it you hate having that responsability you don;t haev to tune the PFC either just don't get the commnander.

anyways, I think you are good to go, just get an Intake, and Intercooler. PFS or M2

kwikrx7

I agree about the PFC - it just seems to works very well with the 3rd gen. A lot of people run midpipes and love them. I had one and hated it. The car was louder than 4 harleys, smelled like a truck stop and I had no low-end power until I got to 6K rpms, then it pulled hard. I switched it out to a hi-flo cat. It was much quieter, the smell of gas went away, and my turbos spooled much quicker and I had more low end power. Midpipes are tough to tune for perfectly and on a cold night you can have boost problems. Also, a hi-flo cat can protect your car more over a midpipe if you somehow get a bad tank of gas - less chance of detonation. Just my 2 cents and experience with the 2.

Pressurized

Go for the midpipe then. All you really need is the ECU, then you'll just have to test the midpipe out on your car, it varies for everyone depending on their mods.

I had excessive creep with my MP, but like I said, your mods aren't the same as mine.


I want to add though, forget about porting the wastegate if you creep. Go to Jegs.com and search for item 3di03r.
This is a collector silencer, and it worked very well for me, and the thing only cost $45, it's worth a try! I bought the 3ring design because I have a lot of mods and because it's cold out, probably during the summer I'll switch it for a 2ring.
But it added just enough back pressure for my ECU to handle.

Magnificent 7

Why or how could your turbos spool up MORE quickly if you increased the restriction in the exhaust pipe which, consequently, decreases the flow of exhaust (which imparts the energy to the turbine blades)?

I believe that's some misinformation there. A catalytic converter does nothing more than take the oxygen supplied to it by the air pump and combines it with the raw exhaust gases. Through a catalytic chemical reaction, the amount of harmful gases (at least what the EPA considers harmful) is reduced. Don't ask me about the pre-cat I'm not sure how that works without the oxygen.

And detonation occurs in the combustion chamber. There's no way a catalytic converter can keep that from happening if you happen to get a tank bad (low octane) gas. The detonation will have already happened and the converter will have no effect on it.

Detonation is the uncontrolled burning of the air/fuel charge that results in dangerously high combustion chamber pressures and temperatures (this is what cracks rotor seals). This can occur when the fuel mixture is too lean and the ignition too far advanced (or some combination of these). These settings are regulated by the ECU. The ECU takes a signal (in the form of a voltage value) from exhaust oxygen sensor (and other sensors NOT the catalytic converter) and adjusts the injector pulse width to maintain the proper air:fuel ratio. It also adjusts the timing advance to preclude detonation. Of course the oxygen sensor is also ahead of the catalytic converter and not influenced by the cat either.

Someone help me out here. Does the Power FC adjust the timing based on any input from the knock or oxygen sensors? I had heard that it didn't, but wasn't sure. If it does not, then what signal or indication does it use to adjust the timing?

So a catalytic converter and/or a midpipe has no affect on detonation--with one exception. A midpipe does allow higher exhaust flow because of its reduced restriction. Higher flow means the turbos pack more air into the engine, which requires more fuel to maintain the proper air:fuel ratio. If the fuel supply is not increased adequately (and it usually isn't if you're using the stock ECU) the mixture will be too lean, and detonation can (and probably will) occur. This is where a high flow cat can help. The restriction (less than a stock cat, but more than a midpipe) can be just enough to keep the incoming air charge from being too lean. However, any restriciton (i.e. a restrictor plate) in the exhaust can accomplish this.

So unless you're required by laws and/or emissions testing to have a catalytic converter, why would you want one?

Remember, the general rule of thumb when it comes to modifications is: Two's the limit without an ECU upgrade. Serious fuel upgrades should always be considered when doing multiple or cumulative mods. Unless you want to lean out, detonate, and pop your motor. But it's your motor so you can do what you want with it.

This isn't a rip or a flame on anyone, and I hope it's not taken as such. It's just a detailed explanation of detonation (as I understand it) as it relates to mods and air-flow-increasing devices such as high-flow cats and midpipes. Someone correct me if I'm wrong. I learn like everyone else.

jspecracer7

Amen....

pp13bnos

iTrader: (1)

Check my sig, for my mods, but i don't get one bit of creep. Even on the cool nights here in Oregon.

As far as an ecu goes....i've had programable FI before. Played with it enough to figure out, i did'nt want to deal with it on my FD. I'm %100 happy with my used Pettit ecu. CJ

pp13bnos

iTrader: (1)

sorry...

billyrohm

yeah dude, just get a mid pipe and a power fc. If youre worried about noise get a resonated mp, I have one not much louder than the cat. Then if you want you can go non sequential and get rid of that boost drop off and youll have the strong boost ( which you feel after 4500 with seq) all the time. I know that youll achieve max boost later but I think that you'll also have better power not under boost for the turbos would then be in parallel and if you add something in parallel the resistance is cut in half, plus theres no boost drop off, just strong boost till redline.

the_saint

Your ability to control your boost may be a result of less flow versus aftermarket catback exhaust. I am not sure how much a gutted stock catback flow, but i suspect it is less than Apex GT, or Apex N1 Duals.

Not a criticism, but rather a possible explanation for your situation.

I had boost creep with my set up until I added some restriction to my exhaust flow.

I ultimately ported the wastegates and don't have any problems now with creep.

Mike

m0t03

So the power FC is the way to go atleast over the Pettit ECU? Whats the difference between the resonated MP and the normal MP by Pettit? Is there a power difference? And should you get your wastegates ported with the addition of a MP?

thanks,
Mike

the_saint

A resonated MP is quieter than a straight MP. I believe that they sound better, slightly deeper tone, and they don't drone on the highway.

Mike

JoeD

there is no real power difference between resonated and non-resonated. i say 1 to 2 hp at most. but the resonated is much, much quieter at cruising. they are the same sound level at WOT.

you should get your WG ported, but a good boost controller can ger rid of creep.

m0t03

[QUOTE]Originally posted by KZ1
[B]PFC is cheaper than pettit, especially if you buy the commander. You don;t need any more gauges, no fan mod, you can get 200$

What do you mean you dont need any guages or fan mod. The PFC takes care of all that. Dont you have to get it programmed an that would cost money.

JoeD

you only need to get it programmed if you want to run more than the base map can handle. the base map can only handle 3 mods. after that, you need to tune it on a dyno.

you dont need more gauges, but i would reccomend having extra gauges. you dont wanna be looking down at the commander the whole time. its better to have the gauges in your line of sight, for example on the A-Pillar.

pp13bnos

iTrader: (1)

I'm sorry, i did'nt tell you, that at one time i did have a apex n1 dual. I still did'nt get any boost creep. I sold it, because with a normal mid pipe, it was just to loud. Not to mention, its a little to aggresive looking for me. I sold the N1 Dual to Colbalt on this forum. The gutted cat back, is more restictive. When i installed the n1, the motor made anouther 1psi of boost. It made more power, but without silencers, its just to much for me. CJ