Is there no need to upgrade the ECU if there are only the 3 basic mods done (dp, cat back, KN filter)? Haven't done the filter yet, will do once the question is answered. Heard through the grapevine that there maybe a risk of running lean...

 

You're fine with those mods. It's when you start thinking about getting a midpipe or raising the boost above stock levels (10psi), you should worry about more fuel. Go to this site its very informative:

http://www.newwave.net/~flanham/wlan...l/fuelfaq.html

 

you'll be fine

 

Boost spiking is a possibility with that combination. You've got a boost gauge, right? Watch it. If it creeps above 10, I'd have a professional install a Prospec B boost controller for that setup. But then, I'm paranoid.

 

yep, got one... okay, I'll watch it for spikes. Usually in 3rd gear, on secondary turbos, right? It should be around 8 psi for the secondary one, I think.

thanks guys.

 

Do a search for 10-8-10 or boost pattern. That should help you out. It may be possible to have some overboost in any gear if you floor it, with the primary coming on. Going up to 11, 12 psi is not a good situation in any gear unless you're built for it. Someone correct me if I'm wrong.

 

I thought that a stock system can handle up to 13 psi. Again, "thought" so correct me if I am wrong. I currently have just a dp but was thinking of getting an exhaust as well. Right now is up in the air of getting a great deal on a exhaust or going for the PFC.

 

The past owner of my car saw boost creep (spiking) up to 15 psi with a custom cold air box with a K&N filter and no muffler (just a straight pipe after the cat). He didn't blow the motor up but thought it was wise to install the boost controller to stay at 10 psi. I kept the cold air box and added the downpipe when I purchased the car but put a stock muffler back on (still at 2 mods). I could run a RB high flow catback safely with the boost controller, but it's just a little bit out of my budget at the moment - the car has a high performance clutch system as well, so it's way faster than I can legally drive it, anyway. Getting back to your question, my understanding is that 13 psi can be tolerated once in a great while but you are risking your engine if you run that sort of boost continuously. The problem appears to be that higher boost levels can require greater amounts of fuel than the stock system can deliver and the stock ecu can manage. Fuel starvation in this instance leads to over lean conditions which results in massive overheating. Good bye engine seals. (Ok, guys, have I got this right?)

For what it's worth, the downpipe is an absolute necessity and in my opinion, the first mod anyone should do. From tests I ran at home with the stock muffler, it's not that restrictive. Based on my findings using my car as a daily driver, I'd recommend the following order of mods:

1. Downpipe.
2. Aluminum AST.
3. Profec B -with a professional install.
4. Cold air box with K&N filter.
5. PFC with a professional install.
6. Free flow exhaust.

I'd have 3&4 and 5&6 done together to get the benefits of the professional tuning that goes with it. This is all based on my desire for maximum reliability with a little fun factor thrown in. You can go the next step up to higher fuel pump and injectors, but I don't believe its wise for daily drivers unless you know how to keep such a system in tune yourself - these systems can get out of control badly if not carefully managed. Do a search. and besides, who needs 350 HP for a streetable daily driver anyway?

 

Before I switched to single, I ran 14lbs all of the time on the stock setup. I had dp, custom cold air intake, and catback. The biggest problem was 3rd and especially 4th gear highway pulls. It would spike sometimes to 16lbs. This has nothing to do with a boost controller (though a good one helps a little). This has to do with the sizing of the wastegate port. The only "real" way to control the boost spike is by porting your wastegate
At least that is the only thing that worked for me.

 

I thought the stock third gen's RX7's were running (at stock) at 12 psi max??? I remember seeing that in all the numbers and catalogs. I've got a catback, and downpipe installed... and I regularly see 11 psi on primary and 8 psi on secondary. Isn't that what it should be? If so, I don't think I need a boost controller or different sized wastegate port, right? Although, I was still hoping I could run a K and N filter with the stock air box, and not worry about boost spiking... am I correct on all these assumptions?

 

It can. I've been running 13psi for quite a while and have never seen over 86% injector duty on stock injectors w/denso pump.

 

10 PSI (or more accurately a 10-8-10 boost pattern) is stock for the American cars. IIRC, the later model turbos (99+?) increased this to 12 PSI.

The 11's fine. The 8 is a little low (but not way off). Realize that many boost gauges can be a pound or more off (mine reads a pound or so high).

When you open up the exhaust, the turbos will spool quicker and build higher pressure. If the wastegate can't handle the sudden increase you may start seeing boost spikes of a few pounds or so. If it's only a couple pounds over stock you should still be within the envelope of safe operation. More than that and you probably need to control your boost either through the use of an external controller or repilling your control lines.

-bill