new to site; couple of questions
 

Please tell me if I'm putting this in the wrong section; I posted to this site last night and my question vanished. (maybe an admin deleted it if I'm in the wrong section?)

Anyhow, I will try again.

My FD has the following "performance mods" : HKS downpipe and Apexi Exhaust.
Nology Wires.

That is it. Do I need to upgrade fuel system/ ECU? Boost controller etc?

The only other thing I'm considering is dropping in a stock sized K&N into the stock airbox.

I don't want to get a power fc or change the ECU if I don't need to. But I'd like to do the things that add reliability without negatively affecting fuel/air etc. Thanks for any input!!!

I'll give you the same answer I did last night, you probably didn't see it. You shouldn't be running a DP and exhaust on a stock computer. Get a PFC or a modern ECU.

Sorry Daniel but absolutely disagree. A downpipe and cat back exhaust are fine on the stock ECU as long as you keep the cat. So is the K & N in the stock airbox. There is no need for an aftermarket ECU. You do want an aftermarket temperature gauge and a boost gauge to monitor those two parameters. Do NOT rely on the stock temp gauge.
I would venture that the vast majority of of longtime owners started out with just those mods on the stock ECU. I did for about six years. If you search in the archives you will find many references to the three mod rule on the stock ECU. You'll be well within those limits.

Thanks guys. Jim, I had read over the years about the 3 mod rule but I just wanted to make sure. Would the Cheap bastard air box mod put me over the limit or would this be another safety mod?? Perhaps I should just leave the air box stock and do the K&N drop in filter. I wasn't sure if it was 2 mods are safe and the 3rd puts you over or if 3 are safe and stop there. I do have a water temp and boost gauge. Thanks again for the time and help.

The need for an aftermarket ECU is dependent on your ability to maintain stock boost levels on the stock twins. Most agree that the MAZDA programmed the stock ECU on the rich side for a safety margin. Stay at 10 psi or below on the stock twins and the stock ECU is fine. The cheap bastard mod is, essentially, just an invisible open intake. Not a reliability mod, but nice for those of you in the land of emissions inspections.
I think mostly you would see quicker spool-up. But less restriction on the intake side can lead to boost SPIKE although it's hard to predict with certainty. Personally I never saw spike on my car until I moved to a larger SMIC and an efini 'Y' pipe. Both flowed better than the stock items and since they are also on the intake side and were combined with a better intake, I started to see spike when conditions were right. If you keep the stock intercooler, I doubt it would be an issue. But if you do get it, it usually appears whenever the air is cooler and denser...like mornings in the spring or fall. It can be addressed relatively easily with a boost controller, either electronic or manual.

I didn't see any mention of the cat still being in place, but to be fair no mention of it being removed either. I just know very few people that do a DP and exhaust and keep a cat.

In my mind, the downpipe was just as much a reliability mod as a performance mod. Yes, it flowed much better. But getting that pre-cat out enabled the owner to be confident it didn't collapse and take out the main-cat...which they did from time to time. It was also just a huge underhood heating element... baking plastic solenoids, check-valves, vacuum hoses etc. And the pre-cat only had an emissions function on cold start-up. I'm an old fart, so I guess it's the crowd we run in, but I know few who DIDN'T keep the cat on the stock twins. Removing it for a mid-pipe can cause boost creep without porting the wastegate. The stench from the exhaust is pretty bad and the car is way louder, but IMO not in a good way.

Thanks for the help here guys. I do still have the main cat on. California car. :nod:

Jim, (or anybody else who wants to chime in) I'd like your opinion on this....... I'm thinking of doing one of the following:

1. cheap bastard air box mod, but keep the stock air filter.

2. Leave the airbox stock, but drop in a K&N filter.


Of those two options, which do you believe is "safer" as far as boost creep/spike etc.


I don't want to do the cheap bastard AND K&N. It would make me nervous with the other mods I've already made without an ecu upgrade or boost controller. (apexi N1 and dp)

THANK YOU!!!

If it can only be one, cheap bastard intake. And then block off the hole in the top of the intercooler duct so it no longer scavenges air from there.

I understand a new owner's nerves and this is unusual because typically I'm trying to caution them. But the car isn't made of fairy dust and kitten tears. The stock intercooler, hoses and stock 'Y' pipe have enough restriction that you could do both and be fine. Again, my car was identically equipped for about 6 years without issue.
Do you have an aftermarket temperature gauge and boost gauge?

Thanks Jim. I do have an after market temp gauge and also a boost gauge. I've owned the car for 17 years, but I just took it out of storage (past 8 years) and feel like its brand new all over again. Except, this time I'm doing alot more research. (probably getting wiser with age. lol) Anyhow, the car has the following "engine" stuff done to it: HKS downpipe and Apexi N1 exhaust and Nology plug wires. Those things were added 8 years ago and I literally have driven it less than 500 miles with those things added. So I took it out of storage a few weeks ago and have been on this site ever since. It has been a tremendous help. But, as you can imagine, sometimes I read things that raise more questions in my head than answers! Thats why I'm asking all these questions. THANK YOU AGAIN, btw. Sometimes I have to ask someone directly vs just read something and try to figure out what it means. When you say block off the intercooler duct, do you mean the part that feeds the stock air filter airbox? Thereby making the air come solely from the new holes cut in the bottom of the airbox?

Yes. The stock intercooler is pretty small. The cheapbastard mod should provide enough air to the intake that you can block that hole in the top of the duct off. Keeping air pressure as high as possible in front of the intercooler will help a little in it's efficiency. Replacing the ducting from the intercooler to the top of the intake box keeps it invisible and stock-looking. And it's reversible.

Jim,

I know I should know exactly the intake duct you are describing (i think i know), but I'm having difficulty being sure. And I don't want to block off the wrong area! So, when I'm looking at my airbox standing in front of my car, you are talking about the opening that feeds directly into the airbox located toward the pasenger side of the car, correct? Its the opening that is hidden by the large rectangular "cover" that is removed with two screws? The opening to the left as opposed to the opening to the right which flows air to the intercooler.

Am I right???

If so, do you have any tips as to how to block it?

Have I shown my ignorance yet? lol

Thanks again.

Remove the tube/duct that runs from the intercooler duct to the air box and is secured with two 10mm bolts. Look on the TOP of the intercooler duct. As your standing in from of the car it will be on the right. There will be a square-ish hole in the top of the intercooler duct. Use duct tape or anything appropriate to block it off after you've done the cheap-bastard mod.

Thanks Jim. I'm going to undertake the CBI mod next week. I'm going to block the squarish hole that just in front of the intercooler (as seen while standing in front of the car). Ignorant question: If I tape that hole shut, where will the intercooler grab air from and will it be sufficient?

possible idea, but tell me if I'm way off or missing something......... what about blocking the hole that directly feeds the airbox instead and leave the intercooler hole open....... since the airbox can grab air from the new CBI holes underneath? Wouldn't that leave more air for the intercooler?

This has been really helpful, thank you sgtblue. I'm in the same position where i'm just trying to do reliability mods and keep the car otherwise stock.

Mellow, where did you mount your temp and boost gauge; on the A pillar?

Cmurphy, Yes on the A pillar.

Gauge placement is pretty much to ones taste. They make a two or three pod guage holder that fits in the center dash speaker spot that many like.

FWIW I'm just over 5'8" so was concern about visibility with guages on the dash or a two guage pod on the A pillar. I also like the boost guage right in front of the tach. Went with Pettit Racing pod there and single pod for temp down low on A pillar. Not a very good pic but...
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