http://www.newwave.net/~flanham/wlan.../3modrule.html

 

would it be safe to say, more mods = less room for error when trying to keep your boost levels in check?

 

downpipe is a great mod. Car runs cooler. I use HKS downpipe. Fitment is top notch.

 

Well, I put a downpipe and catback on... 2 mods and I was boosting at 14 psi. I quickly added a manual boost controller instead of other upgrad, then continued with ECU and adam_c "cheap bastard intake". The boost controller kept everything at about 10.5 psi. Then I added a hi-flow cat and I'm still boosting a solid 10.5... after a little adjusting. I'll probably increase it to 12 when I get the car dynoed again and check the a/f mixture.

OK, I lied I had a turbo timer in there too... does that count as 3 mods?

 

Whassup Dan? How's life been treating you -- probably less expensively without the FD. My car's at Rick's right now for a full rebuild.


Clayne, long time no see, coming back to the forum?


Speedking: thanks for posting the link to Wade's site, I was too lazy to look it up earlier.

 

I would also say that every FD is different. My first FD had intake, SMIC, DP, CB on Stock ECU. I was boost creeping all the 14 psi but never had a problem with the motor going boom. After I got the boost under control found out that my car was in the high 10 A/F ratio reading. Now my current FD has all the above + mp and a FMIC instead. I never saw boost creep. My A/F reading at 10 psi were low- mid 11's. So I wil agree that the 3 rule thing is not true, the part that needs attention is the boost control.

 

Let me throw a wrench in the gears here.

We know that pressure drops as increase in flow goes up - and as flow decreases (as a limit of pressure), pressure continually goes up.

Knowing that most of the mods we are discussing are actually flow-increasing mods - what we think 10 psi across the system (or measured at MAP) is, is actually not the same CFM the original system saw at 10 psi.

Since we are not using a MAF sensor the system is actually flowing more air, period. The stock ECU has fuel mapped for a given MAP value and RPM. However this was done with the stock system flowing stock rates.

Now while we may measure things "fine" with a lamba this is only because Mazda may have added a safety zone of fuel (which BTW could easily go away if the overall intake pre or post-charge temperature goes up or saturates).

In addition consider what the exhaust side of the turbochargers may be seeing as a result of increased flow and the now additional wastegate dumping (via a more aggressive boost control setup) as a result of more VOLUME.

We have no easy way of measuring their shaft speeds but unless I'm having a small moment of insanity, increasing the volumetric output of the exhaust and dumping more charge to regulate 10 psi system pressure (remember this 10 psi doesn't equate to the same max CFM of the original system) means their shaft speeds have gone up (how else will they make 10 psi in a system that now has an increased volumetric flow?).