CSMCanuck

Before I start I have read almost every thread about boost control on this site but I have a few questions.

For starter the car:
DP
CP
Pettit ECU
MBC on wastegate

I am at 4000 feet so my boost readings are off by a good 2 psi plus whatever my Autometer boost gauge is off by!!!

Currently my boost patern is

14-8-12

Which is about 12-6-10 (at high altitude there is more loss durring transition thats why I get the 6)

I would like to run a sea level equivalent 12-6-12 if possible, however if Itry and up the boost I end up with more creep from my primary.

Should I run another MBC to the precontrol actuator, I know some people are doing this but I have heard others say it is imposible to tune right for it.

Should I remove the precontrol pill all together?

Any sugestions would be helpful. I can only imagine it will egt worse if I get a MP.

Thanks

rebuild FD

no boost controller will fix creep

you must port the wastegate or add more restriction to the exhaust

quicksilver_rx7

I would suggest using a MBC for both lines. You're limited by the pill in the pre-control line. Rob Robinette has an excellent write-up on using this setup on his website.

It IS possible to tune the two controllers right. It just takes a lot of patience and reserve. You're still going to get some creep with the stock wastegate.

DaveW

Some people have had trouble tuning a needle-valve controller in the P-C line. However, ball/spring controllers (one in the P-C and one in the WG line) work very well.

See this thread:

https://www.rx7club.com/showthread.p...hlight=results

rebuild FD

mine works great *shrugs*

but I still have boost creep....I'm fixing that (BNRs)

rynberg

He is NOT experiencing boost creep.

I'm guessing that the main problem he is having is that he is still running a stock intake and intercooler. The primary can hit higher boost than 12 but the system cannot flow enough air to make over 12 psi at high rpm when both turbos are active. Adding a pre-control controller may alleviate this somewhat.

If you want your turbos to last, you should not be running them at 12+ psi with the stock intercooler and stock cat. There is too much pressure drop/back pressure to run those poor things that hard. Running the turbos at 12 psi on the stock IC is like running them at 14 psi with an aftermarket IC. Compounding that, the intake temps will skyrocket because the little stocker IC is getting overloaded.

Until you have opened up the air flow path more, I would just stick at 10-11 psi. Get your pre-control controller and get as close to 11-9-11 as you can and enjoy the car until you have the proper mods to support higher boost.

adam c

iTrader: (2)

I do not recommend a needle valve on the precontrol line. I tried it. After 6 weeks of trying over and over to get the two controllers working properly, I gave up. I reinstalled the original oem precontrol line. Now I get a solid 8 psi at transition. I can still use the wastegate valve to adjust primary and secondary boost. If you want to raise your transition, you might try replacing the precontrol line with the oem wastegate line. The slightly larger pill in the wastegate line should give you a little higher psi at transition. I have been considering trying this, but have not gotten around to it yet. I don't know if anyone else has tried this.

Boost creep is when your boost keeps going up as rpms increase at WOT. This doesn't usually happen with a stock cat. Are you getting creep?

CSMCanuck

Ya I have absolutely no spike, but my primary continues to creep up tp 14 psi before transition then I am back down to 12 after if I try to increase my Secondary the primary goes up too.

David Beale

Yes, as others have said, this isn't "boost creep", it's loss of full control of boost. You can regain control by adjusting the pills or the replacement valves if you are going without pills.

"Boost creep" (def) - there is more exhaust gas than the wastegate can get rid of, therefore the turbo(s) start to compress "too much" air (more than the wastegate controller system calls for). Result is too much intake pressure - loss of control of the boost system at high RPM.
(symptom) - boost pressure functions normally until about 6000 RPM (depending on efficiency of turbos) then starts to rise with RPM - often to destructive levels. Easilly controlled by left foot - release accellerator pedal. It doesn't happen suddenly (unless you're in a lower gear), so if you pay attention to the boost gauge you can avoid destructive results.

rynberg

Wow, I knew you Canucks were different but....

David Beale

Ok, Ok, the other left .

CSMCanuck

I installed another needle valve this time in the precontrol line. I was worried it was going to be tough to tune, but it was fairly easy. I was able to pull back my primary boost, and I still have no spike during transition.

However it seems like transition takes a bit longer!!! But maybe the atmospheric pressure is a bit low tonight.