mr g lord focker

OK, got my BNR stage 2 rebuild in today thanks to XTRlooney. Wanted to ask a few Q's. First, you guys who are running this same turbo set-up what kind of boost do you guys run and how do the turbos perform? On my mods I should be able to run high boost without problem so I just wanna know what boost gets the most out of these bad boys. Also, how many miles do rebuilds tend to last at or around 15 psi boost (as I have planned right now). Also, I plan to have the commander installed into my center console so I can manually adjust boost during my drive. I was wondering if I had the PFC tuned to control boost at 14 psi, if I could turn it up to 16 or 17 PSI for a track day and not have to dick with any other controls on the PFC to make it work safely? I mean while changing the boost does the PFC then automatically change everything else that is needed to boost that high if all other mods are programmed in? Thanks for the help on both Q's.

DCrosby

As I understand the PFC, unless you get an add-on module you're not controlling boost, and if you then are... you're adjusting the wastegate, and not auto adjusting the fuel maps... if you want to risk it try... but I'd have my car tuned 2X once for track and once for Road, and in my case 1X for Smog, and then upload whichever map you need... knowing that the race map requires race gas, and gets you 17 psi of boost....

So No I don't think any ecu will auto adjust the fuel when you raise the boost... due to the lack of a destinkt psi+XFuel = Good AFR curve... it's pretty dependant on mods... due to your exhaust and or IC not beeing able to sufficinety cool or get rid of that kind of pressure while at 15 it's fine...

FormerPorscheGuy

Two thinks here. First off you need to get a separate boost controller to control your boost. The PFC is notorious for being way off in its boost reading and controlling ability. Get a profec B, they are simple and work great.

Secondly, after you get your PFC tuned you shouldn't have to mess with it at all. With your BNR's and a proper fuel supply (you did upgrade your fuel system right?) you should be ok at the boost levels that you want. As long as your PFC is properly tuned for that pressure you should be fine. If it is not properly tuned you will be needing a new engine to compliment your new turbo's very soon.

mr g lord focker

yes, fuel system upgrade 1300cc secondaries. Supra TT fuel pump. I like the idea of you Crosby. Having 3 different maps would be a nice idea. As for Formerporscheguy it is to my knowledge that when the boost is set on the PFC it boosts exactly at what you want it to boost. just the reading on the PFC is messed up, so you install a boost gauge to get the correct reading. That is just what I have heard, may be incorrect. Thanks for the responses thus far though! If anyone has any more knowledge on this sit. please PM me or post here.

SleepR1

The Power FC controls boost through the precontrol and wastegate solenoid/actuators, just like the stock ECU does. The exception is you can adjust the base duty cycle for each of the actuators to suit the boost control you want to run. "Pr" refers to primary boost control, which is essentially the precontrol solenoid/actuator...this controls boost BEFORE the 4000 rpm transition. "Sc" refers to secondary boost control, which is handled throught the wastegate solenoid/actuator AFTER the 4000 rpm transition. Base duty cycle refers to the frequency of open/closed cycles of the actuators. The lower the base duty, the lower the boost. The higher base duty, the higher achieved boost. The target boost is adjustable in 0.05 kg/cm^2 increments. Adjusting the base duty for each (Pr and Sc) is where the boost control tuning comes in. It takes a good while for the Power FC to "learn", and at times you need to play with the duty cycle to dial it in. I've found that the Power FC for boost control works fine if you have a cat or high-flow cat. I've recently replaced my clogged hi-flow cat with a midpipe. The exhaust is much freer flowing, and so the boost control is not as "tight" as it was with more exhaust restriction with the hi-flo cat. I've seen 1 to 2 psi spikes past the target boost, during transition. Before and after transition the target boost is achieved.

FWIW, I hope you mean drag strip, and not road racing track, when you're setting your boost control to 16 or 17 psi. From my experience with a midpipe, you need to set your target for 1.05 with a base duty cycle of 60ish %, and adjust upward from there. You need to find what your spikes are FIRST. Don't just set the Power FC to 1.2 kg/cm^2 (17 psi) target boost without knowing what your turbos spiking behavior is. With a midpipe, more than likely @ 1.2 kilo, you'll spike to 1.3 or 1.4 kilo/cm^2 (18.5 to 20 psi, respectively). If your AFR maps aren't setup to deal with momentary spiking at that level, you'll surely chip an apex seal! Note that if your actual boost exceeds your target boost by 0.25 kg/cm^2, the Power FC goes into fuel cut. The car feels like sh*t. Don't ever go into fuel cut. Not good for the motor at all...

Please read the Power FC manually carefully, and consult the Power FC forum. There are many knowledgeable Power FC users in that forum.

SleepR1

BTW, you shouldn't need different Power FC maps for different purposes. Once your Power FC is tuned properly (dyno or street), all you need to do is play with the boost control settings. The tuning takes into account air-fuel-ratios and ignition timing, based on boost pressure, fuel grade, and engine loads. Tune for the most extreme cases so you fill thoses cells on the map with the proper values, so when/if you encounter those cells again in a real-life situation (drag/street race etc.), you've got the proper map values there to deal with it.

artguy

a boost controller aint gonna cut it boys..and neither is the pfc alone if you are running that much boost....you will need a 3bar map sensor or the pfc kit to control boost past 16lbs. it needs to be tuned properly for the boost you want to run.

*******...did you read the other thread you made in the west forum about those junk maps you are about to purchase from sr motorsports??? dont do it. YOU CAN NOT TUNE YOUR CAR BY MAIL. see that other thread for more info.


period


j

SleepR1

The manual states explicitly that boost pressure over 1.2 kg/cm^2 cannot be read accurately with the stock MAP sensor. The exhaust gas temp warning light will illuminate when the boost hits 1.1 kilo. If you plan to run boost pressures greater than 1.2 kg/cm^2 (17 psi), you will need to replace your stock MAP sensor, and add the Power FC boost control kit.

BTW 1 kg/cm^2 and 1 Bar are DIFFERENT.

1 Bar = 14.5 psi

1 kg/cm^2 = 14.22 psi

They're close but not the same. When tuning for boost pressure, the Power FC uses the kg/cm^2 units NOT Bar units. Keep this in mind.

SleepR1

Mailorder tuners will tune more conservatively since they don't want you to blow your motor. This means rich AFRs and conserative ignition timing. My base map was modified by KDR. They built my motor with large street ports. I ran the base map for a year, and just recently dyno-tuned the car for a midpipe (did have a clogged high-flow cat). The only adjustments made to the map were AFRs--leaned out from 10 to 11 AFR. Dave Bargninger's ignition map was spot-on--we tried advancing the timing only to lose HP, so we retarded the timing back to where it was. Leaning the AFR from 10 to 11 yielded ~8% increase in rwhp (Mustang Dyno).

matty

what happen to this forum...

the power fc controls boost fine for my car...

SleepR1

Power FC Forum

https://www.rx7club.com/forumdisplay...100&forumid=47

artguy

sleep...well dave tuned my maps by mail and they were undrivable...he did remove the negative split in timing that xs had.

the stock map sensor will not read properly past 16.3lbs. it aint worth risking running more boost than that without either the pfc boost kit/map sensor (which is what i run) or a gm 3bar map sensor customization.

tune by mail maps are not accurate...do some research.

not a single guy who does tuning right would ever recommend such a thing. you cant guess at tuning...there are many factors that can shift what your car should be vs how it is actually performing.

you can NOT properly tune without having afr readings from either a dyno or a wideband o2 sensor kit.

goodfella...where are ya....i apparently need backup on this one.

I had two shops attempt to do that...one shop tried TWICE...when i actually did my tuning with the datalogit the first time the maps were a mess.

all our cars perform differently. no two perform the same...theoretically it should work....but it doesnt.

in sleeps case he seems to have gotten lucky. i on the other hand had so much detonation that if i was running stock apex seals instead of the ianetti ceramic 3mm set Id have lost my brand new motor right then and there.

fd racer saw what kdr and xs did with those maps when we tuned my car....it was nasty. i had more areas lean or rich (you can blow it running too rich) than in the proper range of 11.2-11.5. there were chunks of the map in the nines and chunks in the fourteens....the area of highest load was the worst...lean as hell...and thus detonation occurred.


j

SleepR1

j, sorry to read about your experience with XS and KDR. As I posted above, my KDR-modified base maps were fine. Dave loaded the maps onto a new Power FC (version 5.08) and shipped that along with my KDR large streetported motor. The maps were dyno-tuned from another large streetported motor he did with the same mods as mine (at the time, high-flow cat, NOT midpipe, RB dual-tip cb, J-spec twins, GReddy 2-row FMIC, GReddy Airinx, 1300-cc secondaries, Nippondenso comp fuel pump, underdrive pulley, 8.5-lb flywheel, 92 octane pump gas). The KDR base maps were conservative in AFRs (10s), but ignition was fine. I also have splits in my timing, and some are negative, but they're areas of the map that my car will probably never go. I'm not sure why the negative splits are there? I can only assume the negative splits are remnants from the original Apexi Power FC base map? I don't think Dave put them there?

artguy

sleep...fix yer timing maps man...lol...probably will never go is risky isnt it? it aint hard to fix negative split...just adjust the maps.

you got lucky with your maps....it is beyond rare that getting someone elses maps that will work well in your machine. i would hardly call timing maps with negative split and maps in the tens as something Tuned. the fact that your maps were all on the rich side is interesting...mine were all over the place each time...same goes for spyfish and goodfellas long ago...same goes for dozens of people on these forums who were jacked by the mail order tuning scam.

not taking out negative split on their part....no matter where it is is LAZY. once again shows if you want it done right ya gotta do it yerself...or ya gotta pay for dyno time.


j