1 bar loop

Yea I did the 1bar loop as well - awesome free power!

do you have an aftermarket guage? i did the loop awhile back, unfortunately mine tops out around .8 bar.. i haven't had a chance to put in my profec b yet.

nope no gauge yet..next step is a aem truboost and a wideband.

I've got a gauge in - mine boosts 15psi at WOT after the 1bar loop.

can you explain what is the 1 bar loop ..
and how can i do it ??

i have a boost controller and boost gauge + EGT +wideband .. and i know what those gauge means .

pump the boost until i'm 14.7 psi ?? or 1 bar is a 1 bar loop ???

s3by, the 1 bar loop gets rid of the boost control solenoid. I did up a picture on the modifiers forum a while back. I'll find it for you.

connect the red with red, and the blue with blue and you're set.
however, a boost controller would probably be a better bet. Take the pipe from the induction tube right off and plug the hole. After that, take the T piece that is in the picture out and put your boost controller there. the controller is inline between the manifold pressure and the wastegate so you can use your boost guage and the controller to set whatever boost you want.

why then if you put the wastegate strait inline whit the intake pressure the boost goes up ???

i thought that whit a boost controller when you let all the air pass the boost would have been lower than when you restrict air.

am I wrong ????

it acts like a bleed valve. the intake pipe is in vacuum at that location.

tryed it and it work like shit ..
the wideband i have is telling me super lean condition over 6000 RPM .. replug all that and put a boost controller whit the stock solenoid and work great .. reading are steady and at 11.0 so its perfect..

P.S seem like my computer see when the solenoid is not connected to a vacuum .. because it those lean even if the boost is stock whit the solenoid bypass

ok sorry for that , my car had a problem that I finaly find and its now ok whit a 1 bar loop ..

BOOST LEAK IS NOT HELPING ANYTHING !!!!

seby, where's the boost leak coming from? And if I read your last post right, the one bar loop is good for the entire rev range and doesn't run lean anywhere? I think I'm going to go greddy profec b spec II for mine. Can't wait for the spring.

i did the one bar loop tonight... 3 words... oh my god. the car wake up so much more, it seems like my car run better like that. I am not pushing it until I can get it all tuned properly but its pretty fun to have the extra wooomph! The HKS ssqv went from LOUD to LOOK AT ME LOUD now... and the exhaust has got raspier too... :(

the boost leak was comming from my BOV ...

change the spring in it and everything is find ..

put a tie-rap on the vacuum hose on the FPR ... it tend to fall at15 psi and you'll be running lean because of this to ..

the fpr work whit a 1 for 1 ratio .. 1 psi of boost add 1 psi of fuel pressure ..

have fun whit the 1 bar loop .. and have a boost gauge that is accurate and a wideband is not luxery 400 $ instead of 2000 for an engine .

just make sure ur gettin enough fuel or goodbye piston

do you have to fit an aftermarket boost controller when you do this?

So... do you need to do this when you get a boost controller? or is just a free way of doing what a boost controller does? Since you just connect the two ports of the solenoid valve can you just take the solenoid right out?

i dont get it...i did this and i still read 9 MAX thats it...except for my line is ran a bit different but its still running to the same place...im not getting any more power...and even if i have the controller in line i dont make more the 8 psi...im stumped

Maybe you just have a mean boost leak somewhere?

a) you have an old and tired wastegate actuator
or
b) you're missing the restrictor in the first hose off the intake manifold, worth .2bar

i tested leaks around 2 weeks ago up to 20 psi and im good it could be my wastegate...sence it does flutter a little

try putting a soft spring attach on the arm that hold the wastegate as a test, the srt4 guys all do this to hold more boost and it will be an easy and cheap way to test.

hi guys so im having kinda the same deal... i did the loop... red to red, blue to blue like in the picture but im also getting only .8 KM/cm2... Nick posted a) the wastegate actuator.... and b) missing the restrictor... what does that mean exactly, im missing what restrictor???? if anyone can help out id appreaciate it!

Oh and also i had another question.. when installing a BOV did everyone here have to re-hose the quad throttle bodies with 1 single hose going from each throttle to the top of the BOV? As seen in Mightmods Ep. 9 :)

please and thank you!

Hey SpHiNxXx,

I found the loop did not work for me either, so I checked into things. There is a restrictor in the vac line from the "air box" under the intake plenum that heads to the wastegate solenoid. I put in a restrictor I got from an Evo X and it hits the 1 bar point perfectly now.

I also did re-hose for the oem bypass valve, only untill I eliminate the valve all together.

so are most people able to get away with the 1 bar boost mod without any troubles? do the loop and it's good to go for another 5000 kms til the rebuild, or are most people still doing fine with it?

just an updated fuel pump, basic maintenance and ur good... it wont make the most power but its safe and daily usable.  2.5yrs going strong here

alright thanks nick.

Now, you're going to sh!t yourself at the next question - where is your notepad of basic maintenance? I just replaced my engine this summer and would rather not have to do it again in the near future. :| so I don't want to miss anything.

cap rotor from a p10 g20 (once a year)
plugs copper ngk 7's or 8's ( i use bcpr's) check gap.. i use a pretty large gap and havent had any issues (twice a year)
wires from a p10 g20 (2.5 years going strong, i may change it next spring)
fuel fitler from a 300zx ( bigger) or a nissan stanza for direct fit in cup ( i change this twice a year)
fuel pump walbro 255, reuse the oem pickup, trim fuel pump holder tang so it can slide further down in the tank, make sure ur tank never drains below 1/4 tank, fuel keeps the pump cool, no fuel over heat pump and u have a dead pump (2.5years going strong)
clean ur air filter (every 3 months)
rad fluid, oil summer i'd use a 5w40 shell rotella t synthetic, winter i'd go with a 0w40 or 0w30.  i'd check it constantly at 0w30 tho. ( every 4-5000km's)
check timing (once a year i look it over)
hose clamps ( every couple of months i check if stuff is tight, with our very rattly motors)
reground maf to instake manifold 
i actually built my own grounding kit, doesn't hurt, regrounded the battery to chassis, regrounded intake manifold to chassis
check injectors are on tight as well as clips
clean ur intercooler if ur still top mounted, some gasoline or degreaser works, takes a long time to dry, but i have a heat gun which i use
check belt tensions

i should mention u'd be quite surprised how dirty filters, fuel filters get.  and how corroded rotors and caps, wires etc get.  it may sound like a lot of work, but we're talking less than 85$ a year.
fuel filter 10$x2
cap n rotor 20$
plugs 25$ (8 copper plugs)
kn filter cleaning kit 12$

Not really sure where else to put my comment, but i don't want to make a new thread.
So i did this 1 bar loop, but then put a boost controller in. set it to 14 psi, which it hits. (really it hits 14 or so and spikes to 15) Then, once i get to about 5250rpm it starts to drop off again, once i hit around 7000 the boost is sitting at around 11 psi. what could this be from?

tired wastegate actuator, turbo getting tired are definite possibilities, restrictive exhaust system, dirty intake, 

I come from subaru tuning, and don't know these cars yet, but isn't the boost supposed to taper as you get closer to redline. If it were to stay at 15psi it will be pushing to much air, and the engine is demanding more as it revs higher and the turbo is just pushing hot air, which is never good.

Hopefully I'm not way off.

i dont see why, the turbo can easily run 16psi all day long everyday. mine holds 16psi all the way to redline in all gears

Not sure if my car has 1 bar loop or not. The hose from the intake goes into the boost controller. The exit is just capped off, and the hose going into the actuator has been changed and is just a straight hose. Reading the stock boost gauge it goes up to about 6.5. Is there more power to be had if I were to rewire everything like the rest of you have it?

do you already have an after market boost controller installed?  

Not that I can see on the car. I just picked it up.

Looking at the stock gauge I think it's just maxed out when I hit boost. I'm going to have to get a aftermarket one to see what's really going on.

that would be a good first step

the max on your oem boost gauge 7 mmhg times 100 = 13.53 psi . The guage is to small for these cars !! :)

Haven't tried this modification myself but later on for sure.

Here's a colorized photo of the stock hookup on the left with the 1-bar loop illustration to the right.
In the lower panels there's a cartoon of a proposed 'hypothetical' 4-way valve setup that could be configured either way with a twist of the valve. Anyone doing this or similar or know where to source a valve like that that would bear up?

and the cartoon below that shows the general plan etc. sorta kinda

well maybe not quite but ... any and all comments appreciated, ^^^^^^^ couldn't resist the puns lol

Is the 1-bar loop common to more than Nissan's or the SR20DET?

Do it right and put a boost controller in there. Takes 2 mins to install, and then it's fully adjustable. 1 Bar loop is hokey, and wont give everyone the same result.

That's better advise, I'd wondered on a quickly reversible one-bar loop and had first considered four 3-way valves in a ladder system. The bleed valve on the wastegate could work well with tuning the bov actuation point via another bleed valve or different spring rates. So much to play with on these cars lol
I've got an used Apexi AVC-R in the wings awaiting installation in the springtime, but have to decide where to put the display control.

I've just got a cheap 50 dollar mechanical Hallman in there. Set it to about 6 Torr on the factory gauge. Pulls like a train. Holds boost till redline, doesn't drop off at all. Crosses atmospheric at 1900 rpm and full boost at 3500. I didn't have much success with the one bar loop. Only managed a 13.6 and it's much faster now that I have the boost controller, and the response is better too.

That's what the restrictor looks like. the diameter is exactly a pencil width.
The white plastic block was moving back and forth it would appear within the hose.

If I run a Walbro 255 should I also get a fuel pressure regulator? If so which one do you guys use?

This thread has exploded... If your boost is tapering off at the top end I would also check your OEM BOV,,, they do wear out,,,  and thats a symptom!

you don't need a fpr, the walbro is fine.  make sure to use the oem sock, and trim the holder so it slides down further into the tank.

I had my boost spiking big time at the top with a vac hose leaking air at the connection on the passenger side shown above. The boost gauge needle pinned out suddenly one day with no wastegate actuation and surprising added power and huge flutter/surge on lifting the throttle.

For the holder on the uprated Walbro 255 pump, how much would you recommend be trimmed off? Also wondering if it's hard to replace the stock fuel lines at the same time as the upgrade; or if it's not really essential if using a stock fpr and existing fuel lines are good?

fuel lines, sure the top ones if you can, the ones that run down the side of the tank are a bitch

my lines were old and worn, so they burst shortly after the walbro

thanks Nick,,, adding another project to the winter white board LOL 

So let's see if I have this right...(refer to image) 1. I should remove hose 8(wastegate valve control solonoid to air duct) then cap off at air duct. 2. loop hose 6(wastegate valve control solonoid to 3 way connector) back to now open port on wastegate control solonoid. 3.Remove 3 way connector and put boost tee in place between hose 7 & 9( between wastegate actuator and intake manifold vacuum). Is this Right? Or... Should I put the boost tee in place of the wastegate valve control solenoid? Is the restrictor being discussed in one of the hoses in this pic anywhere? Thanks.

Connect hose 6 to hose 8 for 1 bar loop. The restrictor is in hose 8 near the intake pipe.

Not for 1 bar loop... to add boost tee/controller. Hose 8 looks to small for that restrictor according to gtirgrey's pic.