How many lbs of boost are you running?

**turbox2** · 03-10-2010 06:20 AM

I have searched all morning to see what kind of boost people are running on their 2.7ts with a MBC and i failed.
So I think we should create a general thread devoted to what how many lbs of boost you are running on your 2.7t...
Include your mods, whether its chipped and by whom, if it is a MBC and the overall reliability of your car...

If your car is running stock boost, you need not apply....

**pit viper** · 03-10-2010 06:54 AM

21 psi.

**turbox2** · 03-10-2010 06:56 AM

chipped? mods?

**pit viper** · 03-10-2010 06:58 AM

damn, make me write it all out...

PJK04's
JHM fueling/tune
255 auxiliary fuel pump
ER intercoolers
Aquamist water/meth injection
was running an mbc, now running a Profec B Spec 2
Various other assorted goodies

**nrowensby** · 03-10-2010 07:09 AM

Was hitting 20psi on my B5S4 w/GIAC-X chip, bypassed N249, K&N intake, Samco TBB, 710N DV's & Hallman-Pro MBC... hit boost a lot quicker than stock... also seemed to hold longer than stock.

...not running MBC on A6 until I can figure out a clean place to mount a boost gauge.

**teckjoel1320** · 03-10-2010 09:09 AM

What ever my GIAC X chip is letting me run.

EVO MS intake
GIAC X chip maps for 93 and 100 octane
Samco TB boot
Samco upper inlet pipes
Samco upper intercooler pipes
Samco Diverters
Stock resonators removed from exhaust

Thats it from what i remember, theres other suspension stuff done and a bunch of stereo work and like snub mount and stuff. lots of stuff if you cant tell.

I have no idea how much boost i run but id like to know, i'd also like a boost controller just to hold boost better up top but am a bit weary of running one due to it didnt work well with my old B5

**4ringAR** · 03-10-2010 07:33 PM

spikes to 17psi, holds at ~13psi. Dahlback stage 1 tune with Forge 007 DV's.

**rxphiler** · 03-11-2010 12:41 PM

spike to 18-19ish hold steady 15-16ish GIAC stock diverters

**A62TURBO** · 03-11-2010 12:43 PM

18

**Tamas** · 03-11-2010 01:45 PM

what is stock?

**Asicks** · 03-11-2010 01:50 PM

About 7psi

**turbox2** · 03-11-2010 08:01 PM

breaking in the new turbos:
10psi, spiking 13psi on RP k04s, 034 inlets, piggie pipes, darintake, k&n filter and forge MBC.
Whats the max you can on the N75 with out putting your car into limp mode?

**allroadstomtl** · 03-12-2010 05:13 AM

19, unitronic flash

**SILVER A6 2.7T** · 03-12-2010 01:55 PM

so i dont know much about mbc's but i heard you cant use them with out your car going into limp mode. is there somthing you can bypass so it wont or what? or can you just bump it up like 2-3psi with out the cpu really noticing?

**nrowensby** · 03-12-2010 02:17 PM

TCD (aka diode mod)

**stef2.7t** · 03-12-2010 03:11 PM

Spike to 16- 17 taper to 14, On APR 91 file

**Mantis** · 03-12-2010 03:51 PM

Spike 23.5 hold 19.7 all the way to 7k RPM

**cbock** · 03-12-2010 11:43 PM

19. Mods in sig link.

**Allen3** · 03-29-2010 07:04 AM

I know this is an older thread but my question pertains so i didnt want to start a new one.

I have a stock 2.7t. Am i able to install a MBC and increase the boost without any problems? I am planning on getting the APR tune but the MBC is something i can do in the mean time.

Also, i thought our stock boost was around 6-7PSI. Is that correct? (if not, apparently i have a boost leak)

**Despized** · 03-29-2010 01:49 PM

Stock boost is around 7psi per turbo aka 14 on a biturbo setup. I am runnning apr 93 oct and pushing 28-31psi total.. which is 14-15.5psi based on vagcom. samco tbb and forge 007 dvs. 2.5inch custom exhaust catback no restriction.

**Asicks** · 03-29-2010 01:51 PM

Originally Posted by Despized

Stock boost is around 7psi per turbo aka 14 on a biturbo setup.

*facepalm*

**Allen3** · 03-29-2010 01:56 PM

I dont think i agree with that. Ive seen numbers on forums from 6-7 PSI and also 9-10 PSI for stock system on 2.7t. 14 PSI is not a stock number. Thats what the GIAC or APR ECU flashes claim to push it up to, but thats not stock. Anyone else have input on this?

**A62TURBO** · 03-29-2010 02:01 PM

Originally Posted by Despized

Stock boost is around 7psi per turbo aka 14 on a biturbo setup. I am runnning apr 93 oct and pushing 28-31psi total.. which is 14-15.5psi based on vagcom. samco tbb and forge 007 dvs. 2.5inch custom exhaust catback no restriction.

You don't count boost per turbo, bi-turbo is considered one system and the PSI is measured overall. There is no way you're running 31psi on K03's lol

**Bashar Khalifeh** · 03-29-2010 02:03 PM

7-9 PSI is stock, ~15 PSI is chipped, I think what he is trying to say is that it is 7-9 PSI per Turbo, therefore it is a total of 14 PSI (7psi per turbo)

**4ringAR** · 03-29-2010 02:11 PM

Originally Posted by Bashar Khalifeh

7-9 PSI is stock, ~15 PSI is chipped, I think what he is trying to say is that it is 7-9 PSI per Turbo, therefore it is a total of 14 PSI (7psi per turbo)

But. That. Is. Not. How. It. Works.

**Allen3** · 03-29-2010 02:24 PM

I think your thought process is incorrect, each turbo outputs the same pressure. The pressures dont add together, they combine to maintain a pressure of X. For instance 2 turbos running 7 PSI combine to make 7 PSI, in parallel (like ours are). Not 3.5lbs each but 7 lbs each.
However, if it a twin-turbo set up to run 2 turbos in sequence, then i believe the maximum PSI will take the quantity of the larger Turbo (still dont add the two). These systems use a smaller turbo to spool up quick and then cut-out and let a larger turbo take over at the high end to produce more air-flow. Examples would be Porsche 959, Mazda RX-7, Toyota Supra and Subaru Legacy. Both have advantages and disadvantages but thats not really what my question was. haha

So....What is the out of the factory stock setting for our boost supposed to be? Any definitive answers?

**A62TURBO** · 03-29-2010 02:52 PM

8 psi

**Coors** · 03-29-2010 05:14 PM

You know what? I have no clue what I am running at? I tried doing some runs with Vag-Com on the highway, but I almost wrecked because I didn't care about the road all I wanted to see was the boost pressure. I think the max I saw was 17-18psi to redline? No clue what I spike too.

PJK04's GIAC Stage3 minus. Bosch 5bar FPR w/ stock fuel pump Piggies, stock main cats to 2.5" Magnaflows.

Anyone w/ GIAC stage3 minus software care to chime in for a comparison?

**Mantis** · 03-29-2010 05:18 PM

Vag Com shows 28psi when converted from mbar because it is an absolute pressure not a gauge pressure. It is accounting for your atmospheric pressure. Normal is between 8-10 psi, wastegates crack open on stock K03's at about 3-4psi. Coors, I was at about 19psi with my GIAC 3- tune, so it would seem that your 17-18 at redline is spot on

**Coors** · 03-29-2010 05:23 PM

Originally Posted by nothing77

Coors, I was at about 19psi with my GIAC 3- tune, so it would seem that your 17-18 at redline is spot on

I thought thats what I saw. I think I did the calc correctly, after I convert mbar to psi I subtract 14.75(atmospheric pressure), right? Because it is absolute pressure and not gauge pressure.

**Mantis** · 03-29-2010 05:34 PM

14.7 only if you are at sea level, check vag com to get your actual while the car is not on, I am guessing that you will be at about 14.0 in Philly, pretty close to sea level, high and low pressure weather system also affect atmospheric pressures

**mr.awesome** · 03-29-2010 06:13 PM

20-21ish? peak and hold like...17? im getting a new gauge soon..
giac x
evoms dv's
kn drop in.
that should be it..

**julex** · 03-29-2010 07:58 PM

2500 mbar (touching the upper limit of stock MAP sensor) linearly going down to 2400 at 7k+.

**Mantis** · 03-30-2010 05:11 AM

Originally Posted by julex

2500 mbar (touching the upper limit of stock MAP sensor) linearly going down to 2400 at 7k+.

I ran my tune like that for a bit last summer, definitely pulls hard, I toned it down for longevity

**julex** · 03-30-2010 05:40 AM

Originally Posted by nothing77

I ran my tune like that for a bit last summer, definitely pulls hard, I toned it down for longevity

Yeah, I think I will be bringing it down 100mbar across or so.

**Despized** · 03-31-2010 08:55 AM

I will re-vag this summer/ or ask the guys when my car goes for maint at the apr shop this friday.

**khalimadeath** · 03-31-2010 11:13 PM

In a parallel turbo system, if each turbo is putting out 7 psi, then the total boost pressure is 7pi. The flow rate of each turbo adds together though. So (just coming up with numbers off the top of my head, not necessarily accurate) if each turbo is putting out 100 cfm at 7 psi, then the total pressure is still 7 psi but total flow is 200 cfm.

This is unlike a sequential turbo system like that used in a Toyota Supra. The total pressure adds together. So if the first turbo is running 5 psi and the second turbo is running 10, the total pressure is 15 psi. But in this system, the airflow will be restricted by the smaller turbo.

So it's a tradeoff, do you want lower boost and more flow? Or higher peak boost but less overall flow? They have their advantages and disadvantages each, like allen3 said. Except in the sequential system, the smaller turbo is used to spool up the larger turbo so it can hit higher boost at lower RPMs.

**Mantis** · 04-01-2010 05:08 AM

Originally Posted by khalimadeath

In a parallel turbo system, if each turbo is putting out 7 psi, then the total boost pressure is 7pi. The flow rate of each turbo adds together though. So (just coming up with numbers off the top of my head, not necessarily accurate) if each turbo is putting out 100 cfm at 7 psi, then the total pressure is still 7 psi but total flow is 200 cfm.

This is unlike a sequential turbo system like that used in a Toyota Supra. The total pressure adds together. So if the first turbo is running 5 psi and the second turbo is running 10, the total pressure is 15 psi. But in this system, the airflow will be restricted by the smaller turbo.

So it's a tradeoff, do you want lower boost and more flow? Or higher peak boost but less overall flow? They have their advantages and disadvantages each, like allen3 said. Except in the sequential system, the smaller turbo is used to spool up the larger turbo so it can hit higher boost at lower RPMs.

Kinda off topic, but some of what you explained is a compound setup not sequential