# How much boost can you run on pump gas?



## R32Smoker (Oct 21, 2010)

How much boost are you guys running on pump gas? I'm running a C2 tune, 630cc injectors, built 2.9 VR6 w/ about 8.0:1 compression and 93 octane pump gas. Currently running 18 psi; should I not run more than 20 psi without higher octane?


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## ALLGORIMSHOW (Jul 1, 2002)

R32Smoker said:


> How much boost are you guys running on pump gas? I'm running a C2 tune, 630cc injectors, built 2.9 VR6 w/ about 8.0:1 compression and 93 octane pump gas. Currently running 18 psi; should I not run more than 20 psi without higher octane?


8:1 is nice and low, 20psi+ no problem... even with C2 and 93.


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## 92g60gti (Jul 6, 2004)

Big question, what are you running for a turbo? There's a big difference between 24psi on a t3/t4 and 24psi on a gt4088. Do you have a wideband? As long as you aren't running something huge then the c2 630 file should be able to support 24-25psi. Hopefully you have a wideband, if so then just turn it up a couple psi at a time and keep an eye on the wideband.


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## dubbinmk2 (Jan 15, 2008)

92g60gti said:


> Big question, what are you running for a turbo? There's a big difference between 24psi on a t3/t4 and 24psi on a gt4088. Do you have a wideband? As long as you aren't running something huge then the c2 630 file should be able to support 24-25psi. Hopefully you have a wideband, if so then just turn it up a couple psi at a time and keep an eye on the wideband.




^^^^ his correct running with out a wide is suicidal


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## R32Smoker (Oct 21, 2010)

I'm running a Precision 6265E ball bearing turbo. No wideband though  

I did a dyno run @ 16 psi and the a/f looked good; though the power output was a bit disappointing due to the super low compression (300 whp on a Mustang dyno, so about 335 whp). 

I'm also only running a 5.8 psi wastegate spring, so that could be hurting my numbers. I need to replace it with a 9 or 10 psi spring soon. I'd like to run 20 psi, not too worried about much more than that for the street....yet :laugh:


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## dub_slug (May 12, 2008)

I have a similar setup
6265 journal, 2.9l, 8.5:1, 440cc

I was running 28psi on 93 no w/m and you have bigger injectors :thumbup: 
Get yourself the 25psi spring combo cuz your gonna need it 
I couldn't imagine running just a 5.8 spring...


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## R32Smoker (Oct 21, 2010)

Nice, got any dyno numbers or track times with that setup? 

The 5.8 psi spring just isn't holding the boost quite right, I can feel a bit of stuttering/hesitation at high boost. Guess I might as well go for at least a 12 psi spring than :thumbup:


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## dub_slug (May 12, 2008)

If your running 18psi then get a 12psi spring and use it with your 5.8 :thumbup: 
What boost controller are you using? Depending on that you could be losing power through the boost controller...
No track times but I've rolled on everything I've come across...c6 vette, m3, m5, s5, couple s2ks, 370z and some other ****. It's good enough for me 

BTW; when do you hit full boost and what hotside are you running?? How fast foes boost build while cruising?? I get full boost(~28psi) right smack dab at 4k rpm


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## 92g60gti (Jul 6, 2004)

R32Smoker said:


> Nice, got any dyno numbers or track times with that setup?
> 
> The 5.8 psi spring just isn't holding the boost quite right, I can feel a bit of stuttering/hesitation at high boost. Guess I might as well go for at least a 12 psi spring than :thumbup:


The rule of thumb is to only go double whatever you are running for a wastegate spring. Beyond that it can't efficiently and consistently control boost.


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## boost_addict (Dec 4, 2009)

92g60gti said:


> The rule of thumb is to only go double whatever you are running for a wastegate spring. Beyond that it can't efficiently and consistently control boost.




:thumbup:


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## sp_golf (Nov 28, 2007)

dub_slug said:


> I have a similar setup
> 6265 journal, 2.9l, 8.5:1, 440cc
> 
> I was running 28psi on 93 no w/m and you have bigger injectors :thumbup:
> ...


:what: you know those injectors will max out at ~400-420whp right.. 28psi?
PS: I run a 6psi spring and I've ran 24psi without any problems


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## cabzilla (Jan 3, 2000)

sp_golf said:


> :what: you know those injectors will max out at ~400-420whp right.. 28psi?
> PS: I run a 6psi spring and I've ran 24psi without any problems


The #42 program is "safe" to 470 whp. Don't believe everything people here repeat.


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## pimS (Jan 7, 2009)

with W/M and 4bar fpr i asume?


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## sp_golf (Nov 28, 2007)

cabzilla said:


> The #42 program is "safe" to 470 whp. Don't believe everything people here repeat.


Both the MAF and injectors max out in the low 400whp range, and I'm speaking from experience here, the MAF maxes out at ~430whp, injectors max out a bit earlier. Both of these facts were confirmed by C2 when they saw the logs. The car in question made 440whp with WMI, the AFRs were in the high 12:1 range, the're above 13:1 without WMI. It's been thru 2 motors, one on the 42# and another on 60#/stock MAF.


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## cabzilla (Jan 3, 2000)

sp_golf said:


> Both the MAF and injectors max out in the low 400whp range, and I'm speaking from experience here, the MAF maxes out at ~430whp, injectors max out a bit earlier. Both of these facts were confirmed by C2 when they saw the logs. The car in question made 440whp with WMI, the AFRs were in the high 12:1 range, the're above 13:1 without WMI. It's been thru 2 motors, one on the 42# and another on 60#/stock MAF.




I made 470+ whp years ago on the 42# program, no WMI, under 12.5:1. Old news.


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## sp_golf (Nov 28, 2007)

cabzilla said:


> I made 470+ whp years ago on the 42# program, no WMI, under 12.5:1. Old news.


Which dyno is that? I want a 500+ whp dyno sheet with my T3/T4 :laugh:


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## boost_addict (Dec 4, 2009)

cabzilla said:


> I made 470+ whp years ago on the 42# program, no WMI, under 12.5:1. Old news.


 

i call BS :thumbdown:


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## cabzilla (Jan 3, 2000)

boost_addict said:


> i call BS :thumbdown:


 Good for you, I guess? 


Search my post history, chief.


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## boost_addict (Dec 4, 2009)

OK yea with a 35r. the post above said t3/t4 so i questioned.. my apology


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