What's the most boost I can run with stock downpipes?

rbaldwin28 · 11-01-2010, 01:08 AM

I have a FMIC, fully divorced exaust with no secondary cats and run 14-15 psi on 91 oct but some times I run 100 oct and the procede tunes to 16 psi and Ignition correction at 0. I feel like I could raise that limit to 17 or 18 but my downpipes are stock and I don't know if there are dangers I should consider. Thanks in advance, I searched but found nothing specific.

mycoupe · 11-01-2010, 01:21 AM

I think it has more to do with egt's and eg velocity. Then again, I am just guessing.

rbaldwin28 · 11-01-2010, 01:40 AM

Quote:

Originally Posted by mycoupe

I think it has more to egt's and eg velocity. Then again, I am just guessing.

Yea, I think I remember shiv saying the procede monitors EGT for a margin of safety but I am not sure.

enrita · 11-01-2010, 01:46 AM

just let Autotune do the trick and log the car. I would set max boost at 15.5 psi.

rbaldwin28 · 11-04-2010, 11:20 PM

Quote:

Originally Posted by enrita

just let Autotune do the trick and log the car. I would set max boost at 15.5 psi.

Why 15.5 when the procede auto tunes to 16 psi and ignition correction is at 0 most of the time and never exceeds 30. Seems to me that I could go to 17 or 18 psi on the dyno and auto tune would raise boost and Ignition correction if conditions permit. Just to clarify I am talking about running 100 octane fuel and on the dyno. I am not going to run less boost then I run on the street.

themyst · 11-04-2010, 11:30 PM

FWIW, I know guys who run 18psi through stock downpipes.

Jeff@TopGearSolutions · 11-04-2010, 11:32 PM

Try 17 max and log it.

enrita · 11-05-2010, 02:14 AM

Quote:

Originally Posted by rbaldwin28

Why 15.5 when the procede auto tunes to 16 psi and ignition correction is at 0 most of the time and never exceeds 30. Seems to me that I could go to 17 or 18 psi on the dyno and auto tune would raise boost and Ignition correction if conditions permit. Just to clarify I am talking about running 100 octane fuel and on the dyno. I am not going to run less boost then I run on the street.

because higher boost with Cats would generate a huge amount of backpressure and heat. Those OEM cats are extremely restrictive. If you plan to run higher boost than 16 get some catless dps. Your turbos will thank you

wchoy · 11-05-2010, 02:38 AM

youll be able to get more power from the turbos with out your stock dp's even at the same pressure. i think what you are looking for is the threshold where the back pressure from the cats is so great that you arnt making the power you should be at say 18 psi.

techlogik · 11-05-2010, 10:37 AM

You can push more through the standard downpipes and CATs than our small stock turbos can handle.

rbaldwin28 · 11-07-2010, 02:00 AM

Quote:

Originally Posted by enrita

because higher boost with Cats would generate a huge amount of backpressure and heat. Those OEM cats are extremely restrictive. If you plan to run higher boost than 16 get some catless dps. Your turbos will thank you

California emissions laws are strict and expensive if ignored. Thanks for your input.

rbaldwin28 · 11-07-2010, 02:04 AM

Sounds like it would be relatively safe to increase the max psi to 18 for the trip to the dyno. Thanks to all that replied.

muskamatt · 12-01-2010, 08:21 PM

do you go get your gas from Rancho when you get 100?

rbaldwin28 · 12-01-2010, 11:14 PM

Quote:

Originally Posted by muskamatt

do you go get your gas from Rancho when you get 100?

OCHS in vista has 24 hour 100 octane at the pump. It is sunoco 260GT. The credit card swiper is by the trash cans.
I used to get Vp Streetblaze from rancho but they close at night and my auto tune gets more agressive on the sunoco.

muskamatt · 12-02-2010, 12:47 AM

wow I thought rancho was the only place ridiculous enough to sell 100. Does octane booster work the same or not at all? I have no idea.

rbaldwin28 · 12-02-2010, 02:08 AM

I don't know about octane boosters sorry.

Brey335i · 12-02-2010, 06:36 AM

I would run meth with boost set at 18 fwiw

SitDown · 12-02-2010, 03:19 PM

Ive found 18psi to work well for me, running 104 w/ stock DPs.

11-01-2010, 01:08 AM	#1
rbaldwin28 Lieutenant 13 Rep 408 Posts Drives: E92 335i Sport Prem. White Join Date: Aug 2009 Location: Carlsbad CA and San Diego CA iTrader: (0) Garage List 2007 335I [0.00]	What's the most boost I can run with stock downpipes? I have a FMIC, fully divorced exaust with no secondary cats and run 14-15 psi on 91 oct but some times I run 100 oct and the procede tunes to 16 psi and Ignition correction at 0. I feel like I could raise that limit to 17 or 18 but my downpipes are stock and I don't know if there are dangers I should consider. Thanks in advance, I searched but found nothing specific. __________________ Procede Inside! AutobahnExotics, Vishnu DCI, AR Oil Catch Can, ETS Black Anodized Intercooler, Quaife LSD, Falken FK452, Mtech 6000k HID, 7000k Halos, 15%vlt Ceramic Tint, Matte Black Kidney Grills.
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11-01-2010, 01:21 AM	#2
mycoupe Banned 55 Rep 1,495 Posts Drives: 07 335i coupe 6spd Join Date: Dec 2009 Location: cincinnati, Ohio iTrader: (5)	I think it has more to do with egt's and eg velocity. Then again, I am just guessing. Last edited by mycoupe; 11-01-2010 at 09:59 AM..
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11-01-2010, 01:46 AM	#4
enrita Major General 161 Rep 7,377 Posts Drives: 335i - Big turbos Join Date: Sep 2008 Location: Italian in Sweden iTrader: (0)	just let Autotune do the trick and log the car. I would set max boost at 15.5 psi. __________________ 07 335i AT - MOTIV 750 - MHD E85 BMS flash - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Snow Stg. 3 - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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11-04-2010, 11:30 PM	#6
themyst Major General 177 Rep 6,631 Posts Drives: '16 MK7 GTI Join Date: Feb 2009 Location: NYC iTrader: (8)	FWIW, I know guys who run 18psi through stock downpipes. __________________ E90 LCI N54 6AT
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11-04-2010, 11:32 PM	#7
Jeff@TopGearSolutions 3441 Rep 79,211 Posts Drives: C6 Z06, 09 335i, 10 335xi Join Date: Dec 2008 Location: www.TopGearSolutions.com iTrader: (37)	Try 17 max and log it.
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11-05-2010, 02:38 AM	#9
wchoy First Lieutenant 5 Rep 311 Posts Drives: '08 AW e90 335i Join Date: Apr 2010 Location: Honolulu, Hawaii / LA iTrader: (0)	youll be able to get more power from the turbos with out your stock dp's even at the same pressure. i think what you are looking for is the threshold where the back pressure from the cats is so great that you arnt making the power you should be at say 18 psi.
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11-05-2010, 10:37 AM	#10
techlogik Lieutenant Colonel 70 Rep 1,565 Posts Drives: 2020 M340i Dravit Grey Join Date: Dec 2006 Location: FL iTrader: (2)	You can push more through the standard downpipes and CATs than our small stock turbos can handle. __________________ 2020 M340i: Dravit Grey Mettalic. Loaded.
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11-07-2010, 02:04 AM	#12
rbaldwin28 Lieutenant 13 Rep 408 Posts Drives: E92 335i Sport Prem. White Join Date: Aug 2009 Location: Carlsbad CA and San Diego CA iTrader: (0) Garage List 2007 335I [0.00]	Sounds like it would be relatively safe to increase the max psi to 18 for the trip to the dyno. Thanks to all that replied. __________________ Procede Inside! AutobahnExotics, Vishnu DCI, AR Oil Catch Can, ETS Black Anodized Intercooler, Quaife LSD, Falken FK452, Mtech 6000k HID, 7000k Halos, 15%vlt Ceramic Tint, Matte Black Kidney Grills.
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12-01-2010, 08:21 PM	#13
muskamatt First Lieutenant 9 Rep 348 Posts Drives: e92 335i Join Date: Jul 2010 Location: SoCal iTrader: (0)	do you go get your gas from Rancho when you get 100?
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12-02-2010, 12:47 AM	#15
muskamatt First Lieutenant 9 Rep 348 Posts Drives: e92 335i Join Date: Jul 2010 Location: SoCal iTrader: (0)	wow I thought rancho was the only place ridiculous enough to sell 100. Does octane booster work the same or not at all? I have no idea.
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12-02-2010, 02:08 AM	#16
rbaldwin28 Lieutenant 13 Rep 408 Posts Drives: E92 335i Sport Prem. White Join Date: Aug 2009 Location: Carlsbad CA and San Diego CA iTrader: (0) Garage List 2007 335I [0.00]	I don't know about octane boosters sorry. __________________ Procede Inside! AutobahnExotics, Vishnu DCI, AR Oil Catch Can, ETS Black Anodized Intercooler, Quaife LSD, Falken FK452, Mtech 6000k HID, 7000k Halos, 15%vlt Ceramic Tint, Matte Black Kidney Grills.
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12-02-2010, 06:36 AM	#17
Brey335i Banned 112 Rep 4,771 Posts Drives: e46 ///M3 Join Date: Oct 2009 Location: Austin, TX iTrader: (11)	I would run meth with boost set at 18 fwiw
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12-02-2010, 03:19 PM	#18
SitDown . 8 Rep 247 Posts Drives: Huntin Again... Join Date: Oct 2009 Location: IL iTrader: (0)	Ive found 18psi to work well for me, running 104 w/ stock DPs.
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