# Safe Boost=? w/ GT turbo and stock MKIV 1.8T internals.



## GT28RS_GTI (Apr 5, 2004)

I have been using 18.5 lbs boost with my GT2871R turbo for a while now. REVO tuned and ATP kit. I am getting an EBC soon. All of you guys using the GT series turbo with stock internals, can you hold 22-23 PSI at the redline w/o modifying the internals? I keep up with STIs with 18 PSI, but I am positive if I push 22 PSI I will be able to take them. ATP told me that they dynoed GT2871R turbo with stock internals, 24 PSI and race fuel. But, I am talking about pump gas and daily driving with 22-23 PSI.
Also, any one know what the AGGRESSIVE BOOST setting is on the SPS-3 device?
Is there a turbo performance difference if you set to REVO boost setting 3 & run EBC to restrict to 18 PSI vs setting 1 and let the software max out at 18 PSI.

Any feedback will be highly apprecited.


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## V84LNCH (Aug 29, 2003)

*Re: Safe Boost=? w/ GT turbo and stock MKIV 1.8T internals. (GT28RS_GTI)*


_Quote, originally posted by *GT28RS_GTI* »_I have been using 18.5 lbs boost with my GT2871R turbo for a while now. REVO tuned and ATP kit. I am getting an EBC soon. All of you guys using the GT series turbo with stock internals, can you hold 22-23 PSI at the redline w/o modifying the internals?
*yes you can. not on 91 octane through*
Is there a turbo performance difference if you set to REVO boost setting 3 & run EBC to restrict to 18 PSI vs setting 1 and let the software max out at 18 PSI.
*no there isn't. basically when you get to the highest setting, the software has removed the boost limit on your car. it will still have a requested boost, but if you overshoot it, your car won't hit limp. *

Any feedback will be highly apprecited.


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## GT28RS_GTI (Apr 5, 2004)

*Re: Safe Boost=? w/ GT turbo and stock MKIV 1.8T internals. (V84LNCH)*

So, why can some one NOT boost over 20-21 w/ 91 octane....I have bee told by 4 people atleast in the Denver, Colorado area with over 20 lbs sustanined dyno...I understand the O2 molucule vs boost factor w/ altitude and 91 octane.


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## xgtiride (Oct 23, 2003)

*Re: Safe Boost=? w/ GT turbo and stock MKIV 1.8T internals. (GT28RS_GTI)*


_Quote, originally posted by *GT28RS_GTI* »_So, why can some one NOT boost over 20-21 w/ 91 octane....I have bee told by 4 people atleast in the Denver, Colorado area with over 20 lbs sustanined dyno...I understand the O2 molucule vs boost factor w/ altitude and 91 octane.

In short... at that psi with that turbo, 91 octane would not have enough resistance to predetonation.


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## GTijoejoe (Oct 6, 2001)

*Re: Safe Boost=? w/ GT turbo and stock MKIV 1.8T internals. (xgtiride)*


_Quote, originally posted by *xgtiride* »_
In short... at that psi with that turbo, 91 octane would not have enough resistance to predetonation.

exactly, you will need to lower your compression a lil big more, more than likely to run that kind of boost with pump gas. Detonation is a killer.


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## vwgtiIII (Jan 3, 2005)

Altitude probably plays a pretty large role in your situation though. 20lbs in Denver on a warm day is a lot different than many of us closer to sea-level in a colder climate. Actual air density varies quite a bit between the locations but its less evident once the air is compressed. I lost track of where I was going with this one....


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## matt.e.davis (Mar 27, 2006)

I am running the factory kp3 sport and I am getting 22psi (chip, cold air, light weight pulleys). I think if you want power that you should upgrade the turbo. While the PSI sounds good the turbo runs out of breath moderate load,


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## GT28RS_GTI (Apr 5, 2004)

*Re: (matt.e.davis)*

1st question; any Colorado 1.8T and Garrett GT turbo users here? I would like to know how you guys are doing w/ your kit. Please IM me.
Matt, you probabaly didn't realize that I am running a GT2871R turbo. Check my SIGNATURE out. And I am surprised that you are pushing 22 PSI with yours. You are probably spiking @ 22 PSI for some miliseconds. My K03S w/ x-chip used to spike 1.35 bar from time to time. K03S or K04 won't withstand sustained PSI to redline over 20 because the hot side it going to run really really HOT. Some one I knew ceased his turbo b/c he pushed over 20 PSI w/ EBC for couple of consecutive runs.
Others, Well this APR Stage 3+ (w/ GT28RS .86 a/r kit) user that I used to know spiked @ 24 PSI and tapered off to 20-21 PSI here in Denver with 91 octane pump gas. He drove his w/ that kit for over 6 months by the time I got to meet him. He didn't complain any thing about predetonation issues. What the heck is predetonation any ways? How does it relate to oxygen molecule, A/R ratio and lower/higher altitude?
So, how do you tweak the compression? My long-term goal is to modify the piston rods and related internals, so that it can handle up to 26-28 PSI







w/ GT2871R turbo.
Thanks again all.


_Modified by GT28RS_GTI at 4:59 AM 3-28-2006_


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## bongoRA3 (Oct 8, 2003)

*Re: (GT28RS_GTI)*

Thats a pretty hefty turbo. Lots of people don't realize it...but you can easily throw a rod with 20+ psi on GT2871R. (just for the record....psi don't mean squat, its the cfm's a turbo is putting out in its efficeincy range, thus why a gt2871r makes around 350+ whp at ~ 20psi and a ko3s bairly makes 200whp) .
As for your question on altitude....your turbo is struggling more to compress the air since the air is less dense at your altitude. Once the compression accurs...altitude has nothing to do, trust your boost gauge.








But stronger rods are defiently recommended, since they are known to let go in 1.8t's pushin ~300whp. 
http://****************.com/smile/emthup.gif 


_Modified by bongoRA3 at 11:29 PM 3-29-2006_


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## [email protected] (Mar 16, 2004)

*Re: (GT28RS_GTI)*


_Quote, originally posted by *GT28RS_GTI* »_What the heck is predetonation any ways? 

Pre-ignition is what they mean. Closely related to detonation. To put it very basically its so hot in the combustion chamber that the spark ignites before it is supposed to, which usually means way too soon as well.


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## V84LNCH (Aug 29, 2003)

*Re: ([email protected])*


_Quote, originally posted by *[email protected]* »_
Pre-ignition is what they mean. Closely related to detonation. To put it very basically its so hot in the combustion chamber that the spark ignites before it is supposed to, which usually means way too soon as well. 


and if your knock sensors detect and detonation (which it will at those boost levels and 91 fuel) it will pull all of your timing out of the ignition angle.


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## GT28RS_GTI (Apr 5, 2004)

*Re: (V84LNCH)*

This guy here..is pushing 22 PSI 1.8T Jetta GT28RS 91 octane on a daily basis..no problems for 6 months....but he has the same concerns like me..he is not happy with the WHP..he dynoed 240-ish WHP....


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## wheresyourbackpackbrah (Sep 30, 2009)

*Re: Safe Boost=? w/ GT turbo and stock MKIV 1.8T internals. (GT28RS_GTI)*

so how much exactly would stock internals hold? 
im planning on buying a 50 trim for my 1.8t and id like to keep my internals stock for a little longer even tho its not the best idea =/


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## KubotaPowered (Jan 27, 2005)

*FV-QR*

Holy old post bump Batman!


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## TBT-Syncro (Apr 28, 2001)

*Re: Safe Boost=? w/ GT turbo and stock MKIV 1.8T internals. (wheresyourbackpackbrah)*


_Quote, originally posted by *wheresyourbackpackbrah* »_so how much exactly would stock internals hold? 


300ft/lbs is the safe limit for stock rods, although some have pushed as high as 350


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