Boost creep and DSMlink questions

cantgo2fast · #1 10-24-2007, 03:22 AM

So ive been struggling with boost creep ever since i went to a straight pipe my boost is set at ~17 psi but will creep to 19-20 at 5300-5600 rpm and i just put in a ported o2 (maybe its not ported enough) as a result i get crazy amount of knock at 5300-5600rpm. So ive but the fuel back to stock AFR from 5k up and taken 1 degree of timing out at 5k and 2 degrees at 5.5k. But what i dont understand is that if the boost is up so substantially why isnt the airflow going way up too Is the performance loss due to richening/retarding at what is my optimum power range worth losing the performance of putting the Cat back in? Is the boost est in DSM link very accurate, i trust my boost gauge more but can i trust the est? And my DSMlink isnt working on my vista computer should it? have they come up with an update to run dsmlink on vista? Sorry for the Essay

kjewer1 · #2 10-26-2007, 11:15 PM

The o2 housing is the least of the factors contributing to boost creep. The WG exit area of the turbine housing is the biggest offender, WG hole next, then the o2 housing. The VFAQ and my site have some info on this.

Boost est is accurate only when VE is 100%. This equates to 5500-6k rpm only, for most setups.

Black99GST · #3 10-28-2007, 02:25 AM

does link not even open? or it wont connect to your ECU? if it opens, check the COM port for you DB9 interface, and the DSmlink software itself, and makesure they match up!

cantgo2fast · #4 10-31-2007, 02:35 AM

Kevin are you talking about the flapper hole or the area just after that thats still part of the turbo brfore it goes into the wastegate "hole"

kjewer1 · #5 10-31-2007, 04:46 AM

The WG exit area would be the area just after the flapper. The pocket in the turbine housing that the WG dumps into right before meeting the O2 housing. When you consider that the WGA can only open the flapper about 45 degrees as you look at the WG exit area, you'll know what you have to do.

The WG entry area can provide some min boost reduction gains as well, but you run a risk of upsetting flow at high flow levels (potentially, I have no data to support this). I usually leave that as a last resort. So in order of importance and lowest risk, the WG exit area first, then the hole itself, then the WG entry path.

cantgo2fast · #6 10-31-2007, 04:23 PM

thanks for the help. Guess this means im gonna have to get a ball bearing garret turbo and huge tial wastegate lol I wish

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