Hi guys,



well, idk why, but the highest boost i reach is 7-8 psi in 3rd. gear around 5000rpm, even in 4th gear i dont get more than that.



7,5psi are standard for the S5.. but thats the weird thing.. here my modlist:



1991 S5,

Porting-Job by ArmyOfOne

big/wild streetport

ported exhaust ports

ported intake-system

modified throttlebody

Stock turbo with ported WG

FULL racing-beat exhaust system (w/ presilencer)

APEXi Power FC without MAF and APEXi cone filter.

800cc Secondaries

HKS SSQV BOV



rised oil-pressure and all such stuff.. in fact i should have at least STAGE III of FC3SPRO.COM "From mild to wild" (porting not included)

and we expected at least 12psi of BOOST.. my desired boost was 13- max 14psi

but like i said above.. NO CHANCE for higher than 8psi..



I hear no boostleaks, and the BOV seems to be leakproof, so i have no idea why i get such low boostlevels.



Do you have an idea?



Well, the car runs very nice and has much more power than stock (thanks for the great Porting from ArmyOfOne )

but it seems it could be even a bit faster with 4-5psi more than at the moment



thank you very much.

 

maybe i missed something here, what boost controler are you using?





randy

 

oh i am sorry, i am using NO boost controller yet! because WG is ported and with the mods we have done we shouldnt have more boost than 12psi anyway.. and 12-13 psi was my desired boost, so it means i dont want to go further anyway.. but i want to buy a boost controller for sure. i am just wondering why i get such low boost, with all these mods.



well my last FC s5 had 10,5psi with just a F.C.D. a cone filter and the full racing-beat exhaust (no ported WG) and the actual car has much more mods done on it, and especially the ported exhaust ports should rise the pressure a little bit, but i only get 8psi maximum.. which is just 0,5psi more than stock pressure!

 

Get a boost controller. The ported wastegate actually helps you maintain the closer-to-stock boost level.....

 

i was wondering if it is so.



what you mean is, for example:



FULL exhaust with testpipe without WG porting , up to 10psi

same with WG porting, prevents "overboosting" and keeps the boost at 8psi because of the WG port which can flow more exhaust?



thank you for your replys

 

just a thought ..you said that your running 800cc injector , maybe if its not a leak it may be too rich in tunning ..just a thought

 

oh! well, i am not THAT rich, but thank you very much for the hint.



my settings right now are ~11.3:1 during 0,55kg/cm² (7,8psi) and about 11.7-12.0 during 0,2kg/cm² (~3psi)



i have to setup the mixture and ignition myself, because i want to learn all that stuff, and dont want to LET it tuned by a professional, because on that way i will learn nothing.

in fact i am very satisfied with my current maps and settings, and i always try out new settings. was just wondering about the low boost.. but as mentioned up there, it cant be too rich, because during the "high-load" where it should go up to 10psi or even more, i have an AFR of max. 11,4 and min. 11,2

 

yeah since you are running of the wasgate spring it it boosting around stock the porting of the waste gate makes it easier for the wastegate to relive excess exhaust pressure while why you did not have it ported it would be harder to relive the exhaust the turbine would get more exhaust and cause more boost.your best bet is like what was said above get a boost controller even a cheap manual one will do on a stock turbo

 

thank you so much!! i have asked several people about that WG porting thing, because i was sure its the cause! like you said, its easier to relive excess exhaust pressure. but there were several people mentioning that the porting has no effect to the boost level..

now i know i have no boostleak at all. boost controller here i come!



hey well, one mor question. my mod list is above. like you should know, the boost drops about 6700rpm on the stock turbo. could i keep it boosting with a electronic boost controller like AVC-R or EVC?

I know i should get a bigger turbo for high-rpm boost, but all i want to know is, if its possible to keep it boosting around 7000-8000rpm.

AND make it even more boost in 2nd gear, as because of the construction of the turbo and its "lag" the rpm rises much faster than boost pressure (which is total normal) just want to know if i could improve that, and build up more boost in 1-2 gears with an electronic boost controller.



thank you very much

 

I hadnt been online in a little bit - so i wasnt able to backup my ported wastegate comment, but i see others did. This is typically a good idea when you have a mostly stock car. Getting higher boost because the stock WG is not ported is just a side affect of the modifications, doesnt mean you WANT it to do so on its own. Having the ported WG and adding a boost controller will be the best bet. An EBC is not really needed as it performs the same as a MBC and the MBC is way cheaper. The EBC advantage is simply in convenience. I find them to be way to tempting though and on mostly stock cars, the MBC is safest, lol...



The stock turbo will roll up to 10psi with the MBC in place.... if its falling on its face at 6700 than that can be your tuning or just the exhaust setup, etc... I wouldnt go much past 9psi on the stocker anyways, if it goes, it might take the motor with it...