The banner above is an advertisment - if it asks you to download software, please ignore.
Site News -
7/1: Members: Log In to See Fewer Ads! |
5/28: SAAB Evolutions/TSN T-Shirts $14
[General |
Members |
C900 |
9000 |
NG900 & OG93 |
93 |
95 |
NG95 |
99 |
Sonett |
Vintage Models |
Clubs |
Other Cars |
FAQs |
Gifts |
Member Photo Galleries |
Member Directory |
Classifieds |
Manuals |
*Buddy Registry |
*Mileage Registry |
Polls |
What's New |
Raffle |
Photo of the Month |
Sponsors]
[Main Performance Bulletin Board | BBFAQ |
Prev by Date | Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: where is the waste-gate door at base boost??
Posted by Dean [Email] (more from Dean) on Fri, 9 Dec 2005 16:05:22
In Reply to: where is the waste-gate door at base boost??, Smeter, Fri, 9 Dec 2005 15:38:14
Members do not see ads below this line. - Help Keep This Site Online - Signup
Lets say that the target boost is 15 PSI, in this case when you are on WOT and get to 5 PSI, you want the WG to be closed as to not spill any exhaust flow that will get the turbo spinning fast enought to get you to 15 PSI. A classic bleeder valve starts to open early and might be spilling gas flow well before you get near the target boost levels and that means lots of "boost lag". Notice that I did not say "turbo lag" as the turbo's reponse is not controling the boost response, the controller is. Note note that the BPC or APC valve is a solenoid variable "bleeder valve" which does increase "boost lag". A MBC/SMBC/MBC+A with a ball spring mechanism will keep the WG closed until very close to the target boost levels. With an typical undersized OEM turbo, a MBC can easly lead to boost overshoots and fuel cuts on many control systems. The MBC+A has a boost anticipator action that allows the WG to open soon enough to avoid pressure overshoots.
With a MBC/SMBC/MBC+A the boost comes on very fast and very non linear, which is really how a turbo is when not masked by the control system. You get used to some very different throttle techniques. That is what you can expect when the WG does not open early or at base boost.
I hope that that helps you, even though it is vague about whats going on specifically at base boost.
Posts in this Thread:
Members do not see ads below this line. - Help Keep This Site Online - Signup
Post a Followup
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
StateOfNine.com
![](/tsn/xyz/stateofninebutton.gif) |
SaabClub.com
![](/tsn/xyz/scnabutton.gif) |
Jak Stoll Performance
![](/tsn/xyz/jakstollbutton.gif) |
M Car Covers
![](/tsn/xyz/mcarcoversbutton.gif) |
Ad Available
![](/tsn/xyz/buttonavailable.gif) |
![](/tsn/images/tsnmap.gif)
Random Saabnet.com Member Gallery Photos (Click Image)
This is a moderated bulletin board - Posting is a privilege, not a right.
Unsolicited commercial postings are not allowed (no spam). Please, no For Sale or Wanted postings, SERIOUSLY.
Classifieds are to be listed in The Saab Network Classifieds pages.
This is a problem solving forum for over 250,000 Saab owners, so expect to see
problems discussed here even though our cars are generally very reliable. This is not an anything goes
type of forum. Saabnet.com has been a moderated forum since 1988. For usage guidelines, see the
Saabnet.com Mission and Purpose Page. Please remember that you are
not anonymous. Site Contact | Site Donations | Other Sites by SP -
Poverty2Prosperity.org | Run Club Menlo Park | ScreenBot
Site Members do not see red text instructions, bottom of the page anchor ads, or box ads.
Click here to see all
the Site Membership Benefits!