Re: DIY vac advance w/spring -- SUCCESS! (long) - Saab Performance Bulletin Board - Saabnet.com
The banner above is an advertisment - if it asks you to download software, please ignore.
Site News -
4/9 Saab Owners' Convention Day Pass Raffle |
3/26 M Car Covers (by State of Nine)
[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: DIY vac advance w/spring -- SUCCESS! (long)
Posted by MS (more from MS) on Mon, 25 Dec 2006 22:59:04
In Reply to: Re: DIY vac advance w/spring -- SUCCESS! (long), Notnoel [Profile/Gallery]
, Mon, 25 Dec 2006 14:47:35
Members do not see ads below this line. - Help Keep This Site Online - Signup
I'm guessing where you are right now the temps are fairly cool or cold. That makes for ideal conditions for this engine to experience it's boost capacity. When it's summertime hot outside, that's when the limits of the stock intercooler reveals itself. Add to that the advanced timing and you may find that instead of the boost you now enjoy, all you get is ping and sluggish boost because of the knock sensor opening the wastegate. Also, if your engine is not in top tuned condition, you're not allowing for much leeway when things (ignition component wear issues) begin to effect the performance.
Ping doesn't occur under just boost. When cruising, both the centrifugal device inside the distributor, plus the vac line connected to the advance unit advances the timing to help with optimal gas saving. You add 4 more degrees of advance on that and you set up a perfect condition for a low level of pre-ignition at cruise. That's how hot spots develop and eventually burn up a valve or weaken it and eventually a crack and so on.
Then there's carbon build-up inside the combustion chamber. That makes for hot spots which leads to knock. A number of things contribute to carbon. I don't fully know the science of fuel combustion, but I can't imagine a too advanced timing is a good thing at cruise. Something about unburnt or improperly burnt fuel comes to mind. There's also the lowered temperture issue. Those are the things you need to look into.
Electronic mapped timing control really is the best way to extend the range of this engine. But, if you can find a way to address the top end over-advance on this distributor and vac advance unit while keeping the timing set advanced, then you may have yourself a really cool tweak. Just know that a smog test will almost always reveal a non-stock timing.
posted by 72.67....
Posts in this Thread:
- DIY vac advance w/spring -- SUCCESS! (long), Notnoel , Sat, 23 Dec 2006 09:56:36
- Re: adjustable valves for the vac line?, MS, Mon, 25 Dec 2006 13:07:25
- Re: DIY vac advance w/spring -- SUCCESS! (long), MS, Mon, 25 Dec 2006 12:58:32
- Good job!, 900 Aero , Sun, 24 Dec 2006 10:30:20
- Re: DIY vac advance w/spring -- SUCCESS! (long), the#1, Sat, 23 Dec 2006 15:12:02
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
|
SaabClub.com
|
Jak Stoll Performance
|
M Car Covers
|
Ad Available
|
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!