Ignition timing 5.0 SC

General Chat And Help Regarding Turbocharging and Supercharging.

Moderator: phpBB2 - Administrators

Quagmire
Knows His Stuff
Knows His Stuff
Posts: 377
Joined: Wed Jul 30, 2008 9:42 am
Location: Hook, UK

Post by Quagmire »

In my P6 the MS is in the boot, and the MAP sensor line is probably just under 4 metres long by the time is has snaked its way there from the engine bay.

Doesn't seem to cause me any issues.

:D


1974 Rover 3500s
1984 3.5 90
1959 2.25 series 2

User avatar
Rossco
Moderator Gold
Moderator Gold
Posts: 850
Joined: Sun Nov 19, 2006 11:33 am
Location: Too many to even keep count

Post by Rossco »

Providing the tube doesn't collapse under vacuum then its length is utterly irrelevant.

stevieturbo
Forum Contributor
Forum Contributor
Posts: 3979
Joined: Sat Nov 18, 2006 6:22 pm
Location: Northern Ireland

Post by stevieturbo »

Rossco wrote:Providing the tube doesn't collapse under vacuum then its length is utterly irrelevant.
So 100ft long ? 1000ft ? Even in electrical cables length matters, so for pressure readings it will too.

Signal will diminish and take time the longer the tube. Neither are good things. On a lazy old V8, there probably isnt a realistic length you could achieve on a car that would pose a problem though

But it is best practise to keep it short, much the same as it is best practise to keep wiring as short as practicable.
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

User avatar
Rossco
Moderator Gold
Moderator Gold
Posts: 850
Joined: Sun Nov 19, 2006 11:33 am
Location: Too many to even keep count

Post by Rossco »

stevieturbo wrote:
Rossco wrote:Providing the tube doesn't collapse under vacuum then its length is utterly irrelevant.
So 100ft long ? 1000ft ? Even in electrical cables length matters, so for pressure readings it will too.

Signal will diminish and take time the longer the tube. Neither are good things. On a lazy old V8, there probably isnt a realistic length you could achieve on a car that would pose a problem though

But it is best practise to keep it short, much the same as it is best practise to keep wiring as short as practicable.
Ok, if we are being pedantic and I was assuming that not many cars use a 1000ft vacuum tube then eventually friction between the inside of the tube and the air will have an effect.

It also depends on how you're pulling the vacuum. If its by physically moving air (like a vacuum cleaner) then length has a very much greater effect as air flow inside the pipe causes friction. If the vacuum is being pulled and held then length is much less important.

gilps
Newbie
Newbie
Posts: 33
Joined: Mon Dec 14, 2009 9:23 pm

Post by gilps »

Just a bit of an update.
Fitted a 2 bar Map sensor over the weekend and tweaked the ignition map as best as I could on the road (booked in for a RR session on the 9th Aug) but results were very good. Nice clean acceleration very smooth idle and best of all no detonation. TBH I have probably gone a little to much on retarding the ignition while on boost but better to be safe than sorry until its set up properly.
Thanks again for your help and advice
Chris

DaveEFI
Gold Member
Gold Member
Posts: 4603
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Post by DaveEFI »

No experience of pressure charged engines, but on an NA one, the ignition vacuum unit is just used for economy. To advance the ignition under light engine load. The best maximum advance settings under full load would remain much the same.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

Post Reply

Return to “Forced Induction”