Has anyone got any details of what pressures the early saab turbos run at and what the fuel system pressure and control pressures are set to?(K-Jetronic)
I have just fitted a supercharger to my Mini running K-Jet and just want to see what the 'other side' uses as reference pressures! :-)
many thanks in advance!
miniman
I just put 2 gallons of petrol in a can today, £10!!!!! thats about $18, I can hear all you americans laughing at us poor brits!
IIRC K-Jet runs around 80 psi from the pump, I'm not sure what the control pressure is, it should be about the same on any K-Jet car. Volvo, VW and Audi used a lot of those systems too.
in article 2005082022223116807%edamman2000@hotmail, miniman at edamman2000@hotmail wrote on 20/08/2005 22:22:
Hi Mini friend!
Line pressure is just short of 5 bars on normally aspirated cars and somewhere around 5.5 bars for turbocharged cars. This is on a 1985cc car.
You'll probably want to err on the higher side. The pressure can be setup using shims which are placed in the fuel distributor behind the plunger spring. IIRC, 1mm equates to 5 PSI.
I've always found this resource to be a great help:
Paul
Vart tog vägen vägen? SAAB : Nothing on earth comes close
my supercharger is putting out 10psi so I think shimming up the system pressure valve is a good start as it is about 75psi at the moment, although I think that water injection may well be the way to go as it doesn't start knocking till about 7psi! have any of you guys run a pressure switch on the cold start injector so that it comes on at around 5psi? I would be well interested to hear the results!
I think one of the Saabscene guys used to do that, along with WI, but in=20 the end, he kept the water injection, and invested in a K-Star system to=20 fire a proper 5th injector.
in article 2005082113062916807%edamman2000@hotmail, miniman at edamman2000@hotmail wrote on 21/08/2005 13:06:
Most people who need more fuel on CIS powered SAABs are running in excess of
1 bar of pressure! The tuners who thought that utilising the fifth injector found that the fuel did not mix well and overshot the first couple of intake runners, leaving them lean compared to the last couple of cylinders. Of course an extra injector further back down the intake pipe work seems to work well.
The other solution is to run a second "common rail", thus:
... Or similar principles, whereby a second set of injectors are welded onto the intake runners, primed by the CIS fuel distributor and fired/controlled by an aftermarket FI system.
With your boost, I wouldn't think it necessary anyway ... Just give it adequate pressure and perhaps set the timing back a little. Your mixture might need enrichening to compensate, also? My turbo is fine at between 1.5% and 2.0% CO for pressures up to 3/4 bar (12 PSI), but nudging up to 1 bar, I need closer to 3.0% to avoid knock. That does make for a thirsty car, obviously :(
Paul
Vart tog vägen vägen? SAAB : Nothing on earth comes close
I've heard of it being done, but the cold start injector usually doesn't have a particularly good spray pattern, and depending on the manifold design you can run into problems with some cylinders getting a lot of extra fuel and others getting very little.
I didn't think that the cold-start injector was designed to get fuel evenly into each of the intake ports but simply to make the fuel mix richer to help the engine fire easier when it's cold. If a cold-start injector is being used like a '5th injector' it's never going to be very efficient at giving each intake port an even increase in fuel mixture. That's my understanding anyway. 8-)
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