[Subscribe to Daily Digest] |
[Profile/Gallery]
, Mon, 8 Jan 2001 18:21:25
Members do not see ads below this line. - Help Keep This Site Online - Signup
It is my belief that a good stock pump with the stock lines is adequate. What you really have to do, to know for sure, is to test it statically, which I am going to do in a few weeks, as I am still working out fuel problems with my engine too.
I am going to do some tests with the fuel rail off the engine, with the injectors at %100 duty cycle at fuel pressures from 50 to 100psi, to see if the stock pump can keep up with the demand. I am currently running SD's red injectors, which I believe are 30 lb, but I have other injectors that I am messing with, one set I know flows more, but I am unsure about the others. Before I do that total flow test I want to check individual flows of the other injectors that I have.
What are the options, if the stock pump flow is marginal:
An increase of fuel rail size, even though I have the larger rail now, is one of the easiest options to consider and I think the most practical if the flow is only marginal. The larger the rail, the less pressure drop when all four injectors fire at the same time, an after market sequential system would be best though. I still need to check my injector duty cycle under full load high boost conditions.
A better pump that flows more gph and can still maintain the necessary pressure would be my next option. My understanding is that pressure at the injectors should not exceed about about 70 psi, but I believe that the pump needs to be able to maintain at least 100 psi at the desired flow.
The last option is to add a second pump, which just thinking about the complications, I'd pass on, if at all possible.
Things to consider:
A good stock pump can supply over 100 psi, this I know, but what it will actually flow, I don't know.
The larger the injectors, the less fuel pressure you need, but you still have to maintain adequate flow to feed them.
Running the stock electronics, as you and both are, it is tough to get it to run right with the stock map.
My present setup:
SD red injectors
stock turbo and intercooler
.80 over forged pistons and I think higher than stock CR as compression test is 200 psi all the way around. This puts me at about 2.1 liters, with a 2.1 ported head with 2.1 intake also.
Two FPR's run in series: Paxton adjustable and a Microdynamic's 2:1 rising rate. Fuel pressure at idle is 20 psi, at atmosphere it is about 35 psi, all controlled by the Paxton, the RRFPR takes over at about 40 psi, 5psi of boost. In first and second I am running 12 psi of boost, fuel pressure reaches 60 psi, other gears are 20 psi of boost, so I reach and will usually exceed 80 psi of fuel pressure.
I do not use APC, except for tuning and to let me know when the engine thinks it is sensing knock. Once I decide that a certain grade of fuel is safe at certain boost levels and ignition advance, I set my boost with grainger valves, and use microswitches on my shifter to let it know if I'm at 1-2 or a higher gear, this switches a solenoid valve to avoid wheel spin in the lower gears.
I've had a lot of setbacks with this project, first off it was a built motor which I bought off the net, there were no timing marks as they went away when the flywheel was lightened, finding actual TDC was trickier than I would have thought. The car I put it in is my beater, an old '85 Turbo, in which I thought all all the electrical problems had been fixed, boy was I wrong. Getting good consistant fuel delivery was a big part of getting this thing running strong, timing was the other mountain I had to climb. Having too many things that I could change or mess with also made things difficult, four sets of injectors, five FPR's, the AAM, etc. Even though my A/F gauge does not show that I am overly rich, my plugs tell me otherwise, checked at various engine loads with a simutanious clutch in shut down.
About the timing, I am running 93 octane and this motor did not come to life until I went over 18 degress BTDC. I am currently at 22.5 degrees BTDC using a modified vacumn/retard that has served me well for years. I checked the curve the other day and it does not seem to match what Kevin has stated about the stock units, mine should be the same, except for allowing more retard at boost. My unit is modified by filing off the stop to allow for more retard. My timing curve:
10 psi or greater 9.5 degrees full retard
8 psi 4.0 degrees retard
6 psi 2.0 degrees retard
4 psi 1.5 degress retard, maybe less
0-4 psi 0.0 no change
5" hg 5.0 degrees advance
10" hg or greater 10.5 degrees total advance
Don't get me wrong, this thing runs great, but it just isn't as crisp as I think it should be.
, Thu, 11 Jan 2001 16:21:54, Mon, 8 Jan 2001 18:21:25, Mon, 8 Jan 2001 22:49:03, Mon, 8 Jan 2001 14:15:15, Mon, 8 Jan 2001 18:08:53
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.
 |
 |
 |
 |
 |
