I was wonder what kind of fuel pressure people are running on what type of injection system

I'm running 43 psi base pressure; that's pretty normal for port injection.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

I run 45 psi with Powerjection 3.

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These ones go to eleven...

I was running 45 and thought it was a little rich then blew my regulator, thinking about going to 43

Whatever a caddy northstar runs, that is the rail/regulator im using. With an adjustable regulator, you can do global enrichment by adding a lb or 2

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I didn' t buy it, I built it.....

43 psi was a standard number for quite a while on new cars (90s and some of 2000s?). There are many pressures used now. Changing the pressure does not change the injector output too much (output rises approximately as the square root of the pressure, IIRC). I have used whatever pressure the regulator has given me, and then I adjust my EFI maps from there.

I had an adjustable MSD brand reg on my 68 Dart at first and played around with pressures from 40-60 psi without much feeling of major difference, then settled around 45 psi. That regulator crapped out after about 1-2 yrs, and since then I have had a stock non-adjustable reg from a Ford pickup or something. Got it in a parts store on the road...

Lou

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Home of Slant6-powered fun machines

I run 40-45 psi on a boost referenced regulator ... but my car is not boosted yet so it stays on that 40-45 range all the time with 34 #/hr injectors on a port system fired by megasquirt.

Greg

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http://www.youtube.com/hyperpack

Same as Greg. However, when it was turbo charged, i set it for a base of 35, which went to 45 under boost. I don't know if I ever set it up to 45 after taking off the turbo. I think Lou is right. Anything above 35 and steady will work. I would not go much over 45 though. I can tell you a long story about trying to run a higher pressure because of a faulty gauge. The pump could not maintain that high pressure at all temps and loads, so af ratio was unstable.

Sam

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I have set the pressure for 3 bar (43 PSI). I have noted that the pressure varies little from day to day. Today the slant lost most of the power and the AFR meter also show ultra lean mixture. I assume I have a bad regulator as the fuel pressure was 2bar at idle.

Either that, or you're pulling the most vacuum of any engine I've ever seen.

Seriously, sounds like a bad regulator.

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"Mad Scientist" Matt Cramer

'66 Dart - turbocharged 225

My blog - Mad Scientist Matt's Lair

Yes it was bad. I cant imagine how complicated it could be find such variables if an adaptive ECU works at closed loop. An adaptive ECU will do learning all the time in the system where the fuel pressure could be suddenly half or double of the setting. When the problem comes finally so bad (no fuel pressure at all) then you're at the side of the street...

As I have a built in limitation of power with my injectors (6 pcs @ 230cc and E85) I increased the fuel pressure setting to 4 bars with replacement regulator. It was 3 bars before. Both adjustments with out vacuum line connection.

And what happened? The fixed setting of the idle mixture went noticeable LEANER. Yes, it went leaner because of 33% pressure INCREASE.

I assume that the injector minimum opening time varies strongly depending of the fuel pressure. As I have set idle open time (gross, electric time) to about 2,5ms, the increased pressure drop the real opening time of the injectors more than the pressure increased the flow.

I am thinking of a 198 Turbo / 225 Turbo running off of a Megasquirt system controlling the fuel and spark.

I wonder if I would be better off running a fixed fuel pressure and returnless fuel system (like my 2005 Dodge Neon) and using the Megasquirt to increase / decrease fuel in relation to boost and vaccum instead of having a boost / vaccum referenced fuel pressure regulator, as on the stock Chrysler 2.2 Turbo / 2.5 Turbo cars.

I think it'd be easier to tune with a fixed fuel pressure, to have that as a constant known factor.

Online calculators for injector size are available, I haven't used one yet but I think I'd prefer a lower fuel pressure (20-30 psi) on larger injectors.

Thoughts on this?

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i had planned to use one of these again for this conversion

http://www.speedwaymotors.com/LS1-Fuel- ... 41791.html

but 58psi fixed, not sure, the last 2 swaps i have done have been LS swaps, this worked great, one line, no dramas, nice and neat.

would there be a problem running that pressure?