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Discussion Starter · #1 ·
Hey, i was talking to someone and they are selling the 3.8 bar Fuel Pressure Regulator Valve for my car.
He was saying that this upgrade would add around 25hp.
Does this seem about right?
Let me know
 

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HNNLIC
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Jeez...that sounds like a good upgrade. I don't know if its about right, but if so let me know where I can get one too. I'm looking for a 3 bar MAP sensor and larger injectors as well.
 

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he he - I can get the 3 bar FPR now for almost nothing for the c900's Just got myself one the other day for the SPG and the 9000 i already put one in on. (tho i've heard rumor it won't help unless i take the fuel rail too.... made me question a few things and then I just as best said :meh:)
 

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trexturk said:
He was saying that this upgrade would add around 25hp.
Does this seem about right?
No, that's BS. It will make you run rich and actually lower your hp. Crushed fuel pressure regulators are used when you are running high boost and max out the fuel system. Or to compensate for an ECU tweak. I crushed mine when I added a resistor to the MAP sensor. However when I had my Saab on the dyno Frank Stromqvist said I was running rich so I changed back to the stock regulator. I recommend you stick with the stock FPR.

Here is a picture of my stock and crushed FPR, 3mm to 4.2 bar.
 

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Discussion Starter · #5 ·
Well, thanks for your help.
He said that after around 3200RPM my car will scream. He put this 3.8FPR on his ng900 N/A and said he felt the biggest performance gains from it.

Just a scam i guess.
 

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Ced, do you have any info on the stock flow rate and pressure of the stock injectors?

I have some archived info on them, but nothing like I was looking for. On the Turbo Buicks, you can go from the stock 28psi injectors, to 36psi injectors without changine anything in the computer.
 

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Alright this sucks, i just purchased a Bosch 4.0 bar fuel pressure regulator off of ebay and your trying to tell me its only going to do harm?/??????
 

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Tweek's Turbos said:
Ced, do you have any info on the stock flow rate and pressure of the stock injectors?

I have some archived info on them, but nothing like I was looking for. On the Turbo Buicks, you can go from the stock 28psi injectors, to 36psi injectors without changine anything in the computer.
Tweek, unfortunately I don't have the stock pressure rates. Eric may have them however.

Phil...Im don't know what effects the 4.0 bar fpr will have on your car. I too thought it would help, but couldn't understand why the 4.0 bar was less expensive than the 3.0 bar fpr. So I'm definately confused as to what the difference is.
 

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its alright, i guess ill just have to figure it out for myself. I just figured more fuel=more power you know?
 

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Phil said:
its alright, i guess ill just have to figure it out for myself. I just figured more fuel=more power you know?
Only if you've got the extra air to match it. Otherwise, you'll just run rich.

Paying *any* money for a higher pressure FPR is a waste, unless you're buying an adjustable or rising rate FPR. Otherwise, you can "re-calibrate" (a.k.a. crush :D ) your stock FPR to whatever pressure you want.

And, like someone said above, unless you've got other mods that support or demand the higher pressure, it'll make your car run worse, not better. Plopping a higher pressure FPR on a car that doesn't need it will just make it run rich. How do you tell if you need it or not? Dyno your car with a wideband o2 sensor - if you're running lean across the board, you need it. I'm going to venture a guess that you'd have to be forcing quite a lot of additional air in before needing 4.0 bar. On the older Saabs (og 900 and 9000) the stock FPR is a limiting factor with minor mods, but even then, a small jump to 3.0 bar is usually enough. On the newer cars, it seems like the stock unit is sufficient, especially since you can get so much flexibility with chip tuning that you don't have with the older models.
 

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With just an intake, you won't be near needing fuel pressure modifications. Follow the "stage" upgrade paths from your favorite tuner and you'll be all set.
 

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phil, you'll be able to bring in a substantial amount of air, even with the mild airbox mod (the 3-inch pipe mod)...
 

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Computers can only control (when it comes to fuel injection) the time the injectors are open. The higher the pressure the more fuel flows in the same period of injector time. The computer can conpensate sometimes for having too much fuel by "trimming" the pulse width. Unfortunately a 4.0 bar regulator probably forces more fuel in than the injectors are allowed to trim for.

Also when the car runs "open loop" under high boost it ignores the feedback and "trim" on the injectors. (The term open loop refers to the computer switching to a pre-programmed fuel/boost/timing map.) That means when under full boost that computer compensation no longer used and it runs excessively rich.

In other words, don't tamper with the fuel system unless you're sure you need it and are willing to run richer than you should. Basically this means you'll only want to raise fuel pressure if you're running LEAN and do not have funds to correct it any other way.

C900's frequently do this as altering the fuelling computer on those is difficult. But with Trionic it's best just to buy an upgraded chip.

Adrian~
 

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3.8 Bar FPRV and High Flow Fuel Rail.

Gentlemen,

I'm the one with the 3.8 Bar FPRV, and yes they do WORK! If you increase the Flow as well as the Bar's (which is Pressure, 14.75 Lbs. Per Square Inch at sea level or better known a 1 BAR or 1 Atmosphere) You will increase the amount of fuel and pressure in to the head. This by tests have increased the power on most applications by as much as 21 -24%.

This application will give you VERY Noticable increase in power from 3200 RPM on thru out the rest of your Power Band. Sometines if you follow the normal thought, by going to larger Injectors, you will lose Power. The best way to proceed with modifications to an engine in in SMALL STEPS! If you pour to much fuel into a SAAB motor, you will run RICH and it'll give you a Check Engine Lite and will burn out your Catalytic Converter.

I am 61 years old, and worked for FoMoCo as a driver/engineer in the 1960's - 1970's. I hold 5 World Championships, 6 World Records, and several other Awards in NHRA, AHRA, SCCA, and CANAM. I do bring just a little experiance to the table!! LOL :)

Mike C. AKA 900S - Meatball
 

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3.8 BAR FPRV - BOCH MOTROINC / TRIONIC ECU's

Gentlemen,

I forgot to mention in my last post that the Bosch ECU's (Motronic - Trionic) used in SAABS, Have a built in Fuel Correction MAP that will allow a range of minus 25% thru a plus 25% fuel correction. In other words, the ECU will tollerate that range of Decrease or Increase in Fuel Application.

If you do the math on the differance between the 3.0 Bar and 3.8 Bar FPRV, you will see that it is a Plus 24% differance. :) Small step are better to give a better handle on performance building.

Mike AKA 900S / Meatball
 

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HNNLIC
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Im glad you cleared that up. So saying that, does is a 4.0 bar FPR too extensive? Also what about a variable rate FPR?

One last question. If im running slightly lean, would adding a FPR (without upgrading my ECU) be most efficient?
 
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