400ft-lbs of torque?

[ycode90]

I still didn't understand how are you running stock Fuel Pressure Regulator. I did get the part where you've installed huge fuel injectors.

Stocker is rising rate .

im sorry if i missed this but my question is do you have to put out more boost at the turbo to get a good amount at the engine with this type of setup? or does the amount of boost stay the same from all the way back thier?

Boost is boost . Pressure is pressure . Lag is the only concern and is minimal . Turbo's nowadays spool fast .

 

[Art5]

Let me ask another thing then, why is it that before nobody used much bigger injectors with stock FPR on superchargers and NOS kits? Is there any difference the way you're using them?

 

[Sho Amo]

The problem is with the fuel pump and the stock regulator. If you run larger than 190lph you will have issues. On cars past 1990, 190 will even give you issues.

 

[ycode90]

The internal passages in the stock regulator are to small resulting in Fuel pressure going way too high and causing a rich condition . The better regulator flows alot more allowing you to better control fuel pressure . It does not do anything for the rest of the system witch is way to small for any real power .The stock fuel syatem wil support about 300-325 whp that is all .

 

[yamahaSHO]

After the rich conditin, it will lean out from learned KAMRF's at WOT when the injectors are releasing pressure.

 

[ycode90]

Yea that too.

 

[Art5]

Sorry guys but i still don't understand why in Doug's case huge injectors work fine with stock FPR then, unless I missed something previously in this discussion.

I know all that about fuel pump and all that, but this is the first time I see stock FPR with forced induction.

 

[yamahaSHO]

It's not the injectors, IT'S the PUMP.

 

[Art5]

60lb injectors, high volume pump in the tank and the stock regulator.

Why didn't that work before on supercharged cars and NOS cars?

 

[Toolman]

Lots FI SHOs used stock regulators back in the day, some still. It can work, but you will have to reset your tune from time to time.

 

[Toolman]

The first gen cars handle it better as they have a resistor that will cut voltage to the pump at low TP voltage.

 

[Art5]

so if I wanted to use 100shot of NOS direct port in my car, it will be possible to keep my stock FPR? How would I need to set up my fuel system then?

 

[ycode90]

Yes. You'll want a stand alone fuel system for the N20 . An electric pump for a carb app. and a regulator a small tank and some line . Do it right or don't do it at all.

 

[gmorrell]

60lb injectors, high volume pump in the tank and the stock regulator.

Why didn't that work before on supercharged cars and NOS cars?

It worked, just not well.

High flow fuel pumps like the 255 overwhelm the stock FPR at low load when most of the pumped fuel wants to return to the tank, the regulator opens as wide as it can, but its tiny passages simply won't allow all the unneeded fuel out of the rail. This causes the fuel rail pressure to rise above spec at low load, the engine runs rich, EEC sees this and pulls back (leans) the fuel trims. Unfortunately then, EEC applies these learned trims across the board, including high load tables, and the engine runs lean in the high load modes where it desperately needs more fuel.

I've measured this low load pressure creep and even mitigated it by temporarily running the fuel pump on a variable DC power supply.

As Tim pointed out, the early cars with 2-speed fuel systems generally got around this.

The answer for the big-ass fuel pumps is the SHONut external FPR systems.

 

[AREA 91]

The first gen cars handle it better as they have a resistor that will cut voltage to the pump at low TP voltage.

It worked, just not well.

High flow fuel pumps like the 255 overwhelm the stock FPR at low load when most of the pumped fuel wants to return to the tank, the regulator opens as wide as it can, but its tiny passages simply won't allow all the unneeded fuel out of the rail. This causes the fuel rail pressure to rise above spec at low load, the engine runs rich, EEC sees this and pulls back (leans) the fuel trims. Unfortunately then, EEC applies these learned trims across the board, including high load tables, and the engine runs lean in the high load modes where it desperately needs more fuel.

I've measured this low load pressure creep and even mitigated it by temporarily running the fuel pump on a variable DC power supply.

As Tim pointed out, the early cars with 2-speed fuel systems generally got around this.

The answer for the big-ass fuel pumps is the SHONut external FPR systems.

Just to be clear, only the 89 and 90 SHO's used the 2 speed fuel pump.

 

[Art5]

wooooooooooooowwwwwwwwww!!!!!!!!!! My mind is about to explode!!!!
NOw I am very confused about all this.

 

[gmorrell]

What is the source of your confusion, Grasshopper?

 

[Art5]

What is the source of your confusion, Grasshopper?

Some say you have to use FPR other say don't. I do understand explonation why you need to use it , but at the same time don't understand how other don't use them.

 

[jonheese]

 

[yamahaSHO]

What Gary posted above is very clear.

CN: Big pump overruns stock FPR at idle/low load causing fueling issues at nearly all loads.