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Discussion Starter #1
I'm kind of lost on the FPR thing. I think I know how they work, but I have a few questions. Basically a FPR is like this: You have a base pressure (which is at idle) lets say 43 psi (think that's stock), and then as you boost, it will raise at a 1:1 ratio. So if I'm running a stock FPR and I'm boosting 19 psi my fuel pressure under boost would be 61 psi. Reason I'm asking this is because Jeff Fazio made what I thought was a good point when he said his base pressure was set to 30 psi and was running 22 psi of boost. Someone figured his base would be set at 50 psi, but 50 psi (base) + 22 psi (boost) would make his fuel pressure 72 psi, and he stated that he didn't believe that the stock system should go about 60-70 psi.

With that said... Would the ATS Regulator (raises base to 50 psi) be a good idea. I know these questions come up all the time and I hate to be the one to ask it, but with this setup: 550cc's (Supra), Either Wolfkatz or ATS Bored Rail, Walbro Pump would an ATS Regulator benefit me. I'm going to be running the factory fuel lines for the supply and the return. Basically I have no intention of changing anything but the rail, injectors, and pump. Lines are all staying the same. Since the ATS is a stock replacement I'll use it if it's recommended.
 

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Hey Nooka,

Base-idle fuel pressure (static) is 36 psi. When I was running 19-20 psi on the 440s,I increased it to much more than that.
I have since reduced fuel pressure because I am on the 550s.

My understanding that 50 psi at idle (no vac applied) would be a lot of FP, especially with the 550s in there.

What turbo are you running?
 

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The OEM rising rate FPR (as well as most aftermarket FPRs) respond to both vacuum and pressure. Vacuum conditioons lower fuel pressure, and boost adds fuel pressure.

According to the BGB, static fuel pressure (sensing hose disconnected) is 27-31 psi. Idle pressure (hose connected) is 33-38 psi.

Based on numerous posts, actual static pressure tends to be ~ 35, and actual idle tends to be ~ 42.

The OEM pump ( and most aftermarket pumps) have the relief valve set at ~ 70 psi.

Unless you have some really unusual fuel system requirements, 50 psi idle pressure is WAY too high.

bill
 

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Discussion Starter #4
JekylandHyde,
I'm going to be running a TD06 or T3/T4, and hoping to make 300+WHP around 18-22 psi.

This is the add from atsracing.net for the FPR modification:
ATS Racing Fuel Pressure Regulator Modification

ATS Racing raises the base fuel pressure of the OEM regulator from 42psi to 50psi. This increases the injector volume by 9%, effectively making a stock 440cc injector into a 480cc injector and a 550cc injector into a 600cc injector. This will support 360 wheel horsepower when combined with our modified fuel rail. Price $75 Core charge $100 See core notes.

Based on what you guys said will I be okay with the stock FPR, or should I start saving for an adjustable one. And definately don't get the ATS modification <---correct?
 

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i'd say the best thing to do in this situation is to contact ATS racing (since they ARE the ones who are selling that part)!!!! :) good luck man!
 

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Discussion Starter #6
flynhighaf23 said:
i'd say the best thing to do in this situation is to contact ATS racing (since they ARE the ones who are selling that part)!!!! :) good luck man!
Well if the product does what it says it does, it sounds like its not neccessary, and if anything harmful.
 

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Hey Bill.
Can you briefly explain how you check the Static and Idle pressures. I have an Aeromotive FPR with a gauge. I just check the pressure by turning the ignition to on (engine not running) and jumping the fuel pump at the diagnostic port. What pressure should that be at?
Thanks.

-Scott
 

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Scott, when the car is running you are looking at idle pressure. Simply pop te vac line off from under the AFPR and then what you are looking at is static (no vac applied).

This of course depends on how accesible your AFPR is.
Mine sits up near the top of the d-side strut area and it has the gauge connected to it so I can view and pop off the vac line and view instantly.

HTH
 

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sab0276 said:
Hey Bill.
Can you briefly explain how you check the Static and Idle pressures. I have an Aeromotive FPR with a gauge. I just check the pressure by turning the ignition to on (engine not running) and jumping the fuel pump at the diagnostic port. What pressure should that be at?
Thanks.

-Scott
As J&H stated, idle FP is measured at idle with the manifold pressure hose connected to the FPR, as it normally is.

You can measure static FP by either disconnecting the hose, or manually energizing the pump by jumping +B and FB with ignition on, and engine off.

I posted the approprite values in my post above.

bill
 

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NooKa said:
Well if the product does what it says it does, it sounds like its not neccessary, and if anything harmful.
The ATS FPR is a drop in replacement fuel pressure regulator. We raise the stock fuel pressure from the actual base pressure of 42 psi with no vacuum applied (YES, THE BGB IS 100% WRONG) to 49 psi. Increasing the fuel pressure 7 psi in this case will add approximately 9% more fuel to the engine. This is great for people with stock 440's who are running at the limit as it raises the 440cc limit to ~295 rwhp. It also raises the 550cc limit to ~360rwhp.

Does it increase the strain on the stock fuel pump, well yes. But the stock fuel pump poops out around 300rwhp regardless. With a Supra pump or Walbro 255 (like we sell) you are fine with this fuel pressure even at boost levels of 25 psi.

Is an adjustable FPR better? IMO NO and here is why:

1. cost ATS FPR = $75 Adjustable = $140+ hoses, fittings, installation headaches etc

2. installation time

3. likelyhood of leaks

4. If you are tuning with an FPR then you are using a crutch. The problem with FPR tuning is that it messes up the entire fuel curve all at once.

If you have a 250rwhp motor with 550's and FPR set at 49+ psi and an AFC then you not only wasted your money, but the "proper" tuning is actually going to harm your engine because you will be pulling out numbers like 30% even under load with an AFC. Thsi will of course cause dangerous changes to the timing curve.

My advice for fuel systems is simple. Only buy what you need. If you have 250rwhp then stay stock, if you have 290 rwhp then bore the rail and add an ATS FPR, if you have 330rwhp then bore the rail and get 550's and if you have 330-350rwhp then bore the rail, get 550's and an ATS FPR. Anything after 350rwhp and you are going to want a top feed rail anyway.

The exception to my above rules is people who purchased stand alones early and can actually change your fuel map. If you are using a "black box" for tuning then you need to follow the above recomendations to minimize the amount of correction necessary.

Aaron
 

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Discussion Starter #13
Thanks for the reply Aaron. Based on what has been said, and what I believe I'm going to use the stock FPR/Walbro Pump/550cc/Bored out or Wolfkatz rail. Most likely a VPC/SAFCII will be used to tune.

Nick
 

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so real quick general question regaurding your post aaron. it actually goes around this quote:

"If you have a 250rwhp motor with 550's and FPR set at 49+ psi and an AFC then you not only wasted your money, but the "proper" tuning is actually going to harm your engine because you will be pulling out numbers like 30% even under load with an AFC. Thsi will of course cause dangerous changes to the timing curve."

suppose your running stock injectors, fpr, fuel pump, etc. you dyno the car and like 90% of mr2's that are slightly modded (intake, exhaust, dp, ic, maybe turbo) it runs rich....dead rich, like 10:1 a/f. well, lets say you have an afc and your trying to lean it out to a leaner a/f ratio, like 11.5:1. would you take out fuel from the afc? no, it'll pull ignition and make you less powa. so the question is- how do you lean it out? the only solution i see is to get a ajustable FPR and lower the fuel pressure, then add fuel using the afc. correct?
 

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ATSAaron said:
My advice for fuel systems is simple. Only buy what you need. If you have 250rwhp then stay stock, if you have 290 rwhp then bore the rail and add an ATS FPR, if you have 330rwhp then bore the rail and get 550's and if you have 330-350rwhp then bore the rail, get 550's and an ATS FPR. Anything after 350rwhp and you are going to want a top feed rail anyway.

Aaron
At what point is the stock ECU useless?
 

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Your results may vary

flynhighaf23 said:
suppose your running stock injectors, fpr, fuel pump, etc. you dyno the car and like 90% of mr2's that are slightly modded (intake, exhaust, dp, ic, maybe turbo) it runs rich....dead rich, like 10:1 a/f. well, lets say you have an afc and your trying to lean it out to a leaner a/f ratio, like 11.5:1. would you take out fuel from the afc? no, it'll pull ignition and make you less powa. so the question is- how do you lean it out? the only solution i see is to get a ajustable FPR and lower the fuel pressure, then add fuel using the afc. correct?
I have an aeromotive fpr,440cc,stock pump,safc,50trim t3/t4 @ 16psi.
At idle, vacuum hose connected my gauge reads 22-23psi.
At idle, vacuum hose disconnected gauge reads 29-30psi.
A/f ratio is 11.5 from 3500-7000rpms.
Safc is leaned out from -7 to -17 in some areas between 3k-7k.
Ive been running this since last year in March.
power is 262
tq is 231

Your results will vary!! :dontknow:
 

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oldster - from what i have seen/heard. after 300rwhp you really need a stand alone.

Nooka - why dont you just get a standalone. now adays being SOOO affordable, without getting worried(comparing to black box tuning). instead of finding the best black box route. stand alone seems to be the perfect solution.

james
 

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My advice for fuel systems is simple. Only buy what you need. If you have 250rwhp then stay stock, if you have 290 rwhp then bore the rail and add an ATS FPR, if you have 330rwhp then bore the rail and get 550's and if you have 330-350rwhp then bore the rail, get 550's and an ATS FPR. Anything after 350rwhp and you are going to want a top feed rail anyway.
this makes it seem like you can simply drop in these fuel upgrades and be ok. I this what is being said or did i miss the underlying "you need something to control them with" somewhere. (like safc or standalone) Just wanting to clear this up as im running out the stock fuel system soon and would like to get a little more out of it.
 
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