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Discussion Starter #1
I've noticed a lot of NA-T cars with and without FPR's.... why do some people run them and some don't? When does it become a necessity?

I'm going to be running a T61 on stock headgasket and injectors, with a walbro fuel pump. I'm shooting for around 7-9 PSI. Am I going to need a FPR?
 

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feeding your habit
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The OE FPR is a rising rate FPR but you cannot set the base pressure. An aftermarket FPR will allow you to set a higher base pressure. What this allows you to do is spray more fuel across the range. This means you have effectively more fuel from the same injector so you increase your fuel pressure at the FPR, scale back your whole range and this means you have the same flow across the board but you have a little more head room at the top. There are also rising rate FPR's which for each pound of reference (boost) pressure they add x (4,8,10,12, etc) pounds of fuel pressure. You need to be careful in selecting an FPR.

you need an FPR when your injectors are apporaching max reliable duty cycle (85%) and you want to squeeze out a little more performance but you don't need so much (or don't want to spend so much) to go to bigger injectors.

Good example is a stock set of 330's running 3xx WHP - you'll be pushing thier limits. But if you're running about as much as you want to run for power, then don't spend 800 on your fuel system when a $200 FPR will get you over the hump with less expense and work.

Check over at clubna-t for more info on fuel systems and FPR's.
 

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wasting my life on SF
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nice thread! i have been wondering the same thing...are there any downsides to runnigna n aftermarket FRP as opposed to bigger injectors?
 

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I've noticed a lot of NA-T cars with and without FPR's.... why do some people run them and some don't? When does it become a necessity?

I'm going to be running a T61 on stock headgasket and injectors, with a walbro fuel pump. I'm shooting for around 7-9 PSI. Am I going to need a FPR?
why stock headgasket? why not 2.5 mm and be safe?
 

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The OE FPR is a rising rate FPR but you cannot set the base pressure. An aftermarket FPR will allow you to set a higher base pressure. What this allows you to do is spray more fuel across the range. This means you have effectively more fuel from the same injector so you increase your fuel pressure at the FPR, scale back your whole range and this means you have the same flow across the board but you have a little more head room at the top. There are also rising rate FPR's which for each pound of reference (boost) pressure they add x (4,8,10,12, etc) pounds of fuel pressure. You need to be careful in selecting an FPR.

you need an FPR when your injectors are apporaching max reliable duty cycle (85%) and you want to squeeze out a little more performance but you don't need so much (or don't want to spend so much) to go to bigger injectors.

Good example is a stock set of 330's running 3xx WHP - you'll be pushing thier limits. But if you're running about as much as you want to run for power, then don't spend 800 on your fuel system when a $200 FPR will get you over the hump with less expense and work.

Check over at clubna-t for more info on fuel systems and FPR's.
Ok, so with my stock 330's and a fpr like this

from MVP
How much hp would that support
and how much do i need to up the fuel pressure
 

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Discussion Starter #9
why stock headgasket? why not 2.5 mm and be safe?
I will be doing headgasket later down the road. This is my first FI project so I'd like to just get running on low boost. I will do fuel system and headgasket for more boost when I'm comfortable with a basic low boost setup.

Thanks for the info 98mkiv, very helpful! So I guess for my setup an aftermarket FPR would be a good idea since I'm looking for roughly 300-320whp on stock injectors
 

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question... is an aftermarket FPR necessary with larger injectors (ie 525cc)
 

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Ok, so with my stock 330's and a fpr like this

from MVP
How much hp would that support
and how much do i need to up the fuel pressure
the best way to find that out is run a wideband so you can see when you start to go lean and then up the fuel pressure. You will want to keep an eye on injector duty cycle because the rule of thumb is >85% and they start to become nonlinear.

why stock headgasket? why not 2.5 mm and be safe?
2.5mm is very safe. TOO Safe. 8.2:1 compression is too LOW. You will be robbing yourself of bottom end torque and you will make your car less fun to drive. Too high and Too low compresson are not good. I prefer 8.7-9.2:1. Your engine builder should take some time to discuss with you (or you should investigate for yourself) what you want from your setup - if you're building a dragster with a TH400, 8.2:1 is great, but not so good for a street warrior.

question... is an aftermarket FPR necessary with larger injectors (ie 525cc)
Yes, only because you want to get a larger return fitting and lines. A few more reasons; your stock rail can be retained if you use drop in injectors, if not say bye bye to the stock FPR. Your stock FPR and return lines are tiny. If you run big injectors and use a -6 feed line, be sure to run a similarly sized return line. The point to doing this is to make sure you don't dead head your pump and cause premature failure of the pump. It's also nice, (but not required) to be able to dial in the fuel pressure which you cannot do with the stock FPR.

You do not , I repeat you do not need a FPR ! I run 25 psi through one and make some good power.
It all depends on the setup. The whole thing needs to be looked at as a system.
 

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I've noticed a lot of NA-T cars with and without FPR's.... why do some people run them and some don't? When does it become a necessity?

I'm going to be running a T61 on stock headgasket and injectors, with a walbro fuel pump. I'm shooting for around 7-9 PSI. Am I going to need a FPR?
if you are staying with stock injectors, i would say yes. you need an aftermarket FPR. i tried going to the dyno with boost logic stage 1 kit on stock fuel...........other than the Walbro the kit came with. had the Map ECU maxed out and i ran out of fuel during full boost @ 6psi. i would bet that if i had the FPR then, i could have probably turned the pressure up a little and would have been ok

i now have an aftermarket FPR and 525cc's
 

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Discussion Starter #15
if you are staying with stock injectors, i would say yes. you need an aftermarket FPR. i tried going to the dyno with boost logic stage 1 kit on stock fuel...........other than the Walbro the kit came with. had the Map ECU maxed out and i ran out of fuel during full boost @ 6psi. i would bet that if i had the FPR then, i could have probably turned the pressure up a little and would have been ok

i now have an aftermarket FPR and 525cc's
Do you need a gauge to monitor the fuel pressure? The Aeromotive unit doesn't come with a gauge so wouldn't that be tuning blind? Or did you do it by feel (injectors dont respond when adding fuel, so up the pressure a bit)?

A little off topic, but how is the map ecu working out for you. I'm going to be using one as well since I'm a 96.
 

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Do you need a gauge to monitor the fuel pressure? The Aeromotive unit doesn't come with a gauge so wouldn't that be tuning blind? Or did you do it by feel (injectors dont respond when adding fuel, so up the pressure a bit)?

A little off topic, but how is the map ecu working out for you. I'm going to be using one as well since I'm a 96.
You need a gauge. Either one set up perminently or in line when your setting up the car initally. If your planning on playing with the fuel pressure I would go with one mounted perminently. You can get the liquid filled ones that mount right on the FPR for like $20.
 

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I offer the FPR kit with a gauge pretty reasonably priced.
 

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Do you need a gauge to monitor the fuel pressure? The Aeromotive unit doesn't come with a gauge so wouldn't that be tuning blind? Or did you do it by feel (injectors dont respond when adding fuel, so up the pressure a bit)?

A little off topic, but how is the map ecu working out for you. I'm going to be using one as well since I'm a 96.
just like kbprice said. i have the liquid filled one so the needle doesn't jump around. think i got it from supraforums.com

no longer have the map ecu. i had an unsuccessful story with it. only people that i know had success with it is PHR and [email protected] logic. if neither of those guys are tuning it, i wouldn't recommend it. i wouldn't recommend anything except for the AEM EMS now that I have it. car runs like stock :)
 
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