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Installing A Fuel Pressure Regulator

simonthomasgoodwin
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simonthomasgoodwin Collaborator

simonthomasgoodwin

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Posted

heya recently bought a nismo fpr for my rb25det does anyone know about putting it on

1. does the fuel have to be manually primed through it?

2. will my car need to be tuned to the adjusted fuel pressure?

i had a good search around the forums and didnt find anything on topic if there is one set me up with a link ;)

ta simon g

StealthX Veteran

StealthX

Posted
Posted

1) no. Turning the key to ACC will prime the system to the desired pressure.

2) yes. any increase in fuel pressure will (respectively) increase or decrease the amount of fuel going in. i.e. more pressure = more fuel.

Why are you installing one anyway? Do you realise the stock one will do fine for up to 25+psi of boost??

simonthomasgoodwin Collaborator

simonthomasgoodwin

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1) no. Turning the key to ACC will prime the system to the desired pressure.

2) yes. any increase in fuel pressure will (respectively) increase or decrease the amount of fuel going in. i.e. more pressure = more fuel.

oki doke thanks for the info just another couple Q's..

to get a gauge on it can i just t it onto the fuel outlet? and if i have the pressure right down does that mean better fuel economy? atm strugling to get 250 km a tank -__-

why did i want it.. someone told me i would need one soon and i picked up a good bargin on it too ;)

Why are you installing one anyway? Do you realise the stock one will do fine for up to 25+psi of boost??

PM-R33 Grand Master

PM-R33

Posted
Posted

Please have a read of this thread from a few days ago.

http://www.skylinesaustralia.com/forums/topic/347078-upgrading-fpr-worth-it/

Then read my post:

The only reason to "upgrade" the factory FPR is really in three instances:

1. When your injectors are starting to max out, but you don't want to upgrade them, so you bump up the rail pressure with the aftermarket adjustable fuel pressure regulator to push them a little but furthur. Obviously this isn't ideal and most people don't recommend it. Just buy the correct injectors to start with.

2. When you are running huge amounts of boost and the factory fuel pressure regulator can not keep up the 1:1 fuel pressure ratio. Therefore you will need an aftermarket fuel pressure regulator that can handle this high amount of boost pressure and keep up the 1:1 ratio.

3. The factory fuel pressure regulator has failed so you may choose to buy an aftermarket one however still run it at factory fuel pressure.

So as you can see, not many people fall into the second category because a lot of people don't run 2+bar of boost through their car. A few do fall into the first category because they may be on a budget and don't want to upgrade the stock injectors so they choose to bump the rail pressure up instead and obviously a few will fall into the third category.

However there is a fourth category that you will find 90% of people with aftermarket fuel pressure regulators fall into:

4. They have no idea what an adjustable fuel pressure regulator does, but they got told to buy one by a mate or read about one somewhere.

For your situation assuming that you are not running E85, your 700cc injectors should be fine for between 400-500HP therefore you do not need an aftermarket fuel pressure regulator.

You are in category 4 just like so many others. Hate to be a barer of bad news, but you just wasted money.

doo doo Proficient

doo doo

Posted
Posted

Hi Simon, I reckon better fuel economy will come from everything working properly (especially if your intercooler or pipework has a leak somewhere) and a decent tune, I'd pop it on the dyno before making any adjustments to fuel pressure. And yeah, it's really not necessary to have an aftermarket one, if you've got the right sized injectors and pump you should be right. Feel free to pop over again if you want to test the cooler system for leaks or just chat.

simonthomasgoodwin Collaborator

simonthomasgoodwin

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  • Author
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Please have a read of this thread from a few days ago.

http://www.skylinesaustralia.com/forums/topic/347078-upgrading-fpr-worth-it/

Then read my post:

You are in category 4 just like so many others. Hate to be a barer of bad news, but you just wasted money.

at what power level will my fuel system be restictive to power curve/gains? walbro in tank and stock injectors, as im planning for a gt35, im sure i read on here of someones build being restricted by fuel system at 260rwkw...

currently on 230ish

and aparently i dont no how to post w/ quotes haha

hey andrew hows it goin? sounds good mate just have to find the time :P working 2 jobs now, and fulltime girlfriend... haha

PM-R33 Grand Master

PM-R33

Posted
Posted

If you are planning for a GT35 you will want something like Nismo 740cc injectors.

Stock injectors start running dangerously high duty cycle anything around 220rwkw+ Therefore if you are pushing 230rwkw on stock 15+ year old injectors, you are all ready risking an engine.

simonthomasgoodwin Collaborator

simonthomasgoodwin

Posted
  • Author
Posted

wow this ones taking off.. haha i didnt have the intention of lowering pressure just wanted to know if it actually worked like that aswell lol atm i was just guna have it in there running on standard pressure til it needed to be adjusted..

also this was 90$ injectors are not gunna be good for my bank account atm..

thanks for the feedback everyone :|

Beer Baron Grand Master

Beer Baron

Posted
Posted

leave it off. putting it on and know really understanding what you are doing means there is more chance of it doing harm than good. infact it's not going to give you any gain even if you did know what you were doing. seriously it's a waste of time and money. when you get that big turbo you'll need some big injectors and yet you STILL won't need that regulator.....

doo doo Proficient

doo doo

Posted
Posted

at what power level will my fuel system be restictive to power curve/gains? walbro in tank and stock injectors, as im planning for a gt35, im sure i read on here of someones build being restricted by fuel system at 260rwkw...

currently on 230ish

and aparently i dont no how to post w/ quotes haha

hey andrew hows it goin? sounds good mate just have to find the time :P working 2 jobs now, and fulltime girlfriend... haha

mate i've got plenty of time... till Feb, just resigned from music. Let me know how you go time wise, can always give you a hand keeping the budget in check

simonthomasgoodwin Collaborator

simonthomasgoodwin

Posted
  • Author
Posted

Thanks for the input guys ;) will probs give it the flick then, So does anyone know how to put a gauge on so I can check the pressure of the stock fpr ? Just T it between fuel outlet and the rail? Also I may nit have stock injectors... The guy I got the car off didn't know half of what's on it, I've just been discovering new mods when I get under the car.. Haha so how can I check if the injectors are stock or aftermarket ? Not really wanting to pull off plenum either :D Cheers!

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