injectors. - Subaru WRX Forum
 
LinkBack Thread Tools Display Modes
#1 Old 02-01-2008, 09:21 AM
WRXtuners Member
 
Join Date: Oct 2007
Location: Kentucky
Posts: 77
SUBY777 is on thin ice
Question injectors.

i have researched and only get a lot of different answers because there different combinations of parts. i have headers, uppipe,short ram, crank pully,and cat-back exhaust.
i am ordering a walbo fuel pump and perrin fuel rails but i need to know what size injectors to buy. my future mods are downpipe, tune, larger turbo , clutch, intercooler, inlet. how big should i go??????
SUBY777 is offline  
Sponsored Links
Advertisement
 
#2 Old 02-01-2008, 09:50 AM
b7g
WRXtuners Member
 
b7g's Avatar
 
Join Date: May 2007
Location: Illinois
Posts: 232
Images: 4
b7g is an unknown
...it depends on the size of the turbo. Plus, it has been discussed numerous time before--try to search.
Anyway, go big and have a tuner scale them down incase in the future you want a still bigger turbo and more power.

drive = freedom
b7g is offline  
#3 Old 02-01-2008, 10:34 AM
WRXpert
 
dumdum's Avatar
 
Join Date: Sep 2004
Location: Virginia
Posts: 2,800
Images: 12
dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention
Yeah just saying "bigger turbo" is no help.Thats like saying"gonna get bigger rims" then asking what size tires you should get.Common sense would dictate you would need to know the rim size to pick the appropriate tires. Also RC Engineering has a injector calculator on their website.Use .60 as your B.S.F.C. #, desired HP in crank (not WHP) and add what ever your desired max boost is to your rail pressure.So if max boost is 20psi then rail fuel pressure would be 63.5psi due to we have a 1:1 RRFPR (Rising Rate Fuel Pressure Regulator)
RC Fuel Injection

Homebrewed tuned with Opensource!
dumdum is offline  
#4 Old 02-01-2008, 07:01 PM
b7g
WRXtuners Member
 
b7g's Avatar
 
Join Date: May 2007
Location: Illinois
Posts: 232
Images: 4
b7g is an unknown
Quote:
Originally Posted by dumdum View Post
Yeah just saying "bigger turbo" is no help.Thats like saying"gonna get bigger rims" then asking what size tires you should get.Common sense would dictate you would need to know the rim size to pick the appropriate tires. Also RC Engineering has a injector calculator on their website.Use .60 as your B.S.F.C. #, desired HP in crank (not WHP) and add what ever your desired max boost is to your rail pressure.So if max boost is 20psi then rail fuel pressure would be 63.5psi due to we have a 1:1 RRFPR (Rising Rate Fuel Pressure Regulator)
RC Fuel Injection
...rising rate FPR is not needed though, right? Only if a tune is done on limited by size injectors corresponding to the turbo lbs per minute and a race gas tune is also desired. Basically raising the static pressure in fuel rails corespondigly to intake pressure to compensate for the lack of flow of the injectors. Right?

drive = freedom
b7g is offline  
#5 Old 02-02-2008, 07:12 AM
WRXpert
 
dumdum's Avatar
 
Join Date: Sep 2004
Location: Virginia
Posts: 2,800
Images: 12
dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention dumdum is a WRX tech God, pay attention
Quote:
Originally Posted by b7g View Post
...rising rate FPR is not needed though, right? Only if a tune is done on limited by size injectors corresponding to the turbo lbs per minute and a race gas tune is also desired. Basically raising the static pressure in fuel rails corespondigly to intake pressure to compensate for the lack of flow of the injectors. Right?
Every modern fuel injected car has a rising rate FPR regardless of n/a or turboed.Our Subarus have a RRFPR from the factory.At idle rail pressure is around 38psi.To find the static of any vehcile you remove the vacuum line that goes to it.That acts as WOT on a N/A or the crossover to boost threshold for turbos.Static is generally 43.5psi.Our factory FPR are a 1:1 ratio. The fuel pressure is raised 1 psi for every 1 psi boost pressure.I used to use a FMU (type of RRFPR) on my old turboed S10 pickup.It was a 10:1 ratio.It raised the fuel pressure 10psi for every 1 psi boost.Maybe this is where your getting confused.Ours are a fixed ratio/non adjustable while the aftermarket ones are adjustable ratio/adjustable static.I actually run 5psi over base for some injector head room.My injector scaling is now 470cc.
Rising Fuel Pressure Regulator - Factory 2.0L Turbo Powertrain - NASIOC

Homebrewed tuned with Opensource!
dumdum is offline  
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On