Dual Feed Fuel Rail - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 08-23-2006, 01:24 PM   #1
Ben
Supporting Vendor
Thread Starter
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default Dual Feed Fuel Rail

I was wondering how many of you guys are running a dual feed rail? At what level of boost does it become necessary?
FYI, I'm at 7.5 pounds with my 1.6 injectors. If the clutch holds, I'll turn boost up a little when I get bigger injectors.

Edit: Did you notice a difference in egt after installation of the dual feed?

Thanks

Last edited by Ben; 08-23-2006 at 06:01 PM. Reason: revision
Ben is offline   Reply With Quote
Old 08-23-2006, 01:28 PM   #2
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

The fuel rail is benificial to all cars as it distributes the fuel more evenly, to all the injectors. Unless you are going to run very high fp and huge injectors i wouldn't worry about it.
magnamx-5 is offline   Reply With Quote
Old 08-23-2006, 02:15 PM   #3
Elite Member
iTrader: (9)
 
TurboTim's Avatar
 
Join Date: Jun 2006
Location: Chesterfield, NJ
Posts: 6,484
Total Cats: 248
Default

I agree. I doubt the factory fuel rail is doing much harm on a 1.6 at 7 psi. But having balanced flow is good insurance if you have the time to play around. Many people drill/tap the end of the factory fuel rail for 1/8NPT and put a barb fitting in there to make it dual feed. If you like bling and being broke you could buy a Vishnu rail. Jim B sells/sold an aluminum rail that should be better than stock too, but looked too crude for me, so I decided to made my own for shitsngiggles.

TurboTim is offline   Reply With Quote
Old 08-23-2006, 08:32 PM   #4
Senior Member
iTrader: (14)
 
brgracer's Avatar
 
Join Date: Nov 2004
Location: Ambler, PA
Posts: 1,275
Total Cats: 1
Default

Tim that looks really nice. It would look even nicer under my hood.

As for the original question, I agree that balanced flow to all injectors will never hurt. If you have the time and/or $$$, it'll give you an extra measure of safety.

I can't find it, but there was an old thread on another forum where Shiv (maker of the Vishnu rail) said something to the effect that stock injectors will never outflow the stock rail b/c their size so you're probably okay with the stock rail and 1.6 injectors. Bigger injectors and more power is another story as already said.
brgracer is offline   Reply With Quote
Old 08-24-2006, 04:58 AM   #5
Junior Member
 
Join Date: Oct 2004
Posts: 171
Total Cats: 3
Default

Are you guys serious?????

The DIY dual feed mod is so cheap to do and so easy.....why wouldnt you do it...
Ive done it on my car and it didnt take very long to do and is cheap insurance for your motor........DO IT!!!!
4sfed5 is offline   Reply With Quote
Old 08-24-2006, 11:24 AM   #6
Elite Member
iTrader: (14)
 
Join Date: Mar 2006
Location: Edmonton, AB
Posts: 4,921
Total Cats: 0
Default

My only concern with modifying the stock rail is it failing. At over 100psi of fuel pressure it sure would suck having high pressure fuel spraying all over the engine. I guess if you are careful it shouldn't be a problem, but I'm paranoid like that.
jayc72 is offline   Reply With Quote
Old 08-24-2006, 11:52 AM   #7
Junior Member
 
Sirnixalot's Avatar
 
Join Date: Aug 2005
Location: Cayman Islands
Posts: 440
Total Cats: 17
Default

use JB weld as a thread sealant
Sirnixalot is offline   Reply With Quote
Old 08-24-2006, 12:04 PM   #8
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,860
Total Cats: 1,788
Default

I haven't checked the pressures, but from what I understand the Pierburg can supply over 140psi of fuel when clamped off. My JB Welded fitting held the pressure fine, I'm not too worried about it since I'll only be pushing 108psi or so.

Regular fuel injection hose (SAE30R9) is required to have higher working pressure rating (125psi) and minimum burst pressure rating (900psi). If you are worried about pressures in your fuel lines then, look for an SAE rating on the hose. SAE30R6 and SAE30R7 are low pressure hose for carburated enginges (rated for 50 psi and a minimum burst pressure of 250 psi) and SAE30R9 is a higher pressure fuel injection hose. If your hose has a number between R7 and R9 it is a medium pressure hose.

From what I've spoken to with Corky the same thing applies to the rail itself. He's much more conserned with the FPR failing before the lines and hoses fail.

Last edited by Braineack; 08-24-2006 at 12:33 PM.
Braineack is offline   Reply With Quote
Old 08-24-2006, 12:18 PM   #9
Elite Member
iTrader: (14)
 
Join Date: Mar 2006
Location: Edmonton, AB
Posts: 4,921
Total Cats: 0
Default

It's not that the fuel pressure would cause a failure, but sure would suck if it ever did fail at over 100psi.

Having said that ... what sized fitting are you guys using?
jayc72 is offline   Reply With Quote
Old 08-24-2006, 12:26 PM   #10
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,860
Total Cats: 1,788
Default

1/8" to 5/16
Braineack is offline   Reply With Quote
Old 08-24-2006, 01:06 PM   #11
Elite Member
iTrader: (9)
 
TurboTim's Avatar
 
Join Date: Jun 2006
Location: Chesterfield, NJ
Posts: 6,484
Total Cats: 248
Default

That's 1/8 NPT to 5/16" barb, I believe.
TurboTim is offline   Reply With Quote
Old 08-24-2006, 02:04 PM   #12
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,860
Total Cats: 1,788
Default

Quote:
Originally Posted by TurboTim View Post
That's 1/8 NPT to 5/16" barb, I believe.
yeah, too many extra letters to type.
Braineack is offline   Reply With Quote
Old 08-24-2006, 07:10 PM   #13
Elite Member
iTrader: (1)
 
Join Date: Jun 2005
Location: Charleston, SC
Posts: 2,980
Total Cats: 14
Default

Quote:
Originally Posted by Ben View Post
I was wondering how many of you guys are running a dual feed rail? At what level of boost does it become necessary?
I run a DIY dual feed (OEM tapped at one end). No idea when you need it but I am running 12-13 psi right now on 440 injectors.
rmcelwee is offline   Reply With Quote
Old 08-24-2006, 07:18 PM   #14
Ben
Supporting Vendor
Thread Starter
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

Exactly. I'm quite confident in my abilities, but if it ain't broke then there's nothing to fix... I'd rather invest limited resources (and time IS a resource) into meaningful mods. If it's not necessary at 8 psi and 230cc injectors, then there's no use. OTOH, if it keeps the temp at #4 down, then it would be worthwhile.


Quote:
Originally Posted by jayc72 View Post
My only concern with modifying the stock rail is it failing. At over 100psi of fuel pressure it sure would suck having high pressure fuel spraying all over the engine. I guess if you are careful it shouldn't be a problem, but I'm paranoid like that.
Ben is offline   Reply With Quote
Old 08-24-2006, 07:18 PM   #15
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,860
Total Cats: 1,788
Default

I think it's safe at any level since it will balance out your flow through the rail. Who needs a #4 failure!?!
Braineack is offline   Reply With Quote
Old 08-24-2006, 07:19 PM   #16
Ben
Supporting Vendor
Thread Starter
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

Thanks for your answers guys. Did anyone notice any change in egt after this mod?

Thanks
Ben is offline   Reply With Quote
Old 08-24-2006, 08:50 PM   #17
Elite Member
iTrader: (1)
 
Join Date: Jun 2005
Location: Charleston, SC
Posts: 2,980
Total Cats: 14
Default

I know several people who have lost #4 @ 8psi. Why risk it?
rmcelwee is offline   Reply With Quote
Old 08-24-2006, 09:22 PM   #18
AFM Crusader
iTrader: (18)
 
olderguy's Avatar
 
Join Date: Oct 2004
Location: Wayne, NJ
Posts: 4,438
Total Cats: 84
Default

Quote:
Originally Posted by rmcelwee View Post
I know several people who have lost #4 @ 8psi. Why risk it?
Loosing #3 and #4 cylinders probably has more to do with poor water circulation than the fuel rail.
olderguy is offline   Reply With Quote
Old 08-24-2006, 10:07 PM   #19
Senior Member
iTrader: (14)
 
brgracer's Avatar
 
Join Date: Nov 2004
Location: Ambler, PA
Posts: 1,275
Total Cats: 1
Default

This post made me do a lot more reading up on dual feed fuel rails and learned two interesting things from some old threads about people who did some actual dyno testing.

#1 dual feed stock rail (~$10) was just about as good as vishnu/FM/****'s for most applications on the dyno. Granted, the more radical the setup, the higher end stuff started to make some gains over the stock mod.

#2 More than just for safety, most people on the dyno were able to advance their timing a few degrees b/c of the dual feed rail and hence make more power. Interesting....
brgracer is offline   Reply With Quote
Old 08-25-2006, 12:32 PM   #20
Junior Member
iTrader: (2)
 
Join Date: Nov 2005
Location: A2, MI
Posts: 474
Total Cats: 0
Default

Someone should post a "How to make a double feed fuel rail." I looked but didn't find anything (with pics), if someone has one with photos then post it if you could.
Dhaark is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 58 Yesterday 10:04 PM
Walbro 255lph Fuel Pump $50 lsc224 Miata parts for sale/trade 2 10-01-2015 10:17 AM
Low oil pressure after 1.8 swap and new turbo setup JesseTheNoob DIY Turbo Discussion 15 09-30-2015 03:44 PM
"Chimney Ethanol" E100 MiataGarage Engine Performance 5 09-30-2015 12:04 AM
3rd Time's a Charm...hopefully. zephyrusaurai Meet and Greet 2 09-28-2015 11:59 PM


Thread Tools

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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 04:27 AM.