NB fuel pump, required? - 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 01-22-2008, 02:26 PM   #1
Senior Member
Thread Starter
 
Join Date: Jun 2005
Location: WA
Posts: 500
Total Cats: 0
Default NB fuel pump, required?

Hey, I have a quick question. Do I need to upgrade the fuel pump in my '99, I plan on running 250whp on 550cc injectors, controlled by EMU. Or will my stock pump flow enough.
RusMan is offline   Reply With Quote
Old 01-22-2008, 02:33 PM   #2
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,328
Total Cats: 1,926
Default

The stock pump in a '92 flows enough for ~200 WHP through 440s, so I imagine the stock pump in a '99 will suffice for ~250WHP through 550s.

The problem with stock fuel pumps in FI applications, and this covers both NA and NB, is not typically flow but rather pressure. This is principally a concern for those people running AFPRs with small injectors, where the pump is called upon to produce pressures in excess of 100 PSI, as compared to the 40 or 50 you see in a non-AFPR application.

At most, you might find that the increase in consumption through the rail necessitates a dual-feed arrangement, but I'd suggest that you try it as-is first and see how it responds.
Joe Perez is offline   Reply With Quote
Old 01-22-2008, 02:34 PM   #3
Elite Member
iTrader: (7)
 
samnavy's Avatar
 
Join Date: Apr 2006
Location: VIRGINIA BEACH, VA
Posts: 6,020
Total Cats: 175
Default

I think people will tell you the stock pump is adequate. As it's a '99, it's still fairly new and should not be showing signs of slowing down. A Walbro 190hp in-tank is cheap insurance at $90.
samnavy is offline   Reply With Quote
Old 01-22-2008, 02:35 PM   #4
Elite Member
iTrader: (13)
 
cjernigan's Avatar
 
Join Date: Oct 2006
Location: Atlanta, GA
Posts: 8,147
Total Cats: 6
Default

If your stock pump is healthy it should be fine. If you're worried you could rig up something in the fuel line to measure fuel pressure. With our returnless style fuel system you should be around 60-65 psi constant. That fuel pressure is enough for 250 whp.
cjernigan is offline   Reply With Quote
Old 01-23-2008, 01:18 AM   #5
Senior Member
Thread Starter
 
Join Date: Jun 2005
Location: WA
Posts: 500
Total Cats: 0
Default

Sounds good boys, I will be doing a dual feed fuel rail, whenever FM gets some in. Sounds like it's not required but wouldn't hurt to put in a 255lph in there right?
RusMan is offline   Reply With Quote
Old 01-23-2008, 01:26 AM   #6
Elite Member
iTrader: (13)
 
cjernigan's Avatar
 
Join Date: Oct 2006
Location: Atlanta, GA
Posts: 8,147
Total Cats: 6
Default

Quote:
Originally Posted by RusMan View Post
Sounds good boys, I will be doing a dual feed fuel rail, whenever FM gets some in. Sounds like it's not required but wouldn't hurt to put in a 255lph in there right?
I would do a 190 instead. The 255 is probably noisier and might over power the stock regulator. Either way, for only 250-300 you should be fine.
cjernigan is offline   Reply With Quote
Old 01-23-2008, 12:24 PM   #7
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,328
Total Cats: 1,926
Default

Quote:
Originally Posted by RusMan View Post
Sounds like it's not required but wouldn't hurt to put in a 255lph in there right?
Well, it'll hurt your wallet for sure. And in the NAs at least it is rumored that the 255 can actually overpower the stock FPR and cause the fuel pressure to rise above stock while not in boost.

Wait... Can you even use a Walbro in a returnless system?
Joe Perez is offline   Reply With Quote
Old 01-23-2008, 12:39 PM   #8
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,908
Total Cats: 1,793
Default

if i had an NB I'd get the 255. since it runs at 60psi static, no reason not to.

I've also heard that some NBs have trouble maintaining the pressure to redline, and the 255 acutally does so.

this is only if I had an NB and if I in fact needed a fuel pump.
Braineack 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 59 12-15-2017 09:00 PM
Walbro 255lph Fuel Pump $50 lsc224 Miata parts for sale/trade 2 10-01-2015 10:17 AM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 11:28 PM
why is my car running like pewp? (tune/datalog) itsMikey MSPNP 3 09-28-2015 07:40 AM


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 02:57 PM.