Max'd out Walbro 400/450? - - Mazda RX7 Forum

Single Turbo RX-7's Questions about all aspects of single turbo setups.

Max'd out Walbro 400/450?

Old 08-25-18, 12:02 AM
Junior Member
Thread Starter
Join Date: Mar 2008
Location: NY
Posts: 5
Thanks: 0
Thanked 0 Times in 0 Posts
Max'd out Walbro 400/450?

What have you guys max'd out your F90000267s at on E85?
Assuming it's properly wired and you have enough injector. Just trying to figure out my fueling situation.

EFR8374 21psi spring
2200cc 4x
6an Feed/Return

Do you think a single F90000267 will do the trick?
Aboogabooga is offline  
Old 08-25-18, 04:51 PM
Automotive Designer
RGHTBrainDesign's Avatar
Join Date: Aug 2012
Location: San Jose, CA
Posts: 1,435
Thanked 40 Times in 37 Posts
On e85? Hahaha, not even close! At 21psi of boost and 43.5psi base pressure the fuel pump sees 64.5psi in which the Walbro flows about 95 gals/hr = 6000 cc/min.

So in a perfect world, you're getting 6000 cc/min on your 8800 cc/min injectors which means the fuel pump runs out at 68% duty cycle (on all four if they are equal) at 43.5psi.

This isn't including ANY losses in the system, which there are quite a few.

I would suggest two Bosch 044s at 70psi base pressure.
RGHTBrainDesign is offline  
Old 08-25-18, 05:11 PM
Eye In The Sky
iTrader: (2)
cewrx7r1's Avatar
Join Date: Feb 2001
Location: In Our Heads
Posts: 7,634
Thanks: 0
Thanked 14 Times in 12 Posts
You have to consider that the fuel flow requirements for alcohol is a lot more than gasoline.
For E85 you need about 37% more flow.
cewrx7r1 is offline  
Old 08-27-18, 07:57 AM
Brap Brap, Fap Fap
iTrader: (7)
Shainiac's Avatar
Join Date: Jun 2006
Location: Lyme, CT
Posts: 1,475
Thanked 7 Times in 7 Posts
You should be okay at 21 psi.

Here’s my math:
  • 21psi = 2.42 atm-a
  • ~200whp (NA) * 2.42 = 485whp
  • 485whp * 0.13 = 63.14 lb/min turbo air flow
  • 63.14 * 0.10 = 8.84 lb/min fuel flow (10:1 AFR, +40% for ethanol)
  • 8.84 * 60 = 530 lb/hr
  • 530 / 6.5* 3.79 = 308.9 LPH
This is assuming zero losses.

A Walbro 400 at 13.5V and 4.5 bar flows ~350 LPH, so you still have some head room

I made 540whp through a single Walbro 400, but at 28psi of boost and the fuel pressure was about 15-20psi below what it should have been! The only caveat- that was through stock hardlines BUT on pumpgas.

IMO, The 400/450 pumps are the best bang for the buck. Quiet, powerful, cool, and cheap. It is difficult to fit two in-tank, but there are some aftermarket options for pump hangers.
Shainiac is offline  
Old 08-27-18, 08:45 PM
Adaptronic Distributor
RX7Club Vendor
iTrader: (12)
Turblown's Avatar
Join Date: Dec 2001
Location: Twin Cities, MN
Posts: 6,859
Thanked 17 Times in 16 Posts
Non hellcat version at e77 or higher starts to run out of pressure above 15 psi( 430rwhp range). E55 is fine to 460range. At the 500rwhp mark( 17/18 psi) you will be down 6 psi on e55, and down 10 plus psi on e77. This is my experience with the 8374 iwg on this combo with a good 40 cars in the past year. Installing the new hellcat version tomorrow, will tune in two weeks on another 8374 iwg.

Turblown is offline  
Related Topics
Thread Starter
Last Post
Single Turbo RX-7's
09-01-16 05:52 PM
Rotary Car Performance
02-23-16 11:58 PM
3rd Generation Specific (1993-2002)
06-04-03 09:46 AM
Single Turbo RX-7's
05-02-02 04:46 AM
More Power
1st Generation Specific (1979-1985)
02-28-02 09:05 PM

Thread Tools
Search this Thread
Quick Reply: Max'd out Walbro 400/450?

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: