Worth 8 bucks? - Page 2 - 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 01-01-2007, 11:50 PM   #21
Elite Member
iTrader: (14)
 
Join Date: Mar 2006
Location: Edmonton, AB
Posts: 4,921
Total Cats: 0
Default

I don't know for sure. I guess it depends on how sensitive the MBC is. If the MBC is set to open at 8psi, will it close at 7.5psi? Will it open and close instantaniously?

That's why someone needs to try
jayc72 is offline   Reply With Quote
Old 01-02-2007, 12:24 AM   #22
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

I don't know, but wouldn't think the resultant ocillation in fuel pressure would be very fun. Maybe a simple pop vent to atmosphere isn't correct for the application. It would have to be coupled with a second bleed. So the resultant would be a pressure rise with boost that progressively reduces its rate of rise. So then there would be two additional adjustments: the pressure to begin the venting event, and the rate of bleed at the vent. Now it should work. ?
Attached Thumbnails
Worth 8 bucks?-whoknows.jpg  
Ben is offline   Reply With Quote
Old 01-02-2007, 12:31 AM   #23
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,847
Total Cats: 1,788
Default

I wonder if a smaller diameter outlet on the MBC would help relieve some pressure...just not all, like the BEGi unit's small port
Braineack is offline   Reply With Quote
Old 01-02-2007, 12:37 AM   #24
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

I'm thinking something along the lines of a mbc that vents through a needle valve instead of a standard port. Then you could control the pressure dump pretty precisely. Whatchya think?

Quote:
Originally Posted by braineack View Post
I wonder if a smaller diameter outlet on the MBC would help relieve some pressure...just not all, like the BEGi unit's small port
Ben is offline   Reply With Quote
Old 01-02-2007, 12:41 AM   #25
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,847
Total Cats: 1,788
Default

im seeing a trip to ACE Hardware tomorrow.
Braineack is offline   Reply With Quote
Old 01-02-2007, 12:45 AM   #26
Elite Member
iTrader: (14)
 
Join Date: Mar 2006
Location: Edmonton, AB
Posts: 4,921
Total Cats: 0
Default

At worst it won't work. At best I'll look like an internet god. Likely somewhere in between.
jayc72 is offline   Reply With Quote
Old 01-02-2007, 01:44 AM   #27
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

Quote:
Originally Posted by adbradley View Post
magna are you running a 12:1 fmu??
yes
magnamx-5 is offline   Reply With Quote
Old 01-02-2007, 09:15 AM   #28
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Feb 2006
Location: Mesa, AZ
Posts: 999
Total Cats: 0
Default

Quote:
Originally Posted by magnamx-5 View Post
yes
I was under the impression that most guys were running 8:1 and that 12:1 was to much fuel...
adbradley is offline   Reply With Quote
Old 01-02-2007, 10:39 AM   #29
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

Quote:
Originally Posted by adbradley View Post
I was under the impression that most guys were running 8:1 and that 12:1 was to much fuel...
He uses a safc to cut fuel.

bradley, you got a fuel pump right?
Ben is offline   Reply With Quote
Old 01-02-2007, 10:47 AM   #30
AFM Crusader
iTrader: (18)
 
olderguy's Avatar
 
Join Date: Oct 2004
Location: Wayne, NJ
Posts: 4,438
Total Cats: 84
Default

If you are running the OEM fuel pump, stay with the 12:1
olderguy is online now   Reply With Quote
Old 01-02-2007, 11:35 AM   #31
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

Quote:
Originally Posted by Ben View Post
I'm thinking something along the lines of a mbc that vents through a needle valve instead of a standard port. Then you could control the pressure dump pretty precisely. Whatchya think?
I spent a little while thinking about this. Essentially the concept creates a rising rate fuel pressure regulator with 2 stages of rise. 2 stage linear, not progressive like I wrote in an earlier post. The first stage would be absolutely identical to a current FMU where the FMU builds fuel pressure with MAP linearly where the rate of fuel pressure rise is controlled by bleeding pressure to atmosphere at the needle valve. The second stage would start at the point when the pressure relief valve opens. When the prv opens, we can then vent additional pressure to atmosphere at a time determined by the prv's pop open point and a rate determined by the second needle valve.

So let us assume that we set our stage 1 needle valve bleed to rise fuel pressure at the rate of 8 psi to every 1 psi of boost pressure. Let us then assume we set our pressure relief to open after 4 psi of boost pressure, and we set our second needle valve to increase fuel pressure at the rate of 3 psi to every 1 psi of boost with any boost over 4 psi

Result of above assumptions:
1 psi boost pressure --> +8 psi fuel pressure
2 psi boost pressure --> +16 psi fuel pressure
3 psi boost pressure --> +24 psi fuel pressure
4 psi boost pressure --> +32 psi fuel pressure
STAGE 2:
5 psi boost pressure --> +35 psi fuel pressure
6 psi boost pressure --> +38 psi fuel pressure
12 psi boost pressure --> +56 psi fuel pressure



Bear in mind my assumed rates are arbitrary, so observe the data as conceptual/hypothetical, but not necessarily correct for the application.

Last edited by Ben; 01-02-2007 at 12:20 PM.
Ben is offline   Reply With Quote
Old 01-02-2007, 12:20 PM   #32
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

i got the safc after trying to run some 460's for all my dyno runs so far i haven't had one. it did help me on top end and driveability though. just not with the 460's. i first stated doing the mbc fmu tweak with my low impedance 305's that i ran for a while and it slowed the fp ramp up becouse my injectors where doing silly things being the wrong impedance and all on boost transition.
magnamx-5 is offline   Reply With Quote
Old 01-02-2007, 01:39 PM   #33
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Feb 2006
Location: Mesa, AZ
Posts: 999
Total Cats: 0
Default

no i only have the stock pump...
adbradley is offline   Reply With Quote
Old 01-02-2007, 01:40 PM   #34
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

80 psi is gonna limit you a 190hp migth help with headroom but for the time being you should be allright.
magnamx-5 is offline   Reply With Quote
Old 01-02-2007, 01:40 PM   #35
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Feb 2006
Location: Mesa, AZ
Posts: 999
Total Cats: 0
Default

whats a safc?
adbradley is offline   Reply With Quote
Old 01-02-2007, 01:41 PM   #36
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Feb 2006
Location: Mesa, AZ
Posts: 999
Total Cats: 0
Default

im not lookin for that much power to start out with anyway
adbradley is offline   Reply With Quote
Old 01-02-2007, 01:42 PM   #37
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

Safc is an Air fuel controller it plugs in between the ecu and afm and tweaks the signal +-50% not the best but for 200 bucks it aint bad i am probably gonna get MS if i cant hit 300whp on stock ecu. if not some nos then MS and 350+whp hopefully. Good luck man
magnamx-5 is offline   Reply With Quote
Old 01-02-2007, 01:45 PM   #38
Senior Member
Thread Starter
iTrader: (2)
 
Join Date: Feb 2006
Location: Mesa, AZ
Posts: 999
Total Cats: 0
Default

do you think this will be drivable magna, 12:1 fmu, no bleeder of any kind, 1.8 injectors, and stock fuel pump?
adbradley is offline   Reply With Quote
Old 01-02-2007, 01:56 PM   #39
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

oh yeah that is what i had for my first setup. minus 1.8 injectors but the 1.8's made driveability better esp on real hot days.
magnamx-5 is offline   Reply With Quote
Old 01-02-2007, 01:58 PM   #40
Elite Member
iTrader: (14)
 
Join Date: Mar 2006
Location: Edmonton, AB
Posts: 4,921
Total Cats: 0
Default

I wouldn't assume you'll get 80psi out of the pump until you confirm it with a pressure gauge while driving. The pump out of my 93 would only give me 65-70psi under boost.
jayc72 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
3rd Time's a Charm...hopefully. zephyrusaurai Meet and Greet 2 09-28-2015 11:59 PM
In what world... curly MEGAsquirt 11 09-22-2015 12:54 PM
Noob from Fort Worth, Texas checking in. Miatabro Meet and Greet 7 09-11-2015 01:13 PM
WTB parts for HPDE car Voltwings WTB 5 09-11-2015 09:23 AM
Project DDoS: '99 "Budget" boost build ProjectDDoS Build Threads 1 09-09-2015 02:52 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 11:55 PM.