Want to turn up the boost to 10psi - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Prefabbed Turbo Kits A place to discuss prefabricated turbo kits on the market
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools
Old 09-07-2007, 06:24 PM   #1
Junior Member
Thread Starter
iTrader: (2)
 
Join Date: Dec 2004
Posts: 201
Total Cats: 1
Default Want to turn up the boost to 10psi

Here's my setup:
93 miata
15g Greddy turbo and manifold
2.5" TurboTony DP
Flyin Miata dual-feed fuelrail
305 Supra injectors (green tops)
Megasquirt PnP

I'm looking to turn up the boost to 10psi from its current 5 psi. I also have an inline fuel pump, but I don't want to put that on unless it's absolutely necessary.

So, possible or not with my current setup? Or should I put the Pierburg pump on there for a little more security?
db84drteg is offline   Reply With Quote
Old 09-07-2007, 06:32 PM   #2
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago (Over two miles from Wrigley Field. Fuck the Cubs. Fuck them in their smarmy goat-hole.)
Posts: 26,317
Total Cats: 1,915
Default

The Pierburg fuel pump is absolutely unnecessary unless you're running an AFPR. My setup uses 440cc injectors at 12-14PSI on the original 16 year old stock fuel pump with no problems.

The injectors themselves are going to be the determing factor for you. Best suggestion is to start turning up the boost very slowly while keeping an eye on the injector duty cycle and A/F ratio. My bet is that 10PSI is gonna be pushing it on 305s.
Joe Perez is offline   Reply With Quote
Old 09-07-2007, 06:34 PM   #3
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

not enough injector for 10 psi at stock fuel pressure.
Ben is offline   Reply With Quote
Old 09-07-2007, 06:48 PM   #4
Senior Member
iTrader: (3)
 
Join Date: Apr 2007
Location: Odenton, MD
Posts: 713
Total Cats: 0
Default

question.... i dont have greddy but i still haev a question. I don't need a fuel pump if i have MS correct? I can simply use MS to tune and watch the duty cycle correct( as you mentioned).
Dow.tom is offline   Reply With Quote
Old 09-07-2007, 07:14 PM   #5
Junior Member
Thread Starter
iTrader: (2)
 
Join Date: Dec 2004
Posts: 201
Total Cats: 1
Default

Sounds good. I'll put the pierburg on there then ^_^ Thanks guys!
db84drteg is offline   Reply With Quote
Old 09-07-2007, 07:14 PM   #6
Guest
iTrader: (1)
 
ray_sir_6's Avatar
 
Join Date: Dec 2006
Location: DFW, TX
Posts: 714
Total Cats: 0
Default

Do you have a FMIC or WI??? Just pushing HOT air if you don't.
ray_sir_6 is offline   Reply With Quote
Old 09-07-2007, 07:18 PM   #7
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

the peirburg won't help you at all. you need bigger injectors if you want more boost.
Ben is offline   Reply With Quote
Old 09-07-2007, 08:07 PM   #8
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago (Over two miles from Wrigley Field. Fuck the Cubs. Fuck them in their smarmy goat-hole.)
Posts: 26,317
Total Cats: 1,915
Default

Quote:
Originally Posted by db84drteg View Post
Sounds good. I'll put the pierburg on there then ^_^ Thanks guys!
You're not listening. The Pierburg pump isn't going to accomplish anything if you don't have an AFPR. That's the whole point of crazy aftermarket fuel pumps: to be able to supply fuel at the increased rail pressures that AFPRs attempt to generate.

That being said, you already have a Megasquirt, which is about as good as it gets. In your position, installing an AFPR would be stupid. Sell the Pierburg pump, and between that and what you'll save not buying an AFPR you can get some 440cc injectors and have money left over to buy liposuction for Loki's sister. (different thread...)
Joe Perez is offline   Reply With Quote
Old 09-07-2007, 08:08 PM   #9
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago (Over two miles from Wrigley Field. Fuck the Cubs. Fuck them in their smarmy goat-hole.)
Posts: 26,317
Total Cats: 1,915
Default

Quote:
Originally Posted by Dow.tom View Post
question.... i dont have greddy but i still haev a question. I don't need a fuel pump if i have MS correct? I can simply use MS to tune and watch the duty cycle correct( as you mentioned).
You do need a fuel pump for most automotive gasoline engines, otherwise no fuel will flow through the lines from the tank to the engine compartment. Very few automotive applications use gravity-fed fuel systems these days, although they are still common on motorcycles and high-wing piston aircraft.

However, the stock fuel pump in a Miata is perfectly adequate for anybody who is using larger injectors and proper engine management to meet their fueling needs, rather than relying upon an AFPR and higher-than-stock fuel pressure.
Joe Perez is offline   Reply With Quote
Old 09-07-2007, 08:22 PM   #10
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,363
Total Cats: 1,323
Default

Sell your 305s and the Pierberg pump and buy a set of 460cc Rx7 injectors. They will take you to 10psi and well past that (I'm starting to max mine at 15-16psi).
Savington is offline   Reply With Quote
Old 09-07-2007, 11:36 PM   #11
Elite Member
iTrader: (7)
 
samnavy's Avatar
 
Join Date: Apr 2006
Location: VIRGINIA BEACH, VA
Posts: 6,020
Total Cats: 175
Default

DB, Sav and Joe are correct. Sell the pump, sell the 305's. Buy 440's or 460's.

After that... you still need an intercooler or water injection to get the charge temps down. You'll have to pull so much timing at high boost due to the air temp that you'll start getting negative returns at higher boost where more boost actually makes no more power... then you'll knock and blow your motor. I'd do the Intercooler before going with bigger injectors. You might find that getting the temps down will let you better manage your timing and give you the power you're looking for now until you can spring for the larger injectors.
samnavy is offline   Reply With Quote
Old 09-07-2007, 11:40 PM   #12
I'm Miserable!
 
Join Date: Jul 2006
Location: sandiego, CA
Posts: 332
Total Cats: 0
Default

yup id look into an intercooler.
drftem is offline   Reply With Quote
Old 09-08-2007, 12:55 AM   #13
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,363
Total Cats: 1,323
Default

If you aren't intercooled, 6psi is the max you can safely do. You need larger injectors and an intercooler to go beyond that.
Savington is offline   Reply With Quote
Old 09-08-2007, 03:01 AM   #14
Junior Member
Thread Starter
iTrader: (2)
 
Join Date: Dec 2004
Posts: 201
Total Cats: 1
Default

Whoops, I forgot to mention that =P I have a spearco bar and plate intercooler, 23-24" x 3" x 8" core with 2.5" end tanks.

Joe, I totally blew over the "un" in unnecessary o_O I'll look into the RX7 injectors.
db84drteg is offline   Reply With Quote
Old 09-08-2007, 01:11 PM   #15
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago (Over two miles from Wrigley Field. Fuck the Cubs. Fuck them in their smarmy goat-hole.)
Posts: 26,317
Total Cats: 1,915
Default

Quote:
Originally Posted by samnavy View Post
you still need an intercooler or water injection to get the charge temps down.
What's this OR business? FMIC and Methanol FTW!
Joe Perez is offline   Reply With Quote
Old 09-09-2007, 12:14 AM   #16
Elite Member
iTrader: (1)
 
Join Date: Jun 2005
Location: Charleston, SC
Posts: 2,980
Total Cats: 14
Default

Quote:
Originally Posted by Savington View Post
Sell your 305s and the Pierberg pump and buy a set of 460cc Rx7 injectors. They will take you to 10psi and well past that (I'm starting to max mine at 15-16psi).
I cannot remember what my duty cycle was (85%??) but I considered my 440's maxed out around 220HP and swapped to low imp 550's and resistors.
rmcelwee is offline   Reply With Quote
Old 09-09-2007, 02:10 AM   #17
Junior Member
Thread Starter
iTrader: (2)
 
Join Date: Dec 2004
Posts: 201
Total Cats: 1
Default

I just bit the bullet on a set of 550cc purple-top turbo RX7 injectors. Shouldn't have much of an issue with fueling when those go in
db84drteg is offline   Reply With Quote
Old 09-09-2007, 03:17 AM   #18
Elite Member
iTrader: (1)
 
Join Date: Jun 2005
Location: Charleston, SC
Posts: 2,980
Total Cats: 14
Default

Quote:
Originally Posted by db84drteg View Post
I just bit the bullet on a set of 550cc purple-top turbo RX7 injectors. Shouldn't have much of an issue with fueling when those go in
Except you won't be able to idle <G>.

I'm not sure at what point injectors become too large. My 550's don't have any issues. Do you have to run resistors with the purple tops?
rmcelwee is offline   Reply With Quote
Old 09-09-2007, 03:22 AM   #19
Junior Member
Thread Starter
iTrader: (2)
 
Join Date: Dec 2004
Posts: 201
Total Cats: 1
Default

According to Braineack's FAQ, they'll go right in. They're high-impedance injectors.
db84drteg is offline   Reply With Quote
Old 09-09-2007, 10:20 AM   #20
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,689
Total Cats: 99
Default

they are a little on the big side. idle quality may suffer a little. the 550s can supply enough fuel for 340 rwhp or so.

i'm running 440's. 74% duty cycle at 255 rwhp, stock fuel pressure.
Ben 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
LucaCarMods's Boosted Dutch Miata Build! LucaCarMods Build Threads 11 02-14-2016 07:13 AM
Going back to stock. Need some 1.6 parts. Trent WTB 2 10-01-2015 01:15 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


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 04:41 AM.