Why do turbos use bigger injectors? - 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 02-13-2007, 12:20 AM   #1
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: May 2006
Location: Phoenix, AZ
Posts: 401
Total Cats: -1
Default Why do turbos use bigger injectors?

I've always been curious about why turbos (Miatas specifically) all seem to use bigger injectors instead of using additional injectors?

So why not use OEM injectors and save your idle and use additional injectors to only add fuel while in boost?
chuckerants is offline   Reply With Quote
Old 02-13-2007, 12:22 AM   #2
Elite Member
iTrader: (9)
 
Join Date: Aug 2006
Location: Concord, North Carolina
Posts: 4,173
Total Cats: 5
Default

4 is easier to tune with than 5...6...8? With an ECU...you don't have to idle bad...and always have headroom.
miatamania is offline   Reply With Quote
Old 02-13-2007, 12:27 AM   #3
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,363
Total Cats: 1,324
Default

Because a lopey, crappy idle is quite possibly the coolest sounding thing a car can do.
Savington is online now   Reply With Quote
Old 02-13-2007, 12:29 AM   #4
Senior Member
iTrader: (2)
 
SamS's Avatar
 
Join Date: Jun 2006
Location: Wisconsin
Posts: 1,254
Total Cats: 7
Default

Because my car gets eleventy billion more hp each time i tell someone i swapped my injectors for ones out of a supra:gay:
SamS is online now   Reply With Quote
Old 02-13-2007, 12:42 AM   #5
Junior Member
iTrader: (3)
 
timhill78's Avatar
 
Join Date: Aug 2006
Location: Oregon
Posts: 241
Total Cats: 0
Default

My car is more classy now that it has Lexus injectors.
timhill78 is offline   Reply With Quote
Old 02-13-2007, 12:55 AM   #6
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,867
Total Cats: 1,790
Default

Quote:
Originally Posted by chuckerants View Post
I've always been curious about why turbos (Miatas specifically) all seem to use bigger injectors instead of using additional injectors?
For some reason us turbo guys like to support our particular amount of HP with the appropriate amount of fuel. Plus the added bonuses of knock supression.

Quote:
So why not use OEM injectors and save your idle and use additional injectors to only add fuel while in boost?
You just need a controller to run the 5th injector anyways.....

It's not like we tune to idle at 12:1 AFR....you still tune for 14.7:1 idle while adding fuel while in boost. Regardless of the injector size.

miata specifically?! ever car needs fuel per a given HP. you cannot support 400BHP with OEM injectors...it's all in the math.

Braineack is offline   Reply With Quote
Old 02-13-2007, 03:02 AM   #7
Senior Member
 
Join Date: Oct 2005
Location: Knoxville
Posts: 1,168
Total Cats: 0
Default

save your idle? you can idle 550s like stock with a standalone ECU. A 5th injector is a very unnecessary complication, and not an ideal setup anyway.

I've always been curious as to why people try to use use ~100hp injectors to make 220hp...
Al Hounos is offline   Reply With Quote
Old 02-13-2007, 09:02 AM   #8
Senior Member
 
Join Date: Dec 2004
Posts: 1,450
Total Cats: -1
Default

Unless you have a custom manifold with extra injectors bungs aimed at the runners (ala BRP or FM's old mani), then you won't get ideal fuel distribution from the one or two injectors dangling off the intake tract in front of the throttle body or wherever, either.

It's just not ideal.
bripab007 is offline   Reply With Quote
Old 02-13-2007, 09:38 AM   #9
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

Quote:
Originally Posted by Brian View Post
Unless you have a custom manifold with extra injectors bungs aimed at the runners (ala BRP or FM's old mani), then you won't get ideal fuel distribution from the one or two injectors dangling off the intake tract in front of the throttle body or wherever, either.

It's just not ideal.
Yes this coupled with the cost of a standalone like EMU &,MS, vs SS system isnt to far off.
magnamx-5 is offline   Reply With Quote
Old 02-13-2007, 08:42 PM   #10
Elite Member
iTrader: (24)
 
kotomile's Avatar
 
Join Date: Oct 2006
Location: Monterey, CA
Posts: 7,578
Total Cats: 40
Default

Most people (not just Miata peeps) use the increasing injector size and/or fuel pressure method. Actually, the only guy I know who had a 5th injector setup was a friend with a 96 Miata...

Besides, to run an extra injector you need the hardware to plumb the thing in and the software to control it, and it'll be an inefficient setup because of how far upstream of the cylinders it'll be. Then by the time you add up the cost of all that you might as well have bought an EMB or Megasquirt.
kotomile is offline   Reply With Quote
Old 02-13-2007, 10:40 PM   #11
Senior Member
iTrader: (7)
 
Join Date: Mar 2005
Location: VT
Posts: 939
Total Cats: 0
Default

Why???

Because Miata owners do it right the first time



I have both

305's in the Engine, 1 550cc before the TB.. Also I have a TB plate that has spots for two..

I would have preferred my PC setup to the EMB, but as already mentioned MS/EMB is cheaper then even purchasing a simple EIC. I needed more fuel. After I added the EMB, adding larger injectors was too simple... Other folks use an EMB/AFPR and larger injectors..
Jefe is offline   Reply With Quote
Old 02-13-2007, 11:15 PM   #12
Elite Member
iTrader: (5)
 
Join Date: Jan 2007
Location: Freehold, NJ
Posts: 1,577
Total Cats: -2
Default

not to thread jack but what would be ideal injectors for 215hp reilable
disturbedfan121 is offline   Reply With Quote
Old 02-13-2007, 11:18 PM   #13
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,867
Total Cats: 1,790
Default

depends....using and FMU or a piggybacy or stand-alone?
Braineack is offline   Reply With Quote
Old 02-13-2007, 11:42 PM   #14
Senior Member
 
Join Date: Dec 2004
Posts: 1,450
Total Cats: -1
Default

Or a combination of two of those options?
bripab007 is offline   Reply With Quote
Old 02-14-2007, 10:31 AM   #15
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

for a FMU and FP i would go with some 265's
For a upgraded ecu either 330's or some 460's which ever you can support.
magnamx-5 is offline   Reply With Quote
Old 02-14-2007, 10:40 AM   #16
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 magnamx-5 View Post
for a FMU and FP i would go with some 265's
For a upgraded ecu either 330's or some 460's which ever you can support.
550s FTMFW
currently 54% max IJDC, probably just north of 200rwhp (and running rich)
Ben is offline   Reply With Quote
Old 02-14-2007, 08:55 PM   #17
Senior Member
 
Join Date: Jan 2007
Location: Maryland
Posts: 701
Total Cats: 0
Default

I dunno, anyone out there taken a look at the Mazdaspeed 3. I'm still trying to crack into the thing for knowledge but if they are not cam controlled (don't see why they would be) and don't require some sort of extra mounting why not use those injectors to handle the extra fuel load. I don't even see how there would be an issue with distribution of fuel between the cylinders.
MX_Eva is offline   Reply With Quote
Old 02-14-2007, 09:04 PM   #18
Elite Member
iTrader: (24)
 
kotomile's Avatar
 
Join Date: Oct 2006
Location: Monterey, CA
Posts: 7,578
Total Cats: 40
Default

SCC wrote a good tech article on the new DISI engine from the 'speed 3,6, and CX7.

What's your question, Eva? How to best increase fuel in a direct-injection system?
kotomile is offline   Reply With Quote
Old 02-14-2007, 11:36 PM   #19
Senior Member
 
Join Date: Mar 2005
Posts: 531
Total Cats: 0
Default

https://www.miataturbo.net/forums/sh...ghlight=max+hp

some additional injector talk in this thread
VRTSid is offline   Reply With Quote
Old 02-14-2007, 11:52 PM   #20
Senior Member
 
Join Date: Dec 2004
Posts: 1,450
Total Cats: -1
Default

You won't be controlling direct-injection injectors anytime soon in your Miata...at least not without a ECU that can process quickly enough and a cam-driven fuel rail pump that can ramp up 1,500+ PSI of pressure.
bripab007 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
WTB MP62 (Hotside) (NB2) Rick02R WTB 3 01-03-2016 08:18 PM
Back to Stock Part Out!! Turbo Parts, MS2 Enhanced 01-05, Suspension, and MOAR! StratoBlue1109 Miata parts for sale/trade 16 10-02-2015 10:39 AM
Time to start learning and play with tuning The Gleas MEGAsquirt 3 10-01-2015 10:30 AM
"Chimney Ethanol" E100 MiataGarage Engine Performance 5 09-30-2015 12:04 AM
1996 Turbo Build Goldwar DIY Turbo Discussion 2 09-29-2015 10:20 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 01:31 PM.