Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Any benefits to 460s over 550s?

 
Old 10-11-2010, 09:01 AM
  #1  
Junior Member
Thread Starter
iTrader: (7)
 
Join Date: Nov 2006
Location: Makakilo
Posts: 437
Total Cats: 0
Default Any benefits to 460s over 550s?

I can't see myself hitting the horsepower ceiling on the 460s given my goals on my Shanghai 2854. So why even use 550s? I've hoarded a set of each to choose from. I plan on initially going Shanghai turbo, cheapo BEGi-S d/p, DIYPNP, eBAY FMIC, stock exhaust & cat, stock clutch. I'm guessing that might be good for 180 RWHP.

Eventually I will upgrade the exhaust & cat and clutch, where the car will be left alone for its next 30,000 miles/2-4 years. After that possibly pulling the engine but then that's a whole new game and I'll be looking bigger than 550s. So considering that I don't see my setup even hitting 230 RWHP (probably more like 210), in my situation are there any benefits other than a little more headroom to running the 550s? Any benefits to running the 460s?
r808 is offline  
Old 10-11-2010, 09:06 AM
  #2  
Boost Czar
iTrader: (62)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 76,503
Total Cats: 2,305
Default

460s have enough capacity to support 230-250rwhp or so depending on rail pressure, BSFC, and AFRs.

550s have enough capacity to support 275-300rwhp or so depending on rail pressure, BSFC, and AFRs.
Braineack is offline  
Old 10-11-2010, 09:50 AM
  #3  
Want fries with that?
iTrader: (3)
 
Join Date: Oct 2009
Location: Twin Cities, Minnesota
Posts: 2,011
Total Cats: 1
Default

Advantage of 460 over 550: Price.
rider384 is offline  
Old 10-11-2010, 09:53 AM
  #4  
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,790
Total Cats: 683
Default

Originally Posted by r808 View Post
...are there any benefits other than a little more headroom to running the 550s?
90cc.

Seriously, if you have both just put the bigger ones in. The benefit is that you won't have to swap them later when you do turn up the boost.

Go ahead, tell us you won't.
curly is offline  
Old 10-11-2010, 10:58 AM
  #5  
Elite Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Warrington/Birmingham
Posts: 2,641
Total Cats: 41
Default

You'll find it easier to find and maintain a stoich idle with 460's over 550's.

Less of an issue with modern injectors with awesome response times and fab spray patterns, but RX7 injectors are distinctly low tech in comparison.

IMO fit the 460's.
richyvrlimited is offline  
Old 10-11-2010, 11:01 AM
  #6  
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago. (The non-murder part.)
Posts: 29,141
Total Cats: 2,863
Default

Originally Posted by richyvrlimited View Post
You'll find it easier to find and maintain a stoich idle with 460's over 550's.
This.

All else being equal, you should run the smallest injectors available which satisfy your power needs and give you a little bit of headroom. The larger the injector, the shorter the pulsewidth required to deliver the small amounts of fuel needed at idle and light cruise, and the more difficult it becomes to control accurately.
Joe Perez is offline  
Old 10-11-2010, 02:09 PM
  #7  
Elite Member
 
codrus's Avatar
 
Join Date: Mar 2007
Location: Santa Clara, CA
Posts: 4,496
Total Cats: 541
Default

Note that an NB uses a fuel pressure regulator in the tank, which has a higher base pressure than an NA but is not proportional to manifold pressure. At 15 psi of boost you've got a lower fuel pressure than an NA, so the injectors won't support as much power as they will on an NA.

I'm hitting close to the max bandwidth of my 550s at 268 rwhp on my 99.

--Ian
codrus is offline  
Old 10-11-2010, 03:42 PM
  #8  
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 15,296
Total Cats: 2,005
Default

^^ +1, if you are still running the returnless system go with the big ones.
__________________
Trackspeed Engineering
High-Performance Turbo Specialists - Sunnyvale, CA - 650-701-7223 - Email us!
Originally Posted by codrus View Post
Basically I've come over to the camp of "If something is a reliability problem on the track, just ask Andrew and do what he says".
Savington is offline  
Old 10-11-2010, 11:10 PM
  #9  
Junior Member
Thread Starter
iTrader: (7)
 
Join Date: Nov 2006
Location: Makakilo
Posts: 437
Total Cats: 0
Default

Good info. Thanks guys.
r808 is offline  
Old 10-11-2010, 11:26 PM
  #10  
Senior Member
iTrader: (3)
 
Join Date: May 2008
Location: Fargo, ND
Posts: 533
Total Cats: 3
Default

As well, RX-8 injectors flow about 420-440cc from the factory, and are plug in sets. At least on my NB. They will offer smoother idle. Much much newer technology, strays away from the old pintle style injectors. Find some on ebay, they are yellow and/or red, but get a set of either or.

I ran these, 315cc's, and RC550's, and by far the best idle is offered by the RX-8 or OEM MSM injectors vs the older style injectors. Just a much better spray pattern and thus atomization, is my theory.
chance91 is offline  
Old 10-11-2010, 11:54 PM
  #11  
Junior Member
iTrader: (3)
 
Join Date: Aug 2010
Location: Oklahoma City
Posts: 73
Total Cats: 1
Default

The newer style injectors seem to deal with E85 a little better, too.

..but then again, if you are looking at ethanol fuels you'd probably be looking at the bigger injectors anyway.
LowFlyin' is offline  
Old 10-12-2010, 12:49 AM
  #12  
VladiTuned
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 35,186
Total Cats: 3,166
Default

probably? lol

on e85 he'd be looking at about 8-10 psi max before they'd be maxed out lol
18psi is offline  
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
StratoBlue1109
Miata parts for sale/trade
21
09-30-2018 01:09 PM
patsmx5
General Miata Chat
46
06-06-2016 10:27 AM
The Gleas
MEGAsquirt
3
10-01-2015 09:30 AM
xmacmiatax
ECUs and Tuning
0
09-08-2015 04:17 PM
zoom2zoom
Prefabbed Turbo Kits
10
01-12-2007 07:13 PM


Thread Tools
Search this Thread
Quick Reply: Any benefits to 460s over 550s?


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 Amazon.com and affiliated sites.