Go Back  Miata Turbo Forum - Boost cars, acquire cats. > Performance & Tuning > Engine Performance
Reload this Page >

Supertech "hi flow" vs "standard flow" intake valves

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

Supertech "hi flow" vs "standard flow" intake valves

 
Old 12-04-2009, 06:43 PM
  #1  
Elite Member
Thread Starter
 
Join Date: Jul 2005
Posts: 6,455
Total Cats: 81
Default Supertech "hi flow" vs "standard flow" intake valves

Valves for the Mazda Miata from HorsepowerFreaks

Towards the bottom, note there is a "std flo" and "hi flo" intake valve for the 1.8.

Anyone know the difference?
JasonC SBB is offline  
Old 12-04-2009, 07:16 PM
  #2  
Elite Member
iTrader: (13)
 
Join Date: Nov 2006
Location: Tigard, Oregon
Posts: 3,880
Total Cats: 0
Default

At face value it looks pretty obvious. The diameter is larger on the hi-flow. I'm curious if it might have to do with extra length too.
cueball1 is offline  
Old 12-04-2009, 07:37 PM
  #3  
Elite Member
Thread Starter
 
Join Date: Jul 2005
Posts: 6,455
Total Cats: 81
Default

I did the right thing and called 'em.

Nope, it's not the diameter.

The hi-flow valves have an back-cut face and undercut stem. This is what WE want. The std-flow don't have those, and are used for racing classes which don't allow "modified" valves.

The shorter length stems are an option on the +1 valves, because they tend to sink in the seat; these will typically require shorter stems so that the shims required are close to standard.

BTW they make shim under bucket lifters too. List price $22 each.
JasonC SBB is offline  
Old 12-04-2009, 07:48 PM
  #4  
Elite Member
iTrader: (13)
 
Join Date: Nov 2006
Location: Tigard, Oregon
Posts: 3,880
Total Cats: 0
Default

Originally Posted by JasonC SBB View Post
I did the right thing and called 'em.
.
Novel concept around here! Great information to have.
cueball1 is offline  
Old 12-04-2009, 07:51 PM
  #5  
Ben
Supporting Vendor
iTrader: (33)
 
Ben's Avatar
 
Join Date: Jul 2006
Location: atlanta-ish
Posts: 12,651
Total Cats: 111
Default

High flow valves are back cut. The standard flow valves are stock replacement. You obviously want high flow. They come in a lot of different lengths, I don't know which are correct.
__________________
DIYAutoTune.com Tech Support
10AE-T|BEGi S4|MSPNP-Pro EMS|Enthuza Duals|6UL|Etc
Track Rat|2001|VVT|MS3-Pro EMS|Enthuza|Exocet in Progress

Originally Posted by concealer404 View Post
Buy an MSPNP Pro, you'll feel better.
Ben is offline  
Old 12-04-2009, 10:06 PM
  #6  
Senior Member
iTrader: (12)
 
Join Date: May 2008
Location: Roselle, Illinois
Posts: 849
Total Cats: -34
Default

do you have any picture to explain the difference? i just bought a set of manley +1 valves and i wonder if those are back cut as well?
Hot_Wheels is offline  
Old 12-04-2009, 10:15 PM
  #7  
Elite Member
Thread Starter
 
Join Date: Jul 2005
Posts: 6,455
Total Cats: 81
Default

Back cut


Undercut stem:
JasonC SBB is offline  
Old 12-04-2009, 10:34 PM
  #8  
Elite Member
iTrader: (12)
 
Join Date: Aug 2006
Location: Central-ish VA
Posts: 4,413
Total Cats: 19
Default

22/ea shim under lifters is a ripoff (probably rebranded MMS). You can get those from miataroadster for $200 for a complete set of 16. Then buy 6mm lash caps for a domestic for dirt cheap (<$20) and grind them.
neogenesis2004 is offline  
Old 12-04-2009, 10:45 PM
  #9  
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,098
Total Cats: 368
Default

I prefer the fatter, lower flowing valve because I've seen so many under-cut valves fail that I'm afraid and alone, in the cold.
hustler is offline  
Old 12-04-2009, 11:04 PM
  #10  
Elite Member
Thread Starter
 
Join Date: Jul 2005
Posts: 6,455
Total Cats: 81
Default

Undercut stems are usually not recommended on exhaust valves.

Are the failures you've seen on exhaust valves?
JasonC SBB is offline  
Old 12-04-2009, 11:17 PM
  #11  
y8s
2 Props,3 Dildos,& 1 Cat
iTrader: (8)
 
y8s's Avatar
 
Join Date: Jun 2005
Location: Fake Virginia
Posts: 19,169
Total Cats: 507
Default

it bothers me how long i've had both undercut valves and shim-under buckets sitting in my basement.
y8s is offline  
Old 12-04-2009, 11:17 PM
  #12  
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,098
Total Cats: 368
Default

Originally Posted by JasonC SBB View Post
Undercut stems are usually not recommended on exhaust valves.

Are the failures you've seen on exhaust valves?
I only have generalizations, not hard facts. NEVER let facts get in the way of a good rant!!!
hustler is offline  
Old 12-04-2009, 11:41 PM
  #13  
Elite Member
iTrader: (8)
 
Join Date: Jun 2009
Location: Albany, NY
Posts: 1,470
Total Cats: 4
Default

Originally Posted by hustler View Post
I only have generalizations, not hard facts. NEVER let facts get in the way of a good rant!!!
These valves will decrease spool by 1000 rpm.
webby459 is offline  
Old 12-05-2009, 01:32 AM
  #14  
Elite Member
iTrader: (2)
 
miata2fast's Avatar
 
Join Date: Aug 2009
Location: Dover, FL
Posts: 3,074
Total Cats: 159
Default

Originally Posted by JasonC SBB View Post
Undercut stems are usually not recommended on exhaust valves.

Are the failures you've seen on exhaust valves?

Most serious engines will have undercut exhaust valves. They are very fragile, and usually get bent from careless handling of the cylinder head with cams still installed. I learned that the hard way. I have also gotten brand new valves that were slightly bent from improper shipping.
miata2fast is offline  
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Full_Tilt_Boogie
Build Threads
67
03-16-2019 08:07 PM
stoves
Suspension, Brakes, Drivetrain
5
04-21-2016 03:00 PM
tazswing
Race Prep
20
10-03-2015 11:04 AM
Aroundcorner
Miata parts for sale/trade
2
10-01-2015 03:20 PM
Trent
WTB
2
10-01-2015 12:15 PM


Thread Tools
Search this Thread
Quick Reply: Supertech "hi flow" vs "standard flow" intake valves


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.