LS1TECH - Camaro and Firebird Forum Discussion

Generation III External Engine LS1 | LS6 | Bolt-Ons | Intakes | Exhaust | Ignition | Accessories
Sponsored by:
Sponsored by:

why are the runners on a FAST intake so small??

Thread Tools
 
Search this Thread
 
Old Feb 17, 2012 | 11:13 AM
Share
  #1  
vbls's Avatar
vbls
Thread Starter
TECH Apprentice
iTrader: (17)
 
Joined: Dec 2010
Posts: 398
Likes: 0
From: Virginia Beach
Default why are the runners on a FAST intake so small??
ok i sold my Weiand aluminum intake, it has 27mm runners on it,
i bought the FAST 92, i measured them and they are only at 24mm, even my heads are at about 25mm. why is this? shouldnt they be bigger? should i get the fast ported? and if i do, will the runners be opened up?
Reply
0
Old Feb 17, 2012 | 09:07 PM
Share
  #2  
gMAG's Avatar
gMAG
TECH Junkie
20 Year Member
iTrader: (1)
 
Joined: Mar 2003
Posts: 3,033
Likes: 4
From: CT
Default
It might have more to do with velocity and runner shape (producing volume), than it does size.
I don't know for sure, just my 3 cents.
Reply
0
Old Feb 17, 2012 | 11:16 PM
Share
  #3  
01ssreda4's Avatar
01ssreda4
TECH Senior Member
15 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (96)
 
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Default
Bigger is not always better when it comes to airflow.
Reply
0
Old Feb 18, 2012 | 12:48 AM
Share
  #4  
trans_am7935's Avatar
trans_am7935
TECH Fanatic
15 Year Member
iTrader: (15)
 
Joined: Mar 2009
Posts: 1,453
Likes: 3
From: Glen Burnie, MD
Default
Originally Posted by 01ssreda4
Bigger is not always better when it comes to airflow.
this is what GM thought as well, which is why the Cathedral port heads were all based on high velocity vs pure volume. this is what allows the LS motors to get such great gas mileage. also if you can get the port velocity up, then you can shove the same amount of air in there then with a big port low velocity port.
Reply
0
Old Feb 18, 2012 | 02:15 AM
Share
  #5  
bww3588's Avatar
bww3588
12 Second Club
20 Year Member
iTrader: (49)
 
Joined: Sep 2005
Posts: 8,139
Likes: 10
From: Chillicothe/Lima, Ohio
Default
Port velocity is where it's at. Higher velocity allows more air in over a given duration of valve off seat time. This allows for smaller cams to make more power.
Reply
0
Old Feb 18, 2012 | 03:57 AM
Share
  #6  
jlcustomz's Avatar
jlcustomz
TECH Enthusiast
10 Year Member
Photogenic
Photoriffic
Liked
 
Joined: Nov 2011
Posts: 609
Likes: 6
From: jacksonville,fl
Default
Also i,m prettysure the runners taper to progressively larger away from heads & have a bellmouth inlet to shove more air in .
I,m currently looking intothis subject as i,m planning on making my own intake.
Reply
0
Old Feb 18, 2012 | 08:23 AM
Share
  #7  
vbls's Avatar
vbls
Thread Starter
TECH Apprentice
iTrader: (17)
 
Joined: Dec 2010
Posts: 398
Likes: 0
From: Virginia Beach
Default
so porting wouldnt make much more difference without the heads being ported as well
Reply
0

Trending Topics

Old Feb 18, 2012 | 08:59 AM
Share
  #8  
trans_am7935's Avatar
trans_am7935
TECH Fanatic
15 Year Member
iTrader: (15)
 
Joined: Mar 2009
Posts: 1,453
Likes: 3
From: Glen Burnie, MD
Default
Originally Posted by vbls
so porting wouldnt make much more difference without the heads being ported as well
this is true to an extent. the FAST 90/92 intakes start to fall off after about 270-275cfm, and if you have heads that flow better then that, then porting will benefit them. but yes on an LS1 the FAST intake on ported heads is usually the restriction. porting could bring the stability up to 285-290 or so
Reply
0
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'

 Brett Foote
story-1

Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

 Pouria Savadkouei
story-2

Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

 Verdad Gallardo
story-3

7 Most Reliable High-Performance Engines GM Has Ever Built

 Verdad Gallardo
story-4

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-5

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-6

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-7

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-8

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-9

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
Old Feb 18, 2012 | 09:15 AM
Share
  #9  
vbls's Avatar
vbls
Thread Starter
TECH Apprentice
iTrader: (17)
 
Joined: Dec 2010
Posts: 398
Likes: 0
From: Virginia Beach
Default
ok i have stock heads, so ill wait on the porting
Reply
0
Old Feb 18, 2012 | 09:21 AM
Share
  #10  
trans_am7935's Avatar
trans_am7935
TECH Fanatic
15 Year Member
iTrader: (15)
 
Joined: Mar 2009
Posts: 1,453
Likes: 3
From: Glen Burnie, MD
Default
Originally Posted by vbls
ok i have stock heads, so ill wait on the porting
you will actully see a loss of power down low, or at least a little lack in throttle response under 2000rpm with a FAST and stock heads/cam, i did
Reply
0
Tags
Back to Subforum
Generation III External Engine
View Next Unread
exhaust opinions




Advanced Search

All times are GMT -5. The time now is 01:26 PM.

story-0
6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'

Don't get dad new socks or a grill brush this year.

By Brett Foote | 2026-06-04 18:13:20


VIEW MORE
story-1
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-2
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-3
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-4
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-5
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-6
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-7
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-8
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-9
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE