Building A New Custom Intake Manifold - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 06-16-2008, 05:30 PM
Registered User
 
Last photo:
Join Date: Oct 2007
Location: new jersey
Posts: 80
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Building A New Custom Intake Manifold

well i had build a custom upper plenum for my turbocharged v6 motor in my camaro and it did wonders for power,its shortened the 19inch long runners to 15 inches and got rid of a huge nasty 187* bend in the runner.not to mention the plenum volume was tripped.

well i think i can improve the whole intake system a whole lot further and ive got a few ides,but im unsure of a few things

first off i plan on cutting out the remaining 53* bend in the runners and shortening the overall runner length to 8 inches down from 15.

problem
i will lose my port injectors, injectors instead of being at the ends of the intake runners will be moved about 4 inches away from the cyl head port entrance
now would i be better off forgetting the port injection and going with a 4barrel tbi setup or dual 2 barrel tbi instead or just move the injectors

heres some pics of the complete stock assembly.



now the middle and upper sections will be scraped and i will be left with the base



what im going to do is extend the runners up vertical 4 inches and build a plenum on the top of them

heres the general idea of what im gonna do to the base


now would i be better off putting the injectors mid runner,at the runner entrance pointed in on an angle? or just putting them 80* to the port at the end of the intake runner?

on the stock manifold they lay over about 45* from straight up and down

    Advertisement

Last edited by Boosted89RS; 06-16-2008 at 05:40 PM.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-16-2008, 09:12 PM
KA67_72's Avatar
Member
 
Last photo:
Join Date: Jan 2003
Location: Knoxville, Tn
Posts: 313
Wiki Edits: 0

Thanks: 1
Thanked 4 Times in 4 Posts
How many RPM are you turning? Is this for race only use? I'd think you'd want to keep the runners long to spool the turbo early and rely on boost for the top end.

Kevin
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-16-2008, 09:36 PM
OneMoreTime's Avatar
Hotrodders.com moderator
 
Last wiki edit: Health and safety in the shop or garage
Last journal entry: Yard Dog pic
Last photo:
Join Date: Jul 2004
Location: Washington State
Age: 70
Posts: 7,520
Wiki Edits: 3

Thanks: 81
Thanked 173 Times in 161 Posts
I would just put them at the ports..If you have gotten this far welding and drilling a boss to install the injectors should not be that hard..The 45 degree layover on the stocker may have something to do with packaging..

Sam
__________________
I have tried most all of it and now do what is known to work..
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-16-2008, 09:50 PM
Registered User
 
Last photo:
Join Date: Oct 2007
Location: new jersey
Posts: 80
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by KA67_72
How many RPM are you turning? Is this for race only use? I'd think you'd want to keep the runners long to spool the turbo early and rely on boost for the top end.

Kevin
7,500 rpm when its said and done(im limited right now to 6,200-6500 due to to small of an ex housing on my turbo), this is a street strip car with emphasis on strip. this isnt something i need to daily drive but do.
on the street yes the long runner would be better,but the stock manifold actually flows less cfm then the cyl heads stock,granted under boost this changes but it is still a big restriction.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-16-2008, 09:54 PM
Registered User
 
Last photo:
Join Date: Oct 2007
Location: new jersey
Posts: 80
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by OneMoreTime
I would just put them at the ports..If you have gotten this far welding and drilling a boss to install the injectors should not be that hard..The 45 degree layover on the stocker may have something to do with packaging..

Sam
i was concerned over changing the angle because of the spray pattern, at the stock angle the injector sprays dead center of the port and at the back of the valve.if i change this angle im unsure of what adverse affects it could have if any, i was hoping someone here could shed some light on that.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-17-2008, 05:32 PM
Member
 
Last photo:
Join Date: Nov 2002
Posts: 493
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
I'm thinkin I would look into an intake off an early to mid 90's Camaro with the SFI 3.4. Looks to me that it would flow allot better than any other 60* Chevy intake I've ever seen....Dan
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-17-2008, 06:28 PM
Registered User
 
Last photo:
Join Date: Oct 2007
Location: new jersey
Posts: 80
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Ohio-Dan
I'm thinkin I would look into an intake off an early to mid 90's Camaro with the SFI 3.4. Looks to me that it would flow allot better than any other 60* Chevy intake I've ever seen....Dan
the 93-94 3.4 sfi camaro intake offers minimal flow improvements,its the same exact base with basically the same mid section,and a different plenum.

pretty way the only way to go with one of the motors is completely custom, or if u can find n old hilborn setup and convert it to efi. would would be fine on an n/a motor but will make for a plumbing nightmare on a forced induction motor
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 06-17-2008, 07:51 PM
Stroke Meister
 
Last photo:
Join Date: Mar 2007
Location: MI, USA
Posts: 703
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
How are you determining total runner length? Check this out for an idea of what I'm asking
Quote:
SOURCE : Swartz Racing Manifolds Tech Page

Technical:

Runner length

Many customers ask for assistance to determine runner length for their manifold. Many others have a number in mind when they call because they have a baseline from a previous manifold. To help you plan your first attempt or verify your next test, I compiled the following graph. It is compiled from popular formulas, personal experience, and feedback from customers.The above graph tends to be more aggressive than conservative. If you have a stick-shift car, it is very close. Automatics tend to need more runner length to accommodate the converter stall and recovery from wider gear changes.

To measure your intake port length, use a length of electrical solder. Straighten the solder and lay it in the port along the floor. Mark it at the valve seat and the manifold gasket face. Straighten it back out and measure between the marks. Repeat for the roof, positioning the solder next to the valve guide. The average of the two measurements is your port length. A tape measure can also be used instead of solder.

Use the same method to measure the manifold runner length, but dont wrap the solder or tape measure around the plenum radius. Just extend it tangent to the runner wall, and measure to a straight-edge running across the top of the runners. Most engine builders use the average of the front and back walls of the runner, but some use the floor and roof. It is common to have two or more different runner lengths in a manifold. If so, use an average length for the next calculation.

Add the average runner length, average port length, and manifold gasket thickness, and you have the total intake tract length.

Example: You have an engine with a 6.25 inch average port length. You want the engine to operate between 8500 and 9500 RPM. From the graph above, you need a total intake tract length of about 10.5. That leaves 4.25 for the runner length and gasket. With a 0.06 gasket, the average runner length should be 4.19.

Runner taper

I quantify runner taper by comparing the cross-sectional area of the intake port (at the gasket) versus the area at the plenum opening of the runner (not including the entry fillet). This is expressed as a percentage of increase in area. I calculate the area at the intake gasket, and then I add the percentage required by the application to determine the runner entry area. Since most applications have round plenum openings, I simply convert the opening area back to the diameter of the required circle.

Obviously, the key is to know what percentage is needed for your application. Several factors seem to be important to determine this number. I cant quantify the impact of these factors, as every engine combination is different. Camshaft events alone can severely affect how taper is tolerated. I can give you the following relative guidelines to determine where to start:
  • Most drag racing manifolds require between 25% and 45% increase in area. There are applications that go beyond these limits, but this is rare.
  • Engines that are built on production platforms tend to like about 30% increase in area. Im referring to the typical bore/stroke/rod ratios derived from OEM engines. As bore/stroke ratios approach 1:1, the increase in area is likely to be 25% or less.
  • Race engine platforms with large bores and short strokes like higher percentages 35-45%.
  • Short deck engines (and resulting rod/stroke ratios) tend to want more taper. The piston motion of a short rod combination will create adequate port velocity in large runners.
  • Stick-shift applications tolerate more taper than automatics.

These guidelines should help you narrow down your taper requirements within a range of a few percent. The combinations are so varied, even within the same class of racing, that set numbers and fixed rules are difficult to derive. My goal is to minimize your testing iterations required to find the best performance.
I've been messing with some 'stuff' too... just a little different.



I am not a compensated endorser/agent/seller of any known product.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 06-19-2008, 09:29 PM
Registered User
 
Last photo:
Join Date: Oct 2007
Location: new jersey
Posts: 80
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Stroke
How are you determining total runner length? Check this out for an idea of what I'm asking

I've been messing with some 'stuff' too... just a little different.



I am not a compensated endorser/agent/seller of any known product.
yeah ive seen the formulas and stuff and to be honest alot of it confuses me.

but i was under the impression that once u throw boost into the mix that the formulas for runner length and volume typically get thrown out the window

everything ive done with this car has been trial and error, i enjoy messing with it,keeps it fun.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Building A 302 Chevy Scorpio Shaping Flow Hotrodding Basics 6 01-16-2007 06:55 AM
Question about intake manifold distrobution for Nitrous experts... sizemoremk Engine 5 04-30-2005 12:16 AM
Replacing Intake Manifold Questions RObs71Nova Engine 1 01-21-2005 11:37 PM
Which intake manifold? WakBordr7387 Engine 13 12-10-2004 08:47 AM
Spacer between carb and intake manifold?... doc_rage Hotrodding Basics 2 02-06-2004 08:40 PM


All times are GMT -6. The time now is 07:13 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.