How Would U Improve This Intake - 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 04-02-2008, 01:29 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
How Would U Improve This Intake

this is a custom plenum i came up with for my car really simnple and basic but it works pretty dam good, i picked up 4 inches of vacum at idle when i swaped this on.

the motor this is on is 3.1L in size and is turbo charged


here is what the stock plenum looks like bolted onto the runners,its got a nasty bend in it and the plenum is very small







heres some shots of the sheetmetal plenum i build as u see it eliminates half the bend and has a much larger volume.im just looking for ideas to improve on it now








    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-02-2008, 01:43 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,702
Wiki Edits: 0

Thanks: 17
Thanked 284 Times in 264 Posts
Awesome! I'll probably have to fab up a simmilar intake when I swap genIII 660 heads onto my 2.8L. It doesn't have the best runner length, but it works and works and will probably work rather well for a homemade job. It looks like you went with gen II heads?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-02-2008, 03:08 PM
Member
 
Last photo:
Join Date: Dec 2004
Location: San Antonio, Texas
Age: 50
Posts: 4,021
Wiki Edits: 0

Thanks: 0
Thanked 23 Times in 23 Posts
nice fab work!

I think it would flow better if you made the runners stick up past the floor a little bit.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-02-2008, 07:01 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
actually i have gen2 and gen 3 aluminum heads,but i decided against using them on my turbo motor,plenty of power can be made from the castiron heads if u port them right.

i thought about picking the runners up off the floor but then i thought about it and i would assume that the nice large radiused runner entrys would flow alot more

i ran this manifold last year after some trial and error with it, first the top was to thin and flexed under vacum and boost so it kept splitting the welds, i it now has a thicker top and reinforcments from the floor to top int he middle.
the second issues was getting the motor to idle properly using the stock idle air system on the 2.8 setup did not work to well i had some cyls running way rich,but instead of plumbing the air into the manifold base liek stock i moved it to the plenum and it fixed the idle issues

my only complaint ab9out the manifold was that just off idle responce sucked but it made a huge diff in the mid range to topend speciialy once i cranked up the boost.

right now its all about improving on it if its even possible
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 04-02-2008, 07:17 PM
Jake_Dragon's Avatar
Member
 

Last journal entry: New Carb
Last photo:
Join Date: Jul 2005
Location: Central Florida
Age: 49
Posts: 771
Wiki Edits: 0

Thanks: 2
Thanked 2 Times in 2 Posts
http://www.trueleo.com/intake1.htm
http://www.trueleo.com/images/fiero_frt_qtr_red.JPG

You could go round
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 04-02-2008, 07:20 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 Jake_Dragon
lol do u see the cost on that sucker, i was with a friend who had picked up one of those manifolds used,when he had his car dynoed back to back vs the stock manifold, car lost power withthe truelo

quess i shouldnt say loss more like no gain
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 04-02-2008, 07:25 PM
Jake_Dragon's Avatar
Member
 

Last journal entry: New Carb
Last photo:
Join Date: Jul 2005
Location: Central Florida
Age: 49
Posts: 771
Wiki Edits: 0

Thanks: 2
Thanked 2 Times in 2 Posts
I don't think he really claims large gains, it just moves the HP and TQ around on the RPM range.
I wasn't suggesting you buy one. Just that a round intake would stand up to boost and vacuum better than a flat panel.
Anyway its good to see people thinking and making things better.
Oh and I do think it cost more than I would pay. But like you did I would just make my own, not everyone can do that.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 04-02-2008, 07:27 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
now if i could get my hands on one of the old mechanical injection setups id deff be running that with the turbo

Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 04-02-2008, 07:32 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 Jake_Dragon
I don't think he really claims large gains, it just moves the HP and TQ around on the RPM range.
I wasn't suggesting you buy one. Just that a round intake would stand up to boost and vacuum better than a flat panel.
Anyway its good to see people thinking and making things better.
Oh and I do think it cost more than I would pay. But like you did I would just make my own, not everyone can do that.

ince i put the 2 round braces from floor to roof of the intaker i didnt have any more issues with flex.but yeah the round would stand up to the boost better.i didnt go that route cause that would have involved fabing up new runners
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 04-02-2008, 07:34 PM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: 1999-2001: Getting it on the road
Last photo:
Join Date: Dec 2005
Location: Pittsburgh, PA
Age: 40
Posts: 5,128
Wiki Edits: 16

Thanks: 0
Thanked 2 Times in 2 Posts
I really like it. I'm not too well versed in recommending actual sizes of plenums, but I do know that plenum volume and runner length/size are somewhat critical for best performance. It looks like it might have a tiny mismatch of large plenum and a small, long runner. In a turbo application it means less than in a carbed setup but it can still pay big dividends.

I had a similar plenum fabbed for an Weber-style SBC intake that I was having converted to EFI. I never got it back from the shop because it closed (fortunately I didn't pay him up front) but picture an intake manifold like this:



He fabbed up two logs (flat on the bottom) from thick walled aluminum tubing with pass-through tubes like you have for the bolts. Mine was going to be twin turbo with two TBs. You'd have to make sure there was a tube connecting the two plenums so that boost stayed constant, but at the time the smaller plenum was a better match to my SBC.

I guess what I'm saying is, do some research on plenum size. You might be just right, but it looks a little big to me. If you want to really match it up to the engine, making it the right size might pay off big time.

And I'm totally jealous of your TIG welding skills
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 04-02-2008, 08:56 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,702
Wiki Edits: 0

Thanks: 17
Thanked 284 Times in 264 Posts
plenum volume has more to do with throttle response and high RPM power than anything. Bigger gives you more power and slightly lazier throttle response, but with fuel injection its not a huge deal... runner length, shape, and volume is still HUGE though.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 04-02-2008, 09:56 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
i di dcome across this design/manifold which is actually for this motor,but its made somewere out in Australia.



i was gonna attempt to build one like this but i went with the much simpler one above

as far as plenum volumes and stuff i did a bunch of research when i built this,and mnost stuff pointed at a large plenum short runner, i mamged to shorted the runners 3 inches but that are still to long si it was a bit of a comprimise.though i was able to port the base and runners the full lenght a good deal to open them up some the castings about a 1/4 thick out of the factory


the rpoblem with making the runners shorter is on this motor the fuel rail and injectors bolt under the plenum so there is no real room to shorten them.in irder to shorten them i would have to build a comlete manifold from the ground up,whihc i have since started,but kinda threw off to the side for now
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 04-03-2008, 08:47 AM
Member
 
Last photo:
Join Date: Dec 2004
Location: San Antonio, Texas
Age: 50
Posts: 4,021
Wiki Edits: 0

Thanks: 0
Thanked 23 Times in 23 Posts
I would add some 4 or 5 inch long tubes that turn 90 degree into the center of the chamber. longer runners will increase the low speed torque.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 04-03-2008, 11:19 AM
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 454C10
I would add some 4 or 5 inch long tubes that turn 90 degree into the center of the chamber. longer runners will increase the low speed torque.
im not worried about the low speed tq more or less im worried about making more power,the car is turbocharged and has a 4:10 rear with a 4k stall converter.and when at the track the car leaves the line @ 12 psi -4k+ rpms so low end isnt even an issue

my one thought was to eliminate the bend int he runner all together and make the plenum angled up in the millde so there is no bend in the runner at all. ill draw up a quick picture in a lil bit to show what i mean
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 04-03-2008, 12:17 PM
Buick Hybrid Guy.
 
Last photo:
Join Date: Oct 2006
Location: Indiana
Age: 42
Posts: 255
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
That's a awful lot of effort to put in to a 60deg V6. 2.8/3.1 ect.

Seems like you'd be much better off putting those efforts towards another base engine.

You'd be better running a 3:42 gear in the rear also. That 4:10's going to not allow the engine to load as much and run through the RPM's too quickly.

The intake design from a airflow point of view is fine. Should be similar distribution of air through it. You can hook up a poor man's flow bench:
Meaning..... Hook up a leaf blower to the throttle body there and feel the quantity of air at each port and compair. Baffle the inside to even it out.
Boost tends to do weird stuff in a plenum. The more even you make it the less prone to detonation you'll have.
What's the car been running (ET's/MPH) ?
What are your goals?
~Scott
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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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
Heads and Intake combo black66 Engine 4 07-23-2005 11:33 PM
Need Hood Clearance - Intake ? 68chevelle_ss Engine 6 06-30-2005 08:10 PM
"Dry" Intake Manifold Question bluesman123 Engine 4 02-11-2004 12:12 PM
Dart intake? Brodix or Dart Heads? Slowass72 Engine 3 01-20-2004 04:52 PM
Cam Help black66 Engine 3 05-12-2003 06:15 PM


All times are GMT -6. The time now is 01:34 PM.


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.