Will my exhaust be too small? - 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 10-14-2009, 07:11 AM
6426yy's Avatar
Member
 
Last photo:
Join Date: Nov 2003
Location: Macomb Il.
Age: 34
Posts: 536
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
Will my exhaust be too small?

+.030 454 Hyperuetectic pop up pistons 9.3:1, Large oval ports 781 mild cleanup, comp cams 4x4 extreme 270, weiand stealth intake with 750 Holley. 1 3/4 full lenght headers.

My truck has true duals with 2 1/4 pipe and Flowmasters; yeah I know they suck, all the more reason to change. Is it going to choke it?

Thanks

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 10-14-2009, 07:52 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 think so. dual 2-1/2 would be the minimum for a mild/moderate 454.

you are looking at maybe 425hp/550 ftlbs with that setup.

dual 2-1/4's would max out at 400hp if it was made with mandrel bent pipe and not run all the way out the back.

I would use an x-pipe after the transmission and dual dynomax super turbos (20 inch case). Then if it still is too loud, then put on some dynomax bullets on the ends.

I would use 2-1/2 inch with mandrel bent pipe or 3 inch with crushed bent pipe.

I build my own exhaust systems using mandrel bent J-pipes from summit racing. It isn't that hard. got a welder?

I hope you are using an oil additive with your cam. www.zdpplus.com
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 10-14-2009, 10:46 AM
Registered User
 
Join Date: Feb 2007
Location: Southeast Missouri
Posts: 121
Wiki Edits: 0

Thanks: 2
Thanked 0 Times in 0 Posts
I actually don't think 2 1/4 is gonna choke the motor very bad. It may a little bit but think about it. You have 2 1/4in for both halves of the engine.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 10-14-2009, 03:40 PM
Jim Rockford's Avatar
World Famous VF-14
 

Last journal entry: Cleaned it up...
Last photo:
Join Date: Dec 2008
Location: Virginia
Age: 42
Posts: 411
Wiki Edits: 0

Thanks: 10
Thanked 0 Times in 0 Posts
2 1/2 is mandatory , even on a mild small block.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 10-14-2009, 05:47 PM
Member
 
Last photo:
Join Date: Feb 2005
Location: chillicothe oh
Age: 47
Posts: 1,445
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
each header tube is 1.75 stuffing the output from 4 of them into a pipe 2.25 ain't gonna get it done. 2.5 minimum 3. better.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 10-14-2009, 06:41 PM
OLNOLAN's Avatar
Registered User
 
Last photo:
Join Date: Apr 2009
Location: Louisiana
Posts: 1,036
Wiki Edits: 0

Thanks: 249
Thanked 77 Times in 67 Posts
Needs More

Hey YY, I like real exhaust on my cars, but not too loud. My way of thinking on your setup is a 1.75 primary tube doubled in size quads the flow. So a 3.5 pipe can match the flow of all four header tubes. Yep, thats big pipe. With this size pipe however you get some wall turbulent flow with laminar flow in the middle of the stream. But if you decrease the size of the pipe slightly you increase the velocity and get more laminar flow which sort of creates a suction to help scavenge exhaust gas out. More cubic inches creates a bigger pump, you gotta get it out before you can get more in. Smaller cubic inch engines don't need as big a pipe, in other words 1.75 headers on a 350 ci engine might need a smaller tail pipe to keep the velocity up to help scavenge the smaller pump. Now mind you they have folks around that understand flow and physics way over my head, but this is my way of thinking. Bottom line, your headers are scavenging pretty good cause they are kinda small. 3" pipe into muffler, 2.75" out is about perfect in my book for your 454. Cross over pipes are supposed to boost midrange cause it balances the exhaust pulsations from both sides of the engine and makes both banks of the engine work(pump) more efficiently as in together, I don't really understand the hows on this, just know it works. This is probably a good topic to bring up now and then cause some have exhaust way too small and sometimes way too big. Food for thought. olnolan
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 10-14-2009, 07:09 PM
Registered User
 
Join Date: Feb 2007
Location: Southeast Missouri
Posts: 121
Wiki Edits: 0

Thanks: 2
Thanked 0 Times in 0 Posts
3 inch true duals? Sorry that's way more than a mild 454 will need. I would bump it up to 2 1/2 true duals tho.

Last edited by GunnerTHB; 10-14-2009 at 07:14 PM.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 10-14-2009, 07:31 PM
chevy1500z71's Avatar
Registered User
 
Last photo:
Join Date: Jan 2009
Location: florida
Posts: 225
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
iv always figured on running 1.75x the primary size. in your case thats about 3". im running 2 and 1/4s on my small block and i really want to change my exhaust to 2.5" setup, one thats not 5 miles long either, truck exhaust systems have a tendency to get ridiculously long when you try and run the tips out the back. id prefer dumped under the bed or out in front of the tire.

iv been using zddplus with my motor as well. if youv got a local atv shop around you should try running motorcycle/atv oil, its got tons of zddp, summits new line of high zddp oil is just repackaged spectro motorcycle oil.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 10-15-2009, 05:56 AM
6426yy's Avatar
Member
 
Last photo:
Join Date: Nov 2003
Location: Macomb Il.
Age: 34
Posts: 536
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
Thank for the replies guys, as far as the ZDDP, yes I'm running that with Rotella oil. The engine was already broke in but I pulled the heads off of it to clean them up, cut for positive seals, set the spring height and install thinner head gaskets. I planned on going 3" with an x pipe and the tips coming out in front of the tires. I don't like the droan when dumped under the bed. I just hope my TH350 will hold up!!
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 10-15-2009, 09:41 AM
chevy1500z71's Avatar
Registered User
 
Last photo:
Join Date: Jan 2009
Location: florida
Posts: 225
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 6426yy
Thank for the replies guys, as far as the ZDDP, yes I'm running that with Rotella oil. The engine was already broke in but I pulled the heads off of it to clean them up, cut for positive seals, set the spring height and install thinner head gaskets. I planned on going 3" with an x pipe and the tips coming out in front of the tires. I don't like the droan when dumped under the bed. I just hope my TH350 will hold up!!
im running a 4l60e behind about 525hp and its doin ok...
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 10-15-2009, 10:27 AM
Exhaust Magician
 
Join Date: Aug 2009
Location: Sacramento,CA
Posts: 44
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 6426yy
+.030 454 Hyperuetectic pop up pistons 9.3:1, Large oval ports 781 mild cleanup, comp cams 4x4 extreme 270, weiand stealth intake with 750 Holley. 1 3/4 full lenght headers.

My truck has true duals with 2 1/4 pipe and Flowmasters; yeah I know they suck, all the more reason to change. Is it going to choke it?

Thanks
I would definitely bump the tubing size up to 2.5" (At minimum from the headers to the mufflers). But, It all depends on the driving you will do with the vehicle. If you plan on getting some rpm out of it I would reccommend going a size larger on the pipe. If you're not on a budget I would reccomend going 3" from the headers to the mufflers then 2.5" for your tailpipes. I know that not everybody is keen to Flowmaster mufflers, but they're not as restrictive as they're made out to be. I ran a 3" SINGLE EXHAUST with a Flowmaster Super 40 on my '94 Z28 and it put down 409rwhp on a dynojet. So, they must flow pretty good.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 10-15-2009, 04:03 PM
Jim Rockford's Avatar
World Famous VF-14
 

Last journal entry: Cleaned it up...
Last photo:
Join Date: Dec 2008
Location: Virginia
Age: 42
Posts: 411
Wiki Edits: 0

Thanks: 10
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by bowtieCYRUS
. I know that not everybody is keen to Flowmaster mufflers, but they're not as restrictive as they're made out to be. I ran a 3" SINGLE EXHAUST with a Flowmaster Super 40 on my '94 Z28 and it put down 409rwhp on a dynojet. So, they must flow pretty good.
flows are junk, imagine how much more you could have made.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 10-15-2009, 06:02 PM
Exhaust Magician
 
Join Date: Aug 2009
Location: Sacramento,CA
Posts: 44
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Jim Rockford
flows are junk, imagine how much more you could have made.
I beg to differ. The first time I had the car tuned I had a Dynomax Ultra Flo welded muffler. If I remember correctly it made 411rwhp around 7000rpm and 380ish ft/lbs torque at around 3800rpm. Then I tried the Super 40 and had it tuned again with a new computer in the vehicle and it made 409rwhp at 6800rpm and 390ft/lbs torque at 3400rpm. The car has a 3500 stall in it and runs 12.7's at 120ish mph with a 2.2-2.3sec 60' (no traction). I don't think the 2 or 3 hp in my case was worth the 10+ft/lb loss.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 10-15-2009, 07:31 PM
chevy1500z71's Avatar
Registered User
 
Last photo:
Join Date: Jan 2009
Location: florida
Posts: 225
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
you guys should read this article, very informative.
http://www.superchevy.com/technical/...xh/index1.html

the whole muffler argument is stupid, flowmasters are fine, as youl read in the article above, you only need 2.2cfm per hp roughly to have near 0 back pressure, a set of flowmaster 40s of adequate size could easily flow enough cfm to support as much hp as you wanted to make. look for some cfm flow rating before you sit and argue what muffler is better.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 10-15-2009, 08:48 PM
Exhaust Magician
 
Join Date: Aug 2009
Location: Sacramento,CA
Posts: 44
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by chevy1500z71
you guys should read this article, very informative.
http://www.superchevy.com/technical/...xh/index1.html

the whole muffler argument is stupid, flowmasters are fine, as youl read in the article above, you only need 2.2cfm per hp roughly to have near 0 back pressure, a set of flowmaster 40s of adequate size could easily flow enough cfm to support as much hp as you wanted to make. look for some cfm flow rating before you sit and argue what muffler is better.
Thanks for the link. I manage a custom exhaust shop in California, and I've seen about all one person could possibly see regarding exhaust. But, that article brought up some very good topics. As a sidenote, I wasn't trying to argue with anyone. I was essentially trying to say the same thing that the article said, just not nearly as technical. lol. IMO most mufflers in the aftermarket realm will be suitable for most street cars, whether it be Magnaflow, Dynomax, Flowmaster, etc.
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
Exhaust tips CrazyRoyExhaustfreak Engine 0 10-29-2006 06:04 PM
Exhaust question for super/turbo members jameskirk1 Engine 7 08-18-2005 06:58 PM
Exhaust formulas vs. computer programs Mean Dean Introduce Yourself 1 07-13-2004 12:26 PM
400 small block 79 Malibu327 Engine 9 03-27-2004 07:19 AM
Cam Help black66 Engine 3 05-12-2003 06:15 PM


All times are GMT -6. The time now is 02:03 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.